Antenna device

Abstract

The present disclosure relates to an antenna device (1) comprising a printed circuit board (2) with a back face (21) and a front face (22). At least one fist high frequency component (3) is configured to transmit and / or receive a radar signal. An antenna layer (4) with a back face (41) and a front face (42) comprises at least one waveguide channel (5) extending from a first waveguide aperture (51) on the back face (41) through the antenna layer (4) to a second waveguide aperture (52) on the front face (42). The back face (41) of the antenna layer (4) is at least partially arranged on the front face (22) of the printed circuit board (2) and the at least one high frequency component (3) is arranged on the back face (21) of the printed circuit board (2) and configured to transmit and / or receive a radar signal to and / or from the first waveguide aperture (51) of the at least one waveguide channel (5) through the printed circuit board (2). At least one signal transmission path (6) is configured to propagate a local oscillator signal from a local oscillator to the at least one first high frequency component (3).

Description

[0001] P28850PC00

[0002] 1 / 49

[0003] Antenna Device

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to an antenna device comprising an antenna arrangement for use in automotive radar applications.

[0006] BACKGROUND OF THE INVENTION

[0007] US2023350008A1 published on 02.11.2023 on behalf of Robert Bosch GmbH relates to a radar sensor. The radar sensor includes an antenna device which at least emits a radar signal, an integrated high frequency component which generates the radar signal, a waveguide structure which transmits the radar signal between the antenna device and the integrated high frequency component and includes at least one waveguide, a signal transmission path for transmitting a local oscillator signal, on which the generated radar signal is based, within the radar sensor. At least portions of the signal transmission path are disposed within the waveguide structure.

[0008] US2023268630A1 published on 24.08.2023 on behalf of Infineon Technologies AG relates to a method for producing a waveguide in a multilayer substrate, the method involving producing at least one cutout corresponding to a lateral course of the waveguide in a surface of a first layer arrangement comprising one or a plurality of layers. A metallization is produced on surfaces of the cutout. A second layer arrangement comprising one or a plurality of layers is applied on the first layer arrangement. The second layer arrangement comprises, on a surface P28850PC00

[0009] 2 / 49 thereof, a metallization which, after the second layer arrangement has been applied on the first layer arrangement, is arranged above the cutout and together with the metallization on the surfaces of the cutout forms the waveguide.

[0010] SUMMARY OF THE INVENTION

[0011] Antenna devices with hollow waveguide channels for radar applications are known. These antenna devices typically comprise a printed circuit board and a thereon arranged electronic component in form of a high frequency component. These antenna devices typically comprise an antenna layer which comprises at least one waveguide channel, typically a plurality of waveguide channels, which is / are interconnected to the electronic component and is configured to transmit and / or receive a radar signal. The back face of the antenna layer may comprise electromagnetic bandgap structures in order to avoid leakage between the electronic component and the antenna layer. They can be present in the form of protruding elements which are arranged periodically. The at least one waveguide channel typically interconnects in the antenna layer a first waveguide aperture arranged at a back face of the antenna layer which is interconnected to the electronic component and configured to transmit and / or receive signal to a second waveguide aperture arranged at a front face of the antenna layer and is configured to transmit and / or receive signal. The antenna layer can be assembled from a number of sub-layers. Good results can be achieved with two sub-layers. But the antenna layer may comprise any arbitrary number of layers, like in the other applications, from 1 to N. P28850PC00

[0012] 3 / 49

[0013] For imaging radar applications, multiple high frequency components, typically in form of Monolithic Microwave Integrated Circuits (MMICs) are needed to increase the number of channels. Increasing the number of channels allows for an increased radar equivalent aperture (total area with antennas) which is inversely proportional to angular resolution (which should be as low as possible). Consequently, it is common to have four or more MMICs for imaging radar. Among these MMICs there is a master MMIC which controls the synchronization of all the others. This synchronization is a signal that is carried at high frequency, the so-called local oscillator signal.

[0014] The local oscillator signal can be a high frequency signal, which typically employs 9, 18, 20, 37, or 77 GHz or any frequency in between. When using low-cost printed circuit board materials, such as FR-4, the losses of the routing lines and the splitters can be significant. Typically, a good coherence of the local oscillator signal requires a balance level of power with no less than 20 dB losses from the output of the local oscillator to the input of every MMIC. Additionally, phase coherence is very important, since all the input signals must preferably be in phase or a multiple of a period of the phase + / - 180°. Since the losses in low-cost substrate can be very high, this limits the maximum distance of the routing lines and consequently the maximum distance between the MMICs. In some cases, this limitation can cause that it is not feasible to include an additional MMIC, making it impossible to improve the radar sensor performance further. In this case, a high- end low loss substrate must be used which increases the cost of the overall sensor, making it less attractive due to commercial reasons. P28850PC00

[0015] 4 / 49

[0016] A solution to this problem is proposed by US20230350008A1 which suggests to arrange a high frequency component in form of a MMIC on the front face of the printed circuit board and arrange a coupling structure on the printed circuit board that connects the local oscillator microstrip signal from the MMIC to a hollow waveguide channel. The local oscillator signal propagates through the hollow waveguide channel and is coupled back to another coupling element connected to another MMIC. Nevertheless, although this solution overcomes the drawbacks of routing lines, it has downsides itself. Hollow waveguide channels transmit transversal electrical (TE) or transversal magnetic (TM) modes, which must have a minimum size of half of lambda at the frequency of operation. A local oscillator waveguide inside of a 77 GHz antenna occupies a large space, since typical frequencies are for example 20 GHz for the local oscillator signal, meaning the waveguide must be about four times bigger than the waveguide used for the antenna radar signal. Additionally, in case of using a plastic metallized antenna, the metallization must be thicker, since the losses in a metallization depends on the skin depth. The skin depth hitherto depends inversely on the frequency, so it will be required to have a metallization approximately four times thicker, compared to the radar signal, in order to have a low loss performance for the local oscillator waveguide routing, which translates in an extra cost and maybe even changing of metallization process.

[0017] One objective of the present disclosure can be seen in overcoming the drawbacks of the prior art as mentioned above. In particular, one objective is to provide an improved transmission of a local oscillator signal within an antenna device. A further objective can be seen in providing a more cost-efficient production thereof. P28850PC00

[0018] 5 / 49

[0019] The present disclosure relates to an antenna device which typically comprises a printed circuit board with a back face and a front face and at least one first high frequency component, which is configured to transmit and / or receive a radar signal. The at least one fist high frequency component can be in form of a Monolithic Microwave Integrated Circuit (MMIC). The MMIC may comprise a launch on package (LoP), which enables the MMIC to launch a radar signal from inside the MMIC. This radar signal can be captured or coupled, e.g. into a waveguide structure.

[0020] The antenna device further typically comprises an antenna layer with a back face and a front face, which antenna layer may comprise at least one waveguide channel extending from a first waveguide aperture on the back face through the antenna layer to a second waveguide aperture on the front face. The waveguide channel is configured to transmit and / or receive the radar signal to and / or from the at least one high frequency component, which is configured to process the radar signal. The waveguide channel may be a single conductor structure which can be designed as an air-filled hollow channel, which transmits and / or receives the radar signal. The waveguide channel can be able to transmit energy in a transversal electrical (TE) or transversal magnetic (TM) mode. The first waveguide aperture can couple directly to a coupling element on the printed circuit board or to a hole in the printed circuit board permeable for electromagnetic waves. The hole in the printed circuit board can be a plated through hole, which is suitable to propagate a fundamental mode TE10 (i.e. a short waveguide).

[0021] Right after the first waveguide aperture, when entering the at least one waveguide channel, deflecting elements, such as protrusions or pins, can be placed to rotate P28850PC00

[0022] 6 / 49 the fundamental mode TE10 by 90°, with the electric field in the waveguide channel being perpendicular to the front face of the antenna layer. Such an arrangement is suitable for waveguide channels, or better waveguides, which have an oblong cross section with a long expansion being parallel to the antenna plane (i.e. parallel to e.g. the front face of the antenna layer). Alternatively, the direction of propagation of the fundamental mode TE10 can be changed, with the electric field in the waveguide channel keeping its direction parallel to the front face of the antenna layer. An additional deflection element can be placed subsequently to rotate the fundamental mode TE10 by an angle from 0 to 90°, with the electric field in the waveguide channel remaining parallel to the front face of the antenna layer. Such an arrangement is suitable for waveguide channels, or better waveguides, which have an oblong cross section with a short expansion being parallel to the antenna plane (i.e. parallel to e.g. the antenna front face).

[0023] This mode propagation has an associated cut-off frequency and a minimum size of the structure. The minimum size is lambda 12 for the transversal extension of the waveguide channel. The transversal extension is the extension perpendicular to the longitudinal extension of the waveguide channel. The waveguide channel can be coated on the inside, preferably with a metal, for transmitting electromagnetic waves. The waveguide channel can have any cross-section. Additionally, the waveguide channel can include a ridge element to lower the cutoff frequency of the structure and / or reduce its size. The minimization of the size can be critical to have a more compact structure and therefore a minimized overall size of the antenna layer. P28850PC00

[0024] 7 / 49

[0025] The back face of the antenna layer is typically at least partially arranged on the front face of the printed circuit board and the at least one high frequency component may be arranged on the back face of the printed circuit board. The at least one fist high frequency component, preferably in form of a MMIC, may be attached to the printed circuit board by solder balls though a soldering process. The at least one high frequency component is typically configured to transmit and / or receive a radar signal to and / or from the first waveguide aperture of the at least one waveguide channel through the printed circuit board. By way of example, the radar signal can be transmitted and / or received via a through-hole which is arranged in the printed circuit board from the back face to the front face. The first waveguide aperture of the at least one waveguide channel can be interconnected to one side of the through hole and a launcher of the at least one high frequency component can be interconnected to the other side of the through hole.

[0026] The antenna device may further comprise at least one signal transmission path, which is configured to propagate a local oscillator signal from a local oscillator to the at least one first high frequency component. The local oscillator signal used in the antenna device can be generated by a local oscillator which is interconnected to the at least one first high frequency component. Alternatively, the local oscillator signal can be generated by a second high frequency component. The at least one first high frequency component can thus be one of the at least two high frequency components. The high frequency component, which is not the primary high frequency component, is denominated slave, since it does not generate an independent local oscillator signal and depends at least partially on the primary master high frequency component for synchronization. The at least one signal transmission path can interconnect the slave high frequency component P28850PC00

[0027] 8 / 49 and the master high frequency component. The local oscillator signal can be a high frequency signal, which typically employs 9, 18, 20, 37, or 77 GHz or any frequency in between.

[0028] The design allows for a flexible implementation of the signal transmission path for the local oscillator signal. The antenna device can capture the environment around a vehicle, and it can be designed as a multiple-input multiple-output (MIMO) antenna device. In the following it is explained how the signal transmission path enables good coherence of the local oscillator signal and a balance level of power with typically no more than 20 dB losses from the output of the local oscillator signal to its input. In addition, a phase coherence is achieved, so that all the input local oscillator signals are in phase or a multiple of a period the phase + / - 180°.

[0029] The at least one high frequency component can be configured to route the local oscillator signal into the signal transmission path. A connection element can be used to transmit the signal from one side of the printed circuit board to the other side. As described in the following, the connection element can have different forms.

[0030] The at least one high frequency component may comprise a launch on package and may be configured to route the local oscillator signal into the signal transmission path through a gap in the printed circuit board, which is permeable to electromagnetic waves. P28850PC00

[0031] 9 / 49

[0032] Launch on package (LoP) enables the MMIC to launch an electromagnetic signal from inside the MMIC, where a patch or planar coupling element is placed. This coupling element is disposed to provide impedance matching when a waveguide opening is placed on the structure. Plated though holes in the printed circuit board can act as a waveguide opening in this configuration.

[0033] Alternatively, a via a transition may bring the signal from one side of the printed circuit board to the other. The via may be or not be connected to a guiding element, e.g. a strip line, coplanar waveguide, grounded coplanar waveguide or a substrate-integrated waveguide. Another variation is to use a planar coupling element, such as a printed circuit board launcher, or a cavity backed patch antenna connected to the via.

[0034] A plated though via sends the signal from one side of the printed circuit board to the opposite one. The via works as a vertical microstrip. A small section of a planar transmission line may be interconnected to the local oscillator and routed to the via.

[0035] In a printed circuit board launcher, a planar transmission line, such as a microstrip, ends in a coupling element like a patch or printed dipole that provides impedance matching to a coupling waveguide opening that is placed adjacent to it.

[0036] The antenna device may comprise a second high frequency component, configured to transmit and / or receive a radar signal, wherein the local oscillator is part of the second high frequency component. In the case of the second high P28850PC00

[0037] 10 / 49 frequency component being both the local oscillator and configured to transmit and / or receive a radar signal, a local oscillator signal must usually also be distributed to itself. The second high frequency component may comprise an output local oscillator, which acts as the master for all high frequency components of the antenna device. The output signal will be transmitted to an input of all other high frequency components. Good results can be achieved if the antenna device comprises at least two high frequency components, each being interconnected to the signal transmission path and each being configured to process a common local oscillator signal. The high frequency components can be cascaded, and the total number of transmitter and / or receiver channels can be increased by adding the channels of the high frequency components. It is alternatively possible that some channels remain unused.

[0038] One solution for implementing the signal transmission path is to transmit the local oscillator signal inside the printed circuit board via an air-filled waveguide or a substrate-integrated waveguide. An air-filled waveguide can be implemented by selectively removing dielectric material from one or more printed circuit board layers to form a hollow structure, which is then fully closed by two metallic layers on top and bottom. The hollow structure may either be metallized on the two sides through e.g. a galvanic process or may be electromagnetically sealed by two rows of vias spaced by a tenth of the operating frequency of the waveguide. The local oscillator signal can be transmitted into the air-filled waveguide or the substrate- integrated waveguide through a via in the substrate and can be launched into the waveguide by means of a coupling structure, such as a strip line, a patch / printed dipole or a microstrip to SIW transition. P28850PC00

[0039] 11 / 49

[0040] The at least one signal transmission path of the antenna device may be arranged on the front face of the printed circuit board. Alternatively, the at least one signal transmission path may be arranged on the back face of the printed circuit board. The at least one first high frequency component may be arranged on the back face of the printed circuit board via solder balls though a soldering process. A connection between the launching structures in the at least one first high frequency component and the signal transmission path can be achieved via a hole in the printed circuit board. The hole must be permeable to electromagnetic high frequency waves of the local oscillator signal. The hole can be filled with a substrate material. Alternatively or in addition, the hole may comprise though vias arranged circumferential with respect to the hole, to confine the waves and avoid leakage.

[0041] Further alternatively, the hole can be realized as a plated though-hole filled with air and a metallized surface. This can be done by either drilling and or milling and a subsequent coating process. This kind of interconnection enables the transmission of energy between the at least one first high frequency component and the signal transmission path in an efficient manner.

[0042] The local oscillator signal may be transmitted on the back face of the printed circuit board. In this case there is no need for launching the signal from one side to the other of the printed circuit board. A coupling structure can couple the output local oscillator signal from the second high frequency component via a transmission line into the signal transmission path to the at least one first high frequency component. P28850PC00

[0043] 12 / 49

[0044] The at least one signal transmission path may be arranged between the back face of the antenna layer and the front face of the printed circuit board. The at least one signal transmission path can be formed by the front face of the printed circuit board and a recess in the back face of the antenna layer. The at least one signal transmission path can be a waveguide channel formed between the front face of the printed circuit board and the back face of the antenna layer, preferably a recess in the back face of the antenna layer. Good results regarding the manufacturability can be achieved when the recess in the back face of the antenna layer is at least partially formed by a deepening in the back face of the antenna layer. This is particularly beneficial for injection molding or diecasting as the parts can be easily demolded. The recess may at least partially formed by a deepening in the back face of the antenna layer and / or protrusions. Alternatively or in addition to the protrusions, intrusions can be arranged in the back face of the antenna layer.

[0045] An EBG structure can be formed by protrusions extending above the back face of the antenna layer and / or a planar metallic structure on the front face of the printed circuit board. The protrusions can be made integrally with the antenna layer, laterally delimiting the recess and form an electromagnetic band-gap structure with the front face of the printed circuit board. The front face of the printed circuit board can be metallized. A stepped structure may be arranged at the beginning of the waveguide channel to implement a planar transition from the printed circuit board to the waveguide. Alternatively or in addition, a planar metallic structure which comprises a number of patches can be arranged on the front face of the printed circuit board, which patches laterally delimit the recess and form an electromagnetic band-gap structure with the protrusions or the back face P28850PC00

[0046] 13 / 49 of the antenna layer. The antenna layer may comprise a ridge, which is arranged within the recess and extends substantially along the waveguide channel. The ridge can be arranged within the recess of the waveguide channel for reducing the overall size of the waveguide channel. The antenna layer can be joined to the front face of the printed circuit board by gluing or soldering. In addition, periodic structures, meta-surfaces or electromagnetic band gap structures can be arranged to avoid the need for galvanic contact and to loosen the requirements for the interconnection between the back face of the antenna layer and the front face of the printed circuit board.

[0047] The signal transmission path can comprise a hybrid planar transmission line, preferably in form of a hybrid strip line, a hybrid grounded coplanar waveguide or a hybrid differential line.

[0048] A multitude of possible hybrid planar transmission lines exists, which only partially propagate energy within a substrate, but partially propagate the energy within air between two metallic surfaces. The hybrid planar transmission line may be a hybrid strip line, which can comprise a lower ground plane, a substrate layer with a first thickness arranged on the ground plane and a strip line arranged on top of the substrate layer. The hybrid strip line can in addition comprise lateral grounding elements which are arranged adjacent to both lateral sides of the strip line and are connected to the lower ground plane. The hybrid strip line can comprise an upper ground plane which is with respect to the strip line arranged above the strip line at a distance which is at least one time, preferably two times, smaller than the first thickness of the substrate layer. The upper ground plane is preferably at least partially attached to the back face of the antenna layer. The distance P28850PC00

[0049] 14 / 49 between the upper ground plane and the strip line is preferably smaller than lambda / 10. The lower and / or upper and / or lateral grounding elements are electrically conductive and typically made from a conductive metal material.

[0050] The lateral grounding elements may be connected to the lower ground plane to improve the grounding and avoid surface wave propagation. Typically, the energy propagates between the strip line and the lower ground plane. By including on top of the strip line an upper ground plane, spaced with the second distance apart from the strip line, the electric field is forced to propagate partially between the strip line and the upper ground plane. Thereby, the losses are reduced. Comprising an upper ground plane, the strip line comprises a sandwich structure, where one of the sides is air instead of substrate. The reduction of losses can go up to 30%. The transmission mode of the hybrid strip line is typically TEM or quasi- TEM. Additionally, on the front face of the printed circuit board or the back face of the antenna layer a meta-surface can be arranged. The meta-surface may comprise a periodic structure to avoid leakage of energy.

[0051] Alternatively, the hybrid planar transmission line may be a hybrid grounded coplanar waveguide which can comprise a lower ground plane, a substrate layer with a given thickness arranged on the lower ground plane and a strip line, which is arranged on top of the substrate layer. Two lateral grounding elements may be arranged on the lateral sides of the strip line and may also be connected to the lower ground plane at a given distance. The hybrid grounded coplanar waveguide can comprise an upper ground plane which is arranged above the strip line at a distance with respect to the strip line which is at least one time, preferably two P28850PC00

[0052] 15 / 49 times, smaller than the thickness of the substrate layer. The upper ground plane is preferably at least partially attached to the back face of the antenna layer.

[0053] The upper ground plane may be arranged with a distance, so that a mode is excited with improved grounding and to avoid surface wave propagation. Typically, the energy propagates between the strip line and the lateral grounding elements. By arranging an upper ground plane, the electric field is forced to propagate partially between the strip line and the upper ground plane. Thereby, the losses are reduced. The upper ground plane can be realized with the antenna back side. The reduction of losses can go up to 30%. The transmission mode of the hybrid grounded coplanar waveguide is typically TEM or quasi-TEM. Additionally, on the front face of the printed circuit board or the back face of the antenna layer, a meta-surface can be arranged. The meta-surface may comprise a periodic structure, in order to avoid leakage of energy.

[0054] A hybrid strip line and a hybrid grounded coplanar waveguide differ with regard to their grounding. If the distance between the strip line and the two lateral grounding elements arranged next to it is smaller than the distance to the lower ground plane, then it is considered a coplanar grounded waveguide. In the opposite case, it is considered a strip line.

[0055] Alternatively, the hybrid planar transmission line may be a hybrid differential line, which can comprise a lower ground plane, a substrate layer with a given thickness, which is arranged on the ground plane and a pair of strip lines arranged on top of the substrate layer. P28850PC00

[0056] 16 / 49

[0057] The hybrid differential line can comprise an upper ground plane which is arranged above the pair of strip lines at a distance with respect to the pair of strip lines which is at least one time, preferably two times, smaller than the thickness of the substrate layer. The upper ground plane is preferably at least partially attached to the back face of the antenna layer.

[0058] Typically, the energy propagates between the pair of strip lines and partially the lower ground plane. By arranging an upper ground plane, the electric field is forced to propagate partially between the pair of strip lines and the upper ground plane. Thereby, the losses are reduced. This upper ground plane can be realized with the antenna back side. The reduction of losses can go up to 30%. The transmission mode of the hybrid differential line is typically TEM or quasi-TEM. Additionally, on the front face of the printed circuit board or the back face of the antenna layer a meta-surface can be arranged. The meta-surface may comprise a periodic structure, to avoid leakage of energy.

[0059] Alternatively, the signal transmission path may be in form of a hybrid magnetic strip line which comprises a strip line and a ground plane arranged on one side of the strip line as well as an artificial magnetic conductor (AMC) arranged on the opposite side of the strip line. The strip line and the ground plane may be configured to guide an electrical field therebetween. AMCs are an approximation of perfect magnetic conductors (PMCs), which do only exist in theory, but can be approximated in a limited bandwidth by AMCs. AMCs can prevent the transmission of a magnetic field parallel to the materials surface. AMCs can be created by periodical or randomized patterns. On a PCB this can be implemented by P28850PC00

[0060] 17 / 49 periodically arranging metallic patches or in a fully metallic surface arranging periodic cavities (the complementary case to patches).

[0061] The underlying theory of AMCs is a perfect magnetic conductor (PMC), which is an idealized material, which does not allow propagation of magnetic field inside of it. In the context of antenna devices, the artificial magnetic conductor can fulfill two purposes. Arranging an AMC structure on the front face of the PCB, which in the mounted state faces the back face of the antenna layer, can form an electromagnetic band gap (EBG) structure between the AMC structure and the back face of the antenna layer. This EBG structure avoids an unwanted propagation of electromagnetic waves outside of the defined waveguide channel. Alternatively or in addition, the parts of the AMC structure which in the mounted state can form together with the recess of the antenna layer a waveguide channel, can allow to decrease the height of the waveguide channel, therefore the height / depths of the recess in the antenna layer and thereby may decrease the overall height of the antenna device.

[0062] With an AMC structure arranged on the front face of the PCB, the waveguide channel can be designed as a half-mode waveguide. The underlying concept of a half-mode waveguide is to halve the height of the waveguide channel. To be able to halve the height and still be able to guide the signal, the concept is to mirror the E-field of the signal with the artificial magnetic conductor (AMC). The patches can be e.g. rectangular, circular or pentagonal, hexagonal, elongated, ellipsoidal in shape. The patches may be placed in a linear symmetrical, glide symmetrical or randomized pattern on the front face of the PCB. An alternative variation for creating an AMC is to arrange a fully metallic plane with polygonal P28850PC00

[0063] 18 / 49 apertures or protrusions, e.g. in form of cavities, on the back face of the antenna layer, instead of having metallic patches on the front face of the PCB.

[0064] The lateral distance between the patches with respect to each other - the periodicity - is typically chosen in relation to the emitted wavelength. The size of the patches is related to the guided wavelength. The wavelength can be calculated as follows:

[0065] A = ^=

[0066] Vsr PCB

[0067] Ao = free air wavelength

[0068] Er PCB = permittivity of the PCB substrate

[0069] The periodicity is usually chosen in a range between Ao / 8 - 2 o. The patches are typically arranged in collinear arrays, with the arrays forming rows and columns. Between neighboring columns, the patches are spaced with a first periodicity (x- direction) and between neighboring rows with a second periodicity (y-direction). As a result, in a top view on the front face of the PCB the patches can form a matrix. In addition, the arrays can be shifted with respect to each other. While the patches within one array are spaced with a distance equal to the periodicity, neighboring arrays can be shifted with respect to each other by a distance which equals to P / n with n being a natural number. This leads to a staggered design. A periodic pattern of patches has the advantages that even a misalignment of the antenna layer with respect to the printed circuit board, either a lateral displacement or angular displacement, does not impact the magnetic and electrical properties. P28850PC00

[0070] 19 / 49

[0071] In a top view on the front face of the PCB, instead of using a conductive lower ground plane below the microstrip, an artificial magnetic conductor, preferably in form of a periodic structure of mushrooms (shorted patches), can be used. The field can thereby not propagate in the gap between the strip line and the artificial magnetic conductor. Consequently, most of the energy will propagate between the ground plane and the strip line. Such a configuration can reduce the losses up to 70% compared to standard strip lines. The hybrid magnetic strip line can comprise an artificial magnetic conductor in form of a periodic EBG structure, particularly a mushroom EBG structure.

[0072] However, these periodic EBG structures are more difficult to realize. To create the mushroom periodic structures, a series of buried vias - vias that go though only one layer of the printed circuit board - instead of vias going through several layers of the printed circuit board - can be used. Modified mushroom EBG structures can be created by extending the though via though at least two layers. The hybrid magnetic strip line can comprise a mushroom EBG structure comprising a series of vias which are arranged in a top layer of the printed circuit board. The mushroom EBG structure may be created by extending the though via though at least two layers. In the layers where the ground via is not needed a coated copper region can be located in order to avoid unnecessary grounding.

[0073] Alternatively, different periodic structures such as metal planes with selective edge patch holes or with artificial mushrooms, which avoid the creation of vias by employing the symmetry properties, can be generated. The periodic structures, such as a metal plane with selective edge patch holes or artificial mushrooms, which avoid the creation of vias by employing the symmetry properties, can be P28850PC00

[0074] 20 / 49 generated. Additionally, on the sides of either the printed circuit board or the antenna back a meta surface can be created by means of periodic structures, to avoid leakage of energy. In the case of using mushrooms and locating the periodic structures on the printed circuit board, a double mushroom can be created.

[0075] Alternatively, the signal transmission path can be a hybrid strip-ridge gap waveguide, which comprises a lower ground plane and a strip line, grounded to the lower ground plane and creating a strip-ridge.

[0076] An upper ground plane may be arranged on top of the strip line and a periodic structure can be arranged laterally of the strip line to avoid leakage of energy. The upper ground plane above the strip line and periodic structures laterally of the strip line avoid leakage of energy. Preferably, the distance from the strip to the back of the antenna is less than lambda / 4.

[0077] In addition, on the front face of the printed circuit board and / or the back face of the antenna layer a meta-surface may be arranged, which can comprise a periodic structure in form of mushroom EBGs to avoid leakage of energy. In addition, periodic structures, meta surfaces or electromagnetic band gap structures can be arranged to avoid the need for galvanic contact and lower the requirements for the interconnection between the antenna layer and the printed circuit board. The meta-surface can create a meta waveguide or gap waveguide. In this case the signal transmission path will propagate a TE / TM mode.

[0078] The signal transmission path may comprise a splitter which is configured to divide the local oscillator signal fed into a principle branch, typically between at least P28850PC00

[0079] 21 / 49 two sub-branches. The at least two sub-branches of the signal transmission path may each be interconnected to a respective high frequency component. Multiple splitters can be foreseen in the case of having more than two high frequency components. Different splitters can be arranged to divide the signal. A typical setup comprises a principle branch and two sub-branches. The local oscillator signal is fed into the principle branch and by the splitter split into two sub-signals, each sub-signal is fed into one sub-branch. Depending on the design of the splitter, the signal can be split symmetrically or asymmetrically. The splitter can be in form of a so-called Wilkinson or Gysel divider, which is a special type of splitter that provides isolation between the two sub-branches of the splitter. A signal coming from a sub-branch to the principal branch cannot be coupled with the other sub-branch. This is possible by incorporating a resistor or termination load in between the sub-branches. Then, the energy that should couple within the subbranches is dissipated. Good results are achieved when a Wilkinson divider is used with strip lines. If hybrid lines are used, a Wilkinson divider can be used if a gap for a resistor or term ination is arranged on the back face of the antenna layer. Alternatively, instead of a resistor an uncoated area in the front face of the PCB or on the back face of the antenna layer can be used to dissipate the signal, without the need for extra components in the form of termination or resistor. Alternatively, a Wilkinson divider based on waveguide technology can be used. Steps in the form or protrusions may be arranged at the splitter for matching purposes and a resistor or terminal load arranged inside the waveguide. Instead of a resistor or terminal load an uncoated area can be used.

[0080] The at least one signal transmission path can be arranged between the back face of the printed circuit board and a heat sink which may be arranged on the back P28850PC00

[0081] 22 / 49 face of the printed circuit board. The heat sink may be arranged on top or next to the at least one first high frequency component. The heat sink dissipates the heat coming from the at least one first high frequency component. The heat sink can be made of a metal material or a material with a high thermal conductivity. The heat sink or heat dissipator may be created by any of the following processes: metal diecasting, metal forming, metal stamping, a milling or cutting process or any kind of process that involves metal injection and or forming a metal. The signal transmission path can be any of the beforementioned. In an alternative embodiment, the signal transmission path can be transmitted in an additional waveguide channel which is arranged on the side of the printed circuit board on which at least one first high frequency component is arranged.

[0082] The at least one signal transmission path may be arranged within the antenna layer in form of a coaxial channel with the channel surface being the outer conductor and an inner conductor being arranged within the coaxial channel electrically isolated from the channel surface. In this case, a TEM or quasi-TEM mode is employed, and the overall size can me miniaturized and a more stable phase response is obtained since TEM or quasi-TEM mode is less dispersive than TE / TM modes. The transmission of transversal electric-magnetic (TEM) or quasi- TEM mode propagation is like the transmission inside of coaxial cables. The benefit of TEM or quasi-TEM transmission is that there is no cut-off frequency and minimum size associated, then a much higher degree of minimization can be achieved, not being limited by the lambda half size. In a preferred embodiment, the waveguide channel or coaxial channel can comprise periodic structures or electromagnetic band gap structures. This can facilitate the assembly in the case of multilayer structures and avoid leakage of energy. P28850PC00

[0083] 23 / 49

[0084] In an alternative aspect, an antenna device according to the present disclosure comprises a printed circuit board with a back face and a front face, at least one high frequency component configured to transmit and / or receive a radar signal and an antenna layer with a back face and a front face, comprising at least one waveguide channel, which each extend from a first waveguide aperture on the back face through the antenna layer to a second waveguide aperture on the front face. The antenna device further comprises at least one signal transmission path which is configured to propagate a local oscillator signal from a local oscillator to the at least one high frequency component and the at least one signal transmission path. The at least one signal transmission path is preferably configured to propagate a signal at frequencies in the range of 5 to 80 GHz, for instance 9, 18, 20, 37 or 77 GHz in a TEM or quasi-TEM mode. The bandwidth is typically less than 1 GHz.

[0085] The antenna device can comprise a back and / or front cover. The front cover is arranged in front of the antenna layer and configured to protect the antenna device from environmental influences. The front cover can be at least partially made of a material permeable to electromagnetic waves. The back cover does not need to be permeable to electromagnetic waves. The back cover can be made of a plastic material or metal. The back cover or housing can be at least partially metallized.

[0086] It is to be understood that both the foregoing general description and the following detailed description present embodiments and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding and P28850PC00

[0087] 24 / 49 are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description explain the principles and operation of the concepts disclosed.

[0088] BRIEF DESCRIPTION OF THE DRAWINGS The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The drawings are showing:

[0089] Fig. 1 a perspective exploded view of a first embodiment of the antenna de- vice from the front and from above;

[0090] Fig. 2 a perspective exploded view of the antenna device according to Figure

[0091] 1 from the back and from above;

[0092] Fig. 3 a perspective exploded view of a second embodiment of the antenna device from the front and from above; Fig. 4 a perspective exploded view of the antenna device according to Figure 3 from the back and from above;

[0093] Fig. 5 a perspective view of a third embodiment of the antenna device comprising a launch on package; P28850PC00

[0094] 25 / 49

[0095] Fig. 6 a perspective view of a fourth embodiment of the antenna device comprising a via transition and strip line;

[0096] Fig. 7 a perspective view of a fifth embodiment of the antenna device comprising a via transition and printed circuit board launcher;

[0097] Fig. 8 a perspective unfolded view of a sixth embodiment of the antenna device comprising a signal transmission path in form of a waveguide inside the antenna layer;

[0098] Fig. 9 a perspective unfolded view of a seventh embodiment of the antenna device comprising a signal transmission path in form of a coaxial waveguide inside the antenna layer;

[0099] Fig. 10 a perspective unfolded view of an eight embodiment of the antenna device comprising a signal transmission path in form of a waveguide defined by two recesses in the antenna layer and the front face of the printed circuit board;

[0100] Fig. 11 a perspective unfolded view of a ninth embodiment of the antenna device comprising a signal transmission path in form of a strip line;

[0101] Fig. 12 a sectional view of a portion of an eleventh embodiment of the antenna device comprising a signal transmission path in form of a strip line; P28850PC00

[0102] 26 / 49

[0103] Fig. 13 a sectional view of a portion of a tenth embodiment of the antenna device comprising a signal transmission path in form of a hybrid grounded coplanar waveguide;

[0104] Fig. 14 a perspective unfolded view of a twelfth embodiment of the antenna device comprising a signal transmission path in form of a hybrid differential line;

[0105] Fig. 15 a perspective unfolded view of a thirteenth embodiment of the antenna device comprising a signal transmission path in form of hybrid magnetic strip line;

[0106] Fig. 16 a detailed view of the embodiment of the antenna device according to Figure 15;

[0107] Fig. 17 a perspective unfolded view of a fourteenth embodiment of the antenna device comprising a signal transmission path in form of hybrid strip-ridge waveguide;

[0108] Fig. 18 a perspective unfolded view of a fifteenth embodiment of the antenna device comprising a signal transmission path in form of second variation of a hybrid strip-ridge waveguide;

[0109] Fig. 19 a perspective view of a sixteenth embodiment of the antenna device comprising a signal transmission path in form of waveguide within the printed circuit board; P28850PC00

[0110] 27 / 49

[0111] Fig. 20 a perspective unfolded view of a seventeenth embodiment of the antenna device comprising a signal transmission path in form of a waveguide within a heat sink;

[0112] Fig. 21 a perspective unfolded view of an eighteenth embodiment of the antenna device comprising a signal transmission path with a first embodiment of a Wilkinson power divider;

[0113] Fig. 22 a perspective unfolded view of a nineteenth embodiment of the antenna device comprising a signal transmission path with a second embodiment of a Wilkinson power divider;

[0114] Fig. 23 a perspective unfolded view of a twentieth embodiment of the antenna device comprising a signal transmission path with a third embodiment of a Wilkinson power divider;

[0115] Fig. 24 a perspective unfolded view of a twenty-first embodiment of the antenna device comprising a signal transmission path with a fourth embodiment of a Wilkinson power divider.

[0116] DESCRIPTION OF THE EMBODIMENTS

[0117] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will P28850PC00

[0118] 28 / 49 satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0119] Figures 1 to 24 show embodiments of the antenna device 1 which all comprise a printed circuit board 2 and at least one fist high frequency component 3 which is configured to transmit and / or receive a radar signal. The at least one fist high frequency component 3 of all embodiments is in form of a Monolithic Microwave Integrated Circuit (MMIC). The embodiments of the antenna device 1 all further comprise an antenna layer 4. In Figures 5 to 7 the antenna layer is not shown at all. In Figures 8 to 24, only the portion of the antenna layer is shown which comprises the signal transmission path.

[0120] Figures 1 and 2 show a first embodiment of the antenna device 1 . The shown antenna device 1 comprises a printed circuit board 2 with a back face 21 and a front face 22. In the shown embodiment, a fist high frequency component 3 and a second high frequency component 7 are arranged on the back face 21 of the printed circuit board 2 as can be seen in Figure 2. The shown antenna layer 4 has a back face 41 and a front face 42 and is assembled from two layers. A number of waveguide channels 5 extend from first waveguide apertures 51 on the back face 41 of the antenna layer 4, through the antenna layer 4 to second waveguide apertures 52 on the front face 42 of the antenna layer 4. Holes in the printed circuit board 2 which are permeable to electromagnetic signals for the radar signal connect the at least one fist high frequency component 3 with the first apertures 51 . P28850PC00

[0121] 29 / 49

[0122] As can be obtained, each waveguide channel 5 mouths into a number of second waveguide apertures 52, which are arranged in columns and rows on the front face 42 of the antenna layer 4. The antenna layer 4 is mounted onto the printed circuit board 2, with the back face 41 of the antenna layer 4 being partially arranged on the front face 22 of the printed circuit board 2. Both high frequency components 3, 7 are arranged on the back face 21 of the printed circuit board 2. Through the first waveguide apertures 51 , the first 3 and the second 7 high frequency components can each transmit and / or receive a radar signal timewise in parallel or in a programmed timing with respect to each other. The shown signal transmission path 6 is configured to propagate a local oscillator signal from one of the two high frequency components 3, 7 to itself as well as the other high frequency component. The various possible designs of transmission paths 6 are described into more detail below.

[0123] Figures 3 and 4 show a second embodiment of the antenna device 1 . The shown antenna device 1 differs from the first embodiment in that the signal transmission paths 6, 6’ as well as the first 3 and second 7 high frequency components are arranged on a heat sink 12. The signal transmission paths 6, 6’ are arranged between the back face 21 of the printed circuit board 2 and the front face 122 of the heat sink 12, which is arranged on the back face 21 of the printed circuit board 2. The heat sink 12 dissipates the heat coming from the first 3 and second 7 high frequency components. The heat sink 12 is therefore made of a material with a high thermal conductivity. The shown heat sink 12 is milled out of a slab of a metallic material. The signal transmission path 6 can be any of the below described. P28850PC00

[0124] 30 / 49

[0125] Figures 5 to 7 show three embodiments of the antenna device 1 with different routing structures for a local oscillator signal into the respective signal transmission path (which is not shown in those figures). The high frequency component 3 of each embodiment is configured to route the local oscillator signal into the signal transmission path through the printed circuit board 2. The shown high frequency components 3 are each arranged on the back face 21 of the respective printed circuit board 2. The high frequency components 3 are attached via solder balls 13 to the printed circuit board 3 through a soldering process.

[0126] Figure 5 shows an embodiment with a first high frequency component comprising a launch on package which is configured to route the local oscillator signal into the signal transmission path through a gap 81 in the printed circuit board 2, which is permeable to electromagnetic waves. The launch on package (LoP) enables the first high frequency component 3 to launch an electromagnetic signal from inside the MMIC, where a patch or planar coupling element is placed. This coupling element is disposed to provide impedance matching when a waveguide opening is placed on the structure. The gap 81 in form of a plated though hole in the printed circuit board 2 acts as a waveguide opening, which in this configuration is the feeding structure into the signal transmission path.

[0127] Figure 6 shows an embodiment with a via transition 82 connected to a hybrid planar transmission line 9. The via transition 82 brings the signal from the back face 21 of the printed circuit board 2 to the front face 22. The shown via transition 82 is connected to the hybrid planar transmission line 9. The via 82 works as a vertical microstrip. A small section of a planar transmission line 9 is interconnected to the local oscillator and routed to the via. P28850PC00

[0128] 31 / 49

[0129] Figure 7 shows another embodiment with a planar coupling element, such as a printed circuit board launcher 83. In the shown embodiment, a planar transmission line 9, such as a microstrip, ends at a via transition 82 which brings the signal to the printed circuit board launcher 83.1 In the shown embodiment, the printed circuit board launcher 83 is in form of a patch that provides impedance matching to a coupling waveguide opening that is placed adjacent to it.

[0130] Figures 8 to 24 show embodiments of the antenna device 1 with depicted antenna layers 4, which each comprise a back face 41 and a front face 42. The antenna layers 4 comprise at least one waveguide channel (not shown) extending from a first waveguide aperture on the back face 41 through the antenna layer 4 to a second waveguide aperture on the front face 42. The waveguide channel is configured to transmit and / or receive the radar signal to and / or from the at least one high frequency component 3, which is configured to process the radar signal. The back face 41 of the antenna layers 4 is in each case at least partially arranged on the front face 22 of the printed circuit board 2 and the at least one high frequency component 3 is arranged on the back face 41 of the printed circuit board 4. The shown antenna devices 1 further each comprise at least one signal transmission path 6, which is configured to propagate a local oscillator signal from a local oscillator to the at least one first high frequency component 3.

[0131] In Figure 8, a connection between the launch on package in the first high frequency component 3 and the signal transmission path 6 in the antenna layer 4, presently formed as a hollow waveguide 62, is achieved via a gap 81 in the printed circuit board 2. The gap 81 is permeable to electromagnetic high frequency waves and made of substrate material. Through vias are arranged P28850PC00

[0132] 32 / 49 circumferential with respect to the gap, to confine the waves and avoid leakage. Alternatively, the gap 81 can be realized as a plated though-hole filled with air and a metallized surface. This kind of interconnection enables the transmission of energy between the shown first high frequency component 3 and the hollow waveguide 62 in an efficient manner.

[0133] The local oscillator signal is transmitted to the front face 22 of the printed circuit board 2. In the shown embodiment, the signal transmission path 6 is designed as a hollow waveguide 62 in the antenna layer 4. On the front face 22 of the printed circuit board 2 a meta-surface 10 is arranged which comprises a periodic structure 101 in form of mushroom EBGs 102 to avoid leakage of energy. In addition, the periodic structure 101 is arranged to avoid the need for galvanic contact between the back face 41 of the antenna layer 4 and the front face 22 of the printed circuit board 2.

[0134] Figure 9 shows an embodiment in which the signal transmission path 6 is arranged within the antenna layer 4 in form of a coaxial channel 96. The channel surface 961 functions as the outer conductor. An inner conductor 962 is arranged within the coaxial channel 96, electrically isolated from the channel surface 961 . The transmission path 6 is designed to propagate a TEM or quasi-TEM mode. The overall channel size can thereby be miniaturized compared to the embodiment shown by Figure 8 and a more stable phase response is obtained in comparison, since a TEM or quasi-TEM mode is less dispersive than TE / TM modes. The transmission is like the transmission inside of coaxial cables. The signal is coupled into the coaxial channel 96 by conventional means, presently by a printed circuit board launcher 83 which is arranged on the front face 22 of the printed P28850PC00

[0135] 33 / 49 circuit board 2. The printed circuit board launcher 83 is connected to the coaxial channel 96 by a hollow wave guide 62 which is arranged perpendicular to the coaxial channel 96.

[0136] Figure 10 shows an embodiment in which the signal transmission paths are formed between the front face 22 of the printed circuit board 2 and two recesses 61 , 6T arranged in the back face 41 of the antenna layer 4. The front face 22 of the printed circuit board 2 is metallized. A stepped structure 63, 63’ is arranged at the beginning of the waveguide channels to implement a planar transition from the printed circuit board 2 to the signal transmission paths. For coupling a signal into the signal transmission paths, a planar transmission line 9 ends in a coupling structure, which couples into a region of the signal transmission path where only a substrate 84 and the stepped structures 63, 63’ are. This acts as a dielectric filled waveguide, which couples into the actual signal transmission path. The antenna layer 4 can be joined to the front face 22 of the printed circuit board 2 by gluing or soldering.

[0137] Figures 11 and 12 show an embodiment in which the hybrid planar transmission line is in form of a hybrid strip line 91 , which comprises a lower ground plane 911 , a substrate layer 912 with a first thickness arranged on the ground plane 911 and a strip line 913 arranged on top of the substrate layer 912. The hybrid strip line 913 in addition comprises lateral grounding elements 914, 914’ which are arranged adjacent to both lateral sides of the strip line 913 and are connected to the lower ground plane 911. As can be seen from Figure 12, the distance D1 between the strip line 91 and the two lateral grounding elements 914, 914’ P28850PC00

[0138] 34 / 49 arranged next to the strip line 91 is larger than the distance D2 to the lower ground plane 911 . The shown lateral grounding elements 914, 914’ are in form of pins.

[0139] The shown hybrid strip line 91 additionally comprises an upper ground plane 915 which is with respect to the strip line 913 arranged above the strip line 913 at a distance which is presently two times smaller than the first thickness of the substrate layer 912. The shown upper ground plane 915 is part of the back face 42 of the antenna layer 4. The lower 911 and / or upper 915 and / or lateral ground planes as well as the lateral grounding elements 914, 914’ are electrically conductive and typically made from a conductive metal material. The lateral grounding elements 914, 914’ are connected to the lower ground plane 911 to improve the grounding and avoid surface wave propagation.

[0140] Typically, the energy propagates between the strip line 913 and the lower ground plane 911. By including on top of the strip line 913 an upper ground plane 915, spaced with the second distance apart from the strip line 913, the electric field is forced to propagate partially between the strip line 913 and the upper ground plane 915.

[0141] The embodiment shown by Figure 11 shows a signal transmission path which comprises a splitter 11 which is configured to divide the local oscillator signal coming from a principal branch 64, between the at least two sub-branches 64, 64’. The two sub-branches 64, 64’ of the signal transmission path 6 are each interconnected to a respective high frequency component. P28850PC00

[0142] 35 / 49

[0143] Figure 13 shows an embodiment in which the hybrid planar transmission line is in form of a hybrid grounded coplanar waveguide 92, which comprises a lower ground plane 921 , a substrate layer 922 with a given thickness arranged on the lower ground plane 921 and a strip line 923, which is arranged on top of the substrate layer 922. Two lateral grounding elements 924, 924’ are arranged on the lateral sides of the strip line 923 and are connected to the lower ground plane 921 at a given distance. The distance D1 between the strip line 923 and the two lateral grounding elements 924, 924’ arranged next to the strip line 923 is smaller than the distance D2 between the strip line 923 and the lower ground plane 921. The hybrid grounded coplanar waveguide 92 additionally comprises an upper ground plane 925 which is arranged above the strip line 923 at a distance D3 with respect to the strip line 923 which is two times smaller than the thickness of the substrate layer 922. The upper ground plane 925 is attached to the back face 41 of the antenna layer 4. The upper ground plane 925 is arranged with a distance such that the grounding of the excited mode is improved to avoid surface wave propagation. Typically, the energy propagates between the strip line 923 and the lateral grounding elements 924, 924’. By arranging an upper ground plane 925, the electric field is forced to propagate partially between the strip line 923 and the upper ground plane 925. Thereby, the losses are reduced.

[0144] Figure 14 shows an embodiment in which the planar transmission line is in form of a hybrid differential line 93, which comprises a lower ground plane 931 , a substrate layer 932 with a given thickness, which is arranged on the ground plane 931 , and a pair of strip lines 933, 933’ arranged on top of the substrate layer 932. The hybrid differential line 93 further comprises an upper ground plane 935 which is arranged above the pair of strip lines 933, 933’ at a distance with respect to the P28850PC00

[0145] 36 / 49 pair of strip lines 933, 933’ which is two times smaller than the thickness of the substrate layer. The upper ground plane 935 is preferably part of the back face 41 of the antenna layer 4.

[0146] Figures 15 and 16 show an embodiment in which the signal transmission path is a hybrid magnetic strip line 94, which comprises a strip line 941 and a ground plane 942 arranged on the top side of the strip line 941 as well as an artificial magnetic conductor 943 arranged on the opposite bottom side of the strip line 941 . The strip line 941 and the ground plane 942 are configured to guide an electrical field therebetween. The electrical field propagates between the strip line 941 and the ground plane 942. The electrical field partially propagates in between the conductive strip line 941 and the conductive ground plane 942 orthogonal to the parallel metal surfaces. Instead of using a conductive lower ground plane below the strip line 941 , an artificial magnetic conductor 943, preferably in form of a periodic structure of EBG 944 (shorted patches) is presently used. The field can thereby not propagate in the gap between the strip line 941 and the artificial magnetic conductor 943. Consequently, most of the energy propagates between the ground plane and the strip line 941. Such a configuration can reduce the losses up to 70% compared to standard strip lines.

[0147] Figure 17 and 18 show two embodiments in which the signal transmission path is a hybrid strip-ridge gap waveguide 95. The hybrid strip-ridge gap waveguide 95 comprises a lower ground plane 951 and a strip line 952, grounded to the lower ground plane 951 and creating a strip-ridge. An upper ground plane 953 is arranged on top of the strip line 952. Figure 18 shows a second embodiment in which the signal transmission path is a hybrid strip-ridge gap waveguide 95. In P28850PC00

[0148] 37 / 49 addition to the features of Figure 17, the shown embodiment comprises on the front face 22 of the printed circuit board 2 (as presently shown) and / or the back face 41 of the antenna layer 4 a meta-surface which comprises a periodic structure 954, which is arranged laterally of the strip line 952 to avoid leakage of energy.

[0149] Figure 19 shows an embodiment in which the signal transmission path 6 is in form of a waveguide channel 24 within the printed circuit board 2. The waveguide channel 24 is a single conductor structure which is designed as a channel which transmits the radar signal. The waveguide channel 24 can transmit energy in a transversal electrical (TE) or transversal magnetic (TM) mode. This mode propagation has associated a cut-off frequency and a minimum size of the structure. The minimum size is lambda / 2 for the longest transversal extension of the shown rectangular waveguide channel 24. The waveguide channel 24 is coated on the inside, preferably with a metal, for transmitting electromagnetic waves. The waveguide channel 24 comprise a cavity which is filled with air. The signal is coupled into the waveguide channel 24 by conventional means.

[0150] Figure 20 shows an embodiment in which the signal transmission path is arranged between the back face 21 of the printed circuit board 2 and a heat sink 12 which is also arranged on the back face 21 of the printed circuit board 2. The heat sink 12 dissipates the heat coming from the high frequency component 3. The heat sink 12 can be made of a metal material or a material with a high thermal conductivity. The heat sink 12 or heat dissipator may be created by any of the following processes: metal diecasting, metal forming, metal stamping, cutting or milling or any kind of process that involves metal injection and or forming a metal. P28850PC00

[0151] 38 / 49

[0152] The front face 122 of the heat sink 12 is at least partially arranged on the back face 21 of the printed circuit board and the back face 121 of the heat sink 12 is configured to dissipate the heat by radiation, convection or conduction.

[0153] Figures 21 to 24 show embodiments with a splitter 11. The splitter 11 is configured to divide the local oscillator signal propagating through the principle branch 64, between two sub-branches 65, 66. A first sub-branch 65is interconnected to the first high frequency component 3, a second sub-branch 66 to the second high frequency component 7. Different splitters 11 can be arranged to divide the signal, as can be seen in Figures 21 to 24. Each design comprises a principle branch 64 and two sub-branches 65, 66. The local oscillator signal is fed into the principle branch 64 and is by the splitter 11 split into two sub-signals, each subsignal is fed into one sub-branch 65, 66. Depending on the design of the splitter 11 , the signal can be split symmetrically or asymmetrically. The embodiments shown in Figures 21 to 24 comprise a splitter 11 in form of a so-called Wilkinson divider. A Wilkinson divider is a particular type of splitter 11 where the signal of the principle branch 64 is split into the signal of the sub-branches 65 and 66 equally. The sub-branches 65 and 66 are isolated from each other and no signal can go from the first sub-branch 65 to the second sub-branch 66, or vice versa. A signal propagating from one of the two sub-branches 65, 66 back to the principal branch 64 cannot be coupled with the other sub-branch 65, 66. This is possible by incorporating a resistor 14 or termination load in between the subbranches. The energy propagating from one sub-branch 65, 66 towards the other sub-branch 65, 66 is transformed into heat in the resistor 14 or dissipates into the printed circuit board 2. P28850PC00

[0154] 39 / 49

[0155] Figure 21 shows an embodiment with a Wilkinson divider used with strip lines 91 . Figures 22 to 24 show embodiments with a Wilkinson divider based on waveguide technology. Steps in the form of protrusions 111 may be arranged at the splitter 11 for matching purposes. Figures 22 and 23 show embodiment which comprise a resistor 14 or terminal load arranged inside the waveguide. Figure 24 shows a variation in which, instead of the resistor or terminal load, an area without coating 25 is arranged on the front face of the printed circuit board.

[0156] Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without depart- ing from the Spirit and scope of the invention.

[0157] P28850PC00

[0158] 40 / 49

[0159] LIST OF DESIGNATIONS

[0160] 1 Antenna device 8 Connection element

[0161] 2 Printed circuit board (PCB) 81 Gap

[0162] 21 Back face 82 Via transition

[0163] 22 Front face 83 Printed circuit board launcher

[0164] 23 Top layer 30 84 Substrate

[0165] 24 Waveguide 9 Planar transmission line

[0166] 25 Uncoated area 91 Hybrid strip line

[0167] 3 First high frequency compo911 Lower ground plane nent 912 Substrate layer

[0168] 4 Antenna layer 35 913 Strip line

[0169] 41 Back face 914 Lateral grounding elements

[0170] 42 Front face 915 Upper ground plane

[0171] 5 Waveguide channel 92 Hybrid grounded coplanar

[0172] 51 First waveguide aperture waveguide

[0173] 52 Second waveguide aperture 40 921 Lower ground plane

[0174] 6 Signal transmission path 922 Substrate layer

[0175] 61 Recess 923 Strip line

[0176] 62 Waveguide 924 Lateral grounding elements

[0177] 63 Stepped structure 925 Upper ground plane

[0178] 64 Principle branch 45 93 Hybrid differential line

[0179] 65 First sub-branch 931 Lower ground plane

[0180] 66 Second sub-branch 932 Substrate layer

[0181] 7 Second high frequency com933 Strip line ponent 934 Lateral grounding elements P28850PC00

[0182] 41 / 49

[0183] 935 Upper ground plane 96 Coaxial channel

[0184] 94 Hybrid magnetic strip line 961 Channel surface

[0185] 941 Strip line 15 962 Inner conductor

[0186] 942 Ground plane 10 Meta-surface 943 Artificial magnetic conductor 101 Periodic structure

[0187] 944 EBG structure 11 Splitter

[0188] 95 Hybrid strip-ridge gap wave111 Protrusionl 2 Heat sink guide 20 121 Back face

[0189] 951 Lower ground plane 122 Front face 952 Strip line 13 Solder ball

[0190] 953 Upper ground plane 14 Resistor

[0191] 954 Periodic structure

Claims

P28850PC0042 / 49PATENT CLAIMS1 . An antenna device (1 ) comprising: a. a printed circuit board (2) with a back face (21 ) and a front face (22); b. at least one fist high frequency component (3) configured to trans- mit and / or receive a radar signal; c. an antenna layer (4) with a back face (41 ) and a front face (42) comprising at least one waveguide channel (5) extending from a first waveguide aperture (51 ) on the back face (41 ) through the antenna layer (4) to a second waveguide aperture (52) on the front face (42); wherein the back face (41 ) of the antenna layer (4) is at least partially arranged on the front face (22) of the printed circuit board (2) and the at least one high frequency component (3) is arranged on the back face (21 ) of the printed circuit board (2) and configured to transmit and / or receive a radar signal to and / or from the first waveguide aperture (51 ) of the at least one waveguide channel (5) through the printed circuit board (2), wherein at least one signal transmission path (6) is configured to propagate a local oscillator signal from a local oscillator to the at least one first high frequency component (3).P28850PC0043 / 492. The antenna device (1 ) according to claim 1 , comprising a second high frequency component (7) configured to transmit and / or receive a radar signal, wherein the local oscillator is part of the second high frequency component (7).

3. The antenna device (1) according to one of claims 1 or 2, wherein the at least one signal transmission path (6) is arranged on the front face (22) of the printed circuit board (2).

4. The antenna device (1) according to one of claims 1 or 2, wherein the at least one signal transmission path (6) is arranged on the back face (21 ) of the printed circuit board (2).

5. The antenna device (1) according to claim 3, wherein at least one high frequency component (3) is configured to route the local oscillator signal into the signal transmission path (6) through the printed circuit board (2).

6. The antenna device (1) according to claim 5, wherein the at least one high frequency component (3) comprises a launch on package (81 ) and is configured to route the local oscillator signal into the signal transmission path (6) through a gap (81 ) in the printed circuit board (2).

7. The antenna device (1) according to claim 5, wherein the at least one high frequency component (3) is configured to route the local oscillator signal into the signal transmission path (6) through a via transition (82).P28850PC0044 / 498. The antenna device (1 ) according to claim 7, wherein the via transition is connected to a guiding element, such as a strip line (82).

9. The antenna device (1 ) according to claim 7, wherein the via transition is connected to a planar coupling element, such as a printed circuit board launcher (83).

10. The antenna device (1 ) according to one of claims 3 or 5 to 9, wherein the at least one signal transmission path (6) is arranged between the back face (41 ) of the antenna layer (4) and the front face (22) of the printed circuit board (2).

11. The antenna device (1 ) according to claim 10, wherein the at least one signal transmission path (6) is formed by the front face (22) of the printed circuit board (2) and a recess (61 ) in the back face (41 ) of the antenna layer (4).

12. The antenna device (1 ) according to at least one of the preceding claims, wherein the signal transmission path (6) comprises a hybrid planar transmission line (9), preferably in form of a hybrid strip line (91 ) or a hybrid grounded coplanar waveguide (92) or a hybrid differential line (93).

13. The antenna device (1 ) according to claim 12, wherein in a top view on the front face of the printed circuit board (2) the hybrid planar transmission line (9) comprises a lower ground plane (911 , 921 ), a substrate layer (912, 922) with a thickness (T) arranged on the ground plane (911 , 921 ) and a strip line (913, 923) arranged on top of the substrate layer (912, 922).P28850PC0045 / 4914. The antenna device (1 ) according to claim 13, wherein the hybrid planar transmission line (9) comprises lateral grounding elements (914, 914’, 924, 924’) which are arranged adjacent to both lateral sides of the strip line (913, 923) at a distance from the strip line (913, 923), which is larger than the thickness (T) of the substrate layer (912, 922) and are connected to the lower ground plane (911 , 921 ).

15. The antenna device (1 ) according to one of claims 12 or 13, wherein the hybrid planar transmission line (9) comprises an upper ground plane (915, 925) which is arranged above the strip line (913, 923) at a distance with respect to the strip line (913, 923) which is two times smaller than the thickness (T) of the substrate layer (912, 922), with the upper ground plane (915, 925) preferably being at least partially attached to the back face (41 ) of the antenna layer (4).

16. The antenna device (1 ) according to one of claims 12 to 15, wherein the hybrid planar transmission line (9) is in form of a hybrid differential line (93) comprising a lower ground plane (931 ), a substrate layer (932) with a thickness (T) arranged on the ground plane (931 ) and a pair of strip lines (933) arranged on top of the substrate layer (932).

17. The antenna device (1 ) according to one of claims 1 to 11 , wherein the signal transmission path (6) is in form of a hybrid magnetic strip line (94) comprising a strip line (941 ) and a ground plane (942) arranged on one side of the strip line (941 ) as well as an artificial magnetic conductor (943) arranged on the opposite side of the strip line (941 ) whereby the strip lineP28850PC0046 / 49(941 ) and the ground plane (942) are configured to guide an electrical field therebetween.

18. The antenna device (1 ) according to claim 17, wherein the hybrid magnetic strip line (94) comprises an artificial magnetic conductor (943) in form of a periodic EBG structure (944), in particular a mushroom EBG structure.

19. The antenna device (1 ) according to claim 18, wherein the hybrid magnetic strip line (94) comprises a mushroom EBG structure (944) comprising a series of vias which are arranged in a top layer (23) of the printed circuit board (2).

20. The antenna device (1 ) according to at least one of claims 1 to 9, wherein the signal transmission path (6) is a hybrid strip-ridge gap waveguide (95) comprising in a top view on the front face of the printed circuit board (2) a lower ground plane (951 ) and a strip line (952) grounded to the lower ground plane (951 ) creating a strip-ridge.

21. The antenna device (1 ) according to claim 20, wherein an upper ground plane (953) is arranged on top of the strip line (952) and a periodic structure (954) is arranged laterally of the strip line (952) to avoid leakage of energy.

22. The antenna device (1 ) according to one of claims 3 or 5 to 21 , wherein on the front face (22) of the printed circuit board (2) and / or the back face (41 ) of the antenna layer (4) a meta-surface (10) is arranged which comprises a periodic structure (101 ) in form of mushroom EBGs (102) to avoid leakage of energy.P28850PC0047 / 4923. The antenna device (1 ) according to at least one of the preceding claims, wherein the signal transmission path (6) comprises a splitter (11 ) which is configured to divide the local oscillator signal between at least two branches (64, 64’).

24. The antenna device (1 ) according to claim 4, wherein the at least one signal transmission path (6) is arranged between the back face (21 ) of the printed circuit board (2) and a heat sink (12) which is arranged on the back face (21 ) of the printed circuit board (2).

25. The antenna device (1 ) according to claim 3, wherein the at least one signal transmission path (6) is arranged within the antenna layer (4) in form of a coaxial channel (96) with the channel surface (961 ) being the outer conductor and an inner conductor (962) being arranged within the coaxial channel (96) electrically isolated from the channel surface (961 ).

26. An antenna device (1 ) comprising: a. a printed circuit board (2) with a back face (21 ) and a front face (22); b. at least one high frequency component (3) configured to transmit and / or receive a radar signal; c. an antenna layer (4) with a back face (41 ) and a front face (42) comprising at least one waveguide channel (5), which each extend from a first waveguide aperture (51 ) on the back face (41 ) throughP28850PC0048 / 49 the antenna layer (4) to a second waveguide aperture (52) on the front face (42); wherein at least one signal transmission path (6) is configured to propagate a local oscillator signal from a local oscillator to the at least one high fre- quency component (3) and the at least one signal transmission path (6) is configured to propagate a signal at frequencies in the range of 5 to 80 GHz in a TEM or quasi-TEM mode.

27. The antenna device (1 ) according to claim 26, wherein the bandwidth is typically less than 1 GHz.

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