Antenna device

Abstract

The present disclosure relates to an antenna layer (1) having a back face (2) and a front face (3) and a method for producing an antenna layer (1). The antenna layer (1) comprises at least two waveguide channels (4), extending at the back face (2) each comprising at least one waveguide aperture (5) for transmitting and / or receiving a signal arranged at the front face (3). The waveguide channels (4) each comprise at least one radiating opening (6), which is arranged in the antenna layer (1) and is interconnected to the waveguide aperture (5) by at least one radiating channel (7). A parting line (8) is arranged in the at least one radiating channel (7) between the back face (2) and the front face (3), which parting line (8) is spaced a distance (D) from the at least one radiating opening (6) towards the at least one waveguide aperture (5) and preferably extends circumferentially within the at least one radiating channel (7). The present disclosure further relates to an antenna assembly (17) comprising the antenna layer (1) and an antenna device (23) comprising the antenna assembly (17).

Description

[0001] Antenna Device

[0002] FIELD OF THE DISCLOSURE

[0003] The present disclosure relates to an antenna layer for an antenna assembly for use in automotive radar applications, which antenna assembly comprises a therein-arranged waveguide.

[0004] BACKGROUND OF THE INVENTION

[0005] WO2019057965, published in the name of Gapwaves AB on 28.03.2019, is directed to a phased array comprising a base layer. The base layer comprises a substrate with a plurality of protruding posts for stopping wave propagation along the base layer and a printed circuit board (PCB) arranged on the base layer. The PCB comprises at least one phased array radio frequency (RF) integrated circuit (IC) on a first side of the PCB facing the base layer and the protruding posts. The PCB further comprises feeds for transferring of RF signals from the phased array RF IC(s) to an opposite second side of the PCB. A radiating layer, comprising a plurality of radiating elements for transmitting and / or receiving RF signals from the phased array antenna is also provided, together with a feeding layer for transfer of RF signals, arranged between the feeds of the PCB on the second side and the radiating elements of the radiating layer.

[0006] W02023020668, published in the name of Continental Autonomous Mobility Germany GmbH on 23.02.2023, is directed to a radar system for detecting surroundings. The radar system comprises a printed circuit board, which carries at least one high-frequency component, with high-frequency signals being guided from the component to the printed circuit board via electrical connections, and a moulded part, which on its upper side has one or more individual antennas for transmitting and / or receiving radar signals. The electrical connection between the printed circuit board and the at least one individual antenna on the upper side of the moulded part is realized at least in part by an inner waveguide. The moulded part is arranged on the same side of the printed circuit board as the at least one high-frequency component and is at least partially and conductively connected to the latter, in particular by soldering and / or conductive adhesive bonding. At least one hollow waveguide is formed by a recess on the side of the moulded part facing the printed circuit board and by a metallized surface of the printed circuit board. The at least one waveguide is electrically fed by the printed circuit board, and the moulded part can consist or does consist of a single-layer, at least partially metallized plastics part or a single-layer metal part, which is preferably produced by die casting, deep drawing or bending technology.

[0007] SUMMARY OF THE INVENTION

[0008] The use of mi Hi meter- wave (MMW) frequencies for communications and automotive radar applications is continuously expanding. Antennas are critical components in all these applications, and come with advanced requirements in terms of performance, size, weight and compliance to environmental standards. In terms of performance, antenna gain, and efficiency are crucial parameters since they directly affect the overall system link budget (translating to link distance and coverage for communication systems, and to maximum detection range for automotive radars).

[0009] A crucial parameter in the design of antenna layers for antenna assemblies with hollow waveguide channels is the positioning of the radiating openings, which are typically interconnected to waveguide apertures for sending and / or receiving a signal. Antenna assemblies, in particular for automotive radar applications, are typically made of at least two antenna layers which are in the mounted state joined along a plane. Typically, at least two waveguide channels extend within the antenna assembly. Each of the at least two waveguide channels extends from a feeding aperture to at least one waveguide aperture. The signal is typically fed through the feeding aperture into the respective waveguide channel in the antenna assembly and sent or reciprocally received by the waveguide aperture. To actually enable the antenna assembly to send and / or receive a signal, the at least two waveguide channels typically each comprise at least one radiating opening. The exact arrangement of the radiating opening with respect to the respective waveguide channel has a significant impact on the elevation pattern of the antenna assembly. Therefore, besides the design and routing of the at least two waveguide channels within the antenna assembly, accurate positioning of the at least one radiating opening with respect to the respective waveguide channel is crucial. The positioning is hugely impacted during the manufacturing of the antenna layer, in particular the tolerances of the die can have a significant impact on the antennas’ transmission and / or receiving characteristic.

[0010] An objective of the present disclosure can therefore be seen in providing an antenna layer with an improved transmission and / or receiving characteristic.

[0011] An antenna layer according to the present disclosure has a back face and a front face. The antenna layer can be made by a shaping process, preferably by injection molding or die casting. Alternatively, the antenna layer can be made by a punching or cutting process. Especially for automotive applications, given the vast production volume and low-weight requirements, the antenna layer is typically made by injection molding from a thermoplastic material. The front and / or back face can in addition be at least partially or fully metalized or coated. The back face and / or the front face are typically essentially planar and / or parabolic. To be able to produce an antenna assembly with an internal routing within the antenna assembly, the antenna assembly comprises typically at least one antenna layers and a printed circuit board (PCB). An antenna assembly according to the present disclosure comprises the antenna layer, which may be the front or middle part of the antenna assembly and optionally a second antenna layer, which is typically the back part of the antenna assembly. Back and front are in the context of the present disclosure to be understood as follows, the back of the antenna assembly is the feeding side, whereas the front face is the side of the antenna assembly for sending and / or receiving a signal. The antenna layer typically comprises at least two waveguide channels, which extend at the back face of the antenna layer and are each interconnected to at least one waveguide aperture for transmitting and / or receiving a signal arranged at the front face of the antenna layer. The waveguide channels can be arranged in the back face of the antenna layer and / or in the front face of the second antenna layer. The waveguide channels each typically interconnect in the antenna assembly a feeding aperture, arranged at the back face of the antenna assembly, to the waveguide aperture, arranged at the front face of the antenna assembly. The feeding aperture is interconnectable to an electronic component and the signal is typically fed via respective feeding apertures into the waveguide channels. To be able to send and / or receive a signal, the waveguide channels each comprise at least one radiating opening which is arranged in the antenna layer and is interconnected to the waveguide aperture by at least one radiating channel.

[0012] A feeding aperture can couple directly to a coupling element on the PCB, or to a hole in the PCB permeable for electromagnetic waves. The hole in the PCB can be a plated through hole, which is suitable to propagate a fundamental mode TE10 (i.e. a short waveguide).

[0013] Right after the feeding aperture, when entering the waveguide channel, deflecting elements, such as protrusions or pins, can be placed in order to: a) Rotate the fundamental mode TE10 by 90°, with the electric field in the waveguide channel being perpendicular to the antenna front face. 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 antenna front face); or b) Change the direction of propagation of the fundamental mode TE10, with the electric field in the waveguide channel keeping its direction parallel to the antenna front face. An additional deflection element can be placed subsequently in order 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 antenna front face. 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 3).

[0014] The waveguide channels have a given length. Length differences between the channels should be kept similar in order to avoid differences of phase between the waveguide channels over changes in temperature. (Due to the expansion coefficient of the materials, channels with a very different length can behave very differently over wide temperature intervals, such as from -40° to +125°. A so-called guided wavelength is the distance that a waveguide channel should add in order to have the same phase than another channel. It can be calculated as 2ir / beta, with beta being the propagation constant of the fundamental mode TE10.

[0015] It is preferable for the present application that the difference of length between at least two waveguide channels of the same type (all receivers or all transmitters) do not differ more than 10 guided wavelengths. In a variation, it is also referable, if the associated phase difference is a multiple of 180° + / - 20°.

[0016] In a variation, the back face of the antenna layer is arranged on the front face of the second antenna layer. The waveguide channels may extend in the antenna assembly at least partially in the front face of the second antenna layer. The back face of the antenna layer and the front face of the second antenna layer can be in full contact with each other. A cost efficient antenna assembly can be obtained with the antenna layer and the second antenna layer each being essentially rectangular plates. The antenna assembly is typically part of an antenna device. An antenna device according to the present disclosure, in particular for automotive radar applications, typically comprises the antenna assembly and an electronic component. The electronic component is typically a radar chip, which is arranged on or interconnected to a printed circuit board. The electronic component is electrically interconnected to the feeding aperture of the antenna assembly. Via the feeding aperture a signal is fed from the electronic component into the antenna assembly or reciprocally a received signal is sent to the electronic component.

[0017] The antenna layer can comprise a number of radiating openings, which can be arranged in arrays of openings. The number of radiating openings of an array are preferably energized by a common waveguide channel which is interconnected to the electronic component via the feeding aperture. Depending on the design, the radiating openings of an array are configured to radiate and / or receive a signal. The inclusion of several parallel radiating openings results in a narrowing of the radiation beam emitted by the antenna layer. This can be beneficial for a long distance radar. For very short range radars, it can be beneficial to have a single opening. Good results can be achieved when the radiating openings are designed as slots. Depending on the field of application, the radiating openings may have different geometries as will become apparent from the variations shown hereinafter in more detail. The waveguide channels each typically comprise a cross section out of the group of the following geometries or a combination thereof: Rectangle, rhomb, ellipse, circle, wherein a main extension direction of the cross section is essentially parallel to the feeding aperture and waveguide aperture. The feeding aperture and the waveguide aperture can be laterally offset with respect to each other. This offset allows that the routing of each waveguide channel is optimized to allow impedance matching and low-loss transmission of the RF signal, to maintain a specified phase relation between the different antenna elements, and to allow a proper manufacturing process.

[0018] The positioning of the at least one radiating opening with respect to the respective waveguide channel has a detrimental effect on the antenna performance, in particular an influence on the radiation pattern. Variations in the pattern between radiating openings with respect to each other and in particular with respect to the waveguide channel can have a noticeable influence on beamforming, causing detection of false targets or not allowing a detection of angular direction. To ensure proper function of the antenna assembly, electrical parameters therefore need to remain stable, nevertheless in real life there are besides the design parameters also manufacturing tolerances, which affect the accuracy. While tolerances of areas which are formed into one part of an injection mold can be reproduced well, the tolerances along the parting line of the mold vary and are subject to precision of tool making, process parameters and wear of the tool. In conventional designs, when producing the antenna layer by injection molding or die casting, the parting plane of the two mold halves is placed between waveguide channel and waveguide aperture and thereby typically defines the most narrow opening / cross section of the aperture. The radiating opening is typically arranged exactly in the parting plane. The waveguide channel is typically arranged in the back face of the antenna layer and is shaped by the first mold half, while the thereto interconnected waveguide aperture is arranged in the front face and shaped by the second mold half. As a consequence, the accuracy of the positioning of the radiating openings in known designs, being arranged between waveguide channel and waveguide aperture, depends strongly on the tolerances of the mold.

[0019] To improve the accuracy, a radiating channel can be arranged between radiating opening and waveguide aperture, interconnecting the at least one radiating opening with the waveguide aperture. The antenna layer according to the present disclosure is typically produced by a conventional mold with two mold halves. To improve the accuracy of the antenna layer, the parting plane of the molds is displaced. Instead of arranging the parting plane between radiating opening and waveguide aperture as known, the parting plane is arranged between radiating channel and waveguide aperture, therefore spaced a distance from the radiating opening. The parting plane of the mold leads to a parting line on the product, typically in form of a burr. A parting line is typically arranged in the at least one radiating channel between the back face and the front face. The parting line is spaced a distance from the at least one radiating opening towards the at least one waveguide aperture. Preferably the parting line extends circumferentially within the at least one radiating channel. As a result, the tolerances at the transition between radiating opening and radiating channel are reduced to the processing tolerances of one mold half and not the closing accuracy of the two mold halves. Techniques such as high-precision plastic injection molding and, if required, metallization process and metal die casting are chosen with regard to the molding parting lines and layer separations. Highly accurate molding parting lines are desired to have minimum impact on the propagation of the electromagnetic signal (i.e., minimum losses and mismatching) once the two antenna layers are joined together. Depending on the design of the radiating channel and the thereto connected aperture, the parting line can be arranged somewhere in the at least one radiating channel or as an extreme at the distal end of the radiating channel. The parting line can therefore be congruent with the transition between radiating channel and aperture. The cross-section of the waveguide aperture then completely falls into the crosssection of the radiation channel, not allowing for a step between the radiation channel and the waveguide aperture. In some other variations, the radiating channel can merge into the aperture in form of a step. The parting line can be congruent with the edge of the step.

[0020] The at least one radiating opening can merge into the radiating channel by a transition area which is rounded or chamfered. In theory, a sharp transition in form of a sharp edge would be preferable for the signal propagation between radiating opening and radiating channel. Nevertheless, for the production demolding bevels are necessary to be able to demold the antenna layer. Therefore a chamfer or rounded edges are necessary. A good compromise between efficient signal propagation and demolding behavior can be achieved by a ratio between the radius of the transition area and the distance between radiating opening and parting line, which is smaller than 1 , preferably smaller than 0.8, most preferably smaller than 0.6.

[0021] The waveguide channels can be each interconnected to a splitter via a primary port which is configured to split a signal to be sent into a first waveguide channel branch, which is typically interconnected to a first secondary port of the splitter and a second waveguide channel branch, which is typically interconnected to a second secondary port of the splitter. In a preferred variation the waveguide channels are with respect to the respective feeding aperture at a distal end interconnected to the waveguide splitter by the primary port. The splitter is configured to split the signal in two parts and if necessary to adjust the orientation of the parts of the signal, e.g. by rotating the polarization from horizontal to vertical and / or vice-versa. The respective splitter routes the first part of the signal power into the first waveguide channel branch interconnected to the first secondary port of the splitter and a second part of the signal power into the second waveguide channel branch interconnected to the second secondary port of the splitter. The length of the at least one waveguide channel is usually larger than the length of the first waveguide channel branch and the length of the second waveguide channel branch combined.

[0022] The primary and the secondary ports of the splitter can be fully integrated into the structure of the waveguide channel and the respective waveguide channel branches and are therefore not necessarily visible from the outside. In a variation, the splitter can be configured to rotate one part of the signal power clockwise and the other part counter clockwise. In a preferred variation of the antenna assembly the E-field is twisted from the horizontal direction (essentially in plane of the antenna assembly) as it arrives in the waveguide primary port to a vertical direction (essentially perpendicular to a front face of the antenna assembly) as it exits the splitter at the waveguide secondary ports. The first and the second waveguide channel branch typically each comprise at least one radiating opening, wherein the radiating openings can be arranged co-linear with respect to a centerline. The at least one waveguide aperture of the first waveguide channel branch and the at least one waveguide aperture of the second waveguide channel branch are optionally interconnected with each other

[0023] The waveguide splitter may comprise at least one deflection element, typically arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees. Alternatively or in addition, at least one deflection element can be arranged adjacent to the first secondary port and the second secondary port configured to twist the polarization back from the vertical direction to the horizontal direction. Deflection elements arranged at the splitter or the waveguide channel are usually configured to introduce a 90° rotation of the E-field. The E-field which is horizontally polarized in the splitter and / or the waveguide channel is twisted such that the E-field in the waveguide channel branches is vertically polarized. When receiving incoming signals the polarization is twisted vice versa. The polarization twist can be also achieved by a number of subsequent deflection elements, arranged along the centerline of the waveguide channel branch to gradually alter and rotate the electric field. The deflection elements are preferably configured as impedance matching features. The at least one deflection element can be configured to twist the polarization of the E-field, such that the polarization of the first waveguide channel branch and the second waveguide channel branch are equally polarized. Alternatively, the deflection element can be configured such that the polarization of the E-field in the first waveguide channel branch and the second waveguide channel branch are reversed with respect to each other. As mentioned above, the at least one deflection element can be configured to twist the polarization of the E-field, such that the electric field is essentially twisted from the horizontal direction, to the vertical direction by 90 degrees and - if appropriate - to provide impedance matching. Alternatively or in addition the deflection elements can be arranged asymmetrically with respect to the splitter such that an asymmetric power / phase distribution between the first and second waveguide channel branch is achieved. This can be beneficial for applications were pointing at angles different than boresight is required.

[0024] In other variations the at least one deflection element, arranged inside and / or outside of the waveguide channel and / or the splitter, comprises at least one out of the group of the following elements or a combination thereof: Step, recess, channel, bump, dented corner, which usually protrude inside and / or outside the cross-section of the waveguide channel and / or the splitter forming a local reduction of the cross-section. Good results can be achieved, when the waveguide channel may comprise in the area of the primary port of the splitter two dented corners which are arranged opposite to each other and which are designed as deflection elements for the E-field. In a preferred variation, of an antenna device according to the disclosure, the length of the waveguide channel of at least one antenna element is larger than the length of the first waveguide channel branch and the length of the second waveguide channel branch combined. Alternatively or in addition, a ridge and ora necking can be arranged at the first and / or second waveguide channel branch configured to introduce an electrical delay of the propagating mode. The electrical delay helps to further reduce the phase error such that higher values of directivity are obtained. In case that the signal power is split in a first and in a second part, the splitter may comprise a necking, e.g. in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged in the splitter in the middle between the first and the second branch, respectively the first and the second secondary port. The necking is configured to help dividing the signal between the first and the second waveguide channel branch. Depending on the distribution to be achieved, the necking can be arranged centered between the first secondary port and the second secondary port, such that the signal is split equally between the first and the second waveguide channel branch. If appropriate, the necking can be arranged with respect to a center point between the first and second secondary port offset to one side between the first secondary port and the second secondary port, such that the signal, respectively its power, is split non-equally between the first and the second waveguide channel branch. Due to the performance advantages of the herein described arrangement, the splitting of the power is almost lossless. Only a negligible amount of power is lost during the splitting.

[0025] To be able to allow an arrangement of the radiating openings collinear with respect to the centerline of the at least one waveguide channel first and the second waveguide channel branch can be designed in a staggered design configured to alter the field such that the at least one radiating opening of the first and the at least one radiating opening of the second waveguide channel branch are aligned collinear with respect to each other. One drawback of standard arrays of openings, as known from the prior art, lays in the offset position of the openings with respect to a centerline. In particular, this offset generates an asymmetric illumination of the effective antenna aperture, which in turn produces asymmetries in the radiated pattern outside of the main radiation planes (i.e., azimuth and elevation plane). These asymmetries typically result in higher radiation levels at specific undesired angles, with consequent degradation of overall system performance. In a preferred variation, the first and the second waveguide channel branch of an individual antenna element can be designed in a staggered design which is configured to alter the E-field. The E-field is advantageously altered such that the at least one radiating opening of the first and the at least one radiating opening of the second wave-guide channel branch can be aligned collinear with respect to each other. The staggered design is configured to avoid an asymmetric illumination when the openings are arranged in one line. Said arrangement has the advantage of being less prone to beam-tilt and offers a wider bandwidth than the designs known form prior art. However, a MIMO antenna based on standard center-fed arrays, though, would require more than two stacked layers, since the feeding needs to be routed through the bottom of the horizontal waveguide. This would consequently result in increased manufacturing costs and complexity.

[0026] The waveguide aperture typically merges via the radiating channel into the waveguide channel or a branch thereof. The radiating channel therefore interconnects the radiating opening with the waveguide aperture. Preferably, the radiating channel has a funnel shaped design in vertical direction with a narrowing cross-section in inward direction. The at least one radiating opening of the first and the at least one radiating opening of the second waveguide channel branch can also be interconnected to at least one funnel, wherein the funnel merges into a common waveguide aperture. This variation allows to increase the radiating surface of the at least one radiating opening. In a preferred variation the funnel can be arranged in an asymmetric manner with respect to the aperture. The at least one funnel can be interconnected to the waveguide aperture laterally displaced to achieve an asymmetric radiation pattern. The asymmetrically displaced funnel creates a tilt in the radiation properties of the antenna device. The impact of the lateral displacement can create local maxima in the antenna directivity. These local maxima can help to focus the antenna energy in certain areas. The tilted pattern can be useful to have a further range in given areas of the radar. Good results can be for example achieved in automotive applications as the tilted pattern makes it possible to have a locally wider range. The radiating openings can have varying cross sections to tilt the radiation pattern. The first and the second waveguide channel branch can each comprise two arrays of radiating openings. Preferably, the arrays are arranged essentially parallel with respect to each other. In a preferred variation, the two arrays are interconnected to at least one common funnel. Depending on the desired radiation characteristic, the common funnel can be arranged laterally offset with respect to two rows of radiating openings. Alternatively or in addition, the radiating openings of the two rows can have varying cross sections to further tilt the radiation pattern. The difference between the cross section of the openings creates a phase difference between the radiation of each opening. The phase difference causes a tilt in the radiation of the pattern. In a preferred variation, two arrays of openings are arranged parallel with respect to each other. The cross sections of the openings of the first array are smaller and / or larger than the cross sections of the openings of the second array. This configuration causes a tilt of the radiation pattern. Alternatively, the cross sections of neighboring openings within one array can be different, such that an opening with a smaller cross section is arranged adjacent to an opening with a larger cross section. Good results can be achieved when openings with smaller and larger cross sections are arranged in a line next to each other in alternating manner. This causes the radiation pattern to be compensated and radiate in a straight manner.

[0027] At least one radiating opening can have an oblong cross-section. It can be oriented with respect to the corresponding waveguide channel in a longitudinal direction. Typically, the radiating opening has an essentially rectangular, in particular a rectangular, cross-section. However, also other shapes are possible, such as polygonal or C-shaped. The orientation of the radiating openings defines the polarization of the radiation sent by the antenna layer.

[0028] In a further embodiment, the radiating opening can be oriented with respect to the longitudinal direction of a corresponding waveguide channel at a specific angle between 0° and 90°. In a variation of this embodiment, all radiating openings of an antenna layer may be rotated by the same angle, in order to rotate polarization. A waveguide can be formed at least partially by one of the at least two waveguide channels extending at the back face of the antenna layer. The waveguide can have an oblong crosssection with a long expansion and a short expansion, which are perpendicular to each other. At least one radiating opening can be arranged in a wall section of the waveguide which is essentially parallel to the long expansion.

[0029] The electric field of the fundamental mode TE10 in the waveguide is generally oriented perpendicular to the long expansion of the cross-section. By arranging the radiating opening in a wall section of the waveguide, which is essentially parallel to the long expansion, the currents in the waveguide can be interrupted by the radiating opening and generate an electric field in the radiating opening that is perpendicular to the electric field of the fundamental mode TE10 in the waveguide. This allows coupling out only part of the radiation energy in the waveguide through a radiating opening. Series of radiating openings can thus be arranged in a given waveguide or waveguide branch.

[0030] In such a setup, arrangement of the parting line in the radiating channel according to the present invention, i.e. spaced a distance from the radiating opening towards the waveguide aperture, is particularly beneficial. Changes in the relative position of the center of the radiating opening and the center of the waveguide strongly influence the performance, due to the fact that both E-fields are orthogonal to each other. Thus, if the geometry of radiating opening and radiating channel is not chosen properly, higher order modes with several orientations may be excited. This should be avoided in waveguide antennas, since only fundamental mode TE10 must be excited.

[0031] The long expansion of the waveguide cross-section should be larger and the short expansion of the waveguide cross-section shorter than the critical cutoff dimension. The critical cutoff dimension corresponds to half the operating wavelength of the waveguide.

[0032] The waveguide can have a cross-section selected from the group consisting of rectangular, trapezoidal, triangular, elliptical, half-elliptical and polygonal. Preferably, the waveguide has a cross-section which is rectangular with rounded edges. Such a shape is suitable for production by injection molding.

[0033] A cross-sectional area of at least one radiating opening can be, and typically is, smaller than a cross-sectional area of the waveguide.

[0034] Typically, the radiating opening has a length between one fourth of the operating wavelength of the waveguide and two thirds of the operating wavelength of the waveguide. The radiating opening then produces proper excitation. Larger openings would behave more like an open end of a waveguide.

[0035] Alternatively or in addition, the waveguide channels can be at least partially replaced by a series of pillars which are based on the gap waveguide technology. In such an antenna assembly, the font part and / or the back part may preferably at least partially comprise pillars at least partially forming the outer contour of the waveguide channel and / or the splitter and / or the first and second waveguide channel branch. The pillars are configured to guide the signal through the waveguide channel. The pillars can be arranged to enable a bandgap structure which is configured to compensate for potential manufacturing and assembly tolerances between the front and the back part, since a direct ohmic contact is not necessarily needed between them. They thus allow to mitigate leakage between the antenna layers. The electromagnetic band gap (EBG) structures are arranged essentially around the hollow waveguide channels. An electromagnetic band gap structure allows to block electromagnetic waves at a given range of frequencies, behaving as a conductive wall without the need to have direct and / or ohmic contact between the antenna layer and the second antenna layer. The pillars can be arranged as a periodic patterns, optionally as mushrooms in PCB technology or pillars in waveguide technology.

[0036] In a preferred embodiment, the waveguide can be defined by a groove in the font part and / or the back part, while the lateral walls are substituted by electromagnetic band gap (EBG) structures, such as a periodic structure of pillars. These pillars can be solely formed of the font part or the back part. They can also be formed of both parts, for instance alternating along the waveguide of the font part and of the back part. Or they can be formed half height of both parts.

[0037] Another possibility is to implement a hard / soft structure defined by creating elongates metal pillars in one axis in the bottom layer and creating a similar structure where the second elongated pillars are rotated an angle between 45° to 90° respect to the first one.

[0038] A method for producing an antenna layer according to the present disclosure includes making the antenna layer by injection molding or die casting. In view of a cost effective production, one goal is to achieve designs and techniques to implement MIMO antenna arrays that can be manufactured using only a minimum number of stacked layers (parts). The herein described disclosure offers the possibility to design antenna assemblies comprising a minimum of two stacked layers, e.g. comprising a back part and front part. An advantageous construction can be achieved, when the waveguide channels extend at least partially in the back face of the antenna layer and partially in the front face of the second antenna layer. The same applies for the splitter and / or the thereto interconnected waveguide channel branches. The back face of the antenna layer and the front face of the second antenna layer do not have to be essentially flat. If appropriate, the antenna layer and / or the second antenna layer can be skeletonized to reduce contact surface. This is advantageously as the minimized contact area increases the surface pressure of the contact area and therefore results in a more accurate alignment of the antenna layer and the second antenna layer in the area of the waveguide channel and / or the splitter and / or the first and second waveguide channel branches.

[0039] The antenna layer can be made by injection molding of a plastic material, followed by metallizing the surface. The antenna layer and / or the second antenna layer can be made by injection molding of at least one plastic material. Alternatively, or in addition, the antenna layer and / or the second antenna layer can be made of metal and / or metallized plastic and / or any other material conductive at the surface. In a variation, the antenna layer and / or the second antenna layer are made of metal and / or metallized plastic and / or any other material conductive at the surface. The design of the waveguide components and the antenna layers may be optimized to be compatible with a variety of joining techniques.

[0040] It is understood that the present invention is by no means restricted to hollow waveguides but may also be embodied with other types of waveguides, such as ridge waveguides.

[0041] 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 are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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:

[0044] Fig. 1 a perspective view from the front and above on a first variation of the antenna device;

[0045] Fig. 2 a perspective view from the back and above on the first variation of the antenna device according to Fig. 1 ;

[0046] Fig. 3 a front view on the first variation of the antenna device according to Fig. 1 , showing the internal routing of the waveguide channels; Fig. 4 a perspective view from the front and above on a first variation of the antenna assembly, showing the internal routing of the waveguide channels;

[0047] Fig. 5 a perspective view from the front and above on a second variation of the antenna assembly in an un folded manner, showing the internal routing of the waveguide channels;

[0048] Fig. 6 a front view on a second variation of the antenna device, showing the internal routing of the waveguide channels;

[0049] Fig. 7 a perspective view from the front and above on the second variation of the antenna device according to Figure 6, showing the internal routing of the waveguide channels;

[0050] Fig. 8 a lateral sectional view of a waveguide channel, interconnected to waveguide apertures via a splitter as known from prior art;

[0051] Fig. 9 a plot showing the propagation characteristics of the conventional design according to Figure 8;

[0052] Fig. 10 a lateral sectional view of a first variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0053] Fig. 11 a plot showing the propagation characteristics of the design according to Figure 10;

[0054] Fig. 12 a perspective view from the front and above on a second variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter; Fig. 13 a lateral sectional view of the second variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0055] Fig. 14 a perspective view from the front and above on a third variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0056] Fig. 15 a lateral sectional view of the third variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0057] Fig. 16 a perspective view from the front and above on a fourth variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0058] Fig. 17 a lateral sectional view of the fourth variation of a waveguide channel, interconnected to a splitter according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0059] Fig. 18 a perspective view from the front and above on a fifth variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0060] Fig. 19 a lateral sectional view of the fifth variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0061] Fig. 20 a perspective view from the front and above on a sixth variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter; Fig. 21 a lateral sectional view of the sixth variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0062] Fig. 22 a perspective view from the front and above on a seventh variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0063] Fig. 23 a lateral sectional view of the seventh variation of a waveguide channel according to the present disclosure, interconnected to waveguide apertures via a splitter;

[0064] Fig. 24 a perspective view from the front and above on an eights variation of a waveguide channel according to the present disclosure;

[0065] Fig. 25 a lateral sectional view of the eights variation of a waveguide channel according to the present disclosure;

[0066] Fig. 26 a perspective view from the front and above on a ninth variation of a waveguide channel according to the present disclosure;

[0067] Fig. 27 a lateral sectional view of the ninth variation of a waveguide channel according to the present disclosure;

[0068] Fig. 28 a perspective view from the front and above on a third variation of an antenna assembly according to the present disclosure;

[0069] Fig. 29 a perspective view from the front and above on the third variation of the antenna assembly according to the present disclosure in an unfolded manner;

[0070] Fig. 30 a lateral sectional view on the third variation of the antenna assembly according to the present disclosure. DESCRIPTION OF THE EMBODIMENTS

[0071] 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 satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0072] Figures 1 to 3 show a first variation of the antenna device 23, in Figure 1 in a perspective view from the front and above, in Figure 2 in a perspective view from the back and above and in Figure 3 as a front view, showing the internal routing of the waveguide channels 4. The shown antenna device 23 for automotive radar applications comprises an antenna assembly 17 and an electronic component 24. The shown electronic component 24 is a radar chip 25, which is arranged on a printed circuit board 26. The electronic component 24 is interconnected to the feeding apertures 28 of the antenna assembly 17. Via the feeding apertures 28 a signal is fed from the electronic component 24 into the antenna assembly 17 or reciprocally a received signal is sent to the electronic component 24. The shown antenna assembly 17 comprises the antenna layer 1 , in the shown variation as front part 18 of the antenna assembly 17. The shown second antenna layer 21 is the back part 20 of the antenna assembly 17. The shown antenna layer 1 is made by injection molding.

[0073] Figure 4 shows a perspective view from the front and above on a first variation of the antenna assembly 17, showing the internal routing of the waveguide channels 4. The shown waveguide channels 4 interconnect in the antenna assembly 17 the feeding apertures 28, arranged at the back face of the antenna assembly 17, to the waveguide apertures 5 arranged at the front face of the antenna assembly 17, which is at the same time also the front face 3 of the antenna layer 1. The shown waveguide channels 4 are partially arranged in the back face of the antenna layer 1 and partially in the front face of the second antenna layer 21 . The feeding apertures 28 are interconnectable to an electronic component and the signal is fed via the feeding aperture 28 into the waveguide channel 4.

[0074] The waveguide channels 4, or better the waveguides 31 , have an oblong cross section with a long expansion a and a short expansion b (not visible in Figure 4). The short expansion is parallel to the antenna plane (i.e. parallel to e.g. the front face 3). Upon entering the waveguides 31 through the feeding apertures 28, the direction of propagation of the fundamental mode TE10 is changed, with the electric field in the feeding apertures 28 and in the waveguides 31 being parallel to the antenna top front face 3.

[0075] In an alternative embodiment, an additional deflection element can be placed subsequently to the feeding apertures 28 in order to rotate the electric field in the waveguide 31 by an angle from 0° to 90° in the antenna plane. In both cases, the electric field remains parallel to the front face 3.

[0076] The waveguide channels 4 are each interconnected to a splitter 10 via a primary port which splits the signal to be sent into the respective first waveguide channel branch 12 and the respective second waveguide channel branch 14. The splitter 10 is configured to split the signal in two parts and if necessary to adjust the orientation of the parts of the signal, e.g. by rotating the polarization from horizontal to vertical and / or vice-versa. The splitter 10 routes the first part of the signal power into a first waveguide channel branch 12 interconnected to a first secondary port of the splitter and a second part of the signal power into the second waveguide channel branch 14 interconnected to a second secondary port of the splitter. The length of each waveguide channel 4 is larger than the length of each of the respective first waveguide channel branch 12 and the length of the respective second waveguide channel branch 14 combined. The shown waveguide apertures 5 are arranged collinear with respect to a centerline (L) of the first waveguide channel branch 12 and the second waveguide channel branch 14. Figure 5 shows a perspective view from the front and above on a second variation of the antenna assembly 17, showing the internal routing of the waveguide channels 4. The shown antenna assembly 17 comprises two stacked layers. The antenna layer 1 is the front part 18 of the antenna assembly 17, the second antenna layer 21 is the back part 20 of the antenna assembly 17. The waveguide channels 4 extend at least partially in the antenna layer 1 and partially in the second antenna layer 21. The shown antenna layer 1 and the second antenna layer 21 are skeletonized to reduce contact surface. This is advantageously as the minimized contact area increases the surface pressure of the contact area and therefore results in a more accurate alignment of the antenna layer 1 and the second antenna layer 21 in the area of the waveguide channel 4 and / or the splitter 10 and / or the first 12 and second 14 waveguide channel branches.

[0077] Figures 6 and 7 show a second variation of the antenna device 23, showing the internal routing of the waveguide channels 4. The shown antenna device 23 for automotive radar applications comprises only a single antenna layer 1 which is with its back face 2 mounted onto the printed circuit board 26. The waveguide channels 4 are interconnected to an electronic component 24. The shown electronic component 24 is a radar chip 25, which is arranged on the printed circuit board 26. The electronic component 24 is interconnected to the feeding apertures 28 of the antenna layer 1 . Via the feeding apertures 28 a signal is fed from the electronic component 24 into the antenna assembly 17 or reciprocally a received signal is sent to the electronic component 24. The shown antenna assembly 17 comprises the antenna layer 1 , in the shown variation as front part 18 of the antenna assembly 17. The waveguide channels 4 are formed by a recess in the back face of the antenna layer 1 and the front face of the printed circuit board 26.

[0078] The waveguide channels 4 have an oblong cross section with a long expansion a and a short expansion b (not visible in Figures 6 and 7). The long expansion is parallel to the antenna plane (i.e. parallel to e.g. the front face 3). Upon entering the waveguide channels 4 through the feeding apertures 28, the fundamental mode TE10 is rotated by 90°, with the electric field in the feeding aperture 28 and in the waveguide channel 4 being orthogonal to each other. The electric field in the feeding aperture 28 is thus parallel to the antenna plane (i.e. parallel to e.g. the front face 3). The electric field in the waveguide channel 4 is perpendicular to its long extension a, i.e. perpendicular to the antenna front face 3.

[0079] Figure 8 shows a lateral view of a waveguide channel 4 as known from prior art. The waveguide channel 4 is interconnected to a splitter 10, splitting a signal into a first waveguide channel branch 12 and a second waveguide channel branch. The shown waveguide channel branches comprise radiating openings 6, which are arranged in the antenna layer 1 and are interconnected to waveguide apertures 5. The radiating openings 6 are arranged in arrays of openings and energized by the common waveguide channel 4 via a feeding aperture, which is interconnected to a respective electronic component at the back face of the antenna assembly 17. The radiating openings 6 of the arrays are designed as slots. The shown waveguide channel 4 extends partially in the front face 22 of the second antenna layer 21 and partially in the back face 2 of the antenna layer 1 . The shown waveguide channel 4 has an essentially rectangular cross section. The back face 2 of the antenna layer 1 and the front face 22 of the second antenna layer 21 are in full contact with each other in the shown variation. The waveguide channel 4 merges via the splitter 10 into the waveguide branches. A radiating channel 7 interconnects each radiating opening 6 with the respective waveguide aperture 5. The shown antenna layer 1 is produced by a conventional mold with two mold halves. The parting plane P of the mold halves is arranged between radiating opening 6 and radiating channel 7. As a result, the parting lines 8 are also arranged between radiating openings 6 and radiating channels 7.

[0080] Figure 9 shows a plot, in particular an array of curves, showing the propagation characteristics of the design according to Figure 6. The plot shown in Figure 7 shows the antenna directivity and spread of the directivity, due to a lateral displacement of the radiating openings with respect to the waveguide channel branches. As described above noted, the positioning of the radiating openings with respect to the waveguide channel has a detrimental effect on the antenna performance, in particular an influence on the radiation pattern. As the parting plane between the two mold halves is arranged exactly at the transition between radiating openings and radiating channel, the positioning of the radiating opening does not only depend on the manufacturing tolerances of the mold, bur in addition on the losing accuracy of the mold. The spread between the individual plots and the occurrence of zeros is caused by an unwanted lateral displacement of the radiating openings with respect to the waveguide channels.

[0081] Figure 10 shows a lateral view of a waveguide channel 4, interconnected to a splitter 10, splitting a signal sent into a first waveguide channel branch 12 and a second waveguide channel branch, according to the present disclosure. Similar to the variation shown in Figure

[0082] 6, the shown waveguide channel 4 comprises radiating openings 6, which are arranged in the antenna layer 1 and are connected to the waveguide apertures 5 via radiating channels

[0083] 7. The radiating openings 6 are arranged in arrays of openings and energized by a common waveguide channel 4 which is interconnected to a respective radiating element at the back face of the antenna assembly 17 via a feeding aperture. The radiating openings 6 of the arrays are designed as slots. The shown waveguide channel 4 extends partially in the front face 22 of the second antenna layer 21 and partially in the back face 2 of the antenna layer 1. The shown waveguide channel 4 has an essentially rectangular cross section. The back face 2 of the antenna layer 1 and the front face 22 of the second antenna layer 21 are in full contact with each other in the shown variation.

[0084] The difference to the variation shown by Figure 8 lies in the design of the radiating channels 7. The shown radiating channels 7 interconnect the radiating openings 6 with the waveguide apertures 5. The radiating channel 6 as shown in Figure 10 comprises a transition area 9, which is rounded. The shown antenna layer 1 is also produced by a mold with two mold halves. Nevertheless, the parting plane P of the mold halves is spaced a distance D from the radiating openings 6 towards the waveguide aperture 5. Displacing the parting plane P into the radiating channel 7 improves the accuracy of the antenna layer 1. A parting line 8 is arranged in each radiating channel 7 between the back face 2 and the front face 3. The parting line 8 is spaced a distance D from the at least one radiating opening 6 towards the at least one waveguide aperture 5 and extends circumferentially within the at least one radiating channel 7. The ratio between the radius of the transition area 9 and the distance between radiating opening 6 and parting line 8 is essentially 0.4 in the shown variation.

[0085] Figure 11 shows a plot, in particular an array of curves, showing the propagation characteristics of the design according to Figure 8. The plots shown in Figure 9 again show the antenna directivity and spread of the directivity, similar to the plot of Figure 7. The parting plane between the two mold halves is arranged spaced a distance from the transition area between radiating openings and radiating channel, towards the front face of the antenna plate. The positioning of the radiating opening therefore does only depend on the manufacturing tolerances of the mold and not additionally on the closing accuracy of the mold. The spread between the individual plots is significantly smaller compared to the spread in Figure 7. Also the occurrence of zeros is mitigated.

[0086] Figures 12 and 13 show a second variation of a waveguide channel 4, interconnected to a splitter 10, splitting a signal sent into a first waveguide channel branch 12 and a second waveguide channel branch 14. In Figure 12 in a perspective view from the front and above, in Figure 13 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees. In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other.

[0087] As can be obtained best from Figure 13, the radiating channels 7 of the shown variation are horn shaped. The waveguide channel 4, the splitter 10, the waveguide channel branches 12, 14, the radiating channel 7 and the waveguide apertures 5 are entirely arranged in the antenna layer 1. The radiating openings 6 merge into the radiating channels 7 by a transition area 9, which is essentially rectangular with demolding bevels for demolding the antenna layer 1 .

[0088] Figures 14 and 15 show a third variation of a waveguide channel, interconnected to a splitter, splitting a signal sent into a first waveguide channel branch and a second waveguide channel branch. In Figure 14 in a perspective view from the front and above, in Figure 15 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees.

[0089] In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other. The radiating openings 6 have an oblong cross-section and are oriented with respect to the corresponding waveguide channel 4, or waveguide branch 31 , in a longitudinal direction. The cross-sectional areas of the radiating openings 6 is smaller than a cross-sectional area of the waveguide 31.

[0090] As can be obtained from Figure 15, the waveguide channel 4, the splitter 10 and the waveguide channel branches 12, 14, or better the waveguide branches 31 , are arranged partially in the antenna layer 1 and partially in the second antenna layer 21. The parting plane P of the antenna layer 1 is arranged in the radiating channel 7 spaced a distance D from the transition area 9 of the radiating channel 7 towards the front face 3 of the antenna layer 1 . The radiating channel 7 merges into the waveguide aperture 5. The shown transition area 9 is chamfered.

[0091] The waveguide branches 31 have an oblong cross-section with a long expansion a and a short expansion b, which are perpendicular to each other, wherein a > b. The radiating openings 6 are arranged in wall sections of the waveguide branches 31 which are essentially parallel to the long expansion a. In the present example, the waveguide branches 31 have a rectangular cross-section. Figures 16 and 17 show a fourth variation of a waveguide channel, interconnected to a splitter, splitting a signal sent into a first waveguide channel branch and a second waveguide channel branch. In Figure 16 in a perspective view from the front and above, in Figure 17 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees.

[0092] In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other.

[0093] As can be obtained from Figure 17, the waveguide channel 4, the splitter 10 and the waveguide channel branches 12, 14 are arranged partially in the antenna layer 1 and partially in the second antenna layer 21. The parting plane P of the antenna layer 1 is arranged in the radiating channel 7 spaced a distance D from the transition area 9 of the radiating channel 7 towards the front face 3 of the antenna layer 1. The radiating channel 7 merges into the waveguide aperture 5. The shown transition area 9 between waveguide channel 4 and radiating channel 7 is rounded. The ratio between the radius of the transition area 9 and the distance between radiating opening 6 and parting line 8 is essentially 0.8 in the shown variation.

[0094] Figures 18 and 19 show a fifth variation of a waveguide channel, interconnected to a splitter, splitting a signal sent into a first waveguide channel branch and a second waveguide channel branch. In Figure 18 in a perspective view from the front and above, in Figure 19 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees.

[0095] In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other. As can be obtained from Figure 19, the waveguide channel 4 is partially arranged in the antenna layer 1 and partially in the second antenna layer 21. The splitter 10 and waveguide channel branches 12, 14 are solely arranged in the back face 2 of the antenna layer 1. The parting plane P of the antenna layer 1 is arranged in the radiating channel 7 spaced a distance from the transition area 9 of the radiating channel 7 towards the front face 3 of the antenna layer 1. The radiating channel 7 merges into the waveguide aperture 5. The shown transition area 9 between waveguide channel 4 and radiating channel 7 is rounded. The ratio between the radius of the transition area 9 and the distance between radiating opening 6 and parting line 8 is essentially 0.3 in the shown variation.

[0096] The cross sections of the radiating openings 6 are modified to influence the directivity. The cross sections of neighboring radiating openings 6 within one array can be different, such that a radiating opening 6 with a smaller cross section is arranged adjacent to a radiating opening 6 with a larger cross section. Good results can be achieved when radiating openings 6 with smaller and larger cross sections are arranged in a line next to each other in alternating manner. This causes the radiation pattern to be compensated and radiate in a straight manner. The difference between the cross section of the radiating openings 6 creates a phase difference between the radiation of the radiating openings 6. The phase difference causes a tilt in the radiation of the pattern.

[0097] Figures 20 and 21 show a sixth variation of a waveguide channel, interconnected to a splitter, splitting a signal sent into a first waveguide channel branch and a second waveguide channel branch. In Figure 20 in a perspective view from the front and above, in Figure 21 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees.

[0098] In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other.

[0099] As can be obtained from Figure 21 , the waveguide channel 4 is partially arranged in the antenna layer 1 and partially in the second antenna layer 21. The splitter 10 and waveguide channel branches 12, 14 are solely arranged in the back face 2 of the antenna layer 1. The parting plane P of the antenna layer 1 is arranged in the radiating channel 7 spaced a distance from the transition area 9 of the radiating channel 7 towards the front face 3 of the antenna layer 1. The radiating channel 7 merges into the waveguide aperture 5. The shown transition area 9 between waveguide channel 4 and radiating channel 7 is rounded. The ratio between the radius of the transition area 9 and the distance between radiating opening 6 and parting line 8 is essentially 0.5 in the shown variation.

[0100] The shown single funnel shaped radiating channel 7 allows to increase the radiating surface of the radiating openings 6. The funnel can be additionally arranged in an asymmetric manner with respect to the centerline of the waveguide channel branches 12, 14 to achieve an asymmetric radiation pattern. The asymmetrically displaced funnel creates a tilt in the radiation properties of the antenna device. The impact of the lateral displacement can create local maxima in the antenna directivity. These local maxima can help to focus the antenna energy in certain areas. The tilted pattern can be useful to have a further range in given areas of the radar.

[0101] Figures 22 and 23 show a seventh variation of a waveguide channel, interconnected to a splitter 10, splitting a signal sent into a first waveguide channel branch and a second waveguide channel branch. In Figure 22 in a perspective view from the front and above, in Figure 23 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees.

[0102] In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other. As can be obtained from Figure 23, the shown variation differs from the other variations in that the parting line of the antenna layer is essentially congruent with the front face 3. The waveguide channel 4 is partially arranged in the antenna layer 1 and partially in the second antenna Iayer21. The splitter 10 and waveguide channel branches 12, 14 are solely arranged in the back face 2 of the antenna layer 1. The parting plane P of the antenna layer 1 is arranged at the front face 3 of the antenna layer. The radiating channels 7 merge into the waveguide apertures 5 arranged at the front face 3 of the antenna layer 1 . The shown transition area 9 between waveguide channel 4 and radiating channel 7 is rounded. The shown radiating openings 6 merge via the radiating channels 7 into the waveguide apertures 5 without an enlargement of the cross section towards the front face.

[0103] Figures 24 and 25 show an eights variation of a waveguide channel 4. In Figure 24 in a perspective view from the front and above, in Figure 25 as a lateral view. The shown waveguide channel 4 differs from the other variations in that the waveguide channel 4 is fed laterally. The shown variations does not comprise a splitter. To be able to allow the radiating openings 6 to be arranged collinear with respect to the centerline L of the waveguide channel 4, the waveguide channel 4 is designed in a staggered manner. This design alters the field such that the radiating openings 6 can be aligned collinear with respect to each other. As can be obtained best from Figure 25, the radiating channels 7 of the shown variation are horn shaped. The waveguide channel 4, the radiating channels 7 and the waveguide apertures 5 are entirely arranged in the antenna layer 1 . The radiating openings 6 merge into the radiating channels 7 by a transition area 9, which is essentially rectangular with demolding bevels for demolding the antenna layer 1 .

[0104] Figures 26 and 27 show a ninth variation of a waveguide channel 4, interconnected to a splitter 10, splitting a signal sent into a first waveguide channel branch 12 and a second waveguide channel branch 14. In Figure 26 in a perspective view from the front and above, in Figure 27 as a lateral view. The waveguide channel 4 is interconnected to the respective splitter 10 via a primary port which splits the signal into two branches. Part of the signal is sent into the first waveguide channel branch 12, which is interconnected to a first secondary port of the splitter and part of the signal into the second waveguide channel branch 14, which is interconnected to a second secondary port of the splitter 10. The shown first 12 and second 14 waveguide channel branches each comprise an array of radiating openings 6, which are arranged collinear with respect to a centerline L of the respective waveguide channel branch 12, 14. The shown waveguide splitter 10 comprises a deflection element 16, arranged adjacent to the primary port and configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees.

[0105] In addition, a necking 29 is arranged at the splitter. The necking 29 is in the form of an inwardly directed protrusion or alternatively in form of a septum which is arranged at the splitter 10 in the middle between the first 12 and the second 14 waveguide channel branch, respectively the first and the second secondary port. To be able to allow an arrangement, wherein the radiating openings 6 are arranged collinear with respect to the centerline L of the first 12 and the second 14 waveguide channel branch, both branches 12, 14 are designed in a staggered manner. This design alters the field such that the radiating openings 6 of the first 12 and the radiating openings 6 of the second 14 waveguide channel branch can be aligned collinear with respect to each other.

[0106] As can be obtained best from Figure 27, the radiating channels 7 of the shown variation are horn shaped. The waveguide channel 4, the splitter 10, the waveguide channel branches 12, 14, the radiating channel 7 and the waveguide apertures 5 are entirely arranged in the antenna layer 1. The radiating openings 6 merge into the radiating channels 7 by a transition area 9, which is essentially rectangular with demolding bevels for demolding the antenna layer 1. In the shown variation, the radiating channel merges into the aperture via a sharp transition in form of a step. The parting line 8 therefore extends along the edge between the radiating channel 7 and the aperture 5.

[0107] Figures 28 to 30 show a third variation of an antenna assembly 17 according to the present disclosure. In this embodiment, one linear- i.e. unbranched - waveguide channel 4 has four waveguide apertures 5, which are arranged in series and through which electromagnetic radiation can be coupled out of the waveguide.

[0108] As in particular apparent from Figure 29, the back face 2 of the antenna layer 1 comprises a periodic array of electromagnetic band gap structures in form of pillars 30, which substitute the lateral walls of the waveguide channel 4. Otherwise, the waveguide channel 4 is defined by a groove 31 in the back face 2 of the antenna layer 1 . The back part 20 of the antenna assembly 17, on the other hand, is a flat plate. It can for instance be formed by a PCB.

[0109] The bandgap structures are configured to compensate for potential manufacturing and assembly tolerances between the front part 18 and the back part 20, since a direct ohmic con- tact is not necessarily needed between them. They thus allow to mitigate leakage between the antenna layers.

[0110] LIST OF DESIGNATIONS

[0111] 1 Antenna layer 25 20 Back part (Antenna

[0112] 2 Back face (Antenna layer) assembly)

[0113] 3 Front face (Antenna layer) 21 Second antenna layer

[0114] 4 Waveguide channel 22 Front face (Second antenna

[0115] 5 Waveguide aperture layer)

[0116] 6 Radiating opening 30 23 Antenna device

[0117] 7 Radiating channel 24 Electric component

[0118] 8 Parting line 25 Radar chip

[0119] 9 Transition area 26 Printed circuit board (PCB)

[0120] 10 Splitter 27 Strip lines

[0121] 11 Primary port 35 28 Feeding aperture

[0122] 12 First waveguide channel 29 Necking branch 30 electromagnetic band gap

[0123] 13 First secondary port structures I pillars

[0124] 14 Second waveguide channel 31 waveguide / waveguide branch 40 branch

[0125] 15 Second secondary port L Centerline

[0126] P Parting plane

[0127] 16 Deflection element

[0128] D Distance

[0129] 17 Antenna assembly a long expansion

[0130] 18 Front part (Antenna

[0131] 45 b short expansion assembly)

[0132] 19 Middle part (Antenna assembly)

Claims

PATENT CLAIMS1 . An antenna layer (1) having a back face (2) and a front face (3), the antenna layer (1) comprising a. at least two waveguide channels (4) extending at the back face (2), wherein b. each of the at least two waveguide channels (4) comprises at least one waveguide aperture (5) for transmitting and / or receiving a signal arranged at the front face (3), wherein each of the at least two waveguide channels (4) comprises at least one radiating opening (6) which is arranged in the antenna layer (1) and is interconnected to the waveguide aperture (5) by at least one radiating channel (7), wherein a parting line (8) is arranged in the at least one radiating channel (7) between the back face (2) and the front face (3), which parting line (8) is spaced a distance (D) from the at least one radiating opening (6) towards the at least one waveguide aperture (5) and preferably extends circumferentially within the at least one radiating channel (7).

2. The antenna layer (1) according to claim 1 , wherein the antenna layer (1) is made by a shaping process, preferably injection molding or die casting,3. The antenna layer (1) according to claim 1 or 2, wherein the at least one radiating opening (6) merges into the radiating channel (7) by a transition area (9) which is rounded or chamfered.

4. The antenna layer (1) according to claim 3, wherein a ratio between the radius of the transition area (9) and the distance between radiating opening (6) and parting line (8) is smaller than 1 , preferably smaller than 0.8, most preferably smaller than 0.6.

5. The antenna layer (1) according to at least one of the preceding claims, wherein the radiating channel (7) is horn shaped.

6. The antenna layer (1) according to any of claims 1 to 5, wherein the at least one waveguide channel (4) is interconnected to a splitter (10) via a primary port (11) which is configured to split a signal to be sent into a. a first waveguide channel branch (12) interconnected to a first secondary port (13) of the splitter (10) and b. a second waveguide channel branch (14) interconnected to a second secondary port (15) of the splitter (10).

7. The antenna layer (1) according to claim 6, wherein the waveguide splitter (10) comprises at least one deflection element (16) arranged adjacent to the primary port (11) configured to twist the polarization of the E-field from the horizontal direction, to the vertical direction by 90 degrees and at least one deflection element (16) arranged adjacent to the first secondary port (13) and the second secondary port (15) configured to twist the polarization back from the vertical direction to the horizontal direction.

8. The antenna layer (1) according to claim 6 or 7, wherein the length of the at least one waveguide channel (4) is larger than the length of the first waveguide channel branch (12) and the length of the second waveguide channel branch (14) combined.

9. The antenna layer (1) according to at least one of claims 6 to 8, wherein the first (12) and the second waveguide channel branch (14) each comprise at least one radiating opening (6), wherein the radiating openings (6) are arranged co-linear with respect to a center line (L).

10. The antenna layer (1) according to claim 9, wherein the first (12) and the second waveguide channel branch (14) are designed in a staggered design configured to alter the field such that the at least one radiating opening (6) of the first (12) and the at least one radiating opening (6) of the second waveguide channel branch (14) is aligned collinear with respect to each other.

11. The antenna layer (1) according to one of claims 9 or 10, wherein the radiating openings (6) have varying cross sections to tilt the radiation pattern.

12. The antenna layer (1) according to claim 6 to 11 , wherein the at least one waveguide aperture (5) of the first waveguide channel branch (12) and the at least one waveguide aperture (5) of the second waveguide channel branch (14) are interconnected with each other.

13. The antenna layer (1 ) according to one of claims 1 to 12, wherein at least one radiating opening (6) has an oblong cross-section and is oriented with respect to the corresponding waveguide channel (4) in a longitudinal direction.

14. An antenna assembly (17) comprising an antenna layer (1) according to at least one of the preceding claims, wherein the antenna layer (1) is the front (18) or middle (19) part of the antenna assembly (17).

15. The antenna assembly (1) according to claim 14, wherein the antenna assembly further comprises a second antenna layer (21), which is the back part (20) of the antenna assembly (17).

16. The antenna assembly (1) according to claim 15, wherein the at least one waveguide channel (4) extends at least partially in the front face (22) of the second antenna layer17. The antenna assembly (1) according to one of claims 14 to 16, wherein a waveguide (31) is formed at least partially by one of the at least two waveguide channels (4) extending at the back face (2) of the antenna layer (1), wherein the waveguide (31) has an oblong cross-section with an long expansion (a) and an short expansion (b), which are perpendicular to each other, wherein (a) > (b), wherein at least one radiating opening (6) is arranged in a wall section of the waveguide (31) which is essentially parallel to the long expansion (a).

18. The antenna assembly (1) according to claim 17, wherein the waveguide (31) has a cross-section selected from the group consisting of rectangular, trapezoidal, triangular, elliptical, half-elliptical and polygonal.

19. The antenna assembly (1) according to one of claims 14 to 18, wherein a cross-sectional area of at least one radiating opening (6) is smaller than a cross-sectional area of the waveguide (31).

20. An antenna device (23), in particular for automotive radar applications, wherein the antenna device comprises an antenna assembly (17) according to one of claims 14 to 19 and an electronic component (24).

21. A method for producing an antenna layer (1) according to at least one of claims 1 to 13, wherein the antenna layer (1) is made by injection molding or die casting.

22. The method of claim 21 , wherein the antenna layer (1) is made by injection molding of a plastic material, followed by metallizing of the surface.

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