CN218827835U - Coplanar feed waveguide slot antenna and radar - Google Patents

Abstract

The application relates to a coplanar feed waveguide slot antenna and a radar. The antenna includes: the single-ridge waveguide comprises a conductor plate and a waveguide slot coplanar with the microstrip feed part, wherein the dielectric plate is arranged between the conductor plate and the waveguide slot, and the conductor plate is electrically connected with the waveguide slot; the waveguide groove is internally provided with a waveguide ridge, the waveguide groove is provided with a plurality of radiation gaps at the position of the waveguide ridge, the radiation gaps are arranged in a staggered mode along the central axis direction of the waveguide ridge, and the microstrip feed portion extends into the waveguide groove and is electrically connected with the waveguide ridge. The structure can realize coplanar feeding of the feed board and the single-ridge waveguide, avoids a connecting gap between the feed board and a port of the single-ridge waveguide, and has the characteristics of simple structure, small overall height, low energy loss, good antenna performance, low cost, small processing difficulty, large-scale mass production and the like.

Description

Coplanar feed waveguide slot antenna and radar

Technical Field

The application relates to the technical field of antennas, in particular to a coplanar feed waveguide slot antenna and a radar.

Background

With the development of antenna technology, the antenna is more and more widely applied, wherein radar is an important application field of the antenna, for example, in millimeter wave vehicle-mounted radar, a millimeter wave antenna plays a role in receiving and transmitting signals by the radar. At present, most of mature radar products adopt planar printed antennas, but with the development of radar technology, the requirements on indexes such as detection distance, distance resolution and the like are higher and higher, the requirements on the functions of the radar are higher and higher, and the future radar needs to have an imaging function. The waveguide slot antenna has the advantages of high efficiency, compact structure and easy realization of low sidelobe, and gradually becomes the first choice of the imaging radar.

In the prior art, the output port of a conventional waveguide antenna is a waveguide, a chip is generally soldered on a dielectric substrate, and the output port of the chip is a planar printed line, such as a microstrip line or a coplanar waveguide line, and is difficult to be directly connected with the waveguide. In this respect, one solution is to transfer the chip to the lower chip through the multilayer waveguide structure, however, this way increases the multilayer structure on the one hand, greatly increases the antenna height, and brings about cost increase, and on the other hand, increases the multilayer waveguide transfer part, which brings about extra loss and leads to gain loss; the other way is to adopt multilayer dielectric slab stacking to enable the microstrip line to feed the waveguide in a stepped transition mode, however, the mode needs multilayer high-frequency dielectric slabs on one hand, the cost is increased, and on the other hand, the adjacent position of the waveguide and the dielectric slabs has gaps, so that the signal matching is poor, and the mode is not suitable for large-scale mass production.

SUMMERY OF THE UTILITY MODEL

In view of the above, it is desirable to provide a coplanar feed waveguide slot antenna and a radar that can realize coplanar feeding of a feed plate and a single-ridge waveguide.

In a first aspect, there is provided a coplanar feed waveguide slot antenna, comprising: the single-ridge waveguide comprises a conductor plate and a waveguide slot coplanar with the microstrip feed part, wherein the dielectric plate is arranged between the conductor plate and the waveguide slot, and the conductor plate is electrically connected with the waveguide slot;

the waveguide groove is internally provided with a waveguide ridge, the waveguide groove is provided with a plurality of radiation gaps at the position of the waveguide ridge, the radiation gaps are arranged in a staggered mode along the central axis direction of the waveguide ridge, and the microstrip feed portion extends into the waveguide groove and is electrically connected with the waveguide ridge.

In one embodiment, the conductor plate is a ground plane of the feed plate.

In one embodiment, the dielectric plate is provided with a plurality of conductive through holes corresponding to the side walls of the waveguide grooves, and the conductor plate is electrically connected with the waveguide grooves through the conductive through holes.

In one embodiment, the dielectric plate is further provided with a conductive layer at a position along the conductive via hole, and the conductive via hole is electrically connected with the waveguide groove through the conductive layer.

In one embodiment, the conductive layer is a conductive strip disposed along the location of the conductive via.

In one embodiment, a transition ridge is arranged on one side of the waveguide ridge close to the microstrip feed, and the waveguide ridge is electrically connected with the microstrip feed through the transition ridge.

In one embodiment, the transition ridge is a step ridge, the step ridge at least comprises a first step, a second step and a third step, the first step is electrically connected with the microstrip feed portion, the second step is respectively electrically connected with the first step and the third step, and the third step is electrically connected with the waveguide ridge.

In one embodiment, the microstrip feed section includes a first microstrip line, an impedance section, and a second microstrip line, one end of the first microstrip line is electrically connected to one end of the second microstrip line through the impedance section, and the other end of the second microstrip line is electrically connected to the waveguide ridge.

In one embodiment, the distance between the radiation slits and the central axis is taylor along the central axis of the waveguide ridge.

In a second aspect, there is provided a radar comprising: a coplanar feed waveguide slot antenna as in any one of the embodiments above.

The coplanar feed waveguide slot antenna and the radar at least have the following beneficial effects:

1) The single-ridge waveguide and the feed board share the conductor board, namely the conductor board is used as a ground layer of the feed board and a side wall of the single-ridge waveguide, meanwhile, the dielectric board of the feed board is arranged between the conductor board of the single-ridge waveguide and the waveguide slot, and the microstrip feed part extends into the waveguide slot, so that coplanar feeding of the feed board and the single-ridge waveguide is realized, on one hand, the overall height of the antenna is reduced, energy loss is reduced, and antenna gain is ensured;

2) The radiation gap and the waveguide ridge are positioned on the same waveguide groove, namely on the same workpiece, so that the processing difficulty is greatly reduced, and the distance between the radiation gap and the central axis of the single ridge waveguide is easier to accurately control, thereby realizing the performance of low side lobe of the antenna;

3) The waveguide slot and the conductive plate are connected through the conductive via hole of the dielectric plate, the conductive via hole can be used as a part of the side wall of the single-ridge waveguide, so that energy leakage is prevented, meanwhile, the conductive layer is arranged between the conductive via hole and the waveguide slot, a connecting gap is further reduced, and the stability of electric connection between the conductive plate and the waveguide slot is ensured;

4) The microstrip feed portion is electrically connected with the waveguide ridge through the transition ridge, and the matching between the microstrip feed portion and the single ridge waveguide is adjusted through the transition ridge, so that the antenna gain is ensured.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an overall block diagram of a coplanar feed waveguide slot antenna in one embodiment;

FIG. 2 is a waveguide slot structure diagram of a coplanar feed waveguide slot antenna in one embodiment;

FIG. 3 is a side block diagram of a coplanar feed waveguide slot antenna in one embodiment;

FIG. 4 is a dielectric slab structure diagram of a coplanar feed waveguide slot antenna in one embodiment;

FIG. 5 is a 76.5GHz pattern for a coplanar feed waveguide slot antenna according to one embodiment;

FIG. 6 is a 77GHz pattern for a coplanar feed waveguide slot antenna according to one embodiment;

FIG. 7 is a comparison of a coplanar feed waveguide slot antenna in one embodiment with prior art testing;

figure 8 is a graph of return loss characteristics of a coplanar feed waveguide slot antenna in one embodiment.

Description of reference numerals:

11. a dielectric plate; 121. a first microstrip line; 122. an impedance section; 123. a second microstrip line; 13. a conductive via; 14. a conductive layer; 21. a conductor plate; 22. a waveguide groove; 221. a waveguide ridge; 222. a transition ridge; 3. a radiation slit.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, 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 be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

Spatial relational terms, such as "under," "below," "under," "over," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations) and the spatial descriptors used herein interpreted accordingly.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be connected to the other element through intervening elements. In addition, "connection" in the following embodiments is understood to mean "electrical connection", "communication connection", and the like if there is a transfer of electrical signals or data between the connected objects.

As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

The coplanar feed waveguide slot antenna provided by the embodiment of the application can be applied to the fields of radars and the like, realizes the coplanar feed of the feed board and the single-ridge waveguide through the antenna structure, namely the coplanarity between the antenna chip and the antenna, and has the characteristics of simple structure, small overall height, low energy loss, good antenna performance, low cost, small processing difficulty, large-scale mass production and the like.

In one embodiment, as shown in fig. 1, there is provided a coplanar feed waveguide slot antenna comprising: the feed board comprises a dielectric board 11 and a microstrip feed part arranged on the upper surface of the dielectric board, the single ridge waveguide comprises a conductor board 21 and a waveguide slot 22 coplanar with the microstrip feed part, wherein the dielectric board 11 is arranged between the conductor board 21 and the waveguide slot 22, and the conductor board 21 is electrically connected with the waveguide slot 22;

the waveguide groove 22 is provided with a waveguide ridge 221, the waveguide groove 22 is provided with a plurality of radiation slots 3 at the position of the waveguide ridge 221, the radiation slots 3 are arranged in a staggered manner along the central axis direction of the waveguide ridge 221, and the microstrip feed portion extends into the waveguide groove 22 and is electrically connected with the waveguide ridge 221.

The feed board is used for feeding antenna signal transmission and reception, wherein the dielectric board is a high-frequency dielectric board to meet the requirement of antenna high-frequency operation, and a microstrip feed part is arranged on the dielectric board and feeds based on a microstrip line.

Specifically, referring to fig. 1 to 3, a radiation slot 3 is opened on a single-ridge waveguide to form a basic structure of a waveguide slot antenna, wherein the single-ridge waveguide is divided into two parts, one part is a waveguide slot 22 disposed on a feeding side of a dielectric plate 11, the waveguide slot 22 is a slot structure composed of three side walls of the single-ridge waveguide, the other part is a conductor plate 21 disposed on the other side of the dielectric plate 11, the conductor plate 21 serves as one side wall of the single-ridge waveguide, the dielectric plate 11 plays a role in fixing between the conductor plate 21 and the waveguide slot 22, and the conductor plate 21 and the waveguide slot 22 are electrically connected, so that a complete single-ridge waveguide, that is, four side walls of the single-ridge waveguide, is formed by combining the conductor plate 21 and the waveguide slot 22. Specifically, a ground layer on the feed board side may be directly used as the conductor board 21, i.e., the metal layer on the dielectric board 11.

The embodiment shares the conductor plate with the feed plate through the single ridge waveguide, namely the conductor plate is used as a ground layer of the feed plate and a side wall of the single ridge waveguide, meanwhile, the dielectric plate of the feed plate is arranged between the conductor plate and the waveguide slot of the single ridge waveguide, the micro-strip feed part extends into the waveguide slot, coplanar feeding of the feed plate and the single ridge waveguide is realized, namely, the antenna chip and the single ridge waveguide can be mounted in a coplanar manner, the integral height of the antenna is greatly reduced, the mounting requirement is effectively reduced, the application scene of the antenna is wider, meanwhile, the problem of energy loss in a traditional multilayer waveguide structure is avoided, the antenna gain is ensured, the problem of connecting gaps between the feed plate and single ridge waveguide ports in the traditional multilayer dielectric plate stacking is avoided, the performance of antenna signal matching is ensured, the structure is simplified, the cost and the processing difficulty are reduced, and the antenna is more suitable for large-scale mass production.

Further, referring to fig. 2 and 3, the single-ridge waveguide is provided with a metal ridge, that is, the waveguide ridge 221, in the waveguide groove 22, and may be specifically disposed on the central axis of the waveguide groove 22, and the waveguide groove 22 is notched along the position of the waveguide ridge 221 to form the radiation slots 3, and the radiation slots 3 are staggered in the direction of the central axis of the waveguide ridge 221, and the microstrip feeding portions extend into the waveguide groove 22 and are electrically connected to one end of the waveguide ridge 221, so that the electromagnetic wave signal transmitted by the microstrip feeding portions can be transmitted along the direction of the waveguide ridge 221 in the single-ridge waveguide and radiate outwards through the radiation slots 3 thereon. The distance between the radiation slots 3 arranged in a staggered manner and the central axis of the waveguide ridge 221 is set based on the antenna side lobe characteristic, and the distance from the microstrip feed portion to the single ridge waveguide can be set according to the signal matching between the microstrip feed portion and the single ridge waveguide.

This embodiment can adjust the antenna side lobe characteristic through adjusting the distance between the axis in radiation gap and the waveguide ridge, can adjust the signal matching between microstrip feed portion and the single ridge waveguide through adjusting the distance that microstrip feed portion extends to in the single ridge waveguide, simultaneously, because radiation gap and waveguide ridge are located same work piece, namely on the waveguide groove, this makes in product processing, the distance between the axis can accurate location processing in radiation gap and the waveguide ridge, there is not the counterpoint error between work piece and the work piece, the processing degree of difficulty has effectively been reduced, product processingquality has been improved.

In one embodiment, referring to fig. 3 and 4, the dielectric plate 11 is provided with a plurality of conductive vias 13 corresponding to the positions of the sidewalls of the waveguide grooves 22, and the conductor plate 21 is electrically connected to the waveguide grooves 22 through the conductive vias 13.

Specifically, a plurality of conductive through holes which are continuously and periodically arranged are formed in the dielectric plate along the side wall of the waveguide slot, the conductive through holes are connected with the conductor plate and the waveguide slot on two sides of the dielectric plate, the conductive through holes are integrally of a U-shaped structure, and the opening of the U-shaped structure is the wiring side of the microstrip feeding portion, so that stable electric connection between the conductor plate and the waveguide slot in all directions is guaranteed. Meanwhile, the conductive through holes are also used as a part of the side wall of the single ridge waveguide, so that the shielding effect is greatly improved, and the electromagnetic wave energy is effectively prevented from leaking from the side of the dielectric plate.

In one embodiment, referring to fig. 3 and 4, the dielectric plate 11 is further provided with a conductive layer 14 at a position along the conductive via 13, and the conductive via 13 is electrically connected with the waveguide groove 22 through the conductive layer 14.

Specifically, the conducting layer is a metal layer on the surface of the dielectric plate and is arranged along the conducting via hole, and the conducting layer is used for connecting the conducting via hole and the waveguide groove, wherein the conducting layer effectively increases the electric contact area between the conducting via hole and the waveguide groove, so that the electric connection stability between the conductor plate and the waveguide groove is ensured, meanwhile, the connecting gap between the conducting via hole and the waveguide groove is further reduced, the energy leakage is prevented, and the antenna gain is ensured. In some embodiments, the conductive layer is a conductive strip disposed along the conductive vias, such that each conductive via is electrically connected to another conductive via, and the shielding effect is further ensured.

In one embodiment, referring to fig. 2 and 3, the waveguide ridge 221 is provided with a transition ridge 222 on a side close to the microstrip feed, and the waveguide ridge 221 is electrically connected with the microstrip feed via the transition ridge 222.

Specifically, the transition ridge is used for transition between the waveguide ridge and the microstrip feed portion, so that structural mutation between the microstrip feed portion and the waveguide ridge is reduced, signal matching between the microstrip feed portion and the single ridge waveguide is guaranteed, energy loss is reduced, and antenna gain is guaranteed. In some embodiments, referring to fig. 2, the transition ridge 222 may adopt a step ridge of a step structure, where the step ridge includes at least a first step, a second step, and a third step, the first step is electrically connected to the microstrip feed, the second step is electrically connected to the first step and the third step, respectively, and the third step is electrically connected to the waveguide ridge, where matching between the microstrip feed and the single-ridge waveguide may be adjusted by adjusting widths and heights of the three steps, so as to ensure antenna gain.

In one embodiment, referring to fig. 1 and 4, the microstrip feeding section includes a first microstrip line 121, an impedance section 122, and a second microstrip line 123, wherein one end of the first microstrip line 121 is electrically connected to one end of the second microstrip line 123 via the impedance section 122, and the other end of the second microstrip line 123 is electrically connected to the waveguide ridge 221.

Specifically, in some application scenarios, the first microstrip line is a 50-ohm microstrip line, the impedance section is a quarter-wavelength impedance variation section, and the third microstrip line is a microstrip line having a width equal to that of the waveguide ridge.

In one example, the distance between the radiation slits and the central axis is taylor along the central axis of the waveguide ridge.

Specifically, in order to realize the performance of the antenna with low sidelobe, the distance between the radiation gap and the central axis direction of the waveguide ridge is adjusted to be distributed in a Taylor manner, so that the antenna has good anti-interference capability, and the working performance stability of the antenna is ensured.

In one embodiment, the length of the radiation slot is one half of the operating wavelength of the antenna, the gap distance is one half of the waveguide wavelength of the single-ridge waveguide, and the distance between the radiation slot and the short-circuit surface of the single-ridge waveguide is one quarter of the waveguide wavelength of the single-ridge waveguide.

The present embodiment will now be described with reference to the relevant test, but is not limited thereto.

Referring to fig. 5 and fig. 6, the directional diagrams of the waveguide slot antenna in the above embodiment at the operating frequencies of 76.5GHz and 77GHz are sequentially shown, and it can be seen from the diagrams that the sidelobe level of the above antenna structure on the elevation plane can be smaller than-20 dB, and the beam width corresponding to-10 dB on the azimuth plane can reach ± 120 degrees, which illustrates that the present embodiment can achieve a large-angle detection distance, and can meet the actual requirements of radars such as an automobile angle radar.

Referring to fig. 7, the antenna of the present embodiment is shown to be compared with the antenna of the conventional art in the 76.5GHz directional pattern, and it can be seen from the figure that the elevation plane is similar, while the gain of the azimuth plane of the present embodiment is flatter, the gain is higher in the + -100 degree azimuth plane, and the beam width is wider.

Referring to fig. 8, a return loss characteristic diagram of the antenna of the present embodiment is shown, and it can be seen from the diagram that the bandwidth is close to 4GHz at less than-10 dB, and the wide standing wave bandwidth can meet the requirement of the working frequency band of the automotive radar, for example.

Based on the same inventive concept, the embodiment of the application also provides a radar based on the coplanar feed waveguide slot antenna. The implementation scheme for solving the problem provided by the radar is similar to the implementation scheme described in the coplanar feed waveguide slot antenna, so that specific limitations in one or more radar embodiments provided below can be referred to as limitations on the coplanar feed waveguide slot antenna in the foregoing, and details are not described herein again.

In one embodiment, there is further provided a radar including the coplanar feed waveguide slot antenna in any one of the above embodiments, wherein the coplanar feed waveguide slot antenna includes at least: the single-ridge waveguide comprises a conductor plate and a waveguide slot coplanar with the microstrip feed part, wherein the dielectric plate is arranged between the conductor plate and the waveguide slot, and the conductor plate is electrically connected with the waveguide slot; the waveguide groove is internally provided with a waveguide ridge, the waveguide groove is provided with a plurality of radiation gaps at the position of the waveguide ridge, the radiation gaps are arranged in a staggered mode along the central axis direction of the waveguide ridge, and the microstrip feed portion extends into the waveguide groove and is electrically connected with the waveguide ridge.

In one embodiment, the conductor plate is a ground plane of the feed plate.

In one embodiment, the dielectric plate is provided with a plurality of conductive through holes corresponding to the positions of the side walls of the waveguide grooves, and the conductor plate is electrically connected with the waveguide grooves through the conductive through holes.

In one embodiment, the dielectric plate is further provided with a conductive layer at a position along the conductive via, and the conductive via is electrically connected with the waveguide groove through the conductive layer.

In one embodiment, the conductive layer is a conductive strip disposed along the location of the conductive via.

In one embodiment, a transition ridge is arranged on one side of the waveguide ridge close to the microstrip feed, and the waveguide ridge is electrically connected with the microstrip feed through the transition ridge.

In one embodiment, the transition ridge is a step ridge, the step ridge includes at least a first step, a second step and a third step, the first step is electrically connected with the microstrip feed portion, the second step is electrically connected with the first step and the third step respectively, and the third step is electrically connected with the waveguide ridge.

In one embodiment, the microstrip feed portion includes a first microstrip line, an impedance section, and a second microstrip line, one end of the first microstrip line is electrically connected to one end of the second microstrip line through the impedance section, and the other end of the second microstrip line is electrically connected to the waveguide ridge.

In one embodiment, the distance between the radiation gap and the central axis is taylor along the central axis of the waveguide ridge.

According to the radar, the single-ridge waveguide and the feed board share the conductor board, namely the conductor board is used as a ground layer of the feed board and also used as a side wall of the single-ridge waveguide, meanwhile, the dielectric board of the feed board is arranged between the conductor board of the single-ridge waveguide and the waveguide slot, and the microstrip feed part extends into the waveguide slot, so that coplanar feeding of the feed board and the single-ridge waveguide is realized, on one hand, the overall height of the antenna is reduced, energy loss is reduced, and antenna gain is ensured; in addition, the radiation gap and the waveguide ridge are located on the same waveguide groove, namely on the same workpiece, so that the processing difficulty is greatly reduced, the distance between the radiation gap and the central axis of the single ridge waveguide is easier to accurately control, and the performance of the antenna with low side lobe is realized.

In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A coplanar feed waveguide slot antenna, comprising: the single-ridge waveguide comprises a conductor plate and a waveguide slot coplanar with the microstrip feed part, wherein the dielectric plate is arranged between the conductor plate and the waveguide slot, and the conductor plate is electrically connected with the waveguide slot;

the microstrip feed part extends into the waveguide groove and is electrically connected with the waveguide ridge.

2. A coplanar feed waveguide slot antenna as set forth in claim 1 wherein said conductor plate is a ground plane of said feed plate.

3. The coplanar feed waveguide slot antenna as claimed in claim 1, wherein the dielectric plate is provided with a plurality of conductive via holes corresponding to the positions of the sidewalls of the waveguide slots, and the conductor plate is electrically connected to the waveguide slots through the conductive via holes.

4. A coplanar fed waveguide slot antenna as claimed in claim 3, wherein a conductive layer is further provided on the dielectric plate along the position of the conductive via, and the conductive via is electrically connected to the waveguide slot via the conductive layer.

5. A coplanar fed waveguide slot antenna as set forth in claim 4 wherein said conductive layer is a conductive strip disposed along the location of said conductive via.

6. A coplanar feeding waveguide slot antenna as claimed in any one of claims 1 to 5, wherein the waveguide ridge is provided with a transition ridge on a side thereof adjacent to the microstrip feed, the waveguide ridge being electrically connected to the microstrip feed via the transition ridge.

7. A coplanar feed waveguide slot antenna as claimed in claim 6, wherein the transition ridge is a step ridge, the step ridge comprises at least a first step, a second step and a third step, the first step is electrically connected to the microstrip feed, the second step is electrically connected to the first step and the third step, respectively, and the third step is electrically connected to the waveguide ridge.

8. A coplanar feed waveguide slot antenna as claimed in any one of claims 1 to 5 wherein the microstrip feed comprises a first microstrip line, an impedance segment, and a second microstrip line, one end of the first microstrip line being electrically connected to one end of the second microstrip line via the impedance segment, the other end of the second microstrip line being electrically connected to the waveguide ridge.

9. A coplanar feeder waveguide slot antenna as claimed in any one of claims 1 to 5, wherein the distance between the radiating slot and the central axis of the waveguide ridge is Taylor along the central axis.

10. A radar, comprising: a coplanar feeder waveguide slot antenna as claimed in any one of claims 1 to 9.

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