WAVEGUIDE ANTENNA

Abstract

A waveguide antenna with an antenna proximal side and an antenna distal side. A number of waveguide openings for transmitting and/or receiving electromagnetic signals to and/or from an environmental space is arranged at the antenna distal side. The waveguide antenna includes an antenna interface structure that includes interface waveguide apertures arranged in an interface carrying surface that extends transverse to a normal axis. Each interface waveguide aperture is coupled with at least one associated waveguide opening such that the respective interface waveguide aperture and the associated waveguide opening(s) are offset with respect to each other transverse to the normal axis. Each interface waveguide aperture and at least one coupled waveguide opening are configured for transmitting and/or receiving electromagnetic signals with respective polarizations rotated against each other. At least two neighboring interface waveguide apertures may be interlaced with each other, and/or the interface waveguide apertures may in each case enable a simultaneous and/or alternative transferring of at least two electromagnetic signals of different polarization, and/or the interface waveguide apertures may have different aperture orientations.

Claims

1. Waveguide antenna having at least two signal channels, the waveguide antenna having an antenna distal side and an antenna proximal side, wherein a number of waveguide openings for at least one of transmitting electromagnetic signals to and receiving electromagnetic signals from an environmental space is arranged at the antenna distal side, the waveguide antenna including an antenna interface structure for connecting the waveguide antenna to at least one of a printed circuit board and a semiconductor component, the antenna interface structure being arranged at the antenna proximal side, the antenna interface structure including a number of interface waveguide apertures, the number of interface waveguide apertures being arranged in an interface carrying surface and coupled with the number of waveguide openings via a waveguide channel structure arranged within the waveguide antenna, wherein the interface carrying surface extends transverse to a normal axis, the normal axis extending between proximal and distal, wherein each interface waveguide aperture is coupled with at least one associated waveguide opening such that the respective interface waveguide aperture and the associated at least one waveguide opening are offset with respect to each other transverse to the normal axis, wherein each interface waveguide aperture and at least one thereto coupled waveguide opening are configured for at least one of transmitting and receiving electromagnetic signals with respective polarizations rotated against each other, and wherein the interface waveguide apertures are designed and arranged such that at least two neighboring interface waveguide apertures are interlaced with each other.

2. The waveguide antenna according to claim 1, wherein the interface waveguide apertures have at least one of the following shaped contours: Y shaped, Z-shaped, L-shaped, ridged-L-shaped, S-shaped or N-shaped.

3. The waveguide antenna according to claim 1, wherein the interface waveguide apertures have in each case an identical contour.

4. The waveguide antenna according to claim 1, wherein the interface waveguide apertures are arranged in a pattern of rows and columns.

5. The waveguide antenna according to claim 4, wherein the interface waveguide apertures out of the following: within a row within a column or within a row and a column, have in each case an identical aperture orientation.

6. The waveguide antenna according to claim 1, wherein the interface waveguide apertures have in each case either of a first aperture orientation or a second aperture orientation different from the first aperture orientation, wherein interface waveguide apertures having the first aperture orientation are arranged with interface apertures having the second aperture orientation in an alternating manner.

7. The waveguide antenna according to claim 1, wherein the antenna interface structure includes an electromagnetic band gap (EBG) structure, the electromagnetic band gap structure projecting from the interface carrying surface.

8. The waveguide antenna according to claim 1, the waveguide antenna further including a number of orthomode transducers, the orthomode transducer being electromagnetically arranged between the number waveguide openings and the number of interface waveguide apertures.

9. The waveguide antenna according to claim 8, wherein an orthomode transducer of the number of orthomode transducers is associated and electromagnetically coupled with an associated interface waveguide aperture in a one-to-one manner.

10. The waveguide antenna assembly, the waveguide antenna assembly including a waveguide antenna according to claim 1, the waveguide antenna assembly further including a printed circuit board, the printed circuit board having a printed circuit board proximal side and a printed circuit board distal side, wherein the waveguide antenna is mounted on the printed circuit board distal side.

11. The waveguide antenna assembly according to claim 10, wherein the printed circuit board includes a printed circuit board interface structure with a number of printed circuit board waveguide passages, the printed circuit board waveguide passages each extending through the printed circuit board between the printed circuit board proximal side and the printed circuit board distal side, wherein the printed circuit board waveguide passages are in in each case aligned with a respective interface waveguide aperture.

12. The waveguide antenna assembly according to claim 11, wherein each printed circuit board waveguide passage has a cross section that is different from the contour of the associated interface waveguide aperture.

13. The waveguide antenna assembly according to claim 11, wherein the waveguide antenna assembly further including a semiconductor component, the semiconductor component being mounted on the printed circuit board proximal side, the semiconductor component including a number of electromagnetic signal launchers, the number of electromagnetic signal launchers corresponding to the number of printed circuit board waveguide passages, wherein the printed circuit board waveguide passages are in in each case aligned with a respective electromagnetic signal launcher in a one-to-one manner.

14. The waveguide antenna assembly according to claim 10, wherein the printed circuit board includes a printed circuit board coupling cut-out, the printed circuit board coupling cut-out extending between the printed circuit board distal side and the printed circuit board proximal side, the antenna interface structure projecting into or through the printed circuit board coupling cut-out from the printed circuit board distal side towards the printed circuit board proximal side.

15. The waveguide antenna assembly according to claim 14, wherein the waveguide antenna assembly further including a semiconductor component, the semiconductor component being mounted on the printed circuit board proximal side, the semiconductor component including a number of electromagnetic signal launchers, the number of electromagnetic signal launchers corresponding to the number of interface waveguide apertures, wherein the interface waveguide apertures are in each case aligned with a respective electromagnetic signal launcher in a one-to-one manner.

16. The waveguide antenna assembly according to claim 15, wherein the antenna interface structure directly contacts the semiconductor component.

17. The waveguide antenna assembly according to claim 16, wherein the antenna interface structure and the semiconductor component are coupled via a layer of conductive adhesive, the layer of conductive adhesive being arranged between the antenna interface structure and the semiconductor component.

18. The waveguide antenna assembly according to claim 10 wherein a printed circuited board electromagnetic band gab structure, in particular an electromagnetic band gap structure having mushroom-shaped electromagnetic band gap elements, is arranged on or within the PCB.

19. (canceled)

20. A waveguide antenna having at least two signal channels, the waveguide antenna having an antenna distal side and an antenna proximal side, wherein a number of waveguide openings for at least one of transmitting electromagnetic signals to and receiving electromagnetic signals from an environmental space is arranged at the antenna distal side, the waveguide antenna including an antenna interface structure for connecting the waveguide antenna to at least one of a printed circuit board and a semiconductor component, the antenna interface structure being arranged at the antenna proximal side, the antenna interface structure including a number of interface waveguide apertures, the number of interface waveguide apertures being arranged in an interface carrying surface and coupled with the number of waveguide openings via a waveguide channel structure arranged within the waveguide antenna, wherein the interface carrying surface extends transverse to a normal axis, the normal axis extending between proximal and distal, wherein each interface waveguide aperture is coupled with at least one associated waveguide opening such that the respective interface waveguide aperture and the associated at least one waveguide opening are offset with respect to each other transverse to the normal axis, wherein each interface waveguide aperture and at least one thereto coupled waveguide opening are configured for at least one of transmitting and receiving electromagnetic signals with respective polarizations rotated against each other, and wherein the interface waveguide apertures are in each case designed to enable at least one of a simultaneous and an alternative transferring of at least two electromagnetic signals of different polarization.

21. A waveguide antenna having at least two signal channels, the waveguide antenna having an antenna distal side and an antenna proximal side, wherein a number of waveguide openings for at least one of transmitting electromagnetic signals to and receiving electromagnetic signals from an environmental space is arranged at the antenna distal side, the waveguide antenna including an antenna interface structure for connecting the waveguide antenna to at least one of a printed circuit board and a semiconductor component, the antenna interface structure being arranged at the antenna proximal side, the antenna interface structure including a number of interface waveguide apertures, the number of interface waveguide apertures being arranged in an interface carrying surface and coupled with the number of waveguide openings via a wave-guide channel structure arranged within the waveguide antenna, wherein the inter-face carrying surface extends transverse to a normal axis, the normal axis extending between proximal and distal, wherein each interface waveguide aperture is coupled with at least one associated waveguide opening such that the respective interface waveguide aperture and the associated at least one waveguide opening are offset with respect to each other transverse to the normal axis, wherein each interface waveguide aperture and at least one thereto coupled waveguide opening are configured for at least one of transmitting and receiving electro-magnetic signals with respective polarizations rotated against each other, and wherein the interface waveguide apertures are designed and arranged such that at least two neighboring interface waveguide apertures have different aperture orientations.

Description

DESCRIPTION OF THE DRAWINGS

[0060] The herein described disclosure will be more fully understood from the detailed description given herein below and the accompanying figures which should not be considered limiting to the disclosure described in the appended claims. The figures show

[0061] FIG. 1 shows an embodiment of a waveguide antenna assembly in a first exploded view;

[0062] FIG. 2 shows the waveguide antenna assembly of FIG. 1 in a second exploded view;

[0063] FIG. 3 shows a view from distal towards proximal on the antenna interface structure for the waveguide antenna assembly of FIG. 1;

[0064] FIG. 4 shows a view corresponding to FIG. 3 for a further embodiment of a waveguide antenna assembly;

[0065] FIG. 5 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0066] FIG. 6 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0067] FIG. 7 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0068] FIG. 8 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0069] FIG. 9 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0070] FIG. 10 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0071] FIG. 11 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0072] FIG. 12 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0073] FIG. 13 shows a view corresponding to FIG. 3 for a still further embodiment of a waveguide antenna assembly;

[0074] FIG. 14 shows a waveguide antenna assembly in perspective flipped-open view;

[0075] FIG. 15 shows a further waveguide antenna assembly in perspective flipped-open view;

[0076] FIG. 16a shows a Y-shaped contour of an interface waveguide aperture;

[0077] FIG. 16b shows a polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 16a;

[0078] FIG. 16c shows a further polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 16a;

[0079] FIG. 16d shows a further polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 16a;

[0080] FIG. 16e shows a further polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 16a;

[0081] FIG. 17a shows an S-shaped contour of an interface waveguide aperture;

[0082] FIG. 17b shows a polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 17a;

[0083] FIG. 18a shows a Z-shaped contour of an interface waveguide aperture;

[0084] FIG. 18b shows a polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 18a;

[0085] FIG. 19a shows an L-shaped contour of an interface waveguide aperture;

[0086] FIG. 19b shows a ridged-L-shaped contour of an interface waveguide aperture;

[0087] FIG. 19c shows a polarization of the E-field vector for the interface waveguide aperture pursuant to FIG. 19a or FIG. 19b;

[0088] FIG. 20a shows a further contour of an interface waveguide aperture;

[0089] FIG. 20b shows a still further contour of an interface waveguide aperture;

[0090] FIG. 21 shows an embodiment of a waveguide antenna in an angled perspective view on the antenna proximal side;

[0091] FIG. 22 shows the waveguide antenna of FIG. 21 in an angled perspective view on the antenna distal side;

[0092] FIG. 23 shows a distal antenna layer of the waveguide antenna of FIG. 21, 22;

[0093] FIG. 24 shows a proximal antenna layer of the waveguide antenna of FIG. 21, 22;

[0094] FIG. 25 shows an embodiment of an automotive radar system;

[0095] FIG. 26 shows a further embodiment of an automotive radar system;

[0096] FIG. 27 shows a further embodiment of a part of a waveguide antenna assembly in a perspective view; and

[0097] FIG. 28 shows an illustration of the electromagnetic structure corresponding to FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION

[0098] In the following, reference is first made to FIGS. 1, 2, 3, showing an embodiment of a waveguide antenna assembly 1 in accordance with the present disclosure in two different exploded vies (FIGS. 1, 2) as well as in a view from distal towards proximal (x-direction) of the antenna interface structure (FIG. 3).

[0099] The waveguide antenna assembly 1 includes a waveguide antenna 11 and a printed circuit board (PCB) 12. Both of the waveguide antenna 11 and the PCB 12 have a respective proximal side and a respective distal side. For the PCB 12, the PCB proximal side and PCB distal side are referenced 12P, 12D. For the waveguide antenna 11, only a proximal portion with the proximal side 11P is visible in the figures. The waveguide antenna 11 generally continues in distal direction. The directions proximal and Distal are indicated with P and D, respectively. The direction from proximal towards distal is the ?x-direction). It is noted that other conventions could be used as well.

[0100] The waveguide antenna 11 is typically realized by a stack of layers are arranged on top of the other and may be realized from metalized injection molded plastics and/or other materials and technologies as mentioned above in the general description. From the waveguide antenna 11, only a most proximal layer is shown which realizes the antenna interface structure 111. The proximal side (pointing towards the PCB 12 respectively in the x-direction) of the waveguide antenna 11 is in this design formed by the interface carrying surface 113.

[0101] The antenna interface structure 111 includes in this embodiment a number equally shaped interface waveguide apertures 112 that form proximal openings of corresponding waveguide channels which extend from the interface waveguide apertures 112 into the waveguide antenna 11 in generally distal direction. As best visible in FIG. 3, the interface waveguide apertures 112 are arranged as a matrix respectively a pattern of mutually orthogonal and equidistant rows R (z-direction) and columns C (y-direction). In this embodiment, the interface waveguide apertures 112 each have a contour that includes a central part which merges in the four corners into four peripheral parts. This contour enables the transition of electromagnetic waveguides respectively electromagnetic signals with two mutually orthogonal polarizations. In the shown embodiment, the interface waveguide apertures 112 are arranged side by side, without neighboring interface waveguide apertures respectively their contours being interlaced. It is noted that at least proximal end sections of the waveguide channels have in each case a cross section that corresponds to the contour of the interface waveguide apertures 112.

[0102] The PCB 12 is realized by a stack of layers as generally known in the art. The PCB 12 includes a most proximal metallic layer 121, a most distal metallic layer 123 on which the waveguide antenna 11 is mounted, and a body respectively a stack of intermediate layers 122 between the most proximal layer 121 and the most distal layer 123. The PCB 12 comprises a number of through-going PCB waveguide passages 124 corresponding to and in alignment with the interface waveguide apertures 112.

[0103] The normal axis of the waveguide antenna may be any axis that is aligned with respectively extends parallel to the x-axis.

[0104] It is to be understood that the shown number of two rows and four columns is merely exemplary and for the purpose of illustration.

[0105] In this embodiment, the antenna interface structure 111 includes an EBG structure that projects from the interface carrying surface 113 towards the PCB 12. The EBG structure includes in this embodiment two types of EBG elements, 114a, 114b in a periodic arrangement. The EBG structure is arranged in between respectively around the interface waveguide apertures 112.

[0106] In the following, reference is additionally made to FIG. 4, in a view corresponding to FIG. 3, i.e., in a view on the interface-carrying surface 111 from distal towards proximal as discussed above. Like for further embodiments, only this view is shown. The overall design generally corresponds to the embodiment of FIGS. 1, 2, 3. In particular, the PCB waveguide passages 124 are in each case shaped and designed to have an identical respective substantially identical contour as the interface waveguide apertures 112 and are aligned with the latter in a one-to-one manner. All features regarding the arrangement and contour of shape of the interface waveguide apertures 112 accordingly hold also true for the PCB waveguide passages 124 of the respective embodiments in an analogue manner. An EBG structure may or may not be present in any of the embodiments. Further, in a variant, the PCB waveguide may be differently shaped respectively have a different contour and be in particular be smaller as compared to the interface waveguide apertures 112.

[0107] In the embodiment of FIG. 4, the interface waveguide apertures 112 (and accordingly the PCB waveguide passages 124) have in case an S-shaped contour (see also FIGS. 17a, 17b). Within the row R, neighboring interface waveguide apertures 112 are somewhat interlaced, while neighboring interface waveguide openings 112 are not interlaced within the columns.

[0108] In the following, reference is additionally made to FIG. 5. In this embodiment, the interface waveguide apertures are ridged-L-shaped (see also FIGS. 19a, 19b, 19c). Like in the embodiment of FIG. 4, neighboring interface waveguide apertures 112 are interlaced within the rows R, while they are not interlaced within the columns.

[0109] In the following, reference is additionally made to FIG. 6. In this embodiment, the interface waveguide apertures have an S-shaped contour, similar to the embodiment of FIG. 4. In contrast to the latter, however, the interface waveguide apertures 112 are rotated about the x-axis and not aligned with the y- and z-axes are rotated. It can further be seen that each interface waveguide aperture 112 has either of a first or second aperture orientation, with the first and second aperture orientation alternating within each row R and column C. In the shown design, the first and second aperture orientation are rotated with respect to each other by 90?. Other rotational angles, however, may also be used.

[0110] In the following, reference is additionally made to FIG. 7. In this embodiment, the interface waveguide apertures have a rectangular shape. Like in the embodiment of FIG. 6, each interface waveguide aperture 112 has either of a first or a second aperture orientation which are arranged in an alternating manner within each row R and column C. The first and second aperture orientation are rotated by 90? with respect to each other. It is noted that this design results in a non-constant distance between neighboring rows R and/or columns C.

[0111] In the following, reference is additionally made to FIG. 8. In this design, the interface waveguide apertures 112 each have a Z-shaped contour (see also FIGS. 18a, 18b). Also in this design, the interface waveguide apertures 112 have either of a first or aperture orientation which are arranged in an alternating manner within each row R and column C. Like in the embodiment e.g., of FIG. 6, the interface waveguide apertures 112 are not aligned with the axes.

[0112] In the following, reference is additionally made to FIG. 9 (see also FIG. 14) and FIG. 10 (see also FIG. 15). The design of FIG. 9 is similar to the design of FIG. 8, in that the interface waveguide apertures 112 each have a Z-shaped contour with in each case either of a first or second aperture orientation in an alternating manner. In contrast to the latter, however, the interface waveguide apertures 112 are aligned with the y- and z-axis. The embodiment of FIG. 10 is similar, but with different orientations of the interface waveguide apertures 112.

[0113] In the following, reference is additionally made to FIG. 11 and FIG. 12. In both designs, the interface waveguide apertures 112 have a Z-shaped contour as discussed before. In these embodiments, however, all interface waveguide apertures 112 have a common orientation which is not aligned with the axis in the embodiment of FIG. 11 and aligned with the axis in FIG. 12.

[0114] In the following, reference is additionally made to FIG. 13. In this design, the interface waveguide apertures 112 each have a Y-shaped contour with three angled legs (see also FIGS. 16a, 16b, 16c, 16d, 16e). Like in some before-discussed designs, each interface waveguide aperture 112 has either of a first aperture orientation or a second aperture orientation, with the first and second aperture orientation being rotated with respect to each other by 180? Within each row R, neighboring interface waveguide apertures 112 have an alternating aperture orientation, while they have an identical aperture orientation within each column C: Further, neighboring interface waveguide apertures are interlaced within the rows R, while neighboring interface waveguide apertures 112 are not interlaced within the columns.

[0115] In the following, reference is additionally made to FIG. 14, showing waveguide assembly 1 with an arrangement of Z-shaped interface waveguide apertures 12 pursuant to FIG. 9 in a perspective flipped-open view with the PCB 12 being rotated by 90 degrees with respect to the waveguide antenna 11 and touching along a line (aligned with the y-axis). In this design, a PCB EBG structure with mushroom-shaped EBG elements 114 is arranged in the PCB 12, the mushroom-shaped PCB EBG elements 114c being arranged around the PCB waveguide openings 124.

[0116] In the following, reference is additionally made to FIG. 15, being generally similar to FIG. 14, but showing a design and arrangement of the interface waveguide apertures 112 pursuant to FIG. 10. Further in the embodiment of FIG. 14, the antenna interface structure 111 includes an EBG structure that projects from the interface carrying surface 113 towards the PCB 12. The EBG structure includes a periodic pattern of EBG elements 114a, 114b in an alternating manner, similar to the embodiment of FIGS. 1, 2.

[0117] In the following, reference is additionally made to FIGS. 16a, 16b, 16c, 16d, 16e, illustrating the dimensioning of a Y-shaped interface waveguide aperture 112 and the effect of various design parameters on the polarization. As indicated in FIG. 16a, the Y-shaped interface waveguide aperture 112 has three elements or segments, namely a base segment Sly of length lm.sub.Y, and two arms S2.sub.Y of length lS.sub.Y each. The arm segments S2.sub.Y project from the base segment S1.sub.Y in a symmetrical manner in each case with a base-arm angle ?.sub.Y. The elements have in each case an element width w.sub.Y.

[0118] The base-aria angle ?.sub.Y should favorably be in a range of 90? to 150, ?.sub.Y? [90?, 150? ]. For the relation of the element width w.sub.Y and the wave length ?, the relation w.sub.Y??/3 should hold true and similarly lS.sub.Y, lm.sub.Y? (0, 3?/2).

[0119] For a similar length lm.sub.Y of the base segment S1.sub.Y and length lS.sub.Y of the arm segments S2.sub.Y, i.e., lm.sub.Y?lS.sub.Y, two mutually orthogonal polarizations P are possible (FIGS. 16b, 16c). For the length lm.sub.Y of the base segment Sly being small as compared to the length lS.sub.Y of the arm segments S2.sub.Y, i.e., lm.sub.Y<<lS.sub.Y, one polarization is possible with the E-vector being parallel to the base (FIG. 16d). For the length lS.sub.Y of the arm segments S2.sub.Y being small as compared to the length lm.sub.Y of the base segment S1.sub.Y, i.e., lS.sub.Y<<lm.sub.Y, one polarization is possible with the E-vector being perpendicular to the base (FIG. 16e).

[0120] In the following, reference is additionally made to FIG. 17a, 17b, illustrating the dimensioning of an S-shaped interface waveguide aperture 112 and the resulting polarization.

[0121] As indicated in FIG. 17a, the S-shaped interface waveguide aperture 112 has three elements or segments S1.sub.S, S2.sub.S, S2.sub.S of lengths l1.sub.S, l2.sub.S, l3.sub.S, with the first segment S1.sub.S being connected to the second segment S2.sub.S with an angle ?.sub.S, and the second segment S2.sub.S being connected to the third segment S3.sub.S with an angle ?.sub.S, thereby forming a polygonal line. For a symmetric S-shape, the angles ?.sub.S, ?.sub.S may be equal, which, however is not essential. The segments S1.sub.S, S2.sub.S, S2.sub.S have in each case an element width w.sub.S. For the relation of the element width w.sub.S and the wavelength ?, the relation w.sub.S??/3 should hold true. In a typical design, the angles ?.sub.S, ?.sub.S may be 90?, i.e., right angled. This, however, is not mandatory, generally angles between 60? and 150? may be used, ?.sub.S, ?.sub.S?[60?, 150?]. It is noted that the shapes could also be mirrored with respect to the y- or z-axis (axes respectively directions in the plane of the interface carrying surface). The same holds true for other shapes.

[0122] Regarding the segment length, equal segment lengths are generally favorable l1.sub.S=l2.sub.S=l3.sub.S. For equal segment lengths, l1.sub.S, l2.sub.S, l3.sub.S??/4 may be used. For different segment lengths, l1.sub.S+l2.sub.S+l3.sub.S??.Math.? may be used, but the sum of the segment lengths, l1.sub.S+l2.sub.S+l3.sub.S may also be slightly larger. The resulting polarization P will be transverse to the middle segment, as indicated in FIG. 17b

[0123] In the following, reference is additionally made to FIG. 18a, 18b, illustrating the dimensioning of a Z-shaped interface waveguide aperture 112 and the resulting polarization.

[0124] As indicated in FIG. 18a, the Z-shape is similar to the S-shape as discussed before in that it has generally three segments S1.sub.Z, S2.sub.Z, S3.sub.Z. In contrast to the S-shape, however, the middle segment S2.sub.Z is not connected to an end of the other outer segments S1.sub.Z, S3.sub.Z. Instead, the outer segments S1.sub.Z, S3.sub.Z extend to both sides from the middle segment S2.sub.Z with lengths lu1.sub.Z, lu2.sub.Z, lb1.sub.Z, lb2.sub.Z as referenced in FIG. 18a. The angles ?.sub.Z, ?.sub.Z under which the outer segments S1.sub.Z, S3.sub.Z are connected to the middle segment S2.sub.Z are general equal and ?.sub.Z=?.sub.Z=90?. Other angels may in principle also be used, but are more complex in manufacture. For the relation of the element width w.sub.Z and the wavelength ?, the relation w.sub.Z??/3 should hold true.

[0125] Regarding the segment length, the relation lu1.sub.Z=lb1.sub.Z=lm.sub.Z ideally holds true and may approximately correspond to a quarter wavelength, lu1.sub.Z, lb1.sub.Z, lm.sub.Z??/4. For the other segment parts, lu2.sub.Z, lb2.sub.Z, the relation lu2.sub.Z, lb2.sub.Z?[0, ?/4] should hold true. It is noted that all four segment parts lu1.sub.Z, lu2.sub.Z, lb1.sub.Z, lb2.sub.Z may have an equal length of about ?/4. If the relation lu1.sub.Z=lb1.sub.Z=lm.sub.Z does not hold true, the condition lu1.sub.Z+lb1.sub.Z+lm.sub.Z??.Math.?, and/or lu1.sub.Z+lb1.sub.Z+lm.sub.Z??.Math.?, should be met. The resulting polarization P will be transverse to the middle segment, as indicated in FIG. 18b.

[0126] In the following, reference is additionally made to FIGS. 19a, 19b, 19c, illustrating the dimensioning of an L-shaped or ridged-L-shaped interface waveguide aperture 112 and the resulting polarization.

[0127] The L-shaped and the ridged-L-shaped design are generally similar, in that they both have two connected segments S1.sub.L, S2.sub.L of lengths l1.sub.L, l2.sub.L that fouu a polygonal line. L-shaped design (FIG. 19a) differs from the ridged-L-shaped design (FIG. 19b) in that the latter has a ridge 112 of dimensions r1.sub.L, r2.sub.L, in the outer connecting corner of the segments S1.sub.L, S2.sub.L.

[0128] In a typical design, the ?.sub.L between the segments S1.sub.L, S2.sub.L may be 90?. However, angles between 90? and 150? may be used, ?.sub.S, ?.sub.S?[90?, 150? ]. The length l1.sub.L, l2.sub.L of the segments S1.sub.L, S2.sub.L may be equal or different with l1.sub.L+l2.sub.L??.Math.?, and/or l1.sub.L, l2.sub.L??.Math.?.

[0129] If a ridge 112 is present, the combined length l1.sub.L+l2.sub.L may be reduced, in particular to l1.sub.L+l2.sub.L??.Math.? or similar.

[0130] The resulting polarization P will be diagonal as indicated in FIG. 19c for both the L-shape and the ridged-L-shape.

[0131] It is noted that some deviation is possible without deviating from the general designed operation of the illustrated contours. In particular, straight lines respectively contour segments may be somewhat bent or curved and/or edges may be rounded.

[0132] In the following, reference is additionally made to FIG. 20a, 2b, illustrating designs for interface waveguide apertures 112 with non-straight contour segments respectively rounded edges. Apart from the modifications as described in the following, FIGS. 20a, 20b generally correspond to FIG. 18b.

[0133] In both the design of FIG. 20a and FIG. 20b, the contour of the shown interface waveguide aperture 112 is generally Z-shaped as in FIGS. 18a, 18b, resulting in substantially identical characteristics and following the same design rules. In the design as shown in FIG. 20a, the straight contour segments are replaced by a plurality of circular arc segments 112a that form, in combination, a closed and approximately Z-shaped contour. The circular arc segments 112a are favorably of identical diameter. Interface waveguide apertures 112 according to FIG. 20a may for example be manufactured by drilling multiple holes with the same drill in an overlapping manner between neighboring drillings. As compared to straight contour segments, the manufacture is simplified.

[0134] In the design as shown in FIG. 20b, the contour segments are generally straight, but the joints between in each case adjacent contour segments are rounded.

[0135] In the following, reference is additionally made to FIGS. 21, 22, showing a further embodiment of a waveguide antenna 11 in an angled perspective view on the antenna proximal side 11P (FIG. 21) and the antenna distal side 11D (FIG. 22), respectively. It can be seen that the antenna proximal surface of the antenna proximal side 11P is generally planar and parallel to the antenna distal surface of the antenna distal side 11D.

[0136] In a central region of the antenna proximal surface, the generally planar interface carrying surface is 113 with the antenna interface structure 111 is arranged. The interface carrying surface 113 is parallel to but displaced with respect to the surrounding peripheral antenna proximal surface in proximal direction. The antenna interface structure is designed according to a before-described embodiments, with interface waveguide apertures and an EBG-structure.

[0137] In the antenna distal surface at the antenna distal side 11D a plurality of waveguide openings 115 is arranged. In the shown design, the waveguide openings 115 are arranged in six waveguide opening groups 115 (indicated by ellipses), with each waveguide opening group 115 comprising four waveguide openings 115 arranged consecutively in a line.

[0138] In the area between the waveguide opening groups 115, a plurality of scattering elements 116 is arranged. The scattering elements 116 form, in combination, a scattering surface. The scattering surface enhances the antenna performance by at least partly eliminating multiple reflections resulting e.g., in automotive radar applications from a radome as described further below or a bumper. Electromagnetic waves respectively rays impacting a scattering element 116 are at least partly reflected by the respective scattering element and thereby separated into a first and second secondary ray that cancel each outer out.

[0139] For mounting the waveguide antenna 11 to a PCB, screw holes 117 are foreseen. For alignment purposes, exemplary two alignment pins 118 are provided and project from the antenna proximal side.

[0140] In the following, reference is additionally made to FIGS. 23, 24, illustrating the internal design of the waveguide antenna 11. In the shown design, the waveguide antenna 11 is realized by a stack of two layers, namely a proximal antenna layer 11p with the antenna proximal side and an antenna distal layer 11d with the antenna distal side 11D. FIG. 23 shows a view on the distal antenna layer 11d with a viewing direction from proximal towards distal. Similarly, FIG. 24 shows the proximal antenna layer 11p with a viewing direction from distal towards proximal. FIGS. 23, 24, show the waveguide channel structure 119 via which the waveguide openings 119 and interface waveguide apertures 112 are coupled as explained before.

[0141] In the following, reference is additionally made to FIG. 25, illustrating an automotive radar system 2 in a sectional view. The automotive radar system 2 comprises a housing with a generally box-shaped casing 21 and a radome 22 as cover. Inside the casing 21, a waveguide antenna assembly with a waveguide antenna 11 as described before, e.g., according to the embodiment illustrated in FIGS. 21 to 24, and a PCB 112 are arranged. The waveguide antenna 11 is arranged such that the antenna proximal side with waveguide openings 115 (not visible in FIG. 25) and scattering elements 116 faces the radome.

[0142] On the PCB proximal side 12P, i.e., the side facing away from the waveguide antenna 11, a semiconductor component 13 in form of a Monolithic Microwave Integrated Circuit (MMIC) is arranged. At its distal side, the MMIC comprises a number of electromagnetic signal launches 131, corresponding to the number of interface waveguide apertures 112. Each electromagnetic signal launcher 131 is electromagnetically coupled with a respective associated interface waveguide aperture 112 via a respective associated PCB waveguide passage 124 of the PCB 12. Optionally, further components, e.g., semiconductor components, may be arranged on the PCB proximal side 12P and/or PCB distal side 12D.

[0143] In the following, reference is additionally made to FIG. 26, illustrating a further embodiment of an automotive radar system 2 similar to FIG. 25. In the design of FIG. 26, however, no individual PCB waveguide passages 124 are present. Instead, the antenna interface structure 111 projects through a PCB coupling cut-out 125 of the PCB 12. The antenna interface structure 111 may contact the MMIC at its distal side directly or via a layer of conductive adhesive 132.

[0144] In the following, reference is additionally made to FIG. 27, FIG. 28, illustrating part of a further embodiment of a waveguide antenna assembly 1. FIG. 27 shows a schematic perspective view. In the interest of clarity, only a number of functionally relevant features of the waveguide antenna 11 is shown as explained below. Further, the PCB 12 is shown flipped away from the waveguide antenna 11.

[0145] In the embodiment of FIG. 27, the waveguide antenna 11 includes a number of orthomode transducers 119. Each orthomode transducer 119 is associated and electromagnetically coupled with an associated interface waveguide aperture 112 in a one-to-one manner. Further, two branches 119a, 119 of the waveguide channel structure 119 extend from each orthomode transducer 119. A first branch 119a electromagnetically couples with one or more of the antenna waveguide openings 115, and a second branch 119b electromagnetically couples with one or more further waveguide openings 115. The corresponding electromagnetic coupling structure between an interface waveguide aperture 112, orthomode transducer 119, branches 119a, 119b of the waveguide channel structure 119, and antenna waveguide openings is illustrated in FIG. 28.

[0146] Further, it can be seen that the contour of the interface waveguide apertures 112 is in this embodiment square, while the cross section of the PCB waveguide passages 124 (and accordingly the contour of the PCB waveguide passages 124 in the PCB distal plane 12D) is circular.