Patent Application
20240243465
The present disclosure relates to an antenna device for automotive radar applications.
From the prior art several radiating elements are known e.g., from EP 2676327 B1, WO 2017167916 A1, WO 2017158020 A1, WO 2018001921 A1 of the same applicant.
US 20170271776 A1 by Commscope published in 2017 shows a panel array antenna comprising an input layer including a waveguide network coupling an input feed on a first side thereof to a plurality of primary coupling cavities on a second side thereof, and an output layer on the second side of the input layer. The output layer includes an array of horn radiators, respective horn radiator inlet ports in communication with the horn radiators, and respective slot-shaped output ports in communication with the respective horn radiator inlet ports to couple the horn radiators to the primary coupling cavities.
U.S. Pat. No. 9,692,117 B2 by Nec Corp. published in 2017 shows an antenna including an antenna layer, a coupling layer and a feeder circuit layer. The antenna layer includes horn antennas which are arranged in such a manner that the centers thereof are aligned in a direction and in that the horn antenna is separated from the horn antenna in a direction and centers of the horn antennas are not aligned in the direction and a waveguide is formed in the coupling layer.
US 20200365976 A1 by Waymo published in 2019 shows an antenna including a plurality of waveguide antenna elements arranged in a first array configured to operate with a first polarization. The antenna also includes a plurality of waveguide output ports arranged in a second array configured to operate with a second polarization. The second polarization is different from the first polarization. The antenna further includes a polarization-modification layer with channels defined therein, wherein the channels are oriented at a first angle with respect to the waveguide antenna elements and at a second angle with respect to the waveguide output ports configured to receive input electromagnetic waves having the first polarization and transmit output electromagnetic waves having a first intermediate polarization.
WO 2020052719 A1 by Conti Temic published in 2020 shows a radar system for detecting the surroundings of a motor vehicle having a plastics-based antenna, wherein the plastics antenna, on a front side facing a sensor- and/or vehicle-side cover, has a plurality of individual antennas for transmitting and/or receiving radar signals and the plurality of individual antennas are used for detecting objects and/or determining angles thereof, disclosing solutions by which interference waves on the surface of the antenna and/or reflections between the antenna and the sensor-side and/or vehicle-side cover are suppressed or the negative effects thereof particularly on the determination of angles are prevented or reduced.
US 20200052396 A1 by Denso Corp. published in 2018 shows an antenna device comprising a dielectric substrate, a ground plate, an antenna section and an added-function section. The dielectric substrate includes a plurality of pattern forming layers. The ground plate is formed on a first pattern forming layer among the plurality of pattern forming layers, and functions as an antenna ground surface. The antenna section is formed on a pattern forming layer different from the first pattern forming layer among the plurality of pattern forming layers, and includes one or more antenna patterns configured to function as a radiator element. The added-function section includes one or more non-feed patterns disposed on a propagation path for an acoustic wave propagating on the dielectric substrate, and causes a radiation wave to be generated using the acoustic wave, the radiation wave having a polarization different from that of radio waves transmitted and received by the antenna section.
U.S. Pat. No. 6,262,495 B1 by University of California published in 2001 shows A two dimensional periodic pattern of capacitive and inductive elements defined in the surface of a metal sheet are provided by a plurality of conductive patches each connected to a conductive back plane sheet between which an insulating dielectric is disposed. The elements act to suppress surface currents in the surface defined by them. In particular, the array forms a ground plane mesh for use in combination with an antenna. The performance of the ground plane mesh is characterized by a frequency band within which no substantial surface currents are able to propagate along the ground plane mesh. Use of such a ground plane in aircraft or other metallic vehicles thereby prevents radiation from the antenna from propagating along the metallic skin of the aircraft or vehicle. The surface also reflects electromagnetic waves without the phase shift that occurs on a normal metal surface.
U.S. Ser. No. 10/944,184 B2 by Aptiv Tech. LTD published in 2020 shows an antenna device including a substrate. A plurality of conductive members in the substrate establish a substrate integrated waveguide and a plurality of first and second slots are on an exterior surface of a first portion of the substrate. Each of the second slots is associated with a respective one of the first slots. The first and second slots are configured to establish a radiation pattern that varies across a beam of radiation emitted by the antenna device. A plurality of parasitic interruptions include slots on the exterior surface of a second portion of the substrate. The parasitic interruptions reduce ripple effects otherwise introduced by adjacent antennas.
U.S. Pat. No. 8,390,531 B2 by Nippon Telegraph and Telephone published in 2010 shows a reflect array according to the present disclosure includes a plurality of array elements forming an array configured to control a direction of a reflected wave (scattered wave) by controlling a phase of the reflected wave; and a ground plane (30). The ground plane has a structure with a frequency selective function.
The use of millimeter-wave (MMW) frequencies for communications and automotive radar applications is continuously expanding. Antenna devices 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). Usually, antenna devices for automotive radar applications are mounted behind the shell or surface layer of the bumper. In addition to the focus on antenna characteristics, the continuous search of increased overall sensor performances calls for a mitigation of the interaction of the antenna with its surroundings, such as e.g., bumpers, when mounted behind them, radome, and PCB-interference. Especially in automotive applications the radome and the bumper presence reduce the radar sensor performances, distorting the radiated and/or received pattern and/or increasing noise level and in general decreasing the accuracy of detection. Typically, the antenna device is often arranged at least partially hidden under the surface of the automotive body, e.g., such that an outer shell of a bumper is arranged in front of the antenna assembly which may affect the transmitting and/or receiving capabilities of the antenna assembly in a negative manner. Furthermore, the radome presence in particular can lead to the excitation of surfaces waves which reduces the usable part of energy for radar detection purposes and can introduces false targets.
For the reduction of noise and interference caused by multiple reflected rays between the antenna device and e.g., a bumper mounted in front of the antenna device different approaches are known. From the prior art antenna assemblies are known with dummy antennas which are absorbing excessive rays by diversion in a kind of internal wave guide structure. In this case antenna apertures are arranged at a front face of the antenna which are typically not interconnected to the electronic component but terminate within the antenna assembly such that the received rays are absorbed by the material of the antenna assembly or are absorbed by components arranged on the PCB or the electronic component. The disadvantage of the known assemblies is that dummy antennas are comparatively complex to manufacture. An alternative approach of arranging protrusions on the front face of the antenna assembly is that this solution increases the overall antenna thickness.
An antenna device for automotive radar applications according to the present disclosure usually comprises an antenna assembly configured to receive incoming rays. Depending on the application, the antenna assembly can also be configured to transmit outgoing rays and receive incoming rays. The antenna assembly comprises a front face in which at least one antenna aperture is arranged configured to receive an incoming signal in form of primary rays impacting in the area of the antenna aperture. The antenna assembly usually comprises on the inside a waveguide structure by which the at least one antenna aperture is interconnected to an electronic component and/or a printed circuit board. Depending on the design the antenna aperture arranged at the front face of the antenna assembly can be designed as a horn antenna or alternatively as a slot within the front face. An advantageous simple design can be achieved when the antenna device comprises two layers which are e.g., made of metal, metallized plastic or any at the surface conductive material and flush mounted to one another. The two layers can be made of different materials which are suitable for casting or injection molding, including electromagnetic absorbing materials. Absorbing materials can alternatively be used to avoid interference.
For the mass production of antenna assemblies based on waveguide technology typical techniques include the manufacturing of the components using stacked layers and related joining techniques to connect these layers. As surface finishing is also important at MMW, the antenna assembly is designed with accurate draft angles and radii such that a good moldability of the layers of the antenna assembly is achieved. Metallization techniques like PVD, sputtering, spraying, galvanic coating can also be used to at least partially metallize the front face of the antenna assembly and/or the at least one antenna aperture. In a preferred variation the antenna assembly is horizontally polarized, wherein the half power beam-width (HPBW) is in the range of plus/minus 15° up to plus/minus 75° in the azimuth plane (horizontal plane, respectively E-plane). In the elevation plane, the HPBW can be e.g., plus/minus 1° to plus/minus 3º in the elevation (vertical plane, respectively H-plane). The main beam typically points at boresight. When a radome is mounted onto the antenna assembly, the radome to antenna distance is typically of λ/2 (around 1.9 mm) within the band of operation (76-81 GHz) for automotive radar applications. λ=lambda herby represents the wavelength.
Adjacent to the at least one antenna aperture the front face of the antenna assembly further comprises scattering elements by which primary rays, impacting in the area of the scattering elements, are at least partially reflected by the scattering elements and thereby separated into first secondary rays and second secondary rays, such that the first secondary rays and the second secondary rays are different such that they cancel out each other at least partially by interference. Good results can be achieved when the scattering elements are with respect to the front face designed as protrusions and/or indentations or a combination thereof. Depending on the design, the depth of the at least one indentation may be linked to the specific phase distribution that is targeted to obtain a reflection that cancels out the rays reflected in an unwanted manner by interference. The phase change is typically induced by the reflection on the bottom surface of the at least one indentation. Good results can be achieved, when the bottom surface of the at least one indentation is an essentially planar surface which is arranged essentially parallel with respect to the front face of the antenna assembly. Preferably the scattering elements are having in the front face a layout (footprint) which is at least one element out of the group of the following elements or a combination thereof: rectangle, square, circle, ellipse, C-shaped, ring-shaped, S-shaped. The scattering elements can be designed with a single polarization (rectangular, elliptical, s-shaped, c-shaped) or with multiple polarizations (squared/circular/ring). The at least one indentation has a layout which is related to the working operating frequency and the polarization of the electromagnetic waves. The extension of the scattering elements in the direction perpendicular to polarization vector may correspond with around 0.72 (free space) for rectangular/elliptical and square/circular. The circumference of the ring shaped scattering elements may correspond with double the length. S-shaped and c-shaped scattering elements are used to reduce the dimension. The phase change typically results from the depth of the at least one indentation. A typical dimension for the depth of the at least one indentation is λ/2. A typical dimension for the layout of the aperture of the at least one indentation is λ/4 times 0.72. For automotive applications with a wavelength of 77 GHz this results in a depth of the at least one indentation which is around 1.4 mm and a layout of the aperture of the at least one indentation of 1 mm times 2.8 mm. In a preferred variation the scattering elements are having perpendicular to the front face a cross-section which is essentially rectangular and/or pyramidal and/or a combination thereof.
Good results can be achieved when the scattering elements have a T-shaped layout or a cross shaped layout. A T-shaped layout can be formed by a horizontal rectangle arranged adjacent to a vertical rectangle. Alternatively, a cross shaped layout which can be formed by a horizontal rectangle and a vertical rectangle, whereby the center point of the horizontal rectangle and the center point of the vertical rectangle coincide. Both the T-shaped and the cross shaped layouts allows to cancel both, horizontally and vertically polarized waves. When the scattering elements are designed as indentations which are flush mounted in the front face, the antenna assembly has a favorably thin overall thickness. An antenna device comprising an antenna assembly which comprises scattering elements in form of indentations further has the advantage that a radome can be flush mounted with the front face of the antenna assembly. The protrusions and/or indentations are configured to at least partially reflect the primary rays not impacting in the area of the antenna aperture. Said secondary rays are influenced by the protrusions and/or indentations in a way, that the reflected parts of the primary rays—first secondary rays and second secondary rays—are canceled out to a large extent by each other due to interference. In comparison to blind/dummy antennas, the scattering elements do not require additional waveguide routing. With an antenna assembly designed comprising a front and a back layer the protrusions or indentations are usually arranged at the front layer only. Therefore, the complexity and additional production effort can be reduced significantly. The scattering elements usually have a resonant character such that their dimension is strongly connected to the wavelength. The scattering elements are preferably configured to perturb the electromagnetic field distribution such that a peculiar current distribution is created at the front face of the antenna assembly. Preferably a phase delay is introduced such that the rays which are reflected in an unwanted manner are diminished or cancelled out due to interference with each other.
Good results can be achieved when the scattering elements are arranged at the front face of the antenna assembly in a periodical or quasi-periodical pattern of scattering elements. The scattering elements of the pattern of scattering elements are preferably arranged in rows and/or columns. The scattering elements can e.g., by arranged in at least two parallel rows. The at least two rows are typically laterally spaced apart with respect to each other. Preferably, the scattering elements of each row are equally spaced apart from each other. To achieve a reflection wherein the first secondary rays and the second secondary rays cancel each other out due to interference, the scattering elements of two adjacent rows are usually offset to each other in the direction of the rows. The scattering elements of two adjacent rows are preferably offset to each other in the direction of the rows with a spatial displacement of essentially λ/2 in direction of the rows or in a direction perpendicular to the direction of the rows such that a phase difference of 180° is achieved such that the reflected rays cancel out each other by interference. The scattering elements arranged at the front face adjacent to the at least one antenna aperture are preferably arranged essentially parallel with respect to the at least one antenna aperture such that horizontal plane rays can be cancelled. Alternatively, the at least one antenna aperture can be placed in the vertical plane of the antenna assembly such that rays in the vertical plane can be canceled. Depending on the percentage of the antenna's top surface coverage by scattering elements a reduction of the scattering coefficient of more than 65% can be achieved. Depending on the periodic spacing (p) of the scattering elements and the number of scattering elements at the front face of the antenna assembly, a phase between 0° and 180° is created instead of a uniform phase distribution without the scattering structure. The periodic spacing is defined as the lateral distance between two scattering elements of neighboring rows. In a preferred variation the scattering elements are arranged at the front face of the antenna assembly based on glide symmetry (glide reflection). The scattering elements are therefore preferably mirrored with respect to the at least one antenna aperture and shifted in a lateral direction with respect to the at least one antenna aperture. This particular periodicity supports the generation of the required 0° and 180° phase distribution. Ideally the number of scattering elements arranged adjacent to the at least one antenna aperture in the desired direction may be infinite. In theoretically feasible variations the number of scattering elements could be reduced down to 1. In a preferred variation the periodic spacing is a multiple of λ/2. A different approach to reduce the interference is to use scattering elements with a random depth such that a reflect array like structure is created which has a random phase distribution such that the interference waves are scattered in a diffused way. The scattering elements arranged at the front face can also differ in length. In a variation the scattering elements can each have essentially the same length, which is defined as the base length. In an alternative variation a number of the scattering elements has also the base length and the remaining scattering elements have double the length or a multiple of the base length. Good results can be achieved when the remaining scattering elements have double or four times the base length, but also odd multiple are possible. Preferably the scattering elements of the base length and double the base length are arranged in an alternating manner.
In a variation, the scattering elements are arranged in at least two parallel rows. The at least two rows are typically laterally spaced apart with respect to each other. Preferably, the scattering elements of each row are equally spaced apart from each other and the at least two rows are offset to each other in the direction of the rows with a spatial displacement of essentially λ in direction of the rows. A displacement of essentially λ allows that an additional scattering element can be arranged between two neighboring scattering elements, which additional scattering element can be arranged essentially perpendicular with respect to the scattering elements of the at least two rows. The perpendicular displacement with respect to the direction of the rows makes it possible to also cancel reflections from waves, which are vertically polarized. The scattering elements arranged in the direction of the rows are configured to cancel horizontally polarized waves and the scattering elements arranged rotated by 90° are configured to cancel vertically polarized waves.
Good results to reduce the ripples in the radiation pattern can be achieved, when the antenna assembly comprises at least one outer edge which is saw teeth-shaped. In a preferred variation the antenna assembly comprises at least two outer edges which are saw teeth-shaped and arranged opposite to each other with respect to the antenna assembly. The structure changes the direction of the surface currents on the edge of the antenna leading to destructive interference of backscattering of impinging fields. While minor amplitude and phase errors are introduced by edge effects due to the finite dimensions of the antenna's metallic top surface. By adding the saw tooth structure on the edge the negative influence of edge effects can be reduced. Among others it reduces the ripples in radiation pattern, normally appearing due to the knife edge refraction on the antenna edge. Thanks to this measure the standard deviation of the angular radiation pattern can be reduced which is crucial for optimal performance of the radar. The saw tooth can be realized either by changing the 3D shape of plastic or by selective metallization on the edges.
In a preferred variation the antenna device comprises a radome which at least partially covers the front face of the antenna assembly. In theory, the optimum would be a radome interaction with a radome made of materials similar to air or an extremely thin radome, which is only of limited use from a practical mechanical point of view. The known radomes are arranged with a distance of essentially λ/2 distance (≈2 mm for 77 GHz automotive radome) with respect to the antenna assembly. This distance is usually chosen to avoid strong interaction between the antenna assembly and the radome. With a radome according to the present disclosure the distance between the antenna assembly and the radome can be reduced to essentially zero. In a preferred variation the radome has a back face which is at least partially flush mounted to the front face of the antenna assembly. The scattering elements in form of indentations make it possible that the radome is flush mounted with the antenna assembly. Good results can be achieved when the radome is plate shaped and has an essentially uniform thickness. In a preferred variation the back face of the radome may have at least one recess configured to improve the radiation. Usually, a part of the energy radiated by the antenna assembly remains captured in the radome. The recess minimizes the thickness of the radome and therefore losses of radiation are minimized. In an alternative variation, the back face of the radome follows the contour of front face and the scattering elements. Therefore, the radome may have a pattern of protrusions which corresponds to the pattern of scattering elements arranged at the front face of the antenna assembly and therefore the depth of the scattering structure can be reduced. The protrusions preferably engage the indentations in a mounted state. In a variation the radome comprises in the area above the at least one antenna aperture a dome-shaped lens such that incoming primary rays are focused with respect to the antenna aperture.
Besides the scattering elements which are arranged adjacent to the at least one antenna aperture on the front face of the antenna assembly, the front face of the antenna assembly can further also at least be partially made of or comprise absorbing material. While the scattering elements are configured to at least partially reflect the primary rays impacting in the area of the scattering elements, and thereby separate them into first secondary rays and second secondary rays, the absorbing material is configured to at least partially absorb the primary rays impacting in the area of the absorbing material. The absorbing material can fully or partly cover the antenna assembly. Good results can be achieved when the absorbing material is arranged on or in the front face in form of a layer, thereby covering essentially the overall front face except for the area covered by the at least one antenna aperture and the area covered by the scattering elements.
The absorbing material can be assembled to the antenna assembly in form of a separate layer of absorbing material, which is joined with the front face of the antenna assembly. The layer of absorbing material can be joined mechanically by fastening means, e.g., by screwing or clamping. Alternatively, or in addition, the layer of absorbing material can be joined by welding, gluing, hot stamping, clipping, pressfit, soldering etc. The absorbing material is typically a resin or composite, e.g., a hybrid material with electromagnetic absorbing properties. The absorbing material can either be assembled by embedding it into the front face of the antenna assembly, preferably by injection molding it into a cavity of the base material or be arranged onto the front face.
An efficient manufacturing process can be achieved when the antenna assembly is made by multicomponent injection molding or in-mold-decoration. A multicomponent injection molding processes typically includes more than one plastic material, whereby at least one plastic material has electromagnetic (EM) absorbing properties. Alternatively, or in addition, the antenna assembly can be subjected to a complete or selective surface treatment process. Once the front and the back layer of the antenna assembly are fabricated, a layer of paint or coating can be at least partially applied to the front face of the antenna assembly. The paint or coating preferably also has electromagnetic (EM) absorbing properties. In a variation the plastic material of the antenna assembly can have electromagnetic (EM) absorbing properties. In an alternative variation, the front face of the antenna assembly can be completely metalized in a first step and the metallization is removed partially in a second step in areas where electromagnetic absorption is desired.
Alternatively, or in addition, the absorbing material can be arranged on the inner side of the radome, facing the antenna assembly in the mounted state. A separate layer of absorbing material can be connected to the radome using joining techniques, e.g., screwing, clamping, welding, gluing, hot stamping, clipping, press-fit, soldering etc. The absorbing material can be attached to or embedded in the radome. The absorber can also be assembled with a distance with respect to the radome. The antenna assemblies according to the present disclosure are usually part of an antenna device. In a preferred variation the antenna device comprises an electronic component, a printed circuit board (PCB) and at least one antenna assembly and a radome. Typically, the elements of the antenna device are enclosed in a case which is sealed by the radome for mechanical protection. Although a radome is usually necessary to protect the antenna assembly from environmental influences, the radome usually interacts with the radiation characteristics of the antenna assembly in an unwanted manner and negatively impacts the radiation pattern, gain and phase purity. In a variation of the antenna device, an electronic component is arranged on a printed circuit board. The signal coming from the electronic component (e.g., a radar chip mounted on a PCB board) is typically coupled into a waveguide feeding aperture and propagates towards at least one antenna aperture configured to emit an outgoing signal of rays through the air-filled hollow wave guide structure. The at least one antenna aperture configured to emit an outgoing signal of rays is foreseen to be reflected by an external object and return at least partially as primary rays. The at least one antenna aperture configured to emit an outgoing signal of rays is preferably arranged at the front face of the antenna assembly. The at least one hollow wave guide structure is arranged within the bottom antenna layer or arranged partially within both layers and interconnects the at least one feeding aperture and antenna aperture configured to emit an outgoing signal of rays. Alternatively, or in addition the wave guide structure can also be designed as ridge wave guide, gap wave guide, or ridge gap wave guide. The antenna assembly can also comprise a number of antenna apertures and antenna aperture configured to emit an outgoing signal of rays arranged at the front face of the antenna assembly, wherein the antenna aperture configured to emit an outgoing signal of rays may serve as transmitter (TX) and the at least one antenna aperture serves as receiver (RX). Each antenna aperture consists of at least one radiating element which can be a horn and/or a slot shaped element. The at least one antenna aperture can be designed as a single radiating element and/or an array of radiating elements. The walls of the hollow wave guide structure, the at least one antenna aperture, the waveguide channel, the waveguide splitter, and the waveguide array can be metallic or metallized. All variations of the of the antenna assembly are preferably designed such that they are suitable for molding manufacturing techniques. The antenna assembly is preferably made by either metallized plastic injection molding or die casting. Therefore, the corners of the antenna assembly are typically rounded such that all vertical edges have radii and that all the scattering elements have drafted walls. The scattering elements are preferably designed such that the manufacturability for molding techniques is improved. This results in optimal surface finishing and mechanical stability/robustness of the layers of the antenna assembly. In addition to that, the drafts of the vertical walls are also selected to optimize thickness and quality of the metallization layer if plastic injection molding is selected for the antenna top layer and/or antenna bottom layer. Due to the particular metallization techniques preferably selected for this concept (e.g., PVD, sputtering, spraying), vertical walls would not allow to have the enough thickness and quality of the metallic layer to guarantee satisfactory RF performance at MMW. In this regard, the use of drafted wall allows to have a wider projected surface improving the metallization process.
Antenna devices for automotive radar applications, typically comprise a chip (MMIC), wherein the radar is realized on the chip. Electronic systems/components are usually arranged on a PCB. All of these electronic systems/components emit electromagnetic signals which often contribute to an overall noise level within the antenna device. The single channels of the radar chip emit interference signals at the radar's frequency of operation, which may cause unwanted cross-talk in the other radar channels and/or radar chip if multiple radar chips are used. The continuous search of increased overall sensor performances calls for a mitigation of this interference. The increased noise and the interference reduce the radar sensor performances while the noise level is increased. As a result, the sensor can get desensitized which decreases the accuracy respectively even the probability of detection. In case of printed circuit board antennas, the possibilities to mitigate this problem are limited. Antenna devices with waveguide antenna assemblies show multiple advantages in comparison to printed circuit board antenna assemblies. The antenna assembly can comprise at least one metalized cavity. The metalized cavity is preferably arranged at a back face of the antenna assembly. In case of a plastic waveguide antenna assembly which comprises at least two layers, the metalized cavity is preferably arranged at the back part of the antenna assembly. The at least one chip can be arranged at least partially within a metalized cavity such that the influence from surrounding electronic components and/or other chips is reduced. In an inventive concept, good results can be achieved, when the at least one cavity comprises at least one layer and/or coating of an electromagnetic absorbing material. In known antenna assemblies the at least one layer and/or coating of electromagnetic absorbing material is padded and/or glued to the at least one cavity. This, however, increases the overall cost of the antenna device. Good results can be achieved, when the absorbing material configured to absorb electromagnetic noise and/or unwanted radio frequencies, is already arranged at the antenna assembly by injection molding. Preferably the antenna assembly is injection molded such that at least one layer of absorbing material is injected into the cavity before the base material of the antenna assembly is injected in a second step. Good results can be achieved when the absorbing material is interconnected to the antenna assembly by injection molding. In a preferred variation the antenna assembly is made as a metallized plastic antenna of two or more components, wherein the plastic antenna or at least one of the layers of the plastic antenna includes at least partially absorbing material configured to reduce the interference. The absorbing material is preferably arranged at the antenna assembly in the area and/or above the chip. The part of the antenna assembly which comprises absorbing (lossy material) can either be left uncoated or coated with very thin metallic layer. Thus, the unwanted electromagnetic radiation from the chip and/or electronic components, causing electromagnetic compatibility problems, can be reduced due to absorption in such material. Therefore, the performance of the radar sensor can be sustained and there are no additional expenses on absorber padding. In a variation the antenna assembly can be made of absorbing material only. In this variation the antenna is additionally partially metalized. Preferably the antenna assembly is on the back side at least partially covered by an absorbing material. The same aspect can be used to mitigate the problem of bumper interaction as discussed above. If one of the materials used for injection molding has radio frequency absorbing properties, and this material is used to constitute the front face of the antenna assembly between the apertures, the energy of the secondary rays reflected from the front face of the antenna assembly can be highly reduced. The part of the antenna assembly comprising lossy material can either be left uncoated or coated with a very thin metallic layer to enable required function. Therefore, the applicant reserves the right to focus a divisional patent application on the additional inventive concept mentioned above.
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.
The herein described disclosure will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the disclosure described in the appended claims. The drawings are showing:
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.
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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 departing from the Spirit and scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 00557/21 | May 2021 | CH | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/063535 | 5/19/2022 | WO |
