A circuit-to-waveguide transition structure

Abstract

The application discloses a circuit-to-waveguide conversion structure, comprising: a waveguide and a dielectric substrate, the waveguide is fixedly connected with the dielectric substrate, the waveguide is provided with a waveguide port for energy transfer with the dielectric substrate, an energy limiting part is provided around the waveguide port and is inwardly recessed, the energy limiting part is connected with the dielectric substrate to form a cavity, the opposite upper space of the cavity presents a high impedance surface to electromagnetic waves of a target working frequency band, the high impedance surface can inhibit the propagation of electromagnetic waves in the gap between the upper surface of the dielectric substrate and the lower surface of the waveguide, the transmission of space electromagnetic waves is inhibited, the dielectric substrate is provided with a circuit transmission line and a quasi-waveguide feeding part, the quasi-waveguide feeding part is oppositely arranged with the waveguide port, the end of the circuit transmission line is connected with the quasi-waveguide feeding part, and the quasi-waveguide feeding part is used for transmitting the energy on the circuit transmission line to the quasi-waveguide feeding part and generating excitation, and the electromagnetic wave transmission mode of the quasi-waveguide feeding part is consistent with the electromagnetic wave transmission mode in the waveguide.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic fields and microwave technology, and in particular to a circuit-to-waveguide conversion structure. Background Technology

[0002] The applications of microwaves and millimeter waves in wireless communication, automotive radar, and radar monitoring are gradually increasing. To successfully deploy microwave and millimeter wave systems, various types of transmission lines are typically used, with appropriate transitions to convert electromagnetic waves from one type of transmission line to another. Therefore, wave conversion transitions are particularly important. Rectangular waveguides are widely used in millimeter wave technology due to their low loss and excellent performance, commonly used for transmitting and radiating millimeter wave signals. Planar transmission lines such as microstrip lines, coplanar waveguides, striplines, and grounded coplanar waveguides are well-suited for microwave and millimeter wave integrated circuits. Therefore, to facilitate integration with active circuits and chips, metallic waveguides should transition to planar transmission lines. The performance of the circuit-to-waveguide conversion structure directly affects the performance of the entire microwave and millimeter wave system. This necessitates designing a low-loss, wide-bandwidth, low-cost, easily fabricated, and stable circuit-to-waveguide conversion structure for millimeter wave systems using integrated chips.

[0003] Currently, traditional circuit-to-waveguide conversion structures often suffer from several problems. Common methods for implementing circuit-to-waveguide conversion include printed antennas based on inserted waveguide structures or slotted microstrip coupling structures. However, the former suffers from high parasitic back radiation levels and high dielectric loss, while the latter has narrow bandwidth. Furthermore, impedance matching between the circuit signal and the waveguide is a critical issue due to differences in grounding current paths. Secondly, circuit structures are typically based on dielectric substrates, while waveguides are usually three-dimensional structures, and the two are often bonded together using a press-fit method. Therefore, gaps inevitably exist at the interface between the two, causing electromagnetic wave leakage during transmission in both the circuit and the waveguide. This leakage significantly increases energy coupling between different ports, deteriorating port isolation and increasing the risk of electromagnetic interference and electromagnetic compatibility (EMC) problems.

[0004] In summary, how to maintain low loss and stable transmission characteristics across a wide frequency band, while ensuring robustness during circuit and waveguide installation, and maintaining high isolation between ports even with low electrical connections between circuits and waveguides, thereby reducing the risk of system EMI and EMC, are urgent problems to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a circuit-to-waveguide conversion structure that maintains low loss and stable transmission characteristics over a wide frequency band, while ensuring robustness during circuit and waveguide installation.

[0006] In a first aspect, the present invention provides a circuit-to-waveguide conversion structure, comprising: a waveguide and a dielectric substrate, wherein the waveguide is fixedly connected to the dielectric substrate.

[0007] The waveguide has a waveguide port for energy transfer with the dielectric substrate. The waveguide port is surrounded by an inwardly recessed energy limiting part. The energy limiting part is connected to the dielectric substrate to form a cavity. The space above the cavity presents a high impedance surface to electromagnetic waves in the target operating frequency band. The high impedance surface can suppress the propagation of electromagnetic waves through the gap between the upper surface of the dielectric substrate and the lower surface of the waveguide, suppress the transmission of spatial electromagnetic waves, achieve high isolation between ports during multi-channel conversion, and meet the radio frequency characteristics of the waveguide and the dielectric substrate under low electrical assembly.

[0008] The dielectric substrate has a circuit transmission line and a quasi-waveguide feed section. The quasi-waveguide feed section is disposed opposite to the waveguide port. The end of the circuit transmission line is connected to the quasi-waveguide feed section to transfer energy from the circuit transmission line to the quasi-waveguide feed section and generate excitation.

[0009] The electromagnetic wave transmission mode of the quasi-waveguide feed section is consistent with the electromagnetic wave transmission mode within the waveguide.

[0010] Preferably, the quasi-waveguide feed section includes:

[0011] A power supply probe is used to transfer energy from the circuit transmission line to excite the resonant cavity;

[0012] A resonant cavity is used for power transmission. The resonant cavity is surrounded by a metal hole, and one or more metal pillars can be added inside the resonant cavity to adjust the matching.

[0013] A transmission cavity is used to output the energy of the quasi-waveguide feed section. The output port of the transmission cavity is arranged opposite to the waveguide port. Part of the dielectric is removed from the inside of the transmission cavity, and several metal holes are distributed around the transmission cavity. The transmission mode inside the transmission cavity is consistent with the transmission mode of the rectangular waveguide, which is used to enable the continuous transmission of electromagnetic waves at the interface and realize the transition from the dielectric substrate to the waveguide.

[0014] Matching cavities are used to optimize the impedance matching of the quasi-waveguide feed section. The resonant cavity is surrounded by a metal aperture, and the matching cavity is located on one or more sides of the transmission cavity.

[0015] Preferably, the output port of the transmission cavity is electrically connected to the waveguide port.

[0016] Preferably, the dielectric substrate is a multilayer board structure with more than or equal to 4 layers, including metallized holes, which together with the dielectric substrate form the resonant cavity, transmission cavity and matching cavity in the quasi-waveguide feed section.

[0017] Preferably, the resonant cavity, transmission cavity, and matching cavity within the quasi-waveguide feed section are constituted by transmission lines formed from the dielectric substrate, wherein the transmission lines include one or more of substrate integrated waveguides, gap waveguides, or other quasi-waveguide transmission lines.

[0018] Preferably, the circuit transmission line includes any one of the following radio frequency transmission lines: coplanar waveguide, grounded coplanar waveguide, microstrip line, stripline, and probe.

[0019] Preferably, the waveguide contains a waveguide transmission line, and when the waveguide transmission line is distributed horizontally, a stepped transition waveguide is provided between the waveguide port and the waveguide transmission line to realize the conversion of electromagnetic wave propagation between the vertical and horizontal directions.

[0020] Preferably, the energy limiting part is a groove structure, and by adjusting the depth and width of the groove structure, the cavity formed by the energy limiting part and the dielectric substrate presents a high impedance surface to electromagnetic waves in the target operating frequency band.

[0021] Preferably, the conversion structure is configured as a single-channel or multi-channel structure.

[0022] Secondly, the present invention also provides an electronic device including a circuit-to-waveguide conversion structure as described in any of the above claims.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects: by designing a quasi-waveguide feed section, the energy on the circuit transmission line is transferred to the waveguide. On the one hand, the transmission cavity in the quasi-waveguide feed section has the same transmission mode as the waveguide transmission mode. The transmission cavity is arranged opposite to the waveguide. The transmission cavity transfers the energy of the quasi-waveguide feed section to the waveguide. The consistent mode makes the propagation of the circuit layer and the waveguide layer at the interface more continuous. In low electrical assembly, even if there are some gaps between the circuit layer and the waveguide layer, the performance stability of the transition structure can still be met, and the performance requirements of low reflection coefficient, low loss and wide bandwidth can be achieved. On the other hand, considering practical multi-port application scenarios, an inwardly recessed energy limiting part is introduced around the waveguide port on the waveguide side. The energy limiting part is connected to the dielectric substrate to form a cavity. The space above the cavity presents a high-impedance surface to electromagnetic waves in the target operating frequency band. The high-impedance surface can suppress the propagation of electromagnetic waves through the gap between the upper surface of the dielectric substrate and the lower surface of the waveguide, thereby suppressing the transmission of spatial electromagnetic waves and achieving high isolation between ports during multi-channel conversion. This ensures that the waveguide and the dielectric substrate can maintain high isolation even under low electrical assembly conditions. It reduces the risk of system electromagnetic interference and electromagnetic compatibility problems, and also has the advantages of easy processing and assembly. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1-1 This is an overall three-dimensional view of the grounded coplanar waveguide-to-waveguide conversion structure in Embodiment 1 of the present invention;

[0026] Figure 1-2 This is a side view of a grounded coplanar waveguide-to-waveguide conversion structure in one embodiment of the present invention;

[0027] Figure 2-1 This is a side view of the dielectric substrate of the grounded coplanar waveguide in an embodiment of the present invention, showing the grounded coplanar waveguide-to-waveguide conversion structure.

[0028] Figure 2-2 This is a top view of the dielectric substrate of the grounded coplanar waveguide in an embodiment of the present invention, showing the grounded coplanar waveguide-to-waveguide conversion structure.

[0029] Figure 3-1 This is a three-dimensional schematic diagram of the bottom of waveguide 11 in a waveguide-to-ground coplanar waveguide conversion structure according to an embodiment of the present invention;

[0030] Figure 3-2 This is a side view of waveguide 11 in a grounded coplanar waveguide-to-waveguide conversion structure according to an embodiment of the present invention;

[0031] Figure 4-1 In one embodiment of the present invention, a grounded coplanar waveguide to waveguide conversion structure is implemented to transmit the electric field distribution within the cavity in the quasi-waveguide feed section on the dielectric substrate side;

[0032] Figure 4-2 The electric field distribution at the waveguide port on the waveguide side is shown in an example of the grounded coplanar waveguide to waveguide conversion structure in this invention.

[0033] Figure 5-1 This is a three-dimensional schematic diagram of a two-channel circuit-to-waveguide conversion structure according to an embodiment of the present invention;

[0034] Figure 5-2 This is a side view of an embodiment of the two-channel circuit-to-waveguide conversion structure of the present invention;

[0035] Figure 6 The reflection coefficient curve of the circuit-to-waveguide conversion structure of the second channel of the present invention is shown.

[0036] Figure 7 This is a comparison diagram of the insertion loss under different degrees of gaps between the circuit and the waveguide in the circuit-to-waveguide conversion structure of the second channel of the present invention.

[0037] Figure 8 This is a comparison diagram of the channel isolation under different degrees of gaps between the circuit and the waveguide in the second embodiment of the present invention.

[0038] Figure 9 This is an overall schematic diagram of the circuit-to-waveguide conversion structure of the second channel of the present invention;

[0039] Figure 10-1 This is a top view of the dielectric substrate of the probe-to-waveguide conversion structure according to Embodiment 2 of the present invention;

[0040] Figure 10-2 This is a bottom view of the dielectric substrate of the probe-to-waveguide conversion structure in Embodiment 2;

[0041] Figure 11 This is a top view of a traditional two-channel circuit to waveguide conversion structure;

[0042] Figure 12 This is a comparison of insertion loss for a traditional circuit-to-waveguide conversion structure, with and without a gap between the circuit and the waveguide.

[0043] Figure 13 This is a comparison diagram of channel isolation for traditional circuit-to-waveguide conversion structures, with and without gaps between the circuit and the waveguide. Detailed Implementation

[0044] The following will describe in more detail a circuit-to-waveguide conversion structure of the present invention with reference to schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being broadly known to those skilled in the art and is not intended to limit the invention.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0046] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0047] Example 1

[0048] like Figure 1-1 and Figure 1-2 As shown in Figure 2, this embodiment provides a circuit-to-waveguide conversion structure, including a waveguide 11 and a dielectric substrate 12, wherein the waveguide 11 and the dielectric substrate 12 are fixedly connected. As shown in Figure 2, the dielectric substrate in this embodiment has a 4-layer structure, consisting of metal layer 1201, metal layer 1202, metal layer 1203, and metal layer 1204 from top to bottom.

[0049] The waveguide 11 is provided with a waveguide port 26 for energy transfer with the dielectric substrate 12. It is surrounded by an inwardly recessed energy limiting part 27. The energy limiting part 27 is connected to the dielectric substrate 12 to form a cavity. The space above the cavity presents a high impedance surface to electromagnetic waves in the target operating frequency band. The high impedance surface can suppress the propagation of electromagnetic waves through the gap between the upper surface of the dielectric substrate 12 and the lower surface of the waveguide 11. The space above the cavity refers to the space above the groove, facing the dielectric substrate 12, that is, the part between the groove structure and the dielectric substrate 12.

[0050] The dielectric substrate 12 is provided with a circuit transmission line 20 and a quasi-waveguide feed section 21. The quasi-waveguide feed section 21 includes a feed probe 22, a resonant cavity 23, a transmission cavity 24, and a matching cavity 25. The transmission cavity 24 is arranged opposite to the waveguide port 26. The transmission end of the circuit transmission line 20 is connected to the feed probe 22 to transfer the energy on the circuit transmission line 20 to the feed probe 22 and excite the resonant cavity 23, which in turn is transmitted to the transmission cavity 24.

[0051] The energy limiting part 27 suppresses the propagation of spatial electromagnetic waves and achieves high isolation between ports during multi-channel conversion; the quasi-waveguide feeding part 21 converts the transmission mode on the circuit transmission line into the transmission mode in the rectangular waveguide, that is, the output mode of the transmission cavity is consistent with the transmission mode in the waveguide. The consistency of the mode makes the electromagnetic energy transition from the dielectric substrate to the waveguide more consistent, and satisfies the radio frequency characteristics of the waveguide 11 and the dielectric substrate 12 under low electrical assembly.

[0052] This embodiment describes a circuit-to-waveguide conversion structure operating in the 76-81 GHz frequency band. (Refer to...) Figure 1-1 This is an overall schematic diagram of the circuit-to-waveguide conversion structure of the embodiment, including waveguide 11 and dielectric substrate 12.

[0053] refer to Figure 2-1 and 2-2 The images show a side view and a top view of the dielectric substrate of the grounded coplanar waveguide-to-waveguide conversion structure in this embodiment. In this embodiment, the circuit transmission line 20 is a grounded coplanar waveguide, and the quasi-waveguide feed section 21 is based on a substrate integrated waveguide (SIW) structure. The quasi-waveguide feed section 21 includes a feed probe 22, a resonant cavity 23, a transmission cavity 24, and a matching cavity 25.

[0054] The transmission end of the circuit transmission line 20 is connected to the power supply probe 22, which is implemented by a metallized hole and inserted into the resonant cavity 23 to transfer the energy on the circuit transmission line 20 to the power supply probe 22 and excite the resonant cavity 23.

[0055] The feed probe 22 consists of a feed metal via 2201 and a ground metal blind via 2202. The feed metal via 2201 extends from the layer containing the circuit transmission line 20 into the resonant cavity 23. In this embodiment, it penetrates to the top layer of the resonant cavity 23. Because through-holes are easier to fabricate, a through-hole is directly used in this example, penetrating from metal layers 1204 to 1201. The specific design can be adjusted according to the actual dielectric substrate structure; this is merely an example and not a limitation. The ground metal blind via 2302 penetrates metal layers 1204 and 1203 and is arranged around the metal pillar 2301 to prevent energy from propagating horizontally in the dielectric substrate, thus avoiding unnecessary resonance or crosstalk.

[0056] The resonant cavity 23 is formed by grounding metallized vias 2302 arranged at a certain period, surrounding the dielectric region 2301. One or more matching posts 2303 can be added inside to adjust the matching, achieved through the metallized vias. For ease of fabrication, in this example, the grounding metallized vias 2302 are through-hole structures penetrating four metal layers, used for connecting the layers of the dielectric substrate 12 and forming the resonant cavity. The matching posts are also formed by metallized vias. In this example, a metallized through-hole is provided at a certain distance above and below the feed probe as a matching post to achieve better impedance matching.

[0057] Energy enters the transmission cavity 24 through the resonant cavity 23. The transmission cavity 24 is formed by a metallized aperture 2402 surrounding the dielectric region 2401. A portion of the dielectric region 2401 has the dielectric removed, forming an air-filled cavity structure 2403. The metallized aperture 2402 serves as a connection between the layers of the dielectric substrate 12 and restricts the propagation of electromagnetic waves within the area enclosed by the metal aperture 2402. The air cavity reduces dielectric loss and allows the aperture size of the transmission cavity 24 to be similar to the waveguide port 26 on the waveguide side of Figure 3, resulting in a smoother transition of electromagnetic waves at the interface and reduced energy reflection. Because of the reduced dielectric loss, the overall design requirements for the dielectric substrate material can be significantly lowered. When the required length of the circuit transmission line 20 is short and the loss is within acceptable limits, or when the feed probe 22 of the quasi-waveguide feed section 21 is directly connected to the chip pad without the need for the circuit transmission line 20, even in the millimeter-wave band, a common low-frequency board can be used instead of an expensive high-frequency board that still has low-loss characteristics at high frequencies, greatly reducing costs. Simultaneously, the master mode TE10 mode of transmission within the transmission cavity 24 is consistent with the transmission mode within the waveguide port 26, resulting in better continuity in the transition. Figure 4-1 The electric field distribution within the transmission cavity 24 in the quasi-waveguide feed section on the dielectric substrate side is shown. Figure 4-2 The electric field distribution at waveguide port 26 on the waveguide side is given, and it can be seen that the two electric field distributions are consistent.

[0058] A matching cavity 25 is provided on one side of the transmission waveguide, which is formed by a plurality of grounding metal vias 2502 at a certain period. The grounding metal vias 2602 penetrate four copper layers and are used for the connection between the layers of the dielectric substrate 12, and form a matching cavity to enable the quasi-waveguide feed section 21 to achieve a wider matching bandwidth. The resonant cavity 23, the transmission cavity 24 and the matching cavity 25 are interconnected.

[0059] Refer to Figure 3. Figure 3-1This is a three-dimensional schematic diagram of the bottom of waveguide 11, representing the circuit-to-waveguide conversion structure of Embodiment 1. The waveguide port 26 is positioned opposite the transmission cavity 24 of the dielectric substrate 12. To enhance the isolation between channels during multi-channel conversion, the waveguide port 26 is surrounded by recessed energy-limiting portions 27. By reasonably adjusting the depth and width of the cavity, the space above the recessed structure opposite the dielectric substrate 12 presents a high-impedance surface for electromagnetic waves in the target operating frequency band. This high-impedance surface can suppress the horizontal propagation of electromagnetic waves, i.e., suppress the propagation of electromagnetic waves through the gap between the upper surface of the dielectric substrate 12 and the bottom of the waveguide 11. The groove depth is generally about 1 / 4λg, and the optimal size can be obtained through optimization. At this time, the electromagnetic waves on the surface of the waveguide port 31 are confined around the port by the surrounding energy-limiting portions 32, reducing energy leakage, minimizing the impact on adjacent ports, and improving isolation.

[0060] like Figure 3-2 As shown, a waveguide transmission line is provided within the waveguide 11. When the waveguide transmission line is horizontally distributed, a stepped transition waveguide is provided between the waveguide port and the waveguide transmission line to achieve the conversion of electromagnetic wave propagation between the vertical and horizontal directions. This can be understood as follows: when the waveguide transmission line is horizontally distributed, a stepped transition waveguide can be added between the waveguide port and the waveguide transmission line to better achieve the conversion of electromagnetic wave propagation between the vertical and horizontal directions.

[0061] Referring to Figures 1 and 3, this embodiment employs recessed energy limiting sections 27 around the waveguide port 26 to maintain low loss and stable transmission characteristics across a wide frequency band, while ensuring robustness during circuit and waveguide installation and maintaining high isolation between ports even with low electrical connections between the circuit and waveguide. This suppresses the propagation of spatial electromagnetic waves. Furthermore, the quasi-waveguide feed section 21 is designed to convert the transmission mode on the circuit transmission line 20 into the transmission mode within the rectangular waveguide. That is, the transmission mode of the transmission cavity 24 is consistent with the transmission mode within the waveguide 11. This consistency in mode provides better transmission continuity, allowing energy to transition more effectively from the dielectric substrate 12 to the waveguide 11. Moreover, good RF characteristics are maintained even when the waveguide 11 and the dielectric substrate 12 are assembled with low electrical connections.

[0062] To illustrate the performance under low electrical assembly conditions, Figure 5-1 and Figure 5-2 A three-dimensional schematic diagram and side view of the two-channel circuit to waveguide conversion structure are given, including waveguide 11 and dielectric substrate 12.

[0063] refer to Figure 6 , Figure 6 This is a reflection coefficient curve of the circuit-to-waveguide conversion structure for the second embodiment. This conversion structure has a reflection coefficient below -10dB in the 76GHz-81GHz frequency band. (Reference) Figure 7 , Figure 7 This is a comparison of the insertion loss of the circuit-to-waveguide conversion structure in Example 2, where there are different degrees of gaps between the dielectric substrate 12 (where the circuit is located) and the waveguide 11. It can be seen that when the air gap between the circuit and the waveguide increases to 0.6 mm, the insertion loss of the conversion structure within the target bandwidth remains relatively stable, with a maximum loss below 1.4 dB. (Reference) Figure 8 , Figure 8 This is a comparison of the channel isolation under different degrees of gaps between the circuit and the waveguide in Example 2. It can be seen that when the air gap between the grounded coplanar waveguide and the waveguide increases to 0.6mm, the isolation of the conversion structure is still greater than 48dB, demonstrating high isolation. This fully illustrates that the input ports of this two-channel circuit-to-waveguide conversion structure have good impedance matching, and the loss of each channel before and after conversion is low, making it suitable for various scenarios. The isolation between the ports also fully demonstrates the feasibility and advantages of the isolation scheme used in this design.

[0064] It should be noted that this embodiment only provides an explanation of the two-channel circuit-to-waveguide conversion structure, and its structure can be a single-channel, two-channel, three-channel, four-channel, or other multi-channel conversion structure.

[0065] Example 2

[0066] This embodiment describes a two-channel circuit-to-waveguide conversion structure operating in the 76-81GHz frequency band, referenced... Figure 9 , Figure 9 This is an overall schematic diagram of the circuit-to-waveguide conversion structure of the channel in Embodiment 2, including waveguide 11 and dielectric substrate 12.

[0067] refer to Figure 10-1 and Figure 10-2 This is a top view of the dielectric substrate of the probe-to-waveguide conversion structure in Embodiment 2. A quasi-waveguide feed section 22 is disposed on the dielectric substrate 12. The quasi-waveguide feed section 22 consists of a feed probe 22, a resonant cavity 23, a transmission cavity 24, and a matching cavity 25. The feed probe 22 is directly connected to the chip pads. Energy is fed in by the feed probe 22, exciting the resonant cavity 23, and then the energy is transferred to the transmission cavity 24, transitioning from the transmission cavity 24 to the waveguide 11. The output mode of the transmission cavity 25 is consistent with the transmission mode within the waveguide 11. This consistency allows for a better transition of energy from the dielectric substrate 12 to the waveguide 11, and maintains good RF characteristics even when the waveguide 11 and the dielectric substrate 12 are assembled with low electrical resistance.

[0068] Please refer to Figure 11Traditional circuit-to-waveguide conversion structures achieve this conversion through a microstrip coupling structure between the waveguide and the dielectric substrate. While the microstrip coupling structure can couple and excite the resonance at the waveguide port, its own radiation mode differs from that within the cavity waveguide. When there is a loose electrical connection between the dielectric substrate and the waveguide (i.e., a gap of 0.6 mm), the insertion loss and channel isolation of traditional circuit-to-waveguide conversion structures deteriorate rapidly. (Reference) Figure 12 and Figure 13 , Figure 12 This is a comparison of insertion loss in a traditional circuit-to-waveguide conversion structure, with and without a gap between the circuit and the waveguide. Figure 13 This image shows a comparison of channel isolation in a traditional circuit-to-waveguide conversion structure with and without a gap between the circuit and the waveguide. The structure in this patented invention maintains both low insertion loss and high channel isolation even with a 0.6mm assembly gap between the circuit and the waveguide.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circuit-to-waveguide conversion structure, characterized in that, include: A waveguide and a dielectric substrate, wherein the waveguide is fixedly connected to the dielectric substrate. The waveguide has a waveguide port for energy transfer with the dielectric substrate. The waveguide port is surrounded by an inwardly recessed energy limiting part. The energy limiting part is connected to the dielectric substrate to form a cavity. The space above the cavity presents a high impedance surface to electromagnetic waves in the target operating frequency band. The high impedance surface can suppress the propagation of electromagnetic waves through the gap between the upper surface of the dielectric substrate and the lower surface of the waveguide, suppress the transmission of spatial electromagnetic waves, achieve high isolation between ports during multi-channel conversion, and meet the radio frequency characteristics of the waveguide and the dielectric substrate under low electrical assembly. The dielectric substrate is provided with a circuit transmission line and a quasi-waveguide feed section. The quasi-waveguide feed section is arranged opposite to the waveguide port. The end of the circuit transmission line is connected to the quasi-waveguide feed section to transfer energy from the circuit transmission line to the quasi-waveguide feed section and generate excitation. The electromagnetic wave transmission mode of the quasi-waveguide feed section is consistent with the electromagnetic wave transmission mode in the waveguide. The quasi-waveguide feed section includes: A power supply probe is used to transfer energy from the circuit transmission line to excite the resonant cavity; The resonant cavity is used for power transmission. The resonant cavity is surrounded by a metal hole. One or more metal pillars can be added inside the resonant cavity to adjust the matching. A transmission cavity is used to output the energy of the quasi-waveguide feed section. The output port of the transmission cavity is arranged opposite to the waveguide port. Part of the dielectric is removed from the inside of the transmission cavity, and several metal holes are distributed around the transmission cavity. The transmission mode inside the transmission cavity is consistent with the transmission mode of the rectangular waveguide, which is used to enable the continuous transmission of electromagnetic waves at the interface and realize the transition from the dielectric substrate to the waveguide. A matching cavity is used to optimize the impedance matching of the quasi-waveguide feed section. The resonant cavity is surrounded by a metal aperture and is located on one or more sides of the transmission cavity.

2. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The output port of the transmission cavity is electrically connected to the waveguide port.

3. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The dielectric substrate is a multilayer board structure with more than or equal to 4 layers, including metallized holes. The metallized holes and the dielectric substrate together form the resonant cavity, transmission cavity and matching cavity in the quasi-waveguide feed section.

4. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The resonant cavity, transmission cavity, and matching cavity within the quasi-waveguide feed section are formed by transmission lines formed from the dielectric substrate. The transmission lines include one or more types of substrate integrated waveguides, gap waveguides, or other quasi-waveguide transmission lines.

5. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The circuit transmission line includes any one of the following radio frequency transmission lines: coplanar waveguide, grounded coplanar waveguide, microstrip line, stripline, and probe.

6. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The waveguide contains a waveguide transmission line. When the waveguide transmission line is distributed horizontally, a stepped transition waveguide is provided between the waveguide port and the waveguide transmission line to realize the conversion of electromagnetic wave propagation between the vertical and horizontal directions.

7. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The energy limiting part is a groove structure. By adjusting the depth and width of the groove structure, the cavity formed by the energy limiting part and the dielectric substrate presents a high impedance surface to electromagnetic waves in the target operating frequency band.

8. The circuit-to-waveguide conversion structure as described in claim 1, characterized in that, The conversion structure is configured as a single-channel or multi-channel structure.

9. An electronic device, characterized in that, Includes the circuit-to-waveguide conversion structure as described in any one of claims 1-8.

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