Double-ridge waveguide slot array antenna and vehicle-mounted millimeter wave radar equipment

Abstract

The invention discloses a double-ridge waveguide slot array antenna which comprises a radiation structure, a double-ridge waveguide feed structure and a switching structure. The radiation structure is formed by symmetrically and collinearly arranging a plurality of slots and is used for radiating electromagnetic waves with indexes such as specific beam width and sidelobe level. The double-ridge waveguide feed structure comprises feed double-ridge waveguides, double-ridge waveguide power dividers and radiation snakelike double-ridge waveguides, the feed double-ridge waveguides are connected with the switching structure and the power dividers, the double-ridge waveguide power dividers distribute signals to the radiation snakelike double-ridge waveguides according to a specific power division ratio and phase difference, and radiation slots are formed in the upper portions of the radiation snakelike double-ridge waveguides. And the switching structure is used for switching the double-ridge waveguide to transmission lines such as a rectangular waveguide and a microstrip line, and is finally connected with a test port or a chip and the like. The antenna provided by the invention has the characteristics of wide frequency band, high gain, stable directional diagram and extremely low cross polarization. The invention further provides vehicle-mounted millimeter wave radar equipment.

Description

Technical Field

[0001] The present invention belongs to the field of automobile radar antennas, and in particular relates to a double-ridged waveguide slot array antenna and a radar device. Background Art

[0002] Automotive millimeter-wave radar plays a vital role in modern vehicles, especially in autonomous driving and advanced driver assistance systems (ADAS). Its operating frequency band is 76 GHz to 81 GHz. The wavelength of electromagnetic waves in this frequency band is about 4 mm. It has good penetration and resolution, and can effectively detect objects in the surrounding environment.

[0003] The core advantage of millimeter wave radar is its ability to achieve high-precision object recognition and positioning. To meet these requirements, radar systems are usually equipped with directional antennas with narrow beams, low side lobes, and high gain. This antenna design not only improves the directivity of the signal, but also reduces interference from other directions, thereby enhancing the detection capability of target objects. In addition, the wide bandwidth antenna design further improves the resolution of the radar, enabling it to more accurately identify and track fast-moving objects such as pedestrians and other vehicles in complex environments.

[0004] In practical applications, automotive millimeter-wave radars need to maintain stable performance under various environmental conditions. This means that the radar system must have good anti-interference capabilities and be able to work effectively under adverse conditions such as rainy days, foggy days, and strong light reflections. This places higher demands on the design of the antenna, which must be able to adapt to different electromagnetic environments to ensure reliable transmission and reception of signals.

[0005] With the rapid development of the automotive industry, especially the demand for large-scale production, cost control and simplification of manufacturing processes for radar antennas have become particularly important. In order to reduce production costs, the material selection and manufacturing process of the antenna need to be continuously optimized to ensure that large-scale industrial production can be achieved while ensuring performance. At the same time, the size of the antenna also needs to be minimized as much as possible to facilitate integration in the vehicle and reduce the impact on the overall design of the vehicle.

[0006] Automotive millimeter wave radar is based on a digital beam forming (DBF) system, which consists of several sub-arrays with moderate gain connected to an integrated circuit (IC). Waveguide or gap waveguide antennas are promising options for this application due to their low losses and broadband impedance matching in long feed networks. Nevertheless, low-cost manufacturing of waveguides at high frequencies remains challenging. There are many excellent examples in milling, micromachining or 3D printing. However, these technologies are not suitable for mass production. A promising alternative is to combine plastic injection molding and electroplating to achieve low weight and high efficiency.

[0007] At present, there are some solutions based on waveguide cavity antennas and solutions based on waveguide wide side slots or ridge waveguide wide side slots, but all of them have problems such as too high antenna unit profile, relatively large antenna size, and wide feed waveguide, which are not conducive to the multi-antenna layout and assembly of millimeter wave radar.

[0008] Narrow-wall slot waveguide arrays can minimize the spacing between digital beamforming DBF antenna units, and the minimum antenna spacing can be close to 0.5 wavelengths. In general, narrow-edge slots are usually tilted to produce radiation, and the energy of slot-coupled radiation is controlled by controlling the tilt. However, these tilted slots produce unnecessary cross-polarization, which significantly reduces the efficiency of the linear array and the accuracy of target detection. The researchers suggested placing small electrical bumps on both sides of the non-tilted slots to change the current path, thereby achieving tilted slots and low cross-polarization. Unfortunately, this method is not feasible in the 77GHz band due to its small size and inability to be processed. Summary of the invention

[0009] The main technical problem to be solved by the present invention is to provide a miniaturized, low-profile and low-cross-polarization double-ridged waveguide slot array antenna and millimeter-wave radar equipment in view of the shortcomings of the current existing technology of vehicle-mounted millimeter-wave radar antennas, such as high profile, large size and high cross-polarization of narrow-side waveguide slot array antennas.

[0010] In order to solve the above technical problems, the present invention provides a double-ridged waveguide slot array antenna, comprising: a radiation structure, a double-ridged waveguide feeding structure and a switching structure;

[0011] The radiation structure is composed of a plurality of slot structures symmetrically arranged in a collinear manner, and is used to radiate electromagnetic waves having indicators such as a specific beam width and side lobe level;

[0012] The double-ridged waveguide feeding structure comprises a feeding double-ridged waveguide, a double-ridged waveguide power divider and a radiating serpentine double-ridged waveguide, wherein the feeding double-ridged waveguide is connected to the double-ridged waveguide power divider; the double-ridged waveguide power divider distributes the signal to each radiating serpentine double-ridged waveguide with a specific power division ratio and phase difference; and a radiating slot is provided on the radiating serpentine double-ridged waveguide;

[0013] The switching structure is used to switch the double-ridge waveguide to the rectangular waveguide and the transmission line, and the transmission line is connected to the test interface or the chip.

[0014] In a preferred embodiment, the slot structure is similar to a narrow side slot of a waveguide, and the parameters of the slot structure include slot length, slot width and slot cutting depth.

[0015] In a preferred embodiment, the parameters of the fed double-ridged waveguide include the double-ridged waveguide height, the double-ridged waveguide width, the ridge width and the ridge height of the double-ridged waveguide.

[0016] In a preferred embodiment, the double-ridged waveguide power divider structure includes a matching double-ridged waveguide, the ridge width of the matching double-ridged waveguide is different from that of the feeding double-ridged waveguide; the waveguide width and ridge width of the radiating serpentine double-ridged waveguide are different from those of the feeding double-ridged waveguide; and all the waveguide heights and ridge heights of the double-ridged waveguide feeding structure are the same.

[0017] In a preferred embodiment, the number of the slot structures is an even number.

[0018] In a preferred embodiment, the test interface is a standard WR10 waveguide interface, and the chip transmitter interface is a chip vertical package transmitter interface.

[0019] In a preferred embodiment, the double-ridged waveguide slot array antenna is divided into three layers according to a radiation layer, a feeding layer, and a switching layer, which are processed separately and then assembled.

[0020] The present invention also provides a vehicle-mounted millimeter wave radar device, comprising the low cross-polarization double-ridge waveguide slot array antenna as described above.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention discloses a miniaturized, low-profile and low cross-polarization double-ridged waveguide slot array antenna, the antenna bandwidth covers 76-81GHz, has stable high gain characteristics within the bandwidth, and has narrow beam, low side lobe, and low cross-polarization directional pattern characteristics.

[0023] 2. The product can be produced by machining or injection molding, with low cost and small size.

[0024] 3. The present invention uses a double-ridged waveguide feeding structure, which has a small feeding size and has significant advantages in the multi-receive and multi-transmit antenna layout in millimeter-wave radar.

[0025] 4. The double-ridged waveguide slot array antenna of the present invention has extremely low cross-polarization performance, providing higher resolution for vehicle-mounted millimeter-wave radar detection and target identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the double-ridged waveguide slot array antenna of the present invention;

[0027] Figure 2 It is a schematic diagram of the double-ridged waveguide feeding structure of the double-ridged waveguide slot array antenna of the present invention;

[0028] Figure 3 It is a schematic diagram of the waveguide slot structure and the switching structure of the double-ridged waveguide slot array antenna of the present invention;

[0029] Figure 4Schematic diagram of a waveguide slot structure unit of a double-ridge slot array antenna of the present invention;

[0030] Figure 5 It is a schematic diagram of multi-layer processing of the double-ridged waveguide slot array antenna of the present invention;

[0031] Figure 6 is an impedance curve diagram of the double-ridged waveguide slot array antenna of the present invention;

[0032] Figure 7 is a gain curve diagram of the double-ridged waveguide slot array antenna of the present invention;

[0033] Figure 8 Directivity diagrams of the elevation and azimuth planes of the double-ridged waveguide slot array antenna of the present invention at main frequency points;

[0034] Fig. 9 It is a schematic diagram of another double-ridged waveguide slot array antenna of the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical solutions and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a miniaturized, low-profile and low cross-polarization double-ridged waveguide slot array antenna operating at 76 GHz to 81 GHz, including a radiation structure 11, a double-ridged waveguide feeding structure 12 and a switching structure 13. The radiation structure 11, the double-ridged waveguide feeding structure 12 and the switching structure 13 are connected to form the low cross-polarization double-ridged waveguide slot array antenna.

[0038] like Figure 2 As shown, the double-ridged waveguide feeding structure 12 includes a feeding double-ridged waveguide 21 , a double-ridged waveguide power divider 22 and a symmetrically distributed radiating serpentine double-ridged waveguide 23 .

[0039] The main parameters of the feeding double-ridge waveguide 21 include the width w_wg0 of the double-ridge waveguide and the width w_r i dge0 of the air outside the double ridges in the ridge waveguide. In the present embodiment, they are 1 mm and 0.5 mm respectively. The 0.5 mm width here fully considers the machining accuracy and machining limit of the CNC machining and injection molding processes; the double-ridge waveguide power divider 22 connects the feeding double-ridge waveguide 21 and the radiating serpentine double-ridge waveguide 23. The main parameters thereof include the width w_r i dge1 and the length l_r idge1 outside the ridge. In the present embodiment, they are 0.6 mm and 0.7 mm respectively; the radiating serpentine double-ridge waveguide 23 realizes the swing of the air part in the ridge waveguide by controlling the offset of the double ridges on both sides of the waveguide. The main parameters thereof include the width w_wg1 of the double-ridge waveguide, the width w_r i dge2 of the air outside the ridge in the double-ridge waveguide, and the offsets d0, d1, d2 and d3 of the swing of the double ridges in each section. In the present embodiment, w_wg1 and w_r i The offset of the double-ridge waveguide is related to the coupling energy of the gap. Combined with array synthesis and simulation optimization, in this embodiment, the swing of each ridge is 0.3mm, 0.4mm, 0.3mm, and 0.3mm. For the convenience of processing, the waveguide height h_wg and double ridge height h_r idge of each double-ridge waveguide section in this embodiment are unified, which are 1.8mm and 0.8mm respectively.

[0040] like Figure 3 As shown, the slot structure of the radiation structure 11 realizes radiation by cutting the electric field of the radiating serpentine double-ridge waveguide, which is similar to the radiation principle of the narrow-side slot of the rectangular waveguide. The radiation of the narrow-side slot of the double-ridge waveguide mainly depends on the slot length, slot width, and slot cutting depth. In this embodiment, since the double-ridge waveguide offset scheme is adopted instead of the inclined radiation slot, the slot radiation is also related to the offset of the double-ridge swing. In this embodiment, the width of the slot takes into account the processing technology requirements, and the slot length and the slot cutting depth take into account the half-wavelength resonance of the slot, processing and simulation optimization; the slot length L_s lot, the slot width w_s l ot, the slot cutting depth deep_cut, and the slot spacing period p_s l ot are 2.5mm, 0.5mm, 0.5mm, and 2.2mm respectively. The period of the slot is about 0.6 wavelengths. By controlling the offset of the ridge swing corresponding to each slot, the side lobe is suppressed to achieve low side lobes.

[0041] like Figure 3As shown, the switching structure 13 connects the feeding double-ridge waveguide to the test interface or the chip transmitter interface. The test interface is a standard WR10 waveguide interface with a size of 1.27mm×2.54mm. In order to achieve the matching between the waveguide interface and the feeding double-ridge waveguide, a matching structure is added, including a double-ridge waveguide and a matching block; the air width Rd i ge_wr10 of the double-ridge waveguide is 0.77mm, and the length and depth of the matching block are 0.5mm and 0.5mm respectively.

[0042] The chip transmitter interface is a chip vertical package transmitter interface.

[0043] like Figure 4 The radiation unit structure of the double-ridge waveguide slot array antenna includes a radiation serpentine double-ridge waveguide and a narrow side slot. The unit structure can analyze the state of resonance of the corresponding slot length and slot cutting depth under different double-ridge swing offsets.

[0044] like Figure 5 (a) and Figure 5 As shown in (b), the double-ridge waveguide slot array antenna can be divided into three layers according to the radiation layer, the feeding layer, and the switching layer, which are processed separately and then assembled. The processing technology can be mechanical processing and injection molding. Injection molding has cost advantages in mass production.

[0045] The simulation results of the double-ridged waveguide slot array antenna of this embodiment can be found in Figure 6-Figure 8 .

[0046] Figure 6 This is a return loss graph, the horizontal axis represents frequency, and the vertical axis represents return loss. It can be seen from the figure that in the range of 76GHz-81GHz, the return loss |S11| is better than 10dB, which has an excellent matching effect.

[0047] Figure 7 The gain curve within the frequency band shows that the antenna gain is higher than 16dBi in the range of 76GHz-81GHz, which shows a stable high gain characteristic.

[0048] Figure 8 (a) (b) (c) are the H-plane and E-plane radiation patterns of the main frequency points in the frequency band, and (a) (b) (c) are the azimuth and elevation radiation patterns of the three main frequency points of 76 GHz, 78.5 GHz and 81 GHz respectively. It can be seen from the figure that the sidelobe level of the elevation plane radiation pattern of each frequency point is lower than -15dB, achieving a good sidelobe suppression effect. At the same time, it can be seen that the cross-polarization is lower than -50dB, which has very excellent low cross-polarization performance.

[0049] It can be seen from the simulation results that the double-ridged waveguide slot array antenna in this example has significant advantages such as wide bandwidth, low side lobe, high gain, and extremely low cross-polarization.

[0050] Example 2

[0051] like Fig. 9 As shown, the difference between this example and Example 1 is that the array form of the first example is more inclined to a standing wave array, while the array of this example is more inclined to a traveling wave array. After optimization, the array spacing and the offset of the double-ridge swing can achieve a wider bandwidth and low side lobe, and low cross-polarization radiation pattern performance. At the same time, the traveling wave array has a simpler structure and design optimization procedure than the standing wave array.

[0052] Example 3

[0053] This embodiment includes a millimeter wave radar device, including the double-ridged waveguide array antenna as in the first embodiment and the second embodiment.

[0054] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A double-ridged waveguide slot array antenna, characterized in that: Including radiation structure, double-ridge waveguide feeding structure and switching structure; The radiation structure is composed of a plurality of slot structures symmetrically arranged in a collinear manner, and is used to radiate electromagnetic waves having indicators such as a specific beam width and side lobe level; The double-ridged waveguide feeding structure comprises a feeding double-ridged waveguide, a double-ridged waveguide power divider and a radiating serpentine double-ridged waveguide, wherein the feeding double-ridged waveguide is connected to the double-ridged waveguide power divider; The double-ridge waveguide power divider distributes the signal to each radiating serpentine double-ridge waveguide at a specific power division ratio and phase difference; a radiation slot is provided on the radiating serpentine double-ridge waveguide; The switching structure is used to switch the double-ridge waveguide to the rectangular waveguide and the transmission line, and the transmission line is connected to the test interface or the chip.

2. A double-ridged waveguide slot array antenna according to claim 1, characterized in that: The slot structure is similar to the narrow side slot of a waveguide, and the parameters of the slot structure include slot length, slot width and slot cutting depth.

3. A double-ridged waveguide slot array antenna according to claim 1, characterized in that: The parameters of the feeding double-ridge waveguide include the double-ridge waveguide height, the double-ridge waveguide width, the ridge width and the ridge height of the double-ridge waveguide.

4. A double-ridged waveguide slot array antenna according to claim 1, characterized in that: The double-ridged waveguide power divider structure includes a matching double-ridged waveguide, the ridge width of the matching double-ridged waveguide is different from that of the feeding double-ridged waveguide; the waveguide width and ridge width of the radiating serpentine double-ridged waveguide are different from those of the feeding double-ridged waveguide; and all waveguide heights and ridge heights of the double-ridged waveguide feeding structure are the same.

5. A double-ridged waveguide slot array antenna according to claim 1, characterized in that: The number of the slot structures is an even number.

6. A double-ridged waveguide slot array antenna according to claim 1, characterized in that: The test interface is a standard WR10 waveguide interface, and the chip transmitter interface is a chip vertical package transmitter interface.

7. A double-ridged waveguide slot array antenna according to claim 1, characterized in that: The double-ridged waveguide slot array antenna is divided into three layers according to a radiation layer, a feeding layer, and a switching layer, which are processed separately and then assembled.

8. A vehicle-mounted millimeter wave radar device, characterized in that: A double-ridged waveguide slot array antenna with low cross-polarization comprising the antenna described in any one of claims 1 to 7.

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