OPEN WAVEGUIDE ANTENNA AND SYSTEM HAVING AN OPEN WAVEGUIDE ANTENNA - Patent application

Abstract

The waveguide antenna system includes an electromagnetic (EM) transition portion having a transition region with a signal feed interface and an open waveguide section, the EM transition portion configured to couple EM energy from the signal feed interface through the transition region to a guided waveguide mode of the EM energy into the open waveguide section, and a leaky waveguide antenna portion configured and arranged to radiate electromagnetic energy received from the open waveguide section, the EM transition portion being electromagnetically coupled to the leaky waveguide antenna portion, the EM transition portion being configured to support transfer of electromagnetic energy from the signal feed structure to the leaky waveguide antenna portion.

Description

[Technical field]

[0001] The present disclosure relates generally to open waveguide antennas, and more particularly to open waveguide antenna systems. [Background technology]

[0002] Previous generations of mmWave systems have been built utilizing several dedicated MMIC (monolithic microwave integrated circuit) devices, which typically include a transmitter integrated circuit, a receiver integrated circuit, and a local oscillator circuit to synchronize these systems with each other. An example of this configuration is the Continental ARS-4A long-range radar sensor, an example of which can be found in "Radar Sensors for Radio Frequency Isolation (RFI)", IEEE Transactions on Radio Frequency Isolation (RFIR), vol. 13, no. 1, pp. 1111-1125, 2002. The distributed nature of the transmitter and receiver MMICs in these systems allows the distance between the radiator and the MMIC to be reduced, resulting in acceptable insertion loss despite the electrically large antenna aperture produced by the radar. Recently, CMOS MMIC devices have become available that combine TX and RX functions into a single chip. From a cost perspective, these systems are advantageous, reducing die costs as well as assembly and manufacturing costs for the radar manufacturer. This has the effect of centralizing the MMIC and increasing the transmission line distance between the antenna and the MMIC. In addition to this, this centralization reduces the complexity of RF signal routing between the devices.

[0003] The twin trends of longer transmission lines and reduced complexity of routed signals have made alternative methods of connecting antennas to MMICs more attractive. A common RF interconnect method is to use etched traces on a printed circuit board. This transmission line structure is typically microstrip (signal layer separated from ground by a dielectric) or coplanar waveguide (microstrip with a ground structure next to the trace on the signal layer). This type of transmission line exhibits an insertion loss of about 1 dB per inch at 79 GHz when fabricated on "best in class" PCB materials, and 2 dB per inch when fabricated on typical PCB materials.

[0004] As MMICs become more and more integrated and the number of routed RF transmission lines on a PCB decreases, older transmission structures are becoming more applicable. Waveguides were theoretically studied in the 1890s and employed in practice since the 1940s. At 79 GHz, rectangular waveguides exhibit an insertion loss of about 0.25 dB per inch. When applied to a 3 inch long transmission line, in practice, a 79 GHz system will lose 50% of its power in a microstrip line built on the best laminates, 75% of its power on a typical PCB, but only about 16% of its power in a waveguide. In a radar system, this difference in loss is seen both from the MMIC transmitter block to the antenna and from the antenna to the MMIC receiver block. Thus, the "two-way" loss is twice the loss figure above. This makes the loss reduction even more attractive to radar system designers.

[0005] For designers using waveguide feed networks in mmWave radar or communications systems, there are three additional considerations that determine the system architecture and performance: first, how to transfer power from the MMIC to the waveguide (transition), second, how to transfer power from the waveguide to free space (antenna), and finally, in most systems, cost is an important consideration in addition to system performance.

[0006] Two primary methods have been described for transferring power between the MMIC and the waveguide. The first transition approach is to utilize a package-to-printed circuit board transition. This transition often includes several sub-transitions. First, power is transferred from the semiconductor die to a fan-out or redistribution layer in the device package, and then the power is transferred from the redistribution layer to the printed circuit board through a ground signal ground (GSG) configuration, typically implemented in a ball grid array. The signal / power is then routed through a grounded coplanar waveguide structure, transitioned to a microstrip structure, and then excites a radiator that is used to launch into the waveguide. This approach has the advantage of utilizing well-established technology, but also has the following disadvantages: (i) the need to create a controlled impedance structure on the host printed circuit board, (ii) the cost and supply chain complexity of utilizing low-loss PCB material on the host printed circuit board, and (iii) multiple sets of transition losses. In MMIC-to-RDL, RDL-to-BGA, BGA-to-PCB, PCB-to-waveguide, these transition losses partially negate the advantage of utilizing the waveguide, especially for short transmission line lengths.

[0007] The second proposed transition approach is to launch directly from the package to the waveguide. An exemplary description of this approach is provided on page 30 of the following document: Non-Patent Document 2. This approach negates the following shortcomings of the first approach: (i) the need to create a controlled impedance structure on the host printed circuit board, (ii) the cost and supply chain complexity of utilizing low-loss PCB materials on the host printed circuit board, and (iii) the net reduction in transition losses, i.e., from BGA to PCB. The reduction in PCB cost and supply chain complexity is expected to be attractive to developers of millimeter wave radar and communication systems.

[0008] In the design of a millimeter wave radar or communication system, the selection and design of the antenna is an important consideration. In radar systems, there are two main use cases. First, radar systems intended to operate over long distances, and second, radar systems required to operate over shorter distances, but with a wider coverage area. In the field of automotive sensors, these are typically referred to as long-range radars utilized for functions such as adaptive cruise control, and corner or short-range radars used for functions such as blind spot detection, lane change assist, or parking assist.

[0009] The long-range radar is typically expected to cover the lane in front or behind the vehicle. The corner radar is used to supplement the coverage of the long-range radar with the goal of providing 360-degree coverage around the vehicle. It is also desirable to have redundancy in coverage, and thus the corner radar typically seeks to cover a 120-degree azimuth field of view, while the long-range radar may typically cover a 60-90-degree azimuth field of view. For reference, the elevation plane is typically oriented in the direction of the vehicle's height, while the azimuth plane is perpendicular to the elevation plane. If the vehicle is expected to operate at a higher level of autonomy, e.g., SAE Level 3 or Level 4 autonomy, the vehicle may also use a mid-range radar that operates with an azimuth coverage between the corner radar and the long-range radar. For the sake of total vehicle ownership cost, it is also desirable to manufacture a corner radar with an extended range, thereby eliminating the need for a mid-range radar.

[0010] Antenna architectures are typically selected first for their field of view and then for their bandwidth, but the type of antenna also depends on the type of antenna feed. In printed circuit board based feed networks, the antenna is also typically formed on the PCB, and in waveguide structures, it is desirable to use a construction method similar to how the waveguide is produced. Polarization is another consideration that designers use when selecting an antenna. Finally, sidelobe levels are important in many radar and communication systems. For long range radar antennas, where the field of view (related to the azimuth half power beamwidth of the antenna) is smaller, series fed microstrip patch antennas are typically used. Parallel series feed lines can be used to further reduce the field of view and increase the gain of the antenna and subsequently the range of the radar system.

[0011] To achieve a wide field of view, either comb-line (sometimes called side-fed patch) antennas or slot antennas are typically used. Substrate integrated waveguide (SIW) plus slot antennas can also be used with printed circuit board feed networks. Slot antennas typically offer some of the widest fields of view, but introduce additional PCB manufacturing complexities.

[0012] Two basic antenna types are most frequently used in waveguide-based feed networks. In high-gain applications, a waveguide feed horn is typically used. It can provide both high gain and wide bandwidth (>15% fractional bandwidth). In wide-field applications, a slot antenna is often used. A slot antenna formed in an air-metal waveguide exhibits a larger bandwidth than its counterpart from a substrate-integrated waveguide, but less than desired (e.g., 2 GHz at 79 GHz when 4-5 GHz is desired).

[0013] Bandwidth requirements are highly application dependent. In a Doppler effect radar system, two main advantages can be gained from a wide bandwidth (e.g., 4-5 GHz): (i) a wide fractional bandwidth can be utilized to provide high range resolution (proportional to the speed of light divided by the bandwidth), i.e., a 4 GHz bandwidth provides 3.5 cm range resolution. This is most desirable when the radar is detecting objects close to the sensor. For example, when performing parking assistance, whether a car is 1 meter or 1.05 meters away is important information, but when performing adaptive cruise control, whether a car is 200 meters or 200.05 meters away is not important, and (ii) a wide fractional bandwidth can also be used so that the radar system uses a smaller instantaneous bandwidth (i.e., 500 Mhz) but provides the ability to switch frequencies within that wider fractional bandwidth to avoid interference. Corner or short range radars provide wider angular coverage and are therefore more susceptible to interference from adjacent vehicles. In addition to this, the number of vehicles on the road using corner radar is constantly increasing, so the interference problem is constantly getting worse.

[0014] In summary, in the field of waveguide-fed antennas applied to radar, narrow field-of-view antennas can be produced with wide bandwidths, but the wide bandwidth is not a critical feature for radar applications. In applications where large (wide) bandwidth is important, the narrow field of view of horn antennas is undesirable. Thus, in the field of waveguide-fed radar antennas, a performance gap exists that provides value to the market, but currently does not allow the combination of wide fractional bandwidth (e.g., 4-5 GHz at 79 GHz) and wide field of view (e.g., half-power azimuth beamwidth of 120 degrees) to be cost-effectively achieved.

[0015] Rogers Corporation has developed technology to address the antenna problem, a specific embodiment of a dielectric resonator antenna. The dielectric resonator antenna invented by Rogers Corporation offers a combination of wide field of view and wide bandwidth desirable for corner radar applications. However, to date, it has been utilized with PCB-based substrate integrated waveguide feed networks, which have the above-mentioned problems with insertion loss between the MMIC and the antenna. While it is certainly possible and in some cases desirable to combine a dielectric resonator antenna with a waveguide feed network, the added cost of both systems may preclude its use from some high volume applications. Thus, there exists an unmet need for a waveguide-fed wide field of view, wide bandwidth antenna that can be acquired at a price competitive with a waveguide plus slot antenna alone.

[0016] While the above background focuses on automotive radar, one can envision scenarios where these requirements translate to non-automotive applications; for example, a radar utilized in a factory automation scenario (at 60Ghz) could experience a similar set of challenges.

[0017] With regard to waveguide manufacturing, there are two primary approaches utilized today to produce waveguides plus antennas for high volume radar applications: (i) multi-layer molded conventional waveguides, and (ii) bandgap waveguides. Evaluating the relative merits of both systems is a major challenge when comparing the complexity, and therefore cost.

[0018] Conventional waveguides are formed by molding multiple layers of plastic, metallizing the layers, and bonding the layers together with a conductive adhesive, or by another method that provides a consistent and reliable electrical connection from one layer to another. An example of such a laminate can be found in U.S. Pat. No. 5,399,433. The complexity of this system comes from the number of metallized plastic layers (up to seven for complex structures, two to three for simple structures) and the need to bond the layers with a robust electrical connection between the layers.

[0019] Bandgap waveguides utilize a special structure to form the inner wall of the waveguide. This is called an "electromagnetic bandgap structure" or an "artificial magnetic conductor". The main advantage of this structure is that a strong electrical connection between the top and bottom of the waveguide is not required in this structure, reducing the complexity of the waveguide assembly. This advantage has been shown to have market value.

[0020] However, this structure can introduce some additional complexity in the molding tolerance requirements, with a typical structure requiring four metal layers. The manufacturing complexity increases nonlinearly as the number of layers in the structure increases, and the cost of materials also increases with the number of metal layers. Thus, there is an unmet need in the market for a solution that: (i) provides a feed network that can be excited from an antenna-in-package, or similar MMIC package excitation; (ii) provides low insertion loss, e.g., 0.25-0.5 dB / in at 79 GHz; (iii) has the ability to be manufactured with minimal cost and complexity; (iv) has the potential to provide an antenna solution that provides a wide field of view and wide bandwidth, e.g., 5 GHz bandwidth with a half-power beamwidth of 120 degrees, and a center frequency of 78.5 GHz; (v) alternatively, a system that provides the first three points at reduced cost and complexity, and optionally high gain with wide bandwidth that is desirable for other applications such as long-range radar; and (vi) can be excited from a PCB. or a feed network that can form an antenna-in-package or similar MMIC excitation; (vii) low insertion loss, e.g., 0.25-0.5 dB / in at 79 GHz; (viii) the ability to be manufactured with only one metallized layer, and potentially one dielectric layer (optionally just metallized plastic, or in a preferred embodiment dielectric); (ix) an antenna that provides a solution providing a wide field of view and wide bandwidth, e.g., 5 GHz bandwidth with a half-power beamwidth of 120 degrees, and a center frequency of 78.5 GHz; (x) a system that can alternatively provide high gain and optionally wide bandwidth.

[0021] Some dielectric resonator antennas can be tuned to a desired pattern over a wide bandwidth, but when incorporated into an antenna system have a substantial loss of gain due to losses in the required feed structure and transitions. Some shaped conventional waveguide antennas can be incorporated into antenna systems that minimize losses in the feed and transitions for high gain, but these offer a smaller usable bandwidth (i.e., <3 GHz).

[0022] While existing antennas may be suitable for their intended purposes, there remains a need for a pattern-tunable high-gain antenna system (with minimal feed and transition losses) that can be tuned for high gain with controlled geometry of the antenna pattern versus angle over wide bandwidths (i.e., ≧4 GHz) up to the millimeter wave frequency band.

[0023] The following publications may be considered as useful background art: US Pat. No. 5,399,623, US Pat. No. 5,499,633, US Pat. No. 5,499,623 and US Pat. No. 5,523,633. [Prior art documents] [Patent documents]

[0024] [Patent Document 1] US Patent Application Publication No. 2020 / 313304 [Patent Document 2] U.S. Patent No. 3015100 [Patent Document 3] U.S. Patent No. 6,043,787 [Patent Document 4] US Patent Application Publication No. 2020 / 313304 [Non-patent literature]

[0025] [Non-Patent Document 1] internet<URL:http: / / img009.hc360.cn / k2 / M0A / BF / 43 / wKhQxVq53tuEEmCQAAAAACS5hks768.pdf.> [Non-Patent Document 2] internet <URL:https: / / www.ipcei-me.eu / wp-content / uploads / 2020 / 11 / 4-Pack-Trends-for-mm-wave-Radar-Infineon-Maciej-Wojnowski.pdf.> Summary of the Invention

[0026] An embodiment comprises an open waveguide antenna as defined by the attached independent claim. Further advantageous modifications of the open waveguide antenna are defined by the attached dependent claims. One embodiment includes a waveguide antenna system comprising: an electromagnetic (EM) transition portion comprising a transition region having a signal feed interface and an open waveguide section, the EM transition portion configured to couple EM energy from the signal feed interface through the transition region to the open waveguide section for guided waveguide modes of EM energy; and a leaky waveguide antenna portion configured and arranged to radiate electromagnetic energy received from the open waveguide section, the EM transition portion being electromagnetically coupled to the leaky waveguide antenna portion, the EM transition portion being configured to support transfer of electromagnetic energy from a signal feed structure to the leaky waveguide antenna portion.

[0027] One embodiment includes a waveguide antenna system having a plurality of the waveguide antenna systems disclosed hereinabove configured for antenna-on-package applications.

[0028] One embodiment includes a waveguide antenna system having a plurality of the waveguide antenna systems disclosed hereinabove configured for patch-on printed circuit board applications.

[0029] One embodiment includes an open waveguide signal feed system comprising: a printed circuit board having a signal feed and a signal feed output; an open waveguide having a signal feed input port; and a transition region disposed between and in signal communication with the signal feed output and the signal feed input port, wherein the signal feed comprises a microstrip, coplanar waveguide, or stripline, and the signal feed output comprises a patch or probe.

[0030] One embodiment includes an open waveguide section having one or more bends in a trough waveguide, the one or more bends being in a direction of electromagnetic wave propagation in the trough waveguide, the trough waveguide having a trough with opposing first and second sidewalls, a partition disposed between the first sidewall and the second sidewall, a first base disposed between the first sidewall and the partition, and a second base disposed between the partition and the second sidewall, and all surfaces inside the trough of at least the first sidewall, the second sidewall, the partition, the first base, and the second base are conductive; and an electromagnetic radiation suppressor strategically constructed and positioned to suppress undesired electromagnetic radiation that may result from the one or more bends in the absence of such electromagnetic radiation suppressor.

[0031] One embodiment is an open waveguide antenna comprising a trough having opposing first and second sidewalls, a bulkhead disposed between the first and second sidewalls, a first base disposed between the first and second sidewalls, and a second base disposed between the bulkhead and the second sidewall, wherein at least one or more of the first sidewall, the second sidewall, the bulkhead, the first base, and an interior surface of the trough of the second base are electrically conductive, and the first base is a first base disposed longitudinally along a length of the trough. the second base includes an open waveguide antenna having a series of undulations, the first series of undulations alternatively and continuously following a first curved path and a second curved path, the second curved path being asymmetrical with respect to the first curved path, the second base having a second series of undulations arranged longitudinally along the length of the trough, the second series of undulations alternatively and continuously following the second curved path and the first curved path, the first curved path and the second curved path alternating along the length of the trough from one side of the bulkhead to the other side of the bulkhead.

[0032] The above and other features and advantages of the present invention will become readily apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. Referring to the illustrative and non-limiting drawings, in which like elements are similarly numbered or illustrated, and in which: [Brief description of the drawings]

[0033] [Figure 1A] FIG. 2 is a cross-sectional end view of an exemplary trough waveguide according to one embodiment. [Figure 1B] 2 is a cross-sectional end view of an exemplary trough waveguide antenna according to one embodiment. [Figure 1C] FIG. 1C is a perspective cross-sectional side view of the exemplary trough waveguide antenna of FIG. 1B according to one embodiment. [Diagram 2] FIG. 1D is a rotated isometric perspective view of the exemplary trough waveguide antenna of FIGS. 1B and 1C according to one embodiment. [Diagram 3] 3 illustrates analytically modeled performance characteristics of the exemplary trough waveguide antenna of FIG. 2 in accordance with one embodiment. [Figure 4A] FIG. 1B is a view similar to that of FIG. 1A with a dielectric cover on top of the exemplary trough waveguide and the exemplary trough waveguide antenna according to one embodiment. [Figure 4B] FIG. 1C is a view similar to that of FIG. 1B with a dielectric cover on top of the exemplary trough waveguide and the exemplary trough waveguide antenna, according to one embodiment. [Figure 4C] FIG. 1D is a view similar to that of FIG. 1C with a dielectric cover on top of the exemplary trough waveguide and the exemplary trough waveguide antenna, according to one embodiment. [Diagram 5] FIG. 4D is a rotated isometric perspective view of the exemplary trough waveguide antenna of FIGS. 4B and 4C according to one embodiment. [Figure 6] FIG. 6 illustrates analytically modeled performance characteristics of the exemplary trough waveguide antenna of FIG. 5 in accordance with one embodiment. [Figure 7A] FIG. 1C is a cross-sectional end view of the exemplary trough waveguide antenna of FIG. 1B with a signal feed, according to one embodiment. [Figure 7B] FIG. 1D is a cross-sectional side view of the exemplary trough waveguide antenna of FIG. 1C with a signal feed according to one embodiment. [Figure 8A] FIG. 6 is a top plan view of a single exemplary trough waveguide antenna of either FIG. 2 or FIG. 5 according to one embodiment. [Figure 8B] FIG. 6 is a repeated top plan view of a plurality of the exemplary trough waveguide antennas of either FIG. 2 or FIG. 5 according to one embodiment. [Figure 8C] FIG. 6 is a final top plan view of a plurality of exemplary trough waveguide antennas of either FIG. 2 or FIG. 5 according to one embodiment. [Figure 9] FIG. 8D illustrates analytically modeled performance characteristics of the embodiment of FIG. 8C, according to one embodiment. [Figure 10A] FIG. 13 is a rotated isometric top view of a trough waveguide antenna having features that aid in its manufacturability, according to one embodiment. [Figure 10B] FIG. 13 is a rotated isometric bottom view of a trough waveguide antenna having features that aid in its manufacturability, according to one embodiment. [Figure 11] FIG. 2 is a conceptual top plan view of an antenna-on-package feed having transmit and receive trough waveguide antennas with a transition according to one embodiment. [Figure 12] FIG. 12 is a conceptual end view in the yz plane of the antenna-on-package feed of FIG. 11 according to one embodiment. [Figure 13] FIG. 12 is a conceptual side view in the xz plane of the antenna-on-package feed of FIG. 11 according to one embodiment. [Figure 14A] FIG. 2 is a perspective side view of an exemplary first transition in the form of a ridge waveguide to a trough waveguide antenna according to one embodiment. [Figure 14B] FIG. 14B is an end view of the first transition section of FIG. 14A according to one embodiment. [Figure 14C] FIG. 14B illustrates EM performance characteristics of the embodiment of FIG. 14A according to one embodiment. [Figure 15A] FIG. 13 is a perspective rotated isometric view of an exemplary second transition disposed between a rectangular waveguide and a trough waveguide antenna according to one embodiment. [Figure 15B] FIG. 15B illustrates EM performance characteristics of the embodiment of FIG. 15A according to one embodiment. [Figure 16A] FIG. 13 is a top view of an exemplary third transition in the form of a waveguide bend, according to an embodiment. [Figure 16B] FIG. 16B illustrates EM performance characteristics of the embodiment of FIG. 16A according to one embodiment. [Figure 17A] FIG. 13 is a perspective side view of an exemplary fourth transition in the form of a rectangular waveguide according to an embodiment. [Figure 17B] FIG. 17B is a top plan view of the embodiment of FIG. 17A, according to one embodiment. [Figure 17C] FIG. 17C illustrates EM performance characteristics of the embodiment of FIGS. 17A and 17B according to one embodiment. [Figure 18]1A-1D are block diagram side views of example conceptual diagrams of transition waveguides with patches, bends and transition losses, trough waveguides with losses, and trough waveguide antennas according to an embodiment. [Figure 19] FIG. 13 illustrates analytical modeling results for trough waveguide loss, according to one embodiment. [Figure 20A] FIG. 2 is an exemplary top block diagram plan view of a conceptual model for controlling radiation from a dielectric discontinuity in a trough waveguide antenna according to one embodiment. [Figure 20B] FIG. 2 is an exemplary top block diagram plan view of a conceptual model for controlling radiation from a dielectric discontinuity in a trough waveguide antenna according to one embodiment. [Figure 21A] FIG. 11 is a rotated isometric perspective view of a first patch to trough waveguide transition with patch E-polarization parallel to the bulkhead, according to one embodiment. [Figure 21B] FIG. 13 is a top perspective plan view of a first patch to trough waveguide transition where the patch E-polarization is parallel to the bulkhead, according to one embodiment. [Figure 21C] FIG. 13 is a perspective side view of a first patch to trough waveguide transition with patch E-polarization parallel to the bulkhead, according to one embodiment. [Figure 22A] 11A-11D are rotated isometric perspective views at various levels of detail of a waveguide transition from a second patch to a trough, where the patch E-polarization is perpendicular to the bulkhead, according to one embodiment. [Figure 22B] 11A-11D are rotated isometric perspective views at various levels of detail of a waveguide transition from a second patch to a trough, where the patch E-polarization is perpendicular to the bulkhead, according to one embodiment. [Figure 22C] 11A-11D are rotated isometric perspective views at various levels of detail of a waveguide transition from a second patch to a trough, where the patch E-polarization is perpendicular to the bulkhead, according to one embodiment. [Diagram 23] 21A-21C show performance characteristics of a patch-to-trough waveguide transition according to one embodiment. [Figure 24] FIG. 2 illustrates an exemplary waveguide antenna system having open waveguide and leaky waveguide antennas and configured for antenna-on-package applications according to one embodiment. [Figure 25A] 25A and 25B are block diagram representations of the fundamental differences between the open waveguide (FIG. 25A) and leaky waveguide antennas (FIG. 25B) of the system of FIG. 24, according to one embodiment. [Figure 25B] 25A and 25B are block diagram representations of the fundamental differences between the open waveguide (FIG. 25A) and leaky waveguide antennas (FIG. 25B) of the system of FIG. 24, according to one embodiment. [Figure 26] FIG. 2 illustrates an example guided wave with a given propagation constant k=ikx+jky+kkz, according to one embodiment. [Figure 27] FIG. 2 illustrates a trench waveguide as an example of an open waveguide, according to one embodiment. [Figure 28A] FIG. 2 illustrates a top view of an open groove waveguide and a leaky waveguide antenna according to an embodiment. [Figure 28B] 1A-1D are front perspective views of an open groove waveguide and a leaky waveguide antenna according to an embodiment. [Figure 28C] 1A-1D are side perspective views of an open groove waveguide and a leaky waveguide antenna according to an embodiment. [Figure 29] FIG. 28B illustrates radiation performance characteristics of the open groove waveguide leaky antenna of FIG. 28A according to one embodiment. [Diagram 30] FIG. 2 is a block diagram top plan view of an example transition region between an electromagnetic transmission line and an open waveguide in accordance with one embodiment. [Diagram 31] FIG. 13 is a block diagram side view of another example transition region between an electromagnetic transmission line and an open waveguide in accordance with an embodiment. [Figure 32A] FIG. 13 is a rotated isometric perspective view of an open waveguide bend, according to one embodiment. [Figure 32B] Top plan view of an open waveguide bend. [Figure 32C] FIG. 32C shows related electromagnetic performance characteristics of FIGS. 32A and 32B. [Fig. 32D] FIG. 32C shows related electromagnetic performance characteristics of FIGS. 32A and 32B. [Diagram 33] FIG. 1 is a block diagram longitudinal cross-section through a bend in a two-channel open waveguide having an electromagnetic radiation absorber according to one embodiment. [Figure 34A]FIG. 13 is a block diagram longitudinal cross section through a bend in a two-channel open-ended waveguide with electromagnetic radiation choke (quarter-wavelength trench) according to one embodiment. [Figure 34B] FIG. 13 is a block diagram longitudinal cross section through a bend in a two-channel open-ended waveguide with electromagnetic radiation choke (quarter-wavelength trench) according to one embodiment. [Figure 35A] FIG. 34C is a block diagram longitudinal cross-section through a bend in a single channel open waveguide with electromagnetic radiation choke, alternative to that shown in FIGS. 34A and 34B, according to one embodiment. [Figure 35B] FIG. 34C is a block diagram longitudinal cross-section through a bend in a single channel open waveguide with electromagnetic radiation choke, alternative to that shown in FIGS. 34A and 34B, according to one embodiment. [Figure 35C] FIG. 34C is a block diagram longitudinal cross-section through a bend in a single channel open waveguide with electromagnetic radiation choke, alternative to that shown in FIGS. 34A and 34B, according to one embodiment. [Figure 36A] FIG. 13 is a rotated isometric perspective view of an open waveguide bend with a modified bulkhead within the bend, according to one embodiment. [Figure 36B] FIG. 1 illustrates a side perspective view of an open waveguide bend with a modified bulkhead within the bend, according to one embodiment. [Figure 36C] FIG. 36C illustrates related electromagnetic performance characteristics of FIGS. 36A and 36B, according to one embodiment. [Figure 36D] FIG. 36C illustrates related electromagnetic performance characteristics of FIGS. 36A and 36B, according to one embodiment. [Figure 37A] FIG. 13 is a rotated isometric perspective view of an open waveguide bend with a modified floor structure within the bend, according to one embodiment. [Figure 37B] FIG. 2 illustrates a top plan view of an open waveguide bend with a modified floor structure within the bend, according to one embodiment. [Figure 37C] FIG. 37C illustrates related electromagnetic performance characteristics of FIGS. 37A and 37B, according to one embodiment. [Figure 37D] FIG. 37C illustrates related electromagnetic performance characteristics of FIGS. 37A and 37B, according to one embodiment. [Figure 38] FIG. 2 is a block diagram longitudinal cross-section through an open waveguide bend with a modified waveguide structure within the bend, according to one embodiment. [Figure 39A] FIG. 13 is a rotated isometric perspective view of an open waveguide bend with modified wall structure within the bend, according to one embodiment. [Figure 39B] FIG. 2 illustrates a top plan view of an open waveguide bend with modified wall structure within the bend, according to one embodiment. [Figure 39C] FIG. 39C illustrates related electromagnetic performance characteristics of FIGS. 39A and 39B, according to one embodiment. [Figure 39D] FIG. 39C illustrates related electromagnetic performance characteristics of FIGS. 39A and 39B according to one embodiment. [Figure 40A] FIG. 2 is a block diagram longitudinal cross-section through an open waveguide bend according to one embodiment. [Figure 40B] FIG. 40B illustrates a modified version of FIG. 40A with increased inductance in the bend, according to one embodiment. [Figure 40C] FIG. 40B illustrates a modified version of FIG. 40A with increased capacitance in the bend, according to one embodiment. [Figure 40D] FIG. 40C illustrates associated electromagnetic performance characteristics of FIG. 40B according to one embodiment. [Figure 40E] FIG. 40D illustrates associated electromagnetic performance characteristics of FIG. 40C according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Those skilled in the art will understand that the drawings, further described herein below, are for illustrative purposes only. It is recognized that for simplicity and clarity of illustration, the elements shown in the drawings have not necessarily been drawn to scale. For example, the dimensions or scale of some of the elements may be exaggerated relative to other elements for clarity. Furthermore, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or similar elements, or similar elements may not be repeatedly recited in every drawing, it being recognized and understood that such recited elements are essentially disclosed if not present.

[0035] As used herein, the phrase "embodiments" means "embodiments disclosed and / or illustrated herein," which may not necessarily include specific embodiments of the claimed invention, but are nevertheless provided herein as being useful for a complete understanding of the claimed invention.

[0036] Although the following detailed description includes many details for illustrative purposes, those skilled in the art will appreciate that many variations and alternatives to the following details are within the scope of the appended claims. For example, if a described feature is not mutually exclusive with respect to other described features, such combination of non-mutually exclusive features is considered to be inherently disclosed herein. In addition, common features may be commonly shown in various figures, but may not be specifically listed in all figures for simplicity, but will be recognized by those skilled in the art as being explicitly disclosed features even if not listed in a particular figure. Thus, the following exemplary embodiments are described without loss of generality to, and without imposing limitations on, the claimed invention disclosed herein.

[0037] As shown and described by the various figures and accompanying text, one embodiment provides an antenna system that can be adapted through a transition from a patch feed (i.e., an in-package antenna or on a circuit board structure) to an open waveguide antenna structure with minimal loss throughout the structure, enabling a tunable high gain antenna system that can be used over a wide bandwidth (i.e., > 4 GHz) and up to millimeter wave frequencies.

[0038] For ease of integration and illustration herein, the feed structure used may be a patch, but other feed structures such as a probe (e.g., a coaxial line, a plated hole in a printed circuit board, etc.), a loop, or an aperture are possible and contemplated herein. The patch structure may ideally be part of the antenna chip in a package to minimize distance, enable miniaturization, and reduce cost by avoiding additional RF layers. However, the patch may also be formed on any type of substrate layer, including a build-up layer, or a layer in a printed circuit board.

[0039] Open waveguide antennas can be specifically designed to allow for a desired antenna radiation pattern. For example, a wide field of view can be obtained, as is often useful in corner radar applications for automotive safety systems. In other cases, it may be desirable to achieve maximum gain over a narrower field of view, such as forward-looking long-range automotive radar applications. Open waveguide antenna variables that can be adjusted to achieve a desired pattern may include the size of the open radiating aperture, the angle of the radiating aperture, the base plane undulation, or the dielectric discontinuities that create the radiation. Additionally, a dielectric cover or lens structure may be added over the metal open waveguide to further optimize the pattern. When multiple antenna channels are required, such as in the corner radar application described above, multiple open waveguide antenna structures can be combined into one part for ease of manufacturing, with the individual open waveguide antenna elements separated by distances of 0.5 to 10 times the wavelength of the signal being processed.

[0040] Various features can be included in the open waveguide antenna design to facilitate manufacturing while maintaining the same excellent RF performance. These include "shelling" of the part to reduce material consumption and warpage, recesses and positive features to avoid sticking during metallization by electroplating or other processes, and draft angles and convenient parting line locations to facilitate part removal.

[0041] Manufacturing methods for creating single or multi-channel open waveguide antenna structures may be accomplished by a variety of methods, including metal die casting, dielectric injection molding followed by surface metallization, and extrusion followed by singulation and surface metallization.

[0042] The transition from the feed structure to the open waveguide antenna is designed to minimize losses. Suitable transition structures to achieve this goal include ridge waveguide with patch feed, rectangular waveguide with patch feed, open waveguide with patch or probe feed, coplanar waveguide, etc.

[0043] Another embodiment, as shown and described by various figures and accompanying text, provides a trough waveguide antenna (TWGA) useful, in one example, for automotive radar applications. The TWGA combines the functionality of a trough waveguide with that of an electromagnetic (EM) radiator (antenna). Trough waveguides have symmetry between the left and right sides of their dividing bulkhead and operate primarily as guided mode EM transmission elements. In comparison, trough waveguide antennas have an asymmetry between the left and right sides of their dividing bulkhead and necessarily have at least a partially open top that allows them to operate both as EM transmission and EM radiating elements. As used herein, the phrase "open top" means a top, cover, or ceiling of a TWGA that is open to or allows the passage of EM radiating energy. Thus, an open top does not exclude the presence of a dielectric cover on the TWGA. A monolithic microwave integrated circuit (MMIC) may be used to bring a signal to the input port of the TWGA.

[0044] Although reference is made herein to a trough waveguide antenna, it will be understood that a more general term for describing a trough waveguide antenna is an open waveguide antenna, and that the aforementioned trough waveguide antenna is a specific subset of open waveguide antenna structures.

[0045] As used herein, the term monolithic means a structure integrally formed from a single material composition. Although the embodiments shown and described herein show an exemplary TWGA having a particular three-dimensional (3D) geometry, it is understood that this geometry is only one example of many geometries that may be employed in the design of a TWGA depending on the desired performance characteristics of the TWGA (operating frequency, bandwidth, gain, return loss, radiation pattern, etc.). It is also understood that the disclosed geometry may be modified without departing from the scope of the invention. Thus, the disclosure herein applies to any TWGA design falling within the scope of the appended claims, and any 3D shape that is within the scope of the disclosure herein and suitable for the purposes disclosed herein is contemplated and considered to be complementary to the specific embodiments disclosed herein.

[0046] Reference is now made to Figures 1A-10B, which relate generally to an exemplary open waveguide antenna, and in particular to an exemplary open trough waveguide antenna. 1A, 1B, and 1C respectively show a cross-sectional end view of an exemplary open trough waveguide (TWG) 1000, a cross-sectional end view of an exemplary open trough waveguide antenna (TWGA) 2000, and a perspective cross-sectional side view of the exemplary TWGA 2000 of FIG. 1B. As can be seen, the TWGA 2000 has similar structural features compared to the TWG 1000, but has structural differences with respect to the asymmetry of the left and right bases on either side of the bulkhead and the undulations present in the left and right bases of the TWGA 2000.

[0047] In one embodiment, the TWG 1000 (more generally referred to herein as an open waveguide) has a trough 1010 having a first opposing sidewall 1020 and a second opposing sidewall 1030, a partition 1040 disposed between the first sidewall 1020 and the second sidewall 1030, a first base 1050 disposed between the first sidewall 1020 and the partition 1040, and a second base 1060 disposed between the partition 1040 and the second sidewall 1030, wherein all surfaces 1070 inside the trough 1010 of at least the first sidewall 1020, the second sidewall 1030, the partition 1040, the first base 1050, and the second base 1060 are electrically conductive. In one embodiment, the bulkhead 1040 extends upward from the first base 1050 and the second base 1060 as viewed from the perspective of FIG. 1A. In one embodiment, the TWG 1000 has a monolithic 3D dielectric structure with the conductive surface 1070 described above disposed thereon. In one embodiment, all surfaces within the trough 1010 of the first base 1050 and the second base 1060 are conductive. In one embodiment, the conductive surface 1070 is deposition coated with a conductive material. As used herein, at least with respect to the conductive surfaces (also referred to herein as open waveguide sections) of the TWG 1000, the phrase "conductive" means conductive at the operating frequency of interest and may include surfaces that are non-conductive in the DC sense but have sufficient conductivity in the AC sense at the operating frequency of interest for the purposes disclosed herein.

[0048] In one embodiment, the TWGA 2000 (more generally referred to herein as an open waveguide antenna) includes a trough 2010 having opposing first and second sidewalls 2020 and 2030, a bulkhead 2040 disposed between the first sidewall 2020 and the second sidewall 2030, a first base 2050 disposed between the first sidewall 2020 and the bulkhead 2040, and a second base 2050 disposed between the bulkhead 2040 and the second sidewall 2030. 1C , and a second base 2060 disposed thereon, wherein at least the first sidewall 2020, the second sidewall 2030, the bulkhead 2040, the first base 2050, and all surfaces 2070 inside the trough 2010 of the second base 2060 are electrically conductive, and the first base 2050 has a first series of undulations 2052 disposed longitudinally along the length of the trough 2010, the first series of undulations 2052 alternatively being (as in the high 1C ) and sequentially (from left to right in FIG. 1C ), following a first curved path 2011 and then a second curved path 2012 alternating from high to low (from left to right in FIG. 1C ), the second curved path 2012 being asymmetrical with respect to the first curved path 2011 , the second base 2060 having a second series of undulations 2062 arranged longitudinally along the length of the trough 2010 , the second series of undulations 2062 being alternatively and Successively, the second curved path 2012 and then the first curved path 2011 alternating from low to high (left to right in FIG. 1C ) are followed, with the first curved path 2011 and second curved path 2012 alternating from one side of the bulkhead 2040 to the other side of the bulkhead 2040 along the length of the trough 2010 (best seen with reference to FIG. 2 ), but appearing as a continuous spline from left to right in the perspective side view of FIG. 1C . In one embodiment, the first series of undulations 2052 and the second series of undulations 2062 are asymmetrical about the bulkhead 2040.

[0049] In one embodiment, the partition 2040 extends upwardly from the first base 2050 and the second base 2060 as viewed from the perspective views of Figures 1B-1C. In one embodiment, the TWGA 2000 has a monolithic 3D dielectric structure having the aforementioned conductive surface formed or disposed thereon. In one embodiment, the conductive surface 2070 is deposition coated with a conductive material.

[0050] In one embodiment, at least a portion of the first series of undulations 2052 includes a dielectric material and / or at least a portion of the second series of undulations 2062 includes a dielectric material. By strategically placing dielectric material as part of the undulations 2052, 2062, controlled emission from the leaky TWGA 2000 can be further achieved.

[0051] 1A, the TWG 1000 has an overall waveguide height Hg relative to the outer base surface 500, a base height Hb relative to the outer base surface 500, a sidewall height Hw relative to Hb, and a partition height Hs relative to the first base 1050 or the second base 1060. In one embodiment, Hg is equal to the sum of Hb and Hw. In one embodiment, Hs is less than Hw.

[0052] FIG. 2 shows a rotated isometric perspective view of the exemplary TWGA 2000 of FIG. 1B and FIG. 1C. In one embodiment, the TWGA 2000 is fed by a trough waveguide mode through a signal port 2400 on one end 2100 (first end) of the TWGA 2000. The opposite second end 2200 (second end) of the TWGA 2000 has a conductive short circuit 2500 electrically connected to a conductive surface 2600 disposed on the top end 2300 of the TWGA 2000. In FIG. 2, the visible ones of the first and second series of undulations 2052, 2062 are shown for comparison with those of FIG. 1C.

[0053] From the foregoing discussion and explanation of Figures 1B-1C and 2, it is understood that the embodiments disclosed herein include the following, which may or may not be variations of the structure of the TWGA 2000 shown in Figures 1B-1C and 2. In one embodiment, the exposed surfaces of the first sidewall 2020, the second sidewall 2030, and the partition wall 2040 are not parallel to one another along the length of the trough 2010, which when combined with an appropriate draft angle provides for the manufacture of the TWGA 2000 by molding techniques. In one embodiment, the partition wall 2040 has a height that is less than the height of either the first sidewall 2020 or the second sidewall 2030, at least as shown in Figures 1B and 1C. In one embodiment, the partition wall 2040 is centrally located between the first sidewall 2020 and the second sidewall 2030, however, it is understood from other embodiments disclosed herein that variations to this configuration are possible. In one embodiment, the first series of undulations 2052 alternate in elevation between a first curved path 2011 and a second curved path 2012 along the length of the trough 2010 from left to right as viewed in FIG. 1C, and the second series of undulations 2062 alternate in elevation between the second curved path 2012 and the first curved path 2011 along the length of the trough 2010 from left to right as viewed in FIG. 1C. In one embodiment, as viewed in the side view of FIG. 1C, the first curved path 2011 of the trough 2010 is a first waveform (also referred to herein by reference number 2011) having alternating peaks and valleys, the first waveform 2011 being a composite of a first smooth waveform multiplied by a first square wave. Similarly, the second curved path 2012 of the trough 2010 is a second waveform (also referred to herein by reference number 2012) having alternating peaks and valleys, the second waveform 2012 being a composition of a second smooth waveform multiplied by a second square wave. In one embodiment, the second smooth waveform and the first smooth waveform have different elevations in both the peaks and valleys at all points between and within the first end 2100 and second end 2200 of the trough 2010.

[0054] Figure 3 shows analytically modeled performance characteristics of the exemplary TWGA2000 of Figures 1B, 1C, and 2. The analytical data shown was taken at a point P that is considered to be in the far field, far enough away from the TWGA2000. As shown, one embodiment of the TWGA2000 is configured to function with approximately 12 dBi of boresight (θ=0) realized gain and specific side lobe gain peaks and radiation patterns in the azimuth (φ=0) and elevation (φ=90) planes (compare Figure 6).

[0055] 4A, 4B, 4C, 5, and 6, in which 4A, 4B, and 4C show views similar to 1A, 1B, and 1C, respectively, but with a dielectric Dk cover 3000 (also referred to herein as a lens or lid) on top of the exemplary TWG 1000 and exemplary TWGA 2000, 5 shows a rotated isometric perspective view of the TWGA 2000 of 4C, similar to that of 2, but with a cover 3000, and 6 shows analytically modeled performance characteristics of an exemplary trough waveguide antenna 2000 with a cover 3000 as shown in 5, similar to that of 3. When discussed generally, the Dk cover is referred to herein by reference number 3000, when discussed in relation to the TWG 1000, the Dk cover is referred to herein by reference number 3100, and when discussed in relation to the TWGA 2000, the Dk cover is referred to herein by reference number 3200. As shown, the dielectric cover 3200 is disposed and extends over the top of the trough 2010 of the TWGA 2000 with a width Wc equal to or greater than the top open end width Wt of the trough 2010. The thickness, width, and overall shape of the dielectric cover 3100 on the TWGA 2000 serve to control the azimuth and elevation EM radiation pattern and shape emitted from the TWGA 2000. As an example, the cover 3100 and / or 3200 may include surface disruptions 3010, such as the depressions or protrusions (not shown) shown in Figures 4A and 4B, for control of the azimuth EM radiation pattern and shape as described above. The dielectric cover 3200 also provides an additional degree of freedom in the design of such antennas that complements the overall performance of the antenna. It is envisioned that such performance improvements will manifest in improved return loss, improved side lobe levels, and / or any other antenna output characteristics so affected. In one embodiment, the dielectric cover 3000 has a dielectric constant greater than 1 and less than or equal to 13.

[0056] Figure 5 shows a rotated isometric perspective view of the exemplary TWGA 2000 of Figures 4B and 4C. Similar to the embodiment of Figure 2, the TWGA 2000 of Figure 5 is fed by a trough waveguide mode through a signal port 2400 on one end 2100 of the TWGA 2000. The opposite end 2200 of the TWGA 2000 has a conductive short circuit 2500 electrically connected to a conductive surface 2600 disposed on the top end 2300 of the TWGA 2000.

[0057] FIG. 6 shows analytically modeled performance characteristics of an exemplary TWGA 2000 with cover 3200 of FIG. 5. The measurements shown were taken at a point P sufficiently far from the TWGA 2000 and cover 3200 to be considered in the far field. As shown, one embodiment of the TWGA 2000 with cover 3200 is configured to function with a boresight (θ=0) realized gain of about 12 dBi and specific side lobe gain peaks and radiation patterns in the azimuth (φ=0) and elevation (φ=90) planes (compare FIG. 3). As can be seen by comparing the side lobe gain peaks and radiation patterns of FIG. 3 and FIG. 6, the presence of the Dk cover 3200 is seen to affect the shape and distribution of EM radiation in the side lobes more than it affects the boresight gain. It is also observed that the Dk cover 3200 increases the azimuth radiation gain (φ=0) over a larger angular spread.

[0058] 7A and 7B show cross-sectional end and side views, respectively, of the exemplary TWGA 2000 of FIGS. 1B and 1C having a signal feed 4000 disposed in signal communication with a signal port 2400 at a first end 2100 of the TWGA 2000.

[0059] 8A, 8B, and 8C respectively show top plan views, repeated top plan views, and final top plan views of single and multiple exemplary TWGAs 2000 of either FIG. 2 or FIG. 5, with multiple TWGAs 2000 assembled (FIG. 8C) forming a multi-channel TWGA 2700.

[0060] Figure 9 shows analytically modeled performance characteristics of the embodiment of Figure 8C, which is a single one of the multi-channel TWGA 2700. As can be seen by comparing the analytical plot of Figure 9 with that of Figure 3, the multi-channel TWGA 2700 produces a similar gain profile as seen at φ=90 and a flatter gain profile as seen at φ=0. It is the combination of the TWGA profile and the dielectric cover that allows this multi-channel antenna pattern to have a variety of shapes.

[0061] 10A shows a rotated isometric top view and FIG. 10B shows a rotated isometric bottom view of an example TWGA 2000 having features 5000 that aid in its manufacturability without substantially compromising electromagnetic performance. For example, the manufacturability features 5000 may include one or more of the following: (i) positive manufacturing features 5010 that do not allow the flat surface or surface features to stick during the barrel electroplating process (i.e., the positive features break a continuous flat plane); (ii) screw locations 5020 that are incorporated with or without recessed pockets (as shown) for receiving flat head screws or similar fasteners; (iii) rib features 5030 to reduce material consumption and warping; (iv) recess features 5040 to reduce sticking tendency during electroplating; (v) molded draft features 5050 of 2 degrees or more on the top side / surface of the TWGA2000 monolithic 3D dielectric structure; (vi) molded draft features 5060 of 4 degrees or more on the bottom side / surface of the TWGA2000 monolithic 3D dielectric structure; and (vii) molded parting line features 5070 located proximate the bottom surface of the TWGA2000 monolithic 3D dielectric structure. While particular draft angles are presented herein above, such as 2 degrees and 4 degrees, it is understood that these are merely exemplary draft angles that may be suitable for particular purposes and surfaces, and are in no way intended to be limiting to the invention disclosed herein, but may include any draft angle suitable for manufacturing processes, which may include single axis molding.

[0062] Reference is now made to FIGS. 11-23B, which generally relate to an exemplary TWGA system having one or more TWGAs 2000. 11 illustrates a conceptual top plan view (xy plane) of a TWGA system 6000 having an antenna-on-package (AoP) feed 6100 on a lower package 6050, an electromagnetically coupled waveguide transition (alternatively referred to herein as a transition region) 6200, and transmit and receive antennas 2800 and 2850 in the form of TWGAs 2000, each electromagnetically coupled to the waveguide transition 6200. In one embodiment, the AoP feed 6100 includes a patch antenna 6150 disposed on the lower package 6050. In one embodiment, the AoP feed 6100 and / or the patch antenna 6150 have the form of a planar signal feed structure.

[0063] 12 shows a conceptual end view (yz plane) of the TWGA system 6000 of FIG. 11 with the AoP feed 6100, the waveguide transition (transition region) 6200, and the transmit and receive antennas 2800 and 2850 on the underlying package 6050. Also shown here is the Dk cover 3000 covering the TWGA 2800, 2950. Also shown are solder ball connections 6060 for electrically connecting the TWGA system 6000 to an underlying PCB (printed circuit board) (not shown), and an integrated RFIC (radio frequency integrated circuit) chip 6070. As shown, the waveguide signal feed interface 6205 is disposed between the AoP feed 6100 and the waveguide transition region 6200, forming part of the electromagnetic (EM) transition portion 100. In one embodiment, each EM transition portion 100 is configured to couple EM energy from the signal feed interface 6205 into a guided waveguide mode of the EM energy through the transition region 6200 into the open waveguide section 1000 according to an embodiment of the structure disclosed herein below. In one embodiment, the waveguide signal feed interface 6205 comprises a waveguide input port of the waveguide transition portion 6200. The AoP feed 6100, or any signal feed disclosed herein, in combination with the waveguide signal feed interface 6205, or any signal feed interface disclosed herein, may be considered a region of EM signal launch into the EM transition portion 100.

[0064] FIG. 13 shows a conceptual side view (xz plane) of the TWGA system 6000 of FIG. 11 with the AoP feed 6100 in a left and right configuration, with the lower package 6050, the waveguide transition section 6200, the transmit antenna 2800 and the receive antenna 2850, and the Dk cover 3000 over the TWGAs 2800, 2850.

[0065] Figure 14A shows a perspective side view of an exemplary first transition region 6210 (referenced generally by reference number 6200) in the form of a ridge waveguide 1100 transitioning (from left to right) to a TWGA 2000. Figure 14B shows an end view of the first transition of Figure 14A. Figure 14C shows the EM performance characteristics of the embodiment of Figure 14A. Here, the AoP feed 6100 is centered between the lower ridge (see h1) and the upper ridge (see h3), the first transition 6210 is similar to the TWG 1000 described herein above, but has a bulkhead 1041 similar to the bulkhead 1040 described above, the bulkhead 1041 slopes upward from port-1 6300 (analysis port used for analytical modeling) on ​​the left side of the first transition 6210 to TWGA 2000 on the right side of the first transition 6210, and the total height varies from h1 to h2 relative to the base 500, in this example h2 being greater than h1. In one embodiment, H1 is greater than H2. As shown, the height of the bulkhead 1041 increases from port-1 6300 to TWGA 2000, with h2+H2 being greater than h1+H1. As shown, similar to FIG. 12, the signal feed interface 6205 is disposed between the AoP feed 6100 and the first transition region 6210 to form part of the EM transition section 100, which also includes the ridge waveguide 1100. As shown, port-2 6400 (analysis port used for analytical modeling) is shown on the right side of the TWGA2000. Port-1 6300 and port-2 6400 are used herein for analytical purposes to analyze the S-matrix network parameters S11 and S21, as shown in the S-matrix plot (dB) in FIG. 14, which shows low EM reflection (S11) from the input port 6300, and high EM transmission S21 between the input port 6300 and the output port 6400, both of which are desirable performance characteristics of the embodiments disclosed herein. As shown, favorable return loss S11 and EM transmission S21 are observed at frequencies above 75 GHz.

[0066] Further with respect to FIG. 14A, the functional dependence of the septum height (ie, (h1, H1)) pair on the (h2, H2) pair can be linear or quadratic depending on the relative values ​​of the (h1, H1) and (h2, H2) pairs.

[0067] FIG. 15A shows a perspective rotated isometric view of an exemplary second transition 6220 disposed between a rectangular waveguide 900 and a TWGA 2000. FIG. 15B shows the EM performance characteristics of the embodiment of FIG. 15A. As shown, the second transition 6220 of FIG. 15 is similar in structure to the first transition 6210 of FIG. 14 described above, also in the form of a ridge waveguide 1200, with the following differences: Here, the second transition 6220 has a partition 1042 similar to the partition 1041 described above, but the partition 1042 slopes upward from a height H1 (see, e.g., FIG. 14) equal to zero in the rectangular waveguide 900 (as shown in FIG. 15) to a height H2 in the TWGA 2000 (as shown in FIG. 15). Another difference between the second transition 6220 and the first transition 6210 is that the first and second bases 105, 1060 are not sloped. Similar to the embodiment of FIG. 14, FIG. 15 shows port-1 6300 and port-2 6400, which are used herein for analytical purposes to analyze the return losses S11 and S21 as shown in the S-matrix plot (dB) of FIG. 15, which shows low EM reflection (S11) from the input port 6300 and high EM transmission (S21) between the input port 6300 and the output port 6400, both of which are desirable performance characteristics of the embodiments disclosed herein. As shown, favorable return losses (S11) and EM transmission (S21) are observed at frequencies above 75 GHz.

[0068] 16A-23B, various embodiments of transition sections consistent with embodiments disclosed herein are shown. Figure 16A shows a top block diagram of an exemplary third transition 6230 in the form of a waveguide having a 90 degree bend 6202 between input port-1 6300 and output port-2 6400. Figure 16B shows the EM performance characteristics of the embodiment of Figure 16A. As shown, good return loss S11 and EM transmission S21 are observed at about 80 GHz.

[0069] Figure 17A shows a perspective side view of an exemplary fourth transition 6240 in the form of a rectangular waveguide disposed between a patch 6150 and a TWGA 2000 (not shown), which in one embodiment is disposed on a package 6050 to provide an AoP feed 6100, Figure 17B shows a top plan view of the embodiment of Figure 17A, and Figure 17C shows the EM performance characteristics of the embodiment of Figures 17A and 17B. As shown, good return loss S11 and EM transmission S21 are observed at about 79 GHz.

[0070] FIG. 18 illustrates a block diagram side view of an exemplary conceptual system 6000 having a patch 6150 disposed on a bottom package 6050, a waveguide transition region 6200 with a bend 6202 and transition loss analytically estimated at 0.7 dB, a TWG 1000 with loss analytically estimated at 0.1 dB / 1 inch, and a radiating element in the form of a TWGA 2000, all electromagnetically coupled to one another. As shown, as with other embodiments disclosed herein, a signal feed interface 6205 is disposed between the patch 6150 and the waveguide transition region 6200, forming part of an electromagnetic (EM) transition portion 100. In one embodiment, each EM transition portion 100 is configured to couple EM energy from the signal feed interface 6205 through the transition region 6200 to a guided waveguide mode of the EM energy to the TWG 1000, which then guides the electromagnetic energy to the TWGA 2000.

[0071] FIG. 19 shows exemplary analytical modeling results of (S21) transmission loss versus frequency for an exemplary 1.27 cm (1 / 2 inch) long TWG1000. FIG. 19 shows the dependence of (S21) transmission loss on metal conductivity. Al is aluminum, and the different curves represent the reduction of (S21) transmission loss for different metals (i.e., conductivity relative to aluminum).

[0072] FIGS. 20A and 20B show exemplary top block diagram plan views of a conceptual model for controlling radiation from a dielectric discontinuity of a TWGA2000 having bases 2050, 2060 separated by a partition wall 2040. Here, bases 2050, 2060 may or may not have curved paths 2011, 2012 with undulations 2052, 2062, but include individual dielectric radiation elements 2001, 2002 having a dielectric constant that varies along the direction of EM wave propagation. Comparing the embodiments of FIGS. 20A and 20B, each radiation element 2001, 2002 may be separated by air and provide individual radiation elements (FIG. 20A), or may be coupled via an intervening dielectric medium 2003 (see detail - 20.1) to provide a single integrated structure (FIG. 20B). As shown in detail - 20.1, the individual radiation elements 2001, 2002 may consist of different dielectric constants with a changing Dk value in the direction of EM wave propagation. In one embodiment, they may vary according to the following pattern of dielectric constant values, i.e., Dk1 - Dk2 - Dk3 - Dk2 - Dk1. In one embodiment, Dk1 < Dk2 < Dk3, but the Dk values do not have to follow an ascending or descending order, as long as there is a contrast between adjacent Dk values among the discrete Dk values. As shown in detail - 20.2, the intervening dielectric medium 2003 has a different dielectric constant value Dk4 as opposed to Dk1 - Dk3. In one embodiment, Dk4 is substantially smaller than any one of Dk1, Dk2, and Dk3, and the dielectric constant difference between Dk4 and any one of Dk1, Dk2, and Dk3 is 3 or more.

[0073] FIGS. 21A, 21B, and 21C show, respectively, a rotational isometric view, a perspective top view, and a perspective side view of a waveguide transition 6255 from a first patch to a trough. Here, the E - polarized wave of the patch 6150

[0074]

number

[0075] is parallel to the bulkhead 1040, and a ridge waveguide 6256 is disposed between the patch 6150 and the trough waveguide 6257, combining to form a first patch to trough waveguide transition 6255. Here, the trough waveguide 6257 includes a bend 6258 that does not radiate EM energy as long as symmetry is maintained along the trough waveguide cross section, and the profile of the bulkhead 1040 across the bend maintains a constant wave impedance along the bend, which can be achieved according to embodiments of the structures disclosed herein. FIG. 21A also shows an input port 6300 and an output port 6400, which were used for analytical modeling purposes to establish the performance characteristics shown in FIG. 23 discussed below. In the embodiment of FIG. 21A, the patch 6150 is fed by a microstrip line (generally referenced by reference number 4000) from the side of the waveguide, along the edge to the patch 6150, along the bulkhead 1040, to generate the desired E-polarization parallel to the bulkhead 1040. To allow the microstrip to connect with the patch 6150 without being shorted, appropriate electrical clearance is provided and the impedance of the stripline is the same as and matched to the feedline. Alternatively, the patch 6150 of FIG. 21A can also be fed by a coaxial port from below without material changes to the design. As shown in FIG. 21C, as in other embodiments disclosed herein, a signal feed interface 6205 is disposed between the patch 6150 and the ridge waveguide 6256, forming part of the electromagnetic (EM) transition portion 100, which also includes the trough waveguide 6257. In one embodiment, each EM transition section 100 is configured to couple EM energy from the signal feed interface 6205 via the ridge waveguide 6257 to the trough waveguide 6257 into a guided waveguide mode of the EM energy, which then guides the electromagnetic energy to the TWGA 2000 (not specifically shown in FIG. 21C ).

[0076] 22A, 22B, and 22C show rotated isometric perspective views at various levels of detail of a second patch-to-trough waveguide transition 6260, where the E-polarization of the patch 6150 is perpendicular to the bulkhead 1040. As seen in FIGS. 22A-22C, the signal probe 6160 is positioned edge-to-edge with respect to the patch 6150 (i.e., the signal probe 6160 is positioned proximate to an edge of the patch 6150) and laterally offset from the bulkhead 1040 (i.e., the signal probe 6160 is not in-line with the bulkhead 1040 as in FIGS. 21A-21C) to generate the desired E-polarization perpendicular to the bulkhead 1040.

[0077] It is envisioned that the geometries of Figures 21A-21C and 22A-22C are castable or moldable to have appropriate draft angles included that would typically be included by one skilled in the art of casting or molding techniques suitable for the purposes disclosed herein.

[0078] FIG. 23 shows the S(1,1) and S(1,2) analytical performance characteristics of the patch-to-trough waveguide transition 6255 shown in FIG. 21A. Reference is now made to Figures 24-29, which relate generally to example feed configurations for example waveguide antenna systems.

[0079] FIG. 24 illustrates an exemplary waveguide antenna system 7000 similar to the TWGA system 6000 of FIG. 11, for example, where like elements are numbered similarly. The waveguide antenna system 7000 has an open waveguide 1000, 1500 and a leaky waveguide antenna 2800, 2850, configured for an antenna-on-package 6100 application, where the desired electromagnetic structure for such a system 7000 is one that can be fed by a low-loss waveguide or transmission line and implemented in a series fashion. As shown, the open waveguide can be an open TWG 1000 with no bends, or an open TWG 1500 with one or more bends 1520. Such a structure can be advantageous for use in an automotive radar antenna that is desirably arranged relatively far from the radar MMIC, where cost and complexity of manufacture and implementation are considered. A common form of such a desired electromagnetic structure is an open waveguide 1000, 1500 (generally referred to by the reference number 1000) that feeds a leaky waveguide antenna 2000, 2800, 2850 (generally referred to by the reference number 2000). These two elements are significantly different from each other, since the former aims to keep all electromagnetic energy within its vicinity, whereas the latter aims to convert electromagnetic energy into radiation quickly at its feed point. This is illustrated in Figures 25A and 25B, which show a block diagram representation of the fundamental difference between an open waveguide 1000 (see Figure 25A) and a leaky waveguide antenna 2000 (see Figure 25B) that may be implemented in the system 7000 of Figure 24. The fundamental difference between these two elements (i.e., open waveguide and leaky waveguide antennas) is the type of electromagnetic waves each structure can support, i.e., guided waves for the waveguide 1000 (power input is equal to P1, power output is equal to (approximately equal to) P1), and leaky waves for the antenna 2000 (power input is equal to P1, power radiated is equal to (approximately equal to) P1, and power output is equal to (approximately equal to) zero).As shown in FIG. 24, similar to other embodiments disclosed herein, the EM transition portion 100 includes a waveguide transition region 6200 and a TWG 1000 and is configured to couple EM energy from a signal feed interface 6205 into a guided waveguide mode of EM energy to the TWG 1000 via path 6150, and then guide the electromagnetic energy to the TWGA 2000.

[0080] Reference is now made to FIG. 26, which illustrates an exemplary guided wave. A guided wave is a wave with a given propagation constant

[0081]

number

[0082] where i, j and k are conventional Cartesian coordinate unit vectors, and each wave number kx, ky, and kz is a complex number following the equation: k=-iγ=β-iα, where β represents the phase response of the waveguide / antenna, α represents the amount of leakage across the waveguide / antenna, and γ is called the propagation constant. In the direction of propagation along the z-axis, kz is purely imaginary (apart from material losses), while the transverse propagation constant (ky) along the intermediate phase of the waveguide is purely real (evanescent). On the other hand, leaky waveguide antennas have a propagation constant kz that is complex, with the real part accounting for losses to radiation. The transverse propagation is also complex, which indicates that these waves radiate.

[0083] Guided waves, by definition, do not radiate and can be obtained in a myriad of ways. For example, a rectangular dielectric waveguide that confines the energy within its dielectric, or a rectangular metallic waveguide that confines the energy within its metal walls. An open waveguide is simply a metallic structure that guides waves and is open at one or more of its ends or sides. The only requirement for an open waveguide 1000 is that it supports a waveguide mode. A groove waveguide 1015 with dimensions a1, a2, and b is an example of an open waveguide, as shown in FIG. 27. The main advantage of this type of waveguide is its low loss and potentially cost-effective manufacturing method. The E-field guided mode of the groove waveguide 1015 is represented by the arrow E in FIG. 27.

[0084] The open waveguide 1000 is a natural induction structure for electromagnetically coupling with and feeding the leaky waveguide antenna 2000. The leaky waveguide antenna works by properly designing the amount of leakage (alpha) across the antenna along with the phase response (beta) (see, for example, alpha, α, and beta, β in FIG. 26). Both can be designed so that the radiated beam has specific characteristics, i.e., direction, beamwidth, sidelobe level, and pattern shape. An example of this type of antenna structure with an open waveguide 1000 electromagnetically coupled with and feeding the leaky waveguide antenna 2000 is shown in FIG. 28A, FIG. 28B, and FIG. 28C. 28A, 28B, and 28C respectively show top, front, and side perspective views of an open groove waveguide 1000 electromagnetically coupled to and feeding a leaky waveguide antenna 2000, the radiation performance characteristics of which are shown in Fig. 29. As can be seen in at least Fig. 28A, the sidewalls 1020, 1030 of the waveguide 1000 are free of electromagnetic interference features, while the sidewalls 2020, 2030 of the leaky waveguide antenna 2000 include electromagnetic radiation enhancing features 2004 (e.g., comparable to undulations 2052, 2062) that are configured to provide a desired radiation loss through the leaky waveguide antenna 2000.

[0085] Reference is now made to Figures 30-31 and 33-50, which generally relate to exemplary waveguide launch structures and associated transition regions, as well as exemplary waveguide radiation correction features, for the exemplary waveguide antenna systems disclosed herein.

[0086] 30 depicts a block diagram top plan view of an exemplary transition region 6200 between a signal feed 4000 in the form of an electromagnetic transmission line 4010 on an underlying package 6050, such as a printed circuit board (PCB), and an open waveguide 1000. In one embodiment, the PCB transmission line can be a coplanar waveguide (CPW), microstrip, or stripline. Here, the transition region 6200 is in the form of an edge feed to the open waveguide 1000.

[0087] FIG. 31 shows a side view of a block diagram of another exemplary transition region 6200 between a signal feed 4000 in the form of an electromagnetic transmission line 4020 on an underlying package 6050 such as a PCB and an open waveguide 1000. In an embodiment, the PCB transmission line may be a substrate integrated waveguide (SIW), stripline, or CPW. Here, the transition region 6200 is in the form of a capacitive or inductive coupling through a slot / opening 4030 on a conductive surface 4040 of the PCB transmission line 4020 proximate to the signal input end 1080 of the open waveguide 1000. As shown in FIG. 31, as in other embodiments disclosed herein, a signal feed interface 6205 is disposed between the signal feed 4000 and the transition region 6200, forming part of the electromagnetic (EM) transition portion 100, which also includes the open waveguide 1000. In one embodiment, each EM transition section 100 is configured to couple EM energy from the signal feed interface 6205 through the transition region 6200 into a guided waveguide mode of the EM energy into the open waveguide section 1000, which then guides the electromagnetic energy to the TWGA 2000 (not specifically shown in FIG. 31 ).

[0088] FIG. 32A shows a rotated isometric perspective view of an open waveguide bend 1500, FIG. 32B shows a top plan view of the open waveguide bend 1500, and FIG. 32C and FIG. 32D show relevant electromagnetic performance characteristics of the embodiment of FIG. 32A and FIG. 33B, which serve to show that an open waveguide bend 1520, if left uncorrected, can result in undesired electromagnetic radiation. An open waveguide is desirable to guide electromagnetic waves as long as symmetry within the waveguide is maintained. Thus, bending a waveguide primarily generates a myriad of modes of different strengths, some of which are undesired radiation modes. To remedy this situation, the stronger undesired radiation modes generated by the bend can be minimized by using one or more of the following: strategically placed electromagnetic radiation absorbers; electromagnetic radiation choking mechanisms placed within the waveguide; structural modifications to the height of the bulkhead within the waveguide, such as by slowly tapering the height of the bulkhead from its original height to a lower height within the bend so that the electromagnetic waves are guided by the distance from the bulkhead to the wall; structural modifications to the internal surfaces of the open waveguide that affect the phase velocity and / or waveguide impedance such that the phase velocity and / or waveguide impedance are constant or nearly constant along the path of the bend; and other structural modifications to the internal features of the trough waveguide within the bend that serve to keep the phase velocity and / or waveguide impedance constant along the bend.

[0089] Referring to FIG. 33 in combination with FIG. 32A, FIG. 33 shows a block diagram of a longitudinal cross-section through a bend in a two-channel open waveguide 1600 having an electromagnetic radiation absorber 1610 disposed on a corresponding dielectric cover 3000 having a dielectric constant (Dk) value greater than 1, which serves to eliminate or nearly eliminate undesired electromagnetic radiation from the bend 1520 and improve inter-channel isolation. Although the exemplary embodiment disclosed herein shows the electromagnetic radiation absorber 1610 disposed along the bend 1520 of the open waveguide 1500, it is understood that the electromagnetic radiation absorber may be strategically placed elsewhere in an antenna system as disclosed herein to suppress undesired radiation. The radar absorbing material that may be used is not limited and may be in the form of a composite, i.e., a radar absorbing material combined with a polymer binder. Exemplary radar absorbing materials may be fibrous, or particulate, or in other forms. For example, the radar absorbing material may be carbon fiber, carbon nanotubes, carbon black, polyaniline, ferrite, etc. Exemplary polymers for use as binders may include epoxies, neoprene, polyesters such as polybutylene terephthalate, and the like. The amount of radar absorbing material is selected to provide the desired radar absorption without significantly adversely affecting the desired properties of the composite, such as processability, and may be, for example, in an amount of 1 to 40 volume percent, or 5 to 30 volume percent, or 10 to 20 volume percent, each based on the total volume of the composite. Other additives known in the art may be present. An exemplary material suitable as an electromagnetic radiation absorber for the purposes disclosed herein is poly(butylene terephthalate) (PBT) containing 15 volume percent carbon fiber.

[0090] 34A and 34B in combination with FIG. 32A, which show two versions of a block diagram longitudinal cross-section through a bend 1520 in a two-channel open waveguide 1600 with an electromagnetic radiation choke (quarter-wavelength trench) 1620, which serves to eliminate or nearly eliminate undesired electromagnetic radiation from the bend and improve inter-channel isolation. As shown, an exemplary choke may be formed in the open waveguide bend by creating a quarter-wavelength trench cut into the sidewalls 1020, 1030 of the waveguide. Since electromagnetic radiation exits the waveguide primarily through the parallel plate mode, suppressing this mode by using a quarter-wavelength choke trench serves to suppress undesired radiation. As shown, the quarter-wave choke 1620 may be cut horizontally (FIG. 34A), vertically (FIGS. 34A and 34B), or both horizontally and vertically (FIG. 34A) into one or both of the sidewalls 1020, 1030 of the open waveguide 1600; the quarter-wave choke 1620 may be in the bend 1520 as described, or may be strategically located elsewhere in the antenna system as disclosed herein to suppress undesired radiation.

[0091] 35A, 35B, and 35C in combination with FIG. 32A, FIG. 35A, 35B, and 35C show three versions of a block diagram longitudinal cross-section through a bend 1520 in a single channel open waveguide 1500 with electromagnetic radiation chokes 1621, 1622, 1623 as alternatives to those shown in FIG. 34A and 34B. Here, the alternative choke comprises a quarter-wave trench 1621 formed in the drafted sidewalls 1020, 1030 of the trough 1010 (FIG. 35A) and optionally combined with a cover 3000, a Bragg reflector 1622 dielectric or other electromagnetic reflector with total internal reflection properties used instead of the dielectric cover 3000, and a dielectric material 1623 with a high dielectric constant (Dk of 6 or more) used instead of the dielectric cover 3000.

[0092] 36A, 36B, 36C, and 36D in combination with FIG. 32A, FIG. 36A shows a rotated isometric perspective view of an open waveguide 1500 with one or more bends 1520 with modified bulkheads 1040 in the bends 1520, FIG. 36B shows a side perspective view thereof, and FIG. 36C and 36D show the associated electromagnetic performance characteristics of FIG. 36A and FIG. 36B. Here, a structural modification is made to the height Hs of the bulkhead 1040 in the waveguide 1500, such as by slowly tapering the height of the bulkhead from the original height Hs of the bend 1520 at both ends of the bend 1520 to a smaller height Hsm in the bend 1520, such that the electromagnetic waves are guided by the bulkhead-to-wall distance 1630. The open trough waveguide with a short bulkhead results in a tightly guided trough mode just above its cutoff frequency. The resulting mode tightly guides electromagnetic waves and radiates minimally around the bend because the mode is tightly confined to the diaphragms and walls.

[0093] 37A, 37B, 37C, and 37D in combination with FIG 32A, FIG 37A shows a rotated isometric perspective view, FIG 37B shows a top plan view, and FIG 37C and FIG 37D show the associated electromagnetic performance characteristics of FIG 37A and FIG 37B of an open waveguide 1500 having a bend 1520 with modified floor (base) structures 1050, 1060 within the bend 1520, where structural modifications are made to the inner surface of the open waveguide that affect the phase velocity and / or the waveguide impedance such that the phase velocity and / or the waveguide impedance are constant or nearly constant along the path of the bend. Because the trough waveguide can be thought of as two open rectangular waveguides with a bulkhead 1040 between them (see, e.g., FIG. 1), the waveguide on the outside of the bend 1520 (represented in FIG. 37B by associated base reference number 1060) has a longer travel path than the waveguide on the inside of the bend 1520 (represented in FIG. 37B by associated base reference number 1050). Thus, rather than traveling in phase along the bend, the two waveguide modes each generate a small amount of radiation and reach the end of the bend out of phase with each other. However, if the phase velocity of the outer waveguide gradually increases or the phase velocity of the inner waveguide gradually decreases, both guided waves will travel in phase such that their corresponding radiation components cancel each other out. In one embodiment, this is accomplished by gradually tapering the bottom (base) 1060 of the waveguide trough 1010 between the bulkhead 1040 and the corresponding sidewall 1020, 1030, with the tapered profile determining the most appropriate impedance as well as the correct compensating phase velocity. In the embodiment shown in Figure 37A, the bottom 1060 of the waveguide trough 1010 outside the bend 1520 tapers upwardly from the bulkhead 1040 toward the outer wall 1030. However, it is envisioned that other taper profiles of either of the bottom surfaces 1050, 1060 of the trough 1010 may be suitably employed consistent with the objectives disclosed herein.

[0094] 38 in combination with FIG 32A, FIG 38 shows a block diagram longitudinal cross-section through a bend 1520 of an open waveguide 1500 having a modified waveguide structure within the bend 1520, where other structural modifications are made to the internal features of the trough 1010 of the open waveguide 1500 within the bend 1520 that serve to keep the phase velocity and waveguide impedance constant along the bend 1520. Examples of such structural modifications may include one or more of the following: Changing the bed height of one trough trench (represented by base reference number 1050, see FIG. 1A) compared to the other trough trench (represented by base reference number 1060, see FIG. 1A), changing the width W5 of one trough trench 1050 compared to the width W6 of the other trough trench 1060, changing the lateral positioning of the bulkhead 1040 within the trough 1010 to add asymmetry to the structure of the open waveguide 1500, changing the thickness W4 of the bulkhead 1040, and changing the height H4 of the bulkhead 1040. Such structural modifications may vary along the length of the bend 1520.

[0095] FIG. 39A shows a rotated isometric perspective view of an open waveguide 1500 having a bend 1520 with modified wall structures 1020, 1030 within the bend 1520, FIG. 39B shows a top plan view thereof, and FIG. 39C and FIG. 39D show the associated electromagnetic performance characteristics of FIG. 39A and FIG. 39B. As discussed above, modifications to the trough waveguide 1500 within the bend 1520 can be used to tune the EM waves inside and outside the bend 1520 such that they travel in phase with each other such that corresponding radiation modes within the bend 1520 cancel each other out. The modifications in the bend 1520 act as a radiation suppressor and are configured to affect the phase velocity and waveguide impedance such that they are constant or nearly constant along the path length of one or more bends 1520. As mentioned above, the trough waveguide 1500, and in particular the trough waveguide bend 1520, may be considered as two open waveguides, an inner waveguide (represented by reference number 1050) inside the bend 1520, and an outer waveguide (represented by reference number 1060) outside the bend 1520, with the outer waveguide having a longer travel path than the inner waveguide of the bend. Thus, without modifications as disclosed herein, the two inner and outer waveguide modes do not travel along the bend in phase, generating undesired radiation along the bend. However, if the phase velocities of the inner and outer waveguides are adjusted such that both waves travel in phase, their corresponding radiation modes tend to cancel each other out. In addition to this, if adjustments are made to the impedances of the individual guides, their corresponding radiation modes tend to cancel each other out. An optional way to do this is to tape the bottom side of the trough, the location of the bulkhead within the trough, and the width of the trough, as discussed above in connection with Figures 37A, 37B, and 38, and further below in connection with Figures 40A-40E. In Figures 39A and 39B, another way to achieve the desired effect on the EM phase velocity and impedance within the bend 1520 is to recess the outer sidewall 1030 to narrow the width of the outer waveguide 1060 within the bend 1520, as best seen with reference to Figure 39B.A first sidewall of the one or more bends 1520 is referred to as the inner sidewall 1020, a second sidewall of the one or more bends 1520 is referred to as the outer sidewall 1030, a first base 1050 has a first width between the first sidewall 1020 and the bulkhead 1040, and a second base 1060 has a second width between the bulkhead 1040 and the second sidewall 1030, the first width being greater than the second width. By creating a width difference between the first width of the first base 1050 on the inside of the bend and the second width of the second base 1060 on the outside of the bend, tuning is achieved such that both waves travel in phase with equal wave impedance and their corresponding radiation modes are cancelled out.

[0096] 40A-40E in combination with FIG. 32A, FIG. 40A shows a block diagram longitudinal cross-sectional view through the open waveguide 1500 outside the bend 1520 of the open waveguide 1500, FIG. 40B shows a modified version of FIG. 40A with increased inductance in the bend 1520 of the open waveguide 1500, FIG. 40C shows a modified version of FIG. 40A with increased capacitance in the bend 1520 of the open waveguide 1500, and FIGs. 40D and 40E show the associated electromagnetic performance characteristics of FIGs. 40B and 40C, respectively.

[0097] In the embodiment shown by the combination of Figures 40A and 40B, the trough waveguide 1500 has a first depth D1 (shown in Figure 40A) to the first and second bases 1050 and 1060 on the outside of the one or more bends, and a second depth D2 (shown in Figure 40B) to the first and second bases 1050' and 1060' on the inside of the one or more bends, where the first depth D1 is greater than the second depth D2. By adjusting the depth of the first and second bases inside the bend relative to their respective depths outside the bend, a change in the inductive impedance of the waveguide can be achieved, and by providing a matching impedance through the inductance in the bend, both the inner and outer waves in the bend can be made to travel in phase such that their corresponding radiation modes cancel each other out.

[0098] 40A and 40C in combination, the bulkhead 1040 has a first wall thickness T1 on the outside of the one or more bends 1520 and a second wall thickness T2 on the inside of the one or more bends 1520, where the first wall thickness T1 is less than the second wall thickness T2. By adjusting the wall thickness of the bulkhead 1040' inside the bend 1520 versus outside the bend 1520, a change in capacitance of the waveguide 1500 can be achieved, and by providing a matching impedance through the capacitance in the bend, both the inside wave and the outside wave in the bend can be made to travel in phase such that their corresponding radiation modes cancel each other out.

[0099] 1A-40C collectively, it will be understood that various aspects of an embodiment are disclosed herein, including, but not limited to, at least the following aspects and / or combinations of aspects:

[0100] Aspect 1. A waveguide antenna system comprising: an electromagnetic (EM) transition portion having a transition region having a signal feed interface and an open waveguide section, the EM transition portion configured to couple EM energy from the signal feed interface through the transition region to the open waveguide section for a guided waveguide mode of the EM energy; and a leaky waveguide antenna portion configured and arranged to radiate electromagnetic energy received from the open waveguide section, the EM transition portion being electromagnetically coupled to the leaky waveguide antenna portion, the EM transition portion being configured to support transfer of electromagnetic energy from a signal feed structure to the leaky waveguide antenna portion.

[0101] Aspect 2. The waveguide antenna system of aspect 1, wherein the EM transition portion is configured to support transfer of electromagnetic energy from a planar signal feed structure to the leaky waveguide antenna portion.

[0102] Aspect 3. The waveguide antenna system of any one of aspects 1 or 2, wherein the open waveguide section comprises an open trough waveguide. Aspect 4. The waveguide antenna system of any one of Aspects 1 or 2, wherein the open waveguide section comprises an open groove waveguide.

[0103] Aspect 5. The waveguide antenna system of any one of aspects 1-4, wherein the open waveguide section is lacking a discontinuity along the length of each of the open waveguide sections, and the leaky waveguide antenna portion comprises a substantial discontinuity along the length of each of the leaky waveguide antenna portions, the open waveguide section is electromagnetically coupled to the leaky waveguide antenna portion by electromagnetic coupling between the open waveguide section and the leaky waveguide antenna portion, and a change in discontinuity transitions from the lack of discontinuity in the open waveguide section to the substantial discontinuity in the leaky waveguide antenna portion.

[0104] Embodiment 6. A waveguide antenna system including a plurality of the waveguide antenna systems of any one of embodiments 1-5 configured for antenna-on-package applications. Example 7. A waveguide antenna system comprising a plurality of the waveguide antenna systems of any one of Examples 1-5 configured for patch-on printed circuit board applications.

[0105] Aspect 8. The waveguide antenna system of Aspects 6 or 7, wherein in a transmit mode and configuration, each open waveguide section is arranged and configured to receive electromagnetic energy from an antenna-on-package component or a patch-on printed circuit board component and to transmit said electromagnetic energy to a corresponding leaky waveguide antenna portion, and wherein in a receive mode and configuration, each open waveguide section is arranged and configured to receive electromagnetic energy from a corresponding leaky waveguide antenna portion and to transmit said electromagnetic energy to the antenna-on-package component or a patch-on printed circuit board component.

[0106] Aspect 9. An open waveguide signal feed system comprising: a printed circuit board having a signal feed and a signal feed output; an open waveguide having a signal feed input port; and a transition region disposed between the signal feed output and the signal feed input port and in signal communication with the signal feed output and the signal feed input port, wherein the signal feed comprises a microstrip, a coplanar waveguide, or a stripline, and the signal feed output comprises a patch or a probe.

[0107] Example 10. The open waveguide signal feed system of Example 9, wherein the transition region comprises an enclosed waveguide. Example 11. The open waveguide signal feed system of example 9, wherein the transition region comprises an edge feed between the signal feed output and the signal feed input port.

[0108] Aspect 12. The open waveguide signal feed system of aspect 9, wherein the transition region comprises an opening at the signal feed output that is directly electromagnetically coupled to the signal feed input port.

[0109] Aspect 13. An open waveguide section comprising: one or more bends in a trough waveguide, the one or more bends being in a direction of electromagnetic wave propagation in the trough waveguide, the trough waveguide comprising a trough having opposing first and second sidewalls, a partition disposed between the first sidewall and the second sidewall, a first base disposed between the first sidewall and the partition, and a second base disposed between the partition and the second sidewall, and all surfaces inside the trough of at least the first sidewall, the second sidewall, the partition, the first base, and the second base are conductive; and an electromagnetic radiation suppressor strategically configured and positioned to suppress undesired electromagnetic radiation that may result from the one or more bends in the absence of such electromagnetic radiation suppressor.

[0110] Aspect 14. The open waveguide section of aspect 13, wherein the electromagnetic radiation suppressor includes an electromagnetic radiation absorbing material disposed above an upper open end of the one or more bends of the trough waveguide. Aspect 15. The open waveguide section of aspect 13, wherein the electromagnetic radiation suppressor comprises an electromagnetic choking mechanism disposed within the one or more bends of the trough waveguide.

[0111] Aspect 16. The open waveguide section of aspect 15, wherein the electromagnetic choking mechanism comprises one or more quarter wavelength trenches cut into each of the first sidewall and the second sidewall of the trough.

[0112] Aspect 17. The open waveguide section of aspect 16, wherein the one or more quarter wavelength trenches include one or more pairs of symmetrically arranged trenches disposed on the first sidewall and the second sidewall of the trough.

[0113] Example 18. The open waveguide section of example 16 or 17, wherein the one or more quarter wavelength trenches comprise a horizontal portion and an adjacent vertical portion. Aspect 19. The open waveguide section of aspect 16 or 17, wherein the first sidewall and the second sidewall of the trough have angled sidewalls, and the one or more quarter wavelength trenches are each formed in a corresponding angled sidewall.

[0114] Aspect 20. The open waveguide section of aspect 15, wherein the electromagnetic choking mechanism includes an electromagnetic reflector having total internal reflection (TIR) ​​properties in the form of a cover disposed over the upper open end of the one or more bends of the trough waveguide and extending across the one or more bends of the trough from the first sidewall to the second sidewall, the TIR reflector being made of a dielectric material having a dielectric constant that varies along a direction perpendicular to the cover to generate total internal reflection.

[0115] Aspect 21. The open waveguide section of aspect 15, wherein the electromagnetic choking mechanism comprises a dielectric material disposed above the upper open end of the one or more bends of the trough waveguide and extending across the one or more bends of the trough from the first sidewall to the second sidewall, the dielectric material being made of a dielectric material having a dielectric constant greater than 6.

[0116] Aspect 22. The open waveguide section of aspect 13, wherein the electromagnetic radiation suppressor comprises a modified bulkhead having a reduced height within the one or more bends that is less than an original height of the bulkhead outside the one or more bends.

[0117] Aspect 23. The open waveguide section of aspect 22, wherein the modified septum tapers gradually from the original height to the reduced height. Aspect 24. The open waveguide section of aspect 13, wherein the electromagnetic radiation suppressor comprises a modified inner surface of the trough within the one or more bends configured to affect one or both of the phase velocity and the waveguide impedance such that the one or both of the phase velocity and the waveguide impedance are constant or nearly constant along a path length of the one or more bends.

[0118] Aspect 25. The open waveguide section of aspect 24, wherein the modified inner surface of the trough comprises a tapered bottom surface of the waveguide trough between the partition and one or more of the first sidewall and the second sidewall.

[0119] Aspect 26. The open waveguide section of aspect 25, wherein the tapered bottom surface tapers upwardly from the bulkhead toward the outer wall outside the one or more bends. Aspect 27. The open waveguide section of aspect 24, wherein the modified inner surface of the trough includes a height difference between the first base of the trough and the second base of the trough.

[0120] Aspect 28. The open waveguide section of aspect 24, wherein the trough includes a first trough portion between the first sidewall and the partition and a second trough portion between the second sidewall and the partition, the first trough portion being disposed on an inner curvature of the one or more bends and the second trough portion being disposed on an outer curvature of the one or more bends, and further wherein the modified inner surface of the trough includes a width difference between the first trough portion and the second trough portion.

[0121] Aspect 29. The open waveguide section of aspect 24, wherein the modified inner surface of the trough includes a lateral positioning of the bulkhead within the one or more bends that is asymmetric relative to the first sidewall and the second sidewall.

[0122] Aspect 30. The open waveguide section of aspect 24, wherein the modified inner surface of the trough comprises a thickness of the septum within the one or more bends that is different from a thickness of the septum outside the one or more bends.

[0123] Aspect 31. The open waveguide section of aspect 24, wherein the first sidewall is an inner sidewall of the one or more bends, the second sidewall is an outer sidewall of the one or more bends, the first base has a first width between the first sidewall and the bulkhead forming a first trough portion disposed on an inner curvature of the one or more bends, and the second base has a second width between the bulkhead and the second sidewall forming a second trough portion disposed on an outer curvature of the one or more bends, and the first width is greater than the second width.

[0124] Aspect 32. The open waveguide section of aspect 31, wherein a cross-sectional width of the second trough portion inside the one or more bends is less than the corresponding cross-sectional width outside the one or more bends, thereby serving to increase the capacitance of the second trough portion inside the one or more bends.

[0125] Aspect 33. The open waveguide section of aspect 31 or 32, wherein a cross-sectional width of the first trough portion inside the one or more bends is greater than the corresponding cross-sectional width outside the one or more bends, thereby serving to reduce capacitance of the first trough portion inside the one or more bends.

[0126] Aspect 34. The open waveguide section of aspect 32, wherein the cross-sectional width of the second trough portion inside the one or more bends has a width dimension of 200 micrometers or less. Aspect 35. The open waveguide section of aspect 33, wherein the cross-sectional width of the first trough portion inside the one or more bends has a width dimension that is less than or equal to one-half a wavelength of an operating frequency of the open waveguide section inside the one or more bends.

[0127] Aspect 36. The open waveguide section of aspect 24, wherein the trough waveguide has a first depth relative to the first base and the second base on an outside of the curvature of the one or more bends and a second depth relative to the first base and the second base on an inside of the curvature of the one or more bends, the first depth on the outside of the curvature of the bend being greater than the second depth on the inside of the curvature of the bend.

[0128] Aspect 37. The open waveguide section of aspect 24 or aspect 36, wherein the trough includes a first trough portion between the first sidewall and the partition and a second trough portion between the second sidewall and the partition, and further wherein a cross-sectional depth of the second trough portion inside the one or more bends is less than the corresponding cross-sectional depth outside the one or more bends, thereby increasing the impedance of the second trough portion inside the one or more bends and, if present, serving to increase the phase velocity of electromagnetic waves propagating through the second trough portion.

[0129] Aspect 38. The open waveguide section of aspect 37, wherein a cross-section of the first trough portion inside the one or more bends has a depth greater than the corresponding cross-sectional depth outside the one or more bends, thereby reducing the impedance of the first trough portion inside the one or more bends and, if present, serving to reduce the phase velocity of electromagnetic waves propagating through the first trough portion.

[0130] Aspect 39. The open waveguide section of aspect 37, wherein the cross-sectional depth of the second trough portion is at least as deep as the partition is high. Aspect 40. The open waveguide section of aspect 38, wherein the cross-sectional depth of the first trough portion inside the one or more bends relative to the cross-sectional depth of the first trough portion outside the one or more bends increases by at most one-quarter of a wavelength of an operating frequency of the open waveguide section inside the one or more bends.

[0131] Aspect 41. The open waveguide section of aspect 24, wherein the partition has a first wall thickness on the outside of the one or more bends and a second wall thickness on the inside of the one or more bends, the first wall thickness being less than the second wall thickness.

[0132] Aspect 42. An open waveguide antenna comprising a trough having opposing first and second sidewalls, a bulkhead disposed between the first and second sidewalls, a first base disposed between the first and second sidewalls, and a second base disposed between the bulkhead and the second sidewall, wherein at least one or more of the first sidewall, the second sidewall, the bulkhead, the first base, and an interior surface of the trough of the second base are electrically conductive, and the first base is a first base disposed longitudinally along a length of the trough. an open waveguide antenna having a series of undulations, the first series of undulations alternatively and continuously following a first curved path and a second curved path, the second curved path being asymmetric with respect to the first curved path, the second base having a second series of undulations disposed longitudinally along the length of the trough, the second series of undulations alternatively and continuously following the second curved path and the first curved path, the first curved path and the second curved path alternating along the length of the trough from one side of the bulkhead to the other side of the bulkhead.

[0133] Aspect 43. The open waveguide antenna of aspect 42, wherein all surfaces within the troughs of the first base and the second base are conductive. Example 44. The open waveguide antenna of Example 42, wherein at least a portion of the first series of undulations comprises a dielectric material.

[0134] Aspect 45. The open waveguide antenna of aspect 42, wherein at least a portion of the second series of undulations comprises a dielectric material. Aspect 46. The open waveguide antenna of any one of aspects 42 to 45, wherein the trough is a monolithic non-conductive structure on which the conductive surface is formed.

[0135] Embodiment 47. The open waveguide antenna of any one of embodiments 42-46, wherein the bulkhead extends upward from the first base and the second base. Embodiment 48. The open waveguide antenna of any one of embodiments 42-47, wherein the first sidewall, the second sidewall, and the exposed surfaces of the bulkhead are not parallel to one another along the length of the trough.

[0136] Aspect 49. The open waveguide antenna of any one of aspects 42 to 48, wherein the height of the bulkhead is less than the height of the first sidewall or the second sidewall. Aspect 50. The open waveguide antenna of any one of aspects 42 to 49, wherein the bulkhead is centrally disposed between the first sidewall and the second sidewall.

[0137] Embodiment 51. The open waveguide antenna of any one of embodiments 42-50, wherein the first series of undulations and the second series of undulations are asymmetric with respect to the bulkhead. Embodiment 52. The open waveguide antenna of any one of embodiments 42-51, wherein the first series of undulations alternate in elevation along the length of the trough between the first curved path and the second curved path.

[0138] Embodiment 53. The open waveguide antenna of any one of embodiments 42-52, wherein the second series of undulations alternates in elevation along the length of the trough between the second curved path and the first curved path.

[0139] Aspect 54. The open waveguide antenna of any one of aspects 42 to 53, wherein when observed from a side view of the conductor trough, the first curved path is a first waveform having alternating peaks and valleys, and the first waveform is a combination of a smooth waveform multiplied by a square wave.

[0140] Aspect 55. The open waveguide antenna of aspect 54, wherein when observed from a side view of the conductor trough, the second curved path is a second waveform having alternating peaks and valleys, and the second waveform is a combination of a smooth waveform multiplied by a square wave.

[0141] Aspect 56. The open waveguide antenna of aspect 55, wherein the second smooth waveform and the first smooth waveform have different elevations in both peaks and valleys at all points between and within the ends of the trough.

[0142] Aspect 57. The open waveguide antenna of any one of aspects 42 to 56, further comprising a dielectric cover positioned over at least a portion of the length of the trough, covering and extending across the portion, and extending across the trough from the first sidewall to the second sidewall, the dielectric cover being made of a dielectric material having a dielectric constant greater than 1.

[0143] Aspect 58. The open waveguide antenna of aspect 57, wherein the upper outer surface of the dielectric cover has a longitudinal recess extending along the length of the trough. Aspect 59. The open waveguide antenna of aspect 58, wherein the longitudinal recess is centrally located along the length of the trough.

[0144] Embodiment 60. The open waveguide antenna of embodiment 58 or 59, wherein the longitudinal recess has a concave cross-sectional profile. Aspect 61. The open waveguide antenna of aspect 60, wherein the concave cross-sectional profile is representable by a polynomial curve.

[0145] Aspect 62. The open waveguide antenna of aspect 57, wherein the upper outer surface of the dielectric cover has a longitudinal protrusion extending along the length of the trough. Aspect 63. The open waveguide antenna of aspect 62, wherein the longitudinal protrusion is centrally disposed along the length of the trough.

[0146] Embodiment 64. The open waveguide antenna of embodiment 62 or 63, wherein the longitudinal protrusion has a convex cross-sectional profile. Example 65. The open waveguide antenna of Example 64, wherein the convex cross-sectional profile is representable by a polynomial curve.

[0147] Aspect 66. The open waveguide antenna of aspect 57, wherein the lower inner surface of the dielectric cover has a longitudinal recess extending along the length of the trough. Aspect 67. The open waveguide antenna of aspect 66, wherein the longitudinal recess is centrally located along the length of the trough.

[0148] Embodiment 68. The open waveguide antenna of embodiment 66 or 67, wherein the longitudinal recess has a concave cross-sectional profile. Aspect 69. The open waveguide antenna of aspect 68, wherein the concave cross-sectional profile is representable by a polynomial curve.

[0149] Aspect 70. The open waveguide antenna of aspect 57, wherein the lower inner surface of the dielectric cover has a longitudinal protrusion extending along the length of the trough. Aspect 71. The open waveguide antenna of aspect 70, wherein the longitudinal protrusion is centrally disposed along the length of the trough.

[0150] Example 72. The open waveguide antenna of example 70 or 71, wherein the longitudinal protrusion has a convex cross-sectional profile. Example 73. The open waveguide antenna of Example 72, wherein the convex cross-sectional profile is representable by a polynomial curve.

[0151] Embodiment 74. The open waveguide antenna of any one of embodiments 42-73 having a moldable configuration, the moldable configuration including one or more of: (i) a positive manufacturing feature that does not allow flat surface features to stick during a barrel electroplating process; (ii) one or more screw locations incorporated into the configuration; (iii) a shelled configuration to reduce material consumption and warping; (iv) an integrally formed recess to reduce the tendency to stick during electroplating; (v) a molded draft of 2 degrees or more on the top surface; (vi) a molded draft of 4 degrees or more on the bottom surface; and (vii) a molded parting line located proximate to the bottom surface.

[0152] Example 75. The open waveguide antenna of any one of Examples 42 to 73, wherein the trough is of die-cast construction. Embodiment 76. The open waveguide antenna of any one of embodiments 42 to 73, wherein the trough is an injection molded plastic construction.

[0153] Aspect 77. The open waveguide antenna of aspect 76, wherein the injection molded plastic structure is metallized to provide a conductive surface on the injection molded plastic structure.

[0154] Example 78. An open waveguide antenna system comprising the open waveguide antenna of any one of Examples 42 to 77, further comprising a signal feed port disposed at one end of the trough and an electrical short circuit disposed at an opposing second end of the trough.

[0155] Aspect 79. The open waveguide antenna system of aspect 78, further comprising a conductive surface disposed proximate to an upper end of the trough, the electrical short circuit being electrically connected to the conductive surface, and the conductive surface having an opening configured and arranged to expose the upper end of the trough for electromagnetic coupling with the upper end of the trough.

[0156] Aspect 80. The open waveguide antenna system of aspect 78 or 79, wherein the inductive transition from the patch to the trough is configured such that the patch E polarization is parallel to the bulkhead. Aspect 81. The open waveguide antenna system of aspect 78 or 79, wherein the inductive transition from the patch to the trough is configured such that the patch E polarization is perpendicular to the bulkhead.

[0157] Aspect 82. A multi-channel open waveguide antenna comprising a plurality of open waveguide antennas of any one of aspects 42 to 63 arranged in a parallel configuration, wherein the spacing between the centers of adjacent troughs is greater than or equal to λ / 2 and less than or equal to 10 times λ, where λ is a wavelength at an operating frequency of the multi-channel open waveguide antenna.

[0158] Aspect 83. The multi-channel open waveguide antenna of Aspect 82, wherein the parallel configuration is a multi-monolithic configuration. Aspect 84. The multi-channel open waveguide antenna of aspect 82 or 83, wherein the parallel configuration comprises multiple receiver channels and multiple transmitter channels.

[0159] Aspect 85. The multi-channel open waveguide antenna of aspect 84, wherein the plurality of receiver channels includes four or more receiver channels. Aspect 86. The multi-channel open waveguide antenna of aspect 84, wherein the plurality of transmitter channels includes three or more transmitter channels.

[0160] Aspect 87. An open waveguide antenna system comprising: a signal feed; an EM transition portion comprising a signal feed interface at a first end of the EM transition portion arranged in EM communication with the signal feed; and an open waveguide section having a second end opposite the first end; and an open waveguide antenna of any one of Aspects 42 to 61 arranged in EM communication with the second end of the EM transition portion, wherein the EM transition portion is configured to couple EM energy from the signal feed to the signal feed interface for guided waveguide modes of EM energy to the open waveguide section and to the open waveguide antenna.

[0161] Aspect 88. The open waveguide antenna system of aspect 87, wherein the signal feed includes any one of an antenna-in-package, a circuit board structure, a patch, a signal probe, a signal loop, and a signal aperture.

[0162] Example 89. An open waveguide antenna system comprising: an antenna-on-package; an open waveguide antenna of any one of Examples 42 to 61; and an EM transition portion disposed between the antenna-on-package and the open waveguide antenna and in EM signal communication with the antenna-on-package and the open waveguide antenna.

[0163] Aspect 90. The open waveguide antenna system of aspect 89, wherein the EM transition portion includes a ridge waveguide. Aspect 91. The open waveguide antenna system of aspect 89, wherein the EM transition portion includes a rectangular waveguide.

[0164] Aspect 92. The open waveguide antenna system of aspect 89, wherein the EM transition portion includes a waveguide bend. Some embodiments disclosed herein may have one or more of the following advantages: simultaneous achievement of high gain with minimal feed and transition losses, ability to tailor a given antenna pattern and high bandwidth, less sensitivity to small manufacturing variations than prior art DRA systems with dielectric waveguides, and a highly efficient antenna system formed by strategic merging of open waveguide sections and leaky waveguide antenna portions resulting in an antenna system applicable to modern multiple-input multiple-output (MIMO) automotive radar antennas.

[0165] As used herein, the phrase "about equal to" is intended to account for manufacturing tolerances and / or slight deviations from the nominal value that fall within the scope of the appended claims without departing from the objectives disclosed herein.

[0166] While specific combinations of individual features have been described and illustrated herein, it is understood that these specific combinations of features are for illustrative purposes only, and that any combination of any of such individual features may be used in accordance with an embodiment, whether or not such combination is explicitly illustrated, and is consistent with the disclosure of this specification. Any and all such combinations of features disclosed herein are contemplated herein and are considered to be within the understanding of one of ordinary skill in the art when considering this application as a whole, and are considered to be within the scope of the invention disclosed herein, as long as they are within the scope of the invention as defined by the appended claims, as understood by one of ordinary skill in the art.

[0167] Although the invention has been described herein with reference to exemplary embodiments, those skilled in the art will recognize that various changes may be made and elements may be substituted with equivalents without departing from the scope of the claims. Many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope of the invention. Therefore, the invention is not limited to the particular embodiment or embodiments disclosed herein as the best or only mode contemplated for carrying out the invention, but the invention is intended to include all embodiments that fall within the scope of the appended claims. In the drawings and description, exemplary embodiments have been disclosed and specific terms and / or dimensions may be used, but they are used in a general, illustrative and / or descriptive sense only and not for purposes of limitation, unless otherwise indicated, and therefore the claims are not so limited. When an element, such as a layer, film, region, substrate, or other described feature, is referred to as being "on" or "engaged" with another element, it may be directly on or engaged with the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on" or "directly engaged" with another element, there are no intervening elements. The use of terms such as first, second, etc. does not indicate a sequence or importance; rather, terms such as first, second, etc. are used to distinguish one element from another. The use of terms such as "a", "an", etc. does not indicate a limitation of quantity, but rather indicates the presence of one or more of the referenced items. The use of terms such as "top", "bottom", "up", "down", "left", "right", "front", "rear", etc., or any reference to orientation, does not indicate a limitation of a structure, since the structure may be viewed from more than one orientation, but rather indicates a relative structural relationship between one or more of the relevant features disclosed herein. As used herein, the term "comprising" does not exclude the possible inclusion of one or more additional features. Additionally, any background information provided herein is provided to make known information believed by applicant to be potentially relevant to the invention disclosed herein.No admission is necessarily intended, nor should it be construed, that any such background information constitutes prior art with respect to the embodiments of the present invention disclosed herein.

Claims

1. 1. A waveguide antenna system comprising: an electromagnetic (EM) transition portion comprising a transition region having a signal feed interface and an open waveguide section, the EM transition portion configured to couple EM energy from the signal feed interface through the transition region into the open waveguide section for guided waveguide modes of EM energy; a leaky waveguide antenna portion constructed and arranged to radiate electromagnetic energy received from the open waveguide section; 1. A waveguide antenna system, wherein the EM transition portion is electromagnetically coupled to the leaky waveguide antenna portion, the EM transition portion being configured to support the transfer of electromagnetic energy from a signal feed structure to the leaky waveguide antenna portion.

2. 10. The waveguide antenna system of claim 1, wherein the EM transition section is configured to support the transfer of electromagnetic energy from a planar signal feed structure to the leaky waveguide antenna section.

3. 3. The waveguide antenna system of claim 1, wherein the open waveguide section comprises an open trough waveguide.

4. 3. The waveguide antenna system of claim 1, wherein the open waveguide section comprises an open groove waveguide.

5. the open waveguide sections are devoid of discontinuities along the length of each of the open waveguide sections; the leaky waveguide antenna sections comprise a substantial discontinuity along the length of each of the leaky waveguide antenna sections; 3. The waveguide antenna system of claim 1, wherein the open waveguide section is electromagnetically coupled to the leaky waveguide antenna portion by electromagnetic coupling between the open waveguide section and the leaky waveguide antenna portion, and wherein a change in discontinuity transitions from the absence of discontinuity in the open waveguide section to the substantial discontinuity in the leaky waveguide antenna portion.

6. A waveguide antenna system comprising a plurality of the waveguide antenna systems of claim 1 or 2 configured for antenna-on-package applications.

7. A waveguide antenna system comprising a plurality of the waveguide antenna systems of claim 1 or 2 configured for patch-on printed circuit board applications.

8. In a transmit mode and configuration, each open waveguide section is positioned and configured to receive electromagnetic energy from an antenna-on-package component or a patch-on-printed circuit board component and to transmit said electromagnetic energy to a corresponding leaky waveguide antenna portion; 7. The waveguide antenna system of claim 6, wherein in a receive mode and configuration, each open waveguide section is positioned and configured to receive electromagnetic energy from a corresponding leaky waveguide antenna portion and to transmit said electromagnetic energy to an antenna-on-package component or a patch-on-printed circuit board component.

9. 1. An open waveguide signal feed system comprising: a printed circuit board having a signal feed and a signal feed output; an open waveguide having a signal feed input port; a transition region disposed between the signal feed output and the signal feed input port and in signal communication with the signal feed output and the signal feed input port; the signal feed comprises microstrip, coplanar waveguide, or stripline; An open waveguide signal feed system, wherein the signal feed output comprises a patch or a probe.

10. 10. The open waveguide signal feed system of claim 9, wherein the transition region comprises an enclosed waveguide.

11. 10. The open waveguide signal feed system of claim 9, wherein the transition region comprises an edge feed between the signal feed output and the signal feed input port.

12. 10. The open waveguide signal feed system of claim 9, wherein the transition region comprises an opening at the signal feed output that is directly electromagnetically coupled to the signal feed input port.

13. an open waveguide section, one or more bends in a trough waveguide, the one or more bends being in a direction of propagation of electromagnetic waves in the trough waveguide, the trough waveguide comprising a trough having opposing first and second sidewalls, a partition disposed between the first and second sidewalls, a first base disposed between the first and second sidewalls, and a second base disposed between the partition and the second sidewall, and all surfaces within the trough of at least the first sidewall, the second sidewall, the partition, the first base, and the second base are electrically conductive; an electromagnetic radiation suppressor strategically constructed and positioned to suppress undesired electromagnetic radiation that may otherwise arise from the one or more bends.

14. The open waveguide section of claim 13 , wherein the electromagnetic radiation suppressor comprises an electromagnetic radiation absorbing material disposed over an upper open end of the one or more bends of the trough waveguide.

15. The open waveguide section of claim 13 , wherein the electromagnetic radiation suppressor comprises an electromagnetic choking mechanism disposed within the one or more bends of the trough waveguide.

16. 16. The open waveguide section of claim 15, wherein the electromagnetic choking mechanism comprises one or more quarter wavelength trenches cut into each of the first and second sidewalls of the trough.

17. 17. The open waveguide section of claim 16, wherein the one or more quarter wavelength trenches comprise one or more pairs of symmetrically arranged trenches disposed on the first and second sidewalls of the trough.

18. 18. The open waveguide section of claim 16 or 17, wherein the one or more quarter wavelength trenches comprise a horizontal portion and an adjacent vertical portion.

19. 18. The open waveguide section of claim 16 or 17, wherein the first sidewall and the second sidewall of the trough have angled sidewalls, and the one or more quarter-wavelength trenches are each formed in a corresponding angled sidewall.

20. 16. The open waveguide section of claim 15, wherein the electromagnetic choking mechanism includes an electromagnetic reflector having total internal reflection (TIR) ​​properties in the form of a cover disposed over an upper open end of the one or more bends of the trough waveguide and extending across the one or more bends of the trough from the first sidewall to the second sidewall, the electromagnetic reflector being made of a dielectric material having a permittivity that varies along a direction perpendicular to the cover to produce total internal reflection.

21. 16. The open waveguide section of claim 15, wherein the electromagnetic choking mechanism comprises a dielectric material disposed above an upper open end of the one or more bends of the trough waveguide and extending across the one or more bends of the trough from the first sidewall to the second sidewall, the dielectric material comprising a dielectric material having a dielectric constant greater than 6.

22. 14. The open waveguide section of claim 13, wherein the electromagnetic radiation suppressor comprises a modified septum having a reduced height within the one or more bends that is less than an original height of the septum outside the one or more bends.

23. 23. The open waveguide section of claim 22, wherein the modified septum tapers gradually from the original height to the reduced height.

24. 14. The open waveguide section of claim 13, wherein the electromagnetic radiation suppressor comprises a modified inner surface of the trough in the one or more bends configured to affect one or both of a phase velocity and a waveguide impedance such that the one or both of the phase velocity and the waveguide impedance are constant or nearly constant along a path length of the one or more bends.

25. 25. The open waveguide section of claim 24, wherein the modified inner surface of the trough comprises a tapered bottom surface of the trough between the partition and one or more of the first sidewall and the second sidewall.

26. 26. The open waveguide section of claim 25, wherein the tapered bottom surface tapers upward from the bulkhead to an outer wall outside the one or more bends.

27. 25. The open waveguide section of claim 24, wherein the modified inner surface of the trough includes a height difference between the first base of the trough and the second base of the trough.

28. the trough includes a first trough portion between the first sidewall and the partition wall and a second trough portion between the second sidewall and the partition wall, the first trough portion being disposed on an inner curvature of the one or more bends and the second trough portion being disposed on an outer curvature of the one or more bends; and 25. The open waveguide section of claim 24, wherein the modified inner surface of the trough includes a width difference between the first trough portion and the second trough portion.

29. 25. The open waveguide section of claim 24, wherein the modified interior surface of the trough includes a lateral positioning of the partition within the one or more bends that is asymmetric with respect to the first sidewall and the second sidewall.

30. 25. The open waveguide section of claim 24, wherein the modified interior surface of the trough comprises a thickness of the septum within the one or more bends that is different from a thickness of the septum outside the one or more bends.

31. the first sidewall is an inner sidewall of the one or more bends; the second sidewall is an outer sidewall of the one or more bends; the first base has a first width that defines a first trough portion between the first sidewall and the partition that is disposed on an inner curve of the one or more bends; the second base has a second width between the bulkhead and the second sidewall that defines a second trough portion disposed at an outer curvature of the one or more bends; 25. The open waveguide section of claim 24, wherein the first width is greater than the second width.

32. 32. The open waveguide section of claim 31 , wherein a cross-sectional width of the second trough portion inside the one or more bends is less than a corresponding cross-sectional width outside the one or more bends, thereby serving to increase a capacitance of the second trough portion inside the one or more bends.

33. 33. The open waveguide section of claim 31 or 32, wherein a cross-sectional width of the first trough portion inside the one or more bends is greater than a corresponding cross-sectional width outside the one or more bends, thereby serving to reduce a capacitance of the first trough portion inside the one or more bends.

34. 33. The open waveguide section of claim 32, wherein the cross-sectional width of the second trough portion inside the one or more bends has a width dimension of 200 micrometers or less.

35. 34. The open waveguide section of claim 33, wherein the cross-sectional width of the first trough portion inside the one or more bends has a width dimension that is less than or equal to one-half a wavelength of an operating frequency of the open waveguide section inside the one or more bends.

36. the trough waveguide has a first depth relative to the first and second bases on an outer side of the curvature of the one or more bends and a second depth relative to the first and second bases on an inner side of the curvature of the one or more bends; 25. The open waveguide section of claim 24, wherein the first depth of the bend on an outer side of the curvature is greater than the second depth of the bend on an inner side of the curvature.

37. the trough includes a first trough portion between the first sidewall and the partition wall, and a second trough portion between the second sidewall and the partition wall; and 37. The open waveguide section of claim 24 or claim 36, wherein a cross-sectional depth of the second trough portion inside the one or more bends is less than a corresponding cross-sectional depth outside the one or more bends, thereby increasing the impedance of the second trough portion inside the one or more bends and serving to increase the phase velocity, if present, of electromagnetic waves propagating through the second trough portion.

38. 38. The open waveguide section of claim 37, wherein a cross-section of the first trough portion inside the one or more bends has a depth that is greater than the corresponding cross-sectional depth outside the one or more bends, thereby reducing the impedance of the first trough portion inside the one or more bends and serving to reduce the phase velocity, if present, of electromagnetic waves propagating through the first trough portion.

39. 38. The open waveguide section of claim 37, wherein the cross-sectional depth of the second trough portion is at least as deep as the height of the septum.

40. 39. The open waveguide section of claim 38, wherein the cross-sectional depth of the first trough portion inside the one or more bends relative to the cross-sectional depth of the first trough portion outside the one or more bends increases by at most one-quarter of a wavelength of an operating frequency of the open waveguide section inside the one or more bends.

41. the septum has a first wall thickness on an outer side of the one or more bends and a second wall thickness on an inner side of the one or more bends; 25. The open waveguide section of claim 24, wherein the first wall thickness is less than the second wall thickness.

42. An open waveguide antenna, a trough having opposing first and second side walls, a partition wall disposed between the first and second side walls, a first base disposed between the first and second side walls, and a second base disposed between the partition wall and the second side wall; at least one or more of the first sidewall, the second sidewall, the partition wall, the first base, and an interior surface of the trough of the second base are electrically conductive; the first base has a first series of undulations longitudinally disposed along the length of the trough; the first series of undulations alternately and consecutively follow a first curved path and a second curved path, the second curved path being asymmetric with respect to the first curved path; the second base has a second series of undulations longitudinally disposed along the length of the trough; the second series of undulations alternatively and consecutively follows the second curved path and the first curved path; The open waveguide antenna, wherein the first curved path and the second curved path alternate along the length of the trough from one side of the bulkhead to the other side of the bulkhead.

43. 43. The open waveguide antenna of claim 42, wherein all surfaces inside the troughs of the first base and the second base are conductive.

44. 43. The open waveguide antenna of claim 42, wherein at least a portion of the first series of undulations comprises a dielectric material.

45. 43. The open waveguide antenna of claim 42, wherein at least a portion of the second series of undulations comprises a dielectric material.

46. An open waveguide antenna according to any one of claims 42 to 45, wherein the trough is a monolithic non-conductive structure on which the electrically conductive surface is formed.

47. 46. ​​The open waveguide antenna of any one of claims 42 to 45, wherein the bulkhead extends upwardly from the first base and the second base.

48. 46. ​​The open waveguide antenna of any one of claims 42 to 45, wherein the exposed surfaces of the first sidewall, the second sidewall, and the bulkhead are not parallel to one another along the length of the trough.

49. 46. ​​The open waveguide antenna according to any one of claims 42 to 45, wherein the height of the partition wall is less than the height of the first side wall or the second side wall.

50. 46. ​​The open waveguide antenna of any one of claims 42 to 45, wherein the bulkhead is centrally located between the first sidewall and the second sidewall.

51. An open waveguide antenna according to any one of claims 42 to 45, wherein the first series of undulations and the second series of undulations are asymmetric with respect to the dividing wall.

52. 46. ​​The open waveguide antenna of any one of claims 42 to 45, wherein the first series of undulations alternates in elevation along the length of the trough between the first curved path and the second curved path.

53. 46. ​​The open waveguide antenna of any one of claims 42 to 45, wherein the second series of undulations alternates in elevation along the length of the trough between the second curved path and the first curved path.

54. 46. ​​The open waveguide antenna of claim 42, wherein when observed from a side view of the trough, the first curved path is a first waveform having alternating peaks and valleys, the first waveform being a combination of a smooth waveform multiplied by a square wave.

55. 55. The open waveguide antenna of claim 54, wherein when observed through a side view of the trough, the second curved path is a second waveform having alternating peaks and valleys, the second waveform being a combination of a smooth waveform multiplied by a square wave.

56. 56. The open waveguide antenna of claim 55, wherein the second said smooth waveform and the first said smooth waveform have different elevations in both peaks and valleys at all points between and inside the ends of the trough.

57. 46. ​​The open waveguide antenna of claim 42, further comprising a dielectric cover positioned over, covering, and extending across at least a portion of the length of the trough from the first side wall to the second side wall, the dielectric cover being made of a dielectric material having a dielectric constant greater than 1.

58. 58. The open waveguide antenna of claim 57, wherein an upper outer surface of said dielectric cover has a longitudinal depression extending along said length of said trough.

59. 59. The open waveguide antenna of claim 58, wherein said longitudinal depression is centrally located along said length of said trough.

60. 60. The open waveguide antenna of claim 58, wherein said longitudinal recess has a concave cross-sectional profile.

61. 61. The open waveguide antenna of claim 60, wherein said concave cross-sectional profile is representable by a polynomial curve.

62. 58. The open waveguide antenna of claim 57, wherein an upper outer surface of said dielectric cover has a longitudinal protrusion extending along said length of said trough.

63. 63. The open waveguide antenna of claim 62, wherein said longitudinal protrusion is centrally located along said length of said trough.

64. 63. The open waveguide antenna of claim 62, wherein said longitudinal projection has a convex cross-sectional profile.

65. 65. The open waveguide antenna of claim 64, wherein said convex cross-sectional profile is representable by a polynomial curve.

66. 58. The open waveguide antenna of claim 57, wherein a lower inner surface of said dielectric cover has a longitudinal recess extending along said length of said trough.

67. 67. The open waveguide antenna of claim 66, wherein said longitudinal depression is centrally located along said length of said trough.

68. 67. The open waveguide antenna of claim 66, wherein said longitudinal recess has a concave cross-sectional profile.

69. 69. The open waveguide antenna of claim 68, wherein said concave cross-sectional profile is representable by a polynomial curve.

70. 58. The open waveguide antenna of claim 57, wherein a lower inner surface of said dielectric cover has a longitudinal protrusion extending along said length of said trough.

71. 71. The open waveguide antenna of claim 70, wherein the longitudinal protrusion is centrally located along the length of the trough.

72. 71. The open waveguide antenna of claim 70, wherein said longitudinal projection has a convex cross-sectional profile.

73. 73. The open waveguide antenna of claim 72, wherein said convex cross-sectional profile is representable by a polynomial curve.

74. 46. ​​The open waveguide antenna of any one of claims 42 to 45, having a moldable configuration, The open waveguide antenna, wherein the moldable configuration includes one or more of: (i) a positive manufacturing feature that prevents flat surface features from sticking during a barrel electroplating process; (ii) one or more screw locations incorporated into the configuration; (iii) a shelled configuration to reduce material consumption and warpage; (iv) an integrally formed recess to reduce sticking tendency during electroplating; (v) a molded draft of 2 degrees or more on the top surface; (vi) a molded draft of 4 degrees or more on the bottom surface; and (vii) a molded parting line located proximate to the bottom surface.

75. An open waveguide antenna according to any one of claims 42 to 45, wherein the trough is of die-cast construction.

76. An open waveguide antenna according to any one of claims 42 to 45, wherein the trough is of injection moulded plastic construction.

77. 77. The open waveguide antenna of claim 76, wherein said injection molded plastic construction is metallized to provide a conductive surface on said injection molded plastic construction.

78. An open waveguide antenna system comprising the open waveguide antenna according to any one of claims 42 to 45, a signal feed port disposed at one end of the trough; an electrical short circuit disposed at an opposing second end of the trough.

79. a conductive surface disposed adjacent an upper end of the trough; the electrical short circuit is electrically connected to the conductive surface; 80. The open waveguide antenna system of claim 78, wherein said conductive surface has an opening constructed and arranged to expose said upper end of said trough for electromagnetic coupling with said upper end of said trough.

80. 80. The open waveguide antenna system of claim 78 wherein the guided transition from patch to trough is configured such that patch E polarization is parallel to said bulkhead.

81. 80. The open waveguide antenna system of claim 78 wherein the guided transition from patch to trough is configured such that patch E polarization is perpendicular to said bulkhead.

82. 46. ​​A multi-channel open waveguide antenna comprising a plurality of open waveguide antennas according to any one of claims 42 to 45 arranged in a parallel configuration, wherein the spacing between the centers of adjacent troughs is greater than or equal to λ / 2 and less than or equal to 10 times λ, where λ is a wavelength at an operating frequency of the multi-channel open waveguide antenna.

83. 83. The multi-channel open waveguide antenna of claim 82, wherein said parallel configuration is a multi-monolithic configuration.

84. 83. The multi-channel open waveguide antenna of claim 82, wherein the parallel configuration comprises multiple receiver channels and multiple transmitter channels.

85. 85. The multi-channel open waveguide antenna of claim 84, wherein said plurality of receiver channels comprises four or more receiver channels.

86. 85. The multi-channel open waveguide antenna of claim 84, wherein said plurality of transmitter channels comprises three or more transmitter channels.

87. 1. An open waveguide antenna system comprising: signal feed and an EM transition portion comprising: a signal feed interface at a first end of the EM transition portion disposed in EM communication with the signal feed; and an open waveguide section having a second end opposite the first end; and the open waveguide antenna of any one of claims 42 to 45, positioned in EM communication with the second end of the EM transition portion; the EM transition portion is configured to couple EM energy from the signal feed to the signal feed interface for guided waveguide modes of EM energy to the open waveguide section and the open waveguide antenna.

88. 88. The open waveguide antenna system of claim 87, wherein said signal feed comprises any one of an antenna-in-package, a circuit board structure, a patch, a signal probe, a signal loop, and a signal aperture.

89. Antenna on package; An open waveguide antenna according to any one of claims 42 to 45; an EM transition in EM signal communication with the antenna-on-package and the open waveguide antenna, and disposed between the antenna-on-package and the open waveguide antenna.

90. 90. The open waveguide antenna system of claim 89, wherein said EM transition comprises a ridge waveguide.

91. 90. The open waveguide antenna system of claim 89, wherein said EM transition comprises a rectangular waveguide.

92. 90. The open waveguide antenna system of claim 89, wherein said EM transition comprises a waveguide bend.

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