Abstract
An antenna device for automotive radar applications including an antenna assembly which 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 at least one antenna aperture. The front face of the antenna assembly further includes adjacent to the at least one antenna aperture scattering elements by which primary rays, impacting an 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 cancel out each other at least partially by interference.
Claims
1-24. (canceled)
25. An antenna device for automotive radar applications comprising: a. an antenna assembly comprising a front face in which at least one antenna aperture is configured to receive an incoming signal in a form of primary rays impacting the at least one antenna aperture, and b. the front face comprising, adjacent to the at least one antenna aperture, scattering elements by which primary rays, impacting in an 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 cancel out each other at least partially by interference.
26. The antenna device according to claim 25, wherein the scattering elements are with respect to the front face selected from the group of: indentations, protrusions or a combination thereof.
27. The antenna device according to claim 25, wherein the scattering elements are arranged in at least two parallel rows.
28. The antenna device according to claim 25, wherein the scattering elements of each row are periodically or quasi-periodically spaced apart from each other.
29. The antenna device according to claim 28, wherein the scattering elements of each row are periodically or quasi-periodically spaced apart from each other between each other and between the rows.
30. The antenna device according to claim 25, wherein the scattering elements of two adjacent rows are offset to each other in a direction of the rows with a spatial displacement of essentially ?/2 in 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.
31. The antenna device according to claim 25, wherein the scattering elements of two adjacent rows are offset to each other in a direction of the rows with a spatial displacement of essentially ?/2 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.
32. The antenna device according to claim 25, wherein the scattering elements of two adjacent rows are offset to each other in a direction of the rows with a spatial displacement of essentially ? and a displaced scattering element is arranged between two neighboring scattering elements of the respective rows.
33. The antenna device according to claim 32, wherein the displaced scattering element is arranged essentially perpendicular with respect to the direction of the rows.
34. The antenna device according to claim 25, wherein the scattering elements are arranged in a periodical or quasi-periodical pattern of scattering elements.
35. The antenna device according to claim 25, wherein the scattering elements are having in the front face a layout 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, cross-shaped, T-shaped.
36. The antenna device according to claim 25, wherein 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.
37. An antenna device for automotive radar applications comprising: a. an antenna assembly comprising a front face in which at least one antenna aperture is configured to receive an incoming signal in form of primary rays impacting the at least one antenna aperture, and b. the front face comprising, adjacent to the at least one antenna aperture, scattering elements by which primary rays, impacting in an 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 cancel out each other at least partially by interference, and c. the antenna assembly in the area of the scattering elements is at least partially covered or consists of a material absorbing the primary rays at least partially.
38. The antenna device according to claim 37, wherein the absorbing material is arranged at the antenna assembly which at least partially covers the front face configured to absorb impacting primary rays.
39. An antenna device for automotive radar applications comprising a. an antenna assembly comprising a front face in which at least one antenna aperture is configured to receive an incoming signal in form of primary rays impacting in the at least one antenna aperture, and b. the front face comprising, adjacent to the at least one antenna aperture, scattering elements by which primary rays, impacting in an 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 cancel out each other at least partially by interference. and c. the antenna device comprises a radome which is at least partially covering the front face of the antenna assembly.
40. The antenna device according to claim 39, wherein the radome includes a back face which is at least partially flush mounted to the front face of the antenna assembly.
41. The antenna device according to claim 40, wherein the back face is partially flush mounted to the front face of the antenna and there is at least one selected of the group of: a longitudinal groove, recess or a combination thereof, arranged at the back face of the radome which are configured to stop the surface wave propagation.
42. The antenna device according to claim 40, wherein the back face of the radome comprises at least one protrusion which at least partially engages the scattering elements at the font face of the antenna assembly in a mounted state.
43. The antenna device according to claim 39, wherein the radome comprises, in an area of the at least one antenna aperture, a dome-shaped lens such that incoming primary rays are focused with respect to the antenna aperture.
44. The antenna device according to claim 39, wherein the antenna assembly is on a back side at least partially covered by an absorbing material.
Description
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0027] 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:
[0028] FIG. 1 shows a perspective view of a first embodiment of the antenna assembly;
[0029] FIG. 2 shows a comparison of the radiation pattern without bumper and with bumper in an elevation cut (left) and an azimuth cut (right);
[0030] FIG. 3 shows a second embodiment of the antenna assembly comprising two outer edges which are saw teeth-shaped;
[0031] FIG. 4 shows a comparison of the radiation pattern without saw tooth edge (blue) and with saw tooth edge (orange);
[0032] FIG. 5 shows schematically the separation of primary rays into first and second secondary rays;
[0033] FIG. 6 shows schematically a first and a second embodiment of the scattering elements;
[0034] FIG. 7a shows one suitable layout for the scattering elements;
[0035] FIG. 7b shows one suitable layout for the scattering elements;
[0036] FIG. 7c shows one suitable layout for the scattering elements;
[0037] FIG. 7d shows one suitable layout for the scattering elements;
[0038] FIG. 7e shows one suitable layout for the scattering elements;
[0039] FIG. 7f shows one suitable layout for the scattering elements;
[0040] FIG. 7g shows one suitable layout for the scattering elements;
[0041] FIG. 7h shows one suitable layout for the scattering elements;
[0042] FIG. 7i shows one suitable layout for the scattering elements;
[0043] FIG. 8 shows schematically a first arrangement of scattering elements;
[0044] FIG. 9 shows schematically a second arrangement of scattering elements;
[0045] FIG. 10 shows schematically an embodiment of scattering elements with a T-shaped layout;
[0046] FIG. 11 shows schematically an embodiment of scattering elements with a cross shaped layout;
[0047] FIG. 12 shows a first embodiment of the radome in a perspective view wherein the radome is folded away from the antenna assembly by 90?;
[0048] FIG. 13 shows the first embodiment according to FIG. 8 in a cross-sectional view;
[0049] FIG. 14 shows a second embodiment of the radome in a perspective view wherein the radome is folded away from the antenna assembly by 90?;
[0050] FIG. 15 shows the second embodiment according to FIG. 10 in a cross-sectional view;
[0051] FIG. 16 shows a third embodiment of the radome in a perspective view wherein the radome is folded away from the antenna assembly by 90?;
[0052] FIG. 17 shows the third embodiment according to FIG. 12 in a cross-sectional view;
[0053] FIG. 18 shows a fourth embodiment of the radome in a perspective view;
[0054] FIG. 19 shows the fourth embodiment according to FIG. 14 in a cross-sectional view;
[0055] FIG. 20 shows a first embodiment of the antenna device in a perspective view from above with a cut-out;
[0056] FIG. 21 shows the embodiment of the antenna device according to FIG. 16 in an exploded view;
[0057] FIG. 22 shows a second embodiment of the antenna device in a perspective view from above with a cut-out;
[0058] FIG. 23 shows the embodiment of the antenna device according to FIG. 18 in an exploded view from the rear;
[0059] FIG. 24 shows a perspective view of a third embodiment of the antenna assembly;
[0060] FIG. 25 shows an exploded perspective view of the third embodiment of the antenna assembly according to FIG. 24;
[0061] FIG. 26 shows a perspective view of a fourth embodiment of the antenna assembly;
[0062] FIG. 27 shows an exploded perspective view of the fourth embodiment of the antenna assembly according to FIG. 26;
[0063] FIG. 28 shows a fifth embodiment of the radome in a perspective view; and
[0064] FIG. 29 shows a fifth embodiment of the radome in a perspective exploded view.
DETAILED DESCRIPTION OF THE INVENTION
[0065] 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.
[0066] FIG. 1 shows a perspective view of a first embodiment of the antenna assembly 2. As best visible in FIG. 1, the antenna assembly 2 for an antenna device 1 for automotive radar applications comprises a front face 3 in which at least one antenna aperture 4 is arranged configured to receive an incoming signal in form of primary rays 5 impacting in the antenna aperture 4. In the shown variation several antenna apertures 4 are present which are arranged in groups (schematically indicated by dotted lines). The front face 3 of the antenna assembly 2 comprises adjacent to the at least one antenna aperture 4 scattering elements 6 by which primary rays 5, as schematically indicated in FIG. 5, impacting in the area of the pattern of scattering elements 6, are at least partially reflected by the scattering elements 6 and thereby separated into first secondary rays 7 and second secondary rays 8, such that the first secondary rays 7 and the second secondary rays 8 cancel out each other at least partially by interference. The shown scattering elements 6 are with respect to the front face 3 designed as indentations 10. Alternatively, the scattering elements can also be designed as protrusions 9 and/or a combination of protrusions and indentations 10. The shown scattering elements 6 are arranged in parallel rows 11, wherein the scattering elements of each row are equally spaced apart from each other. In the shown embodiment the scattering elements 6 of two adjacent rows are arranged with respect to each other in a periodic spacing 13 such that the phase shift of the reflected first and second secondary rays is 180?. In a preferred variation, the periodic spacing 13 is a multiple of ?/2. As can be seen in FIG. 2, which shows a comparison of the radiation pattern without bumper and with bumper in an elevation cut (left) In FIG. 2a and an azimuth cut (right) in FIG. 2b. From FIGS. 2a and 2b it can be seen that the scattering elements cause a suppression of ripples in the radiation pattern. The graphs in FIGS. 2a and 2b show the directivity of the antenna assembly over the angle. As can be seen the dotted lines, showing the performance of the antenna assembly without scattering elements 34 and the continuous line showing the performance 35 with scattering elements 6.
[0067] FIGS. 3 and 4 show an embodiment of a metallized antenna assembly 2, wherein the antenna assembly 2 comprises two outer edges 15 which are in the shown embodiment saw teeth-shaped 23 and arranged opposite to each other with respect to the antenna assembly 2. The saw teeth-shaped 23 outer edges 15 change the direction of the currents at the front face 3 such that the outer edges 15 of the antenna assembly 2 cause destructive interferences of backscattering of impinging fields. While minor amplitude and phase errors are introduced by the outer edge 15 of the antenna assembly 2, effects due to the finite dimensions of the antenna's metallic top surface. The saw-teeth shaped 23 outer edges 15 are configured to reduce the negative influence of the edge effects. The saw-teeth shape 23 can be realized either by changing the 3D shape of plastic or by selective metallization on the outer edges 15. As can be seen in FIG. 4, the saw teeth-shaped 23 outer edges 15 reduce the ripples in the radiation pattern which normally appear due to the knife edge refraction on the outer edge 15 of the antenna assembly 2. The saw-teeth shaped 15 outer edges 23 are configured to reduce the standard deviation of the angular radiation pattern which is crucial for optimal performance of the antenna device 1. The graph in FIG. 4 shows the directivity of the antenna assembly over the angle. As can be seen the dotted line shows the performance of the antenna assembly without saw-teeth shaped outer edges 36 and the continuous line showing the performance 37 with saw-teeth shaped outer edges 15.
[0068] FIG. 5 shows schematically the separation of primary rays 5 into first 7 and second 8 secondary rays. The incoming primary rays 5 are reflected by the antenna assembly 2. The first incoming primary ray 5 is reflected by the front face 3 of the antenna assembly 2. The second incoming primary ray 5 is reflected by the scattering element 6. Due to the geometry of the scattering element 6 the resulting first 7 and second 8 secondary rays do have a phase difference of ?/2. As indicated by the dotted lines, the first 7 and the second 8 secondary rays are in opposite phase and therefore cancel each other due to destructive interference. FIG. 6 schematically shows two variations of scattering elements 6. The shown embodiments differ in that the scattering elements 6 differ in length. The scattering elements 6 of the first embodiment (left side in picture) each have essentially the same length, which is defined as the base length. The scattering elements 6 of the second embodiment (right side in picture) have either also the base length or double the length. Preferably the scattering elements 6 of the base length and double the base length are arranged in an alternating manner. The scattering elements 6 of two adjacent rows 12 are offset to each other in the direction of the rows with a spatial displacement of around ?/2 such that in the direction of the rows or in a direction perpendicular to the rows a phase difference of 180? is achieved such that the reflected rays cancel out each other by interference. FIGS. 7a to i show a number of suitable layout 14 geometries (footprint) for the scattering elements 6. In a preferred variation, the layout 14 corresponds to at least one element out of the group of the following elements or a combination thereof: rectangle (FIG. 7a, b), square (FIG. 7c, d), ellipse (FIG. 7e), circle (FIG. 7f), S-shaped (FIG. 7g), C-shaped (FIG. 7h), ring-shaped (FIG. 7i).
[0069] FIGS. 8 and 9 show schematically a first (FIG. 8) and a second (FIG. 9) arrangement of scattering elements 6. The shown scattering elements 6 are arranged in at least two parallel rows. The at least two rows are typically laterally spaced apart with respect to each other. The shown scattering elements 6 of each row are equally spaced apart from each other. In the shown variation, the scattering elements 6 of the shown two adjacent rows are offset to each other in the direction of the rows with a spatial displacement of at least ?/2. Good results can be achieved when the spatial displacement corresponds to ? in direction of the rows. This design has the advantage that additional scattering elements 6 can be arranged which are arranged essentially perpendicular with respect to the two rows, as can be obtained best from FIG. 9. 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 6 arranged in the direction of the rows are configured to cancel horizontally polarized waves and the scattering elements 6 arranged rotated by 90? are configured to cancel vertically polarized waves.
[0070] FIGS. 10 and 11 show an embodiment of scattering elements 6 with a T-shaped layout (FIG. 10) and an embodiment of scattering elements 6 with a cross shaped layout (FIG. 11). The scattering elements shown in FIG. 10 have a T-shaped layout which is formed by a horizontal rectangle arranged adjacent to a vertical rectangle. This layout allows to cancel both, horizontally and vertically polarized waves. The same applies to the cross shaped layout shown by FIG. 11, which is achieved 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. This layout allows to cancel both, horizontally and vertically polarized waves.
[0071] FIGS. 12 and 13 show a first embodiment of a radome 16 in a perspective view wherein the radome 16 is folded away from the antenna assembly by 90?. FIG. 13 shows the first embodiment according to FIG. 12 in a cross-sectional view. The shown radome 16 is essentially flush mounted with the front face 3 of the antenna assembly 2, wherein the back face 17 of the radome 16 is essentially flush mounted to the front face 3 of the antenna assembly 2. This has the advantage that reflections of primary rays 5 by the radome 16 can be prevented and electromagnetic rays are not radiated into the air and bounce back on the radome 16 as they are directly radiated out of the radome 16. Furthermore, the flush mounted radome 16 reduces the overall thickness of the antenna device 1. The radome 16 of the first embodiment comprises a recess 24 which is arranged at the back face 17 of the radome 16, essentially congruent with respect to the at least one antenna aperture 4 arranged at the front face 3 of the antenna assembly 2. The recess 24 can be essentially rectangular. By a radome 16 with an overall thickness of 2 mm (?/2 free space) a big part of the energy radiated by the antenna assembly 2 will remain captured in the radome 16 in form of surface wave. The recess 24 overcomes this problem by making the radome 16 thinner, at least in the area congruent to the antenna aperture 4.
[0072] FIGS. 14 and 15 show a second embodiment of the radome 16 in a perspective view wherein the radome 16 is folded away from the antenna assembly by 90?. FIG. 15 shows the second embodiment according to FIG. 14 in a cross-sectional view. The shown radome 16 is essentially flush mounted with the front face 3 of the antenna assembly 2, wherein the back face 17 of the radome 16 is essentially flush mounted to the front face 3 of the antenna assembly 2. In addition, the radome 16 of the shown embodiment comprises at least one protrusion 25 that is arranged at the back face 17 of the radome 16 and protrudes towards the front face 4 of the antenna assembly. The at least one protrusion 25 arranged at the back face 17 of the radome 16 is configured to at least partially engage with and partially fill in at least one of the scattering elements 6. This has the positive effect that the depth (d) of the scattering elements 6 can be reduced, due to the dielectric loading of the protrusion 25. This also enables a further overall reduction of the thickness of the antenna assembly 2 and therefore the thickness of the antenna device 1 as such can also be reduced.
[0073] FIG. 16 and FIG. 17 a third embodiment of the radome in a perspective view wherein the radome is folded away from the antenna assembly by 90?. FIG. 13 shows the third embodiment according to FIG. 12 in a cross-sectional view. The shown radome 16 is essentially flush mounted with the front face 3 of the antenna assembly 2, wherein the back face 17 of the radome 16 is essentially flush mounted to the front face 17 of the antenna assembly 2. In addition, the shown radome 16 comprises a number of grooves 26. The grooves 26 are arranged at the back face 17 of the radome 16 and preferably arranged spaced apart from each other and in parallel to the at least one antenna aperture 4. The front face 3 of the antenna assembly 2 further comprises a number of bars 27 which are arranged parallel to each other and essentially perpendicular to the at least one antenna aperture 3. The number of bars 27 is designed to engage with a corresponding number of recesses 28 arranged at the back face 17 of the radome 16. The number of grooves 26 is configured to reduce the surface waves. The number of bars 27 is configured to improve the radiation pattern of the antenna assembly 2 and to stop the propagation of surface waves in the vertical direction. The dimension of the grooves 26 arranged at the back face 17 of the radome 16 as well as the number of bars 27 depends on the radome 16 thickness end the dielectric constant of the radome 16 material. For a 1.4 mm thick radome with dielectric constant of 3.46 the grooves' 26 height (h) is 1 mm and width (w) is 0.7 mm. The wall thickness ws is 0.4 mm and hs is 0.4 mm.
[0074] FIG. 18 and FIG. 19 show an embodiment of the radome 16 which comprises at least one lens 28, wherein the lens 28 is designed such that most of the power can be radiated in boresight direction at the front face 3 of the antenna assembly 2 avoiding excitation of surface waves, since the lens 28 help to collimate the power in boresight direction. These, techniques take advantage of 3D structure of the antenna assembly 2 and the radome 16. Furthermore, the lens 28 help to reduce the size of the antenna aperture 4 which can in terms relax the conflict between antenna placement for proper function of beam former and requirements on beam width and directivity of antenna. The radii of the lens 28 depend strongly on the radome 16 material and type of antenna aperture 4.
[0075] FIGS. 20 and 21 show a first embodiment of the antenna device 1, wherein the antenna assembly is arranged within a case 30. In the shown embodiment the antenna assembly 2 is essentially fully enclosed by the case 30. The shown antenna assembly 2 is designed as a waveguide antenna. The at least one antenna aperture 4 connects to a hollow wave guide structure 31 arranged inside the antenna assembly 2. The hollow waveguide structure 31 is interconnected to an electronic component 32. In the shown embodiment the electronic component 32 is arranged at the back side of the antenna assembly 2 with respect to the front face 3 of the antenna assembly 2. The antenna device 1 also comprises a printed circuit board 33 and a thereon arranged electronic component 32. Besides the at least one antenna aperture 4 arranged at the front face 3 the shown antenna assembly 2 further comprises at least one antenna aperture 4 configured to emit an outgoing signal of rays which is foreseen to be reflected by an external object and return at least partially as primary rays 5. Alternatively, the at least one antenna aperture 4 can also be designed as horn antenna. The scattering elements 6 of the shown embodiment are having perpendicular to the front face a cross-section which is essentially rectangular and/or pyramidal and/or a combination thereof. The scattering elements 6 are having in the front face a layout 14 which is at in the shown variation rectangular. As best visible in FIG. 16, the shown radome 16 is arranged spaced apart from the front face 3 of the antenna assembly 2. Alternatively, the radome 16 can also be flush mounted with the front face 3 of the antenna assembly 2. In a variation the antenna assembly 2 can be at least in the area of the scattering elements 6 partially be covered or consist of a material absorbing the primary rays 5 at least partially.
[0076] FIGS. 22 and 23 show a second embodiment of the antenna device 1, wherein the antenna assembly 2 is arranged within a case 30. In the shown embodiment the antenna assembly 2 is essentially fully enclosed by the case 30. The shown antenna assembly 2 is designed as a waveguide antenna. The at least one antenna aperture 4 connects to a hollow wave guide structure 31 arranged inside the antenna assembly 2. The hollow waveguide structure 31 is interconnected to an electronic component 32. In the shown embodiment the electronic component 32 is arranged at the back side of the antenna assembly 2 with respect to the front face 3 of the antenna assembly 2. The antenna device 1 also comprises a printed circuit board 33 and a thereon arranged electronic component 32. Besides the at least one antenna aperture 4 arranged at the front face 3 the shown antenna assembly 2 further comprises at least one antenna aperture 4 configured to emit an outgoing signal of rays which is foreseen to be reflected by an external object and return at least partially as primary rays 5. As best visible in FIG. 16, the shown embodiment comprises a layer of absorbing material 39. The shown embodiment comprises a chip (MMIC) 38. The shown antenna assembly is made by injection molding. The shown embodiment of the antenna assembly 2 comprises two injection molding materials, wherein one of them has electromagnetic absorbing properties. The layer of absorbing material 39 is arranged at the back face of the antenna assembly 2. In a preferred variation the layer of absorbing material 39 and the base material are made in one production step within one cavity. Preferably by two component injection molding.
[0077] FIGS. 24 and 25 show a perspective view of a third embodiment of the antenna assembly 2. In the front face 3 of the shown embodiment antenna apertures 4 are arranged configured to receive an incoming signal in form of primary rays 5 impacting in the antenna aperture 4. The shown antenna apertures 4 are arranged in groups. The shown scattering elements 6 are with respect to the front face 3 designed as indentations 10. In addition, some of the shown scattering elements 6 are arranged in parallel rows 11, wherein the scattering elements 6 of each row are equally spaced apart from each other. Besides the scattering elements 6 which are arranged adjacent to the at least one antenna aperture 4 on the front face 3 of the antenna assembly 2, the shown antenna assembly 2 further comprises a layer of absorbing material 40. While the scattering elements 6 are configured to at least partially reflect the primary rays 5 impacting in the area of the scattering elements 6, and thereby separate them into first secondary rays 7 and second secondary rays 8, the shown layer of absorbing material 40 at least partially absorbs the primary rays 5 impacting at the absorbing material. As can be seen in the figures, the layer of absorbing material 40 can fully or partially cover the antenna assembly 2. In the shown variation the layer of absorbing material 40 is arranged on or in the front face 3 and covers essentially the overall front face 3 except for the area covered by the antenna apertures 4 and the area covered by the scattering elements 6.
[0078] As can be obtained best from FIG. 25, the shown layer of absorbing material 40 is assembled to the antenna assembly 2 in form of a separate layer of absorbing material 40, which is joined with the front face 3 of the antenna assembly 2. The shown absorbing material 40 can be joined mechanically by fastening means, e.g., by screwing or clamping. The shown layer of absorbing material 40 can be joined by welding, gluing, hot stamping, clipping, pressfit, soldering etc. The shown absorbing material 40 is made out of a resin or composite, e.g., a hybrid material with electromagnetic absorbing properties. The shown absorbing material 40 is embedding it into the front face 3 of the antenna assembly 2, into a cavity 41 arranged in the front face 3.
[0079] FIGS. 26 and 27 show a perspective view of a fourth embodiment of the antenna assembly 2. The shown embodiment is similar to the third embodiment shown in FIGS. 24 and 25. Besides the scattering elements 6 arranged adjacent to the at least one antenna aperture 4 on the front face 3 of the antenna assembly 2, the shown antenna assembly 2 further also comprises a layer of absorbing material 40. As can be seen in the figures, the absorbing material 40 can fully or partly cover the antenna assembly 2. In the shown variation the absorbing material 40 is arranged on or in the front face 3 and covers essentially the overall front face 3 except for the area covered by the antenna apertures 4 and the area covered by the scattering elements 6.
[0080] As can be obtained best from FIG. 27, the shown embodiment differs from the embodiment shown by FIGS. 24 and 25 in that the layer of absorbing material 40 is assembled to the antenna assembly 2 in form of a separate absorbing material 40, which arranged onto the front face 3 of the antenna assembly 2. The shown absorbing material 40 can be joined mechanically by fastening means, e.g., by screwing or clamping. The shown layer of absorbing material 40 can be joined by welding, gluing, hot stamping, clipping, pressfit, soldering etc. The shown absorbing material 40 is made out of a resin or composite, e.g., a hybrid material with electromagnetic absorbing properties. An efficient manufacturing process for the shown embodiment can be achieved when the antenna assembly 2 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 2 can be subjected to a complete or selective surface treatment process. Once the front and a back layer of the antenna assembly are fabricated, a layer of paint or coating can be at least partially applied to the front face 3 of the antenna assembly 2.
[0081] FIGS. 28 and 29 show a fifth embodiment of the radome 16 in a perspective view. In the shown embodiment, the absorbing material 40 is arranged on the inner side of the radome 16, facing the antenna assembly 2 in the mounted state. The separate absorbing material 40 is connected to the radome 16 using joining techniques, e.g., screwing, clamping, welding, gluing, hot stamping, clipping, press-fit, soldering etc. The absorbing material 40 can attached to or be embedded in the radome 16. The shown absorbing material 40 can also be assembled with a distance with respect to the radome 16.
[0082] 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.
