A dual-ridge waveguide slot array antenna and vehicle-mounted millimeter wave radar device

Abstract

The application discloses a double-ridge waveguide slot array antenna, which comprises a radiation structure, a double-ridge waveguide feeding structure and a switching structure; the radiation structure is composed of a plurality of symmetrical and collinear arranged slots and is used for radiating electromagnetic waves with specific beam width and sidelobe level indexes; the double-ridge waveguide feeding structure comprises a feeding double-ridge waveguide, a double-ridge waveguide power divider and a radiation serpentine double-ridge waveguide; the feeding double-ridge waveguide is connected with the switching structure and the power divider; the double-ridge waveguide power divider distributes signals to each radiation serpentine double-ridge waveguide with specific power division ratio and phase difference; and the radiation serpentine double-ridge waveguide is provided with radiation slots above; the switching structure is used for switching the double-ridge waveguide to a rectangular waveguide, a microstrip line and other transmission lines and is finally connected with a test port or a chip; and the antenna has the characteristics of wide frequency band, high gain, stable radiation pattern and extremely low cross polarization. The application further provides a vehicle-mounted millimeter wave radar device.

Description

Technical Field

[0001] This invention belongs to the field of automotive radar antennas, specifically relating to a dual-ridge waveguide slot array antenna and radar equipment. Background Technology

[0002] Millimeter-wave radar plays a crucial role in modern vehicles, especially in autonomous driving and advanced driver assistance systems (ADAS). It operates in the 76 GHz to 81 GHz frequency band, where the electromagnetic wave wavelength is approximately 4 millimeters, providing excellent penetration and resolution, enabling effective detection of objects in the surrounding environment.

[0003] The core advantage of millimeter-wave radar lies in its ability to achieve high-precision object identification and localization. To meet these requirements, radar systems are typically equipped with narrow-beam, low-sidelobe, and high-gain directional antennas. This antenna design not only improves signal directivity but also reduces interference from other directions, thereby enhancing the detection capability of target objects. Furthermore, the wide-bandwidth antenna design further improves the radar's resolution, 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 radar needs to maintain stable performance under various environmental conditions. This means that the radar system must have good anti-interference capabilities and be able to operate effectively in adverse conditions such as rain, fog, and strong light reflection. This places higher demands on antenna design, which must be able to adapt to different electromagnetic environments to ensure reliable signal transmission and reception.

[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. To reduce production costs, the selection of antenna materials and manufacturing processes need continuous optimization to ensure performance while enabling large-scale industrial production. At the same time, the antenna size also needs to be minimized to facilitate integration into vehicles and reduce its impact on the overall vehicle design.

[0006] Automotive millimeter-wave radar is based on a digital beamforming (DBF) system, which consists of several subarrays with medium gain connected to integrated circuits (ICs). Waveguide or gapped waveguide antennas are promising options for this application due to their low loss and wideband impedance matching in long feed networks. Nevertheless, low-cost fabrication of waveguides at high frequencies remains challenging. There are many excellent examples in milling, micromachining, or 3D printing, but these techniques are not suitable for mass production. A promising alternative is to combine plastic injection molding and electroplating, achieving low weight and high efficiency.

[0007] Currently, there are some solutions based on waveguide cavity antennas and solutions based on wide-side slots or ridge waveguides, but they all suffer from problems such as excessively high antenna element profiles, relatively large antenna sizes, and wide feed waveguides. These are not conducive to the multi-antenna layout and assembly of millimeter-wave radars.

[0008] Narrow-walled slot waveguide arrays can minimize the spacing between digital beamforming (DBF) antenna elements, achieving a minimum spacing close to 0.5 wavelengths. Typically, narrow-walled slots are tilted to generate radiation, and the energy of the slot-coupled radiation is controlled by adjusting the tilt angle. However, these tilted slots introduce unwanted cross-polarization, significantly reducing the efficiency of linear arrays and the accuracy of target detection. Researchers have proposed placing small electrical bumps on both sides of the non-tilted slots to alter the current path, thereby achieving tilted slots and low cross-polarization. Unfortunately, this approach is not feasible in the 77 GHz band due to its small size and lack of fabrication capability. Summary of the Invention

[0009] The main technical problem to be solved by the present invention is to address the shortcomings of existing vehicle-mounted millimeter-wave radar antennas, such as high profile, large size, and high cross-polarization of narrow-side waveguide slot array antennas. The invention provides a miniaturized, low-profile, and low-cross-polarization dual-ridge waveguide slot array antenna and millimeter-wave radar device.

[0010] To address the aforementioned technical problems, the present invention provides a dual-ridge waveguide slot array antenna, comprising: a radiating structure, a dual-ridge waveguide feeding structure, and a transition structure;

[0011] The radiation structure is composed of multiple symmetrically collinear slot structures, used to radiate electromagnetic waves with specific beamwidth and sidelobe level indicators;

[0012] The dual-ridge waveguide feeding structure includes a feeding dual-ridge waveguide, a dual-ridge waveguide power divider, and a radiating serpentine dual-ridge waveguide. The feeding dual-ridge waveguide is connected to the dual-ridge waveguide power divider. The dual-ridge waveguide power divider distributes the signal to each radiating serpentine dual-ridge waveguide with a specific power ratio and phase difference. Radiation slots are opened on the radiating serpentine dual-ridge waveguide.

[0013] The adapter structure is used to connect the double-ridged waveguide to a rectangular waveguide and a transmission line, which is connected to a test interface or chip.

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

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

[0016] In a preferred embodiment, the dual-ridge waveguide power divider structure includes a matched dual-ridge waveguide, the ridge width of which differs from that of the feeding dual-ridge waveguide; the waveguide width and ridge width of the radial serpentine dual-ridge waveguide differ from those of the feeding dual-ridge waveguide; and all waveguide heights and ridge heights are the same in the dual-ridge waveguide feeding structure.

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

[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 dual-ridge waveguide slot array antenna is divided into three layers: a radiating layer, a feeding layer, and a transition layer, which are then processed and assembled separately.

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

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

[0022] 1. This invention discloses a miniaturized, low-profile, and low-cross-polarization dual-ridge waveguide slot array antenna with a bandwidth covering 76-81 GHz. Within the bandwidth, it has stable high-gain characteristics and features a narrow beam, low sidelobes, and low cross-polarization pattern.

[0023] 2. This product can be manufactured using machining or injection molding processes, resulting in low cost and small size.

[0024] 3. By using a double-ridge waveguide feeding structure, the present invention has a small feeding size, which has a significant advantage in the multi-receiver and multi-transmitter antenna layout in millimeter-wave radar.

[0025] 4. The dual-ridge 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. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the dual-ridge waveguide slot array antenna structure of the present invention;

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

[0028] Figure 3 This is a schematic diagram of the waveguide slot structure and transition structure of the dual-ridge waveguide slot array antenna of the present invention.

[0029] Figure 4This is a schematic diagram of the waveguide slot structure unit of the dual-ridge slot array antenna of the present invention;

[0030] Figure 5 This is a schematic diagram of the multilayer fabrication of the double-ridge waveguide slot array antenna of the present invention; wherein Figure 5 (a) refers to machining. Figure 5 (b) Injection molding;

[0031] Figure 6 This is the impedance curve of the dual-ridge waveguide slot array antenna of the present invention.

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

[0033] Figure 8 These are the elevation and azimuth radiation patterns of the main frequency points of the dual-ridge waveguide slot array antenna of this invention;

[0034] Figure 9 This is a schematic diagram of another dual-ridge waveguide slot array antenna of the present invention. Detailed Implementation

[0035] To make the technical solution and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

[0036] Example 1

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

[0038] like Figure 2 As shown, the dual-ridge waveguide feeding structure 12 includes a feeding dual-ridge waveguide 21, a dual-ridge waveguide power divider 22, and symmetrically distributed radial serpentine dual-ridge waveguides 23.

[0039] The main parameters of the fed double-ridge waveguide 21 include the width w_wg0 of the double-ridge waveguide and the width w_ridge0 of the air outside the double ridges in the ridge waveguide. In this embodiment, they are 1 mm and 0.5 mm, respectively. The 0.5 mm width here fully considers the machining accuracy and processing limits of CNC machining and injection molding processes. The double-ridge waveguide power divider 22 connects the fed double-ridge waveguide 21 and the radial serpentine double-ridge waveguide 23. Its main parameters include the width w_ridge1 outside the ridges and the length l_ridge1. In this embodiment, they are 0.6 mm and 0.7 mm, respectively. The radial serpentine double-ridge waveguide 23... The ridge waveguide 23 achieves the oscillation of the air portion within the ridge waveguide by controlling the offset of the double ridges on both sides of the waveguide. Its main parameters include the width w_wg1 of the double-ridge waveguide, the width w_ridge2 of the air portion outside the ridges in the double-ridge waveguide, and the offsets d0, d1, d2, and d3 of each ridge segment. In this embodiment, w_wg1 and w_ridge2 are 1.5 mm and 0.6 mm, respectively. The offset of the double-ridge waveguide is related to the coupling energy of the slot. Based on array synthesis and simulation optimization, in this embodiment, the oscillation amounts of each ridge segment are 0.3 mm, 0.4 mm, 0.3 mm, and 0.3 mm, respectively. For ease of fabrication, in this embodiment, the waveguide height h_wg and the double ridge height h_ridge of each double-ridge waveguide segment are uniform, at 1.8 mm and 0.8 mm, respectively.

[0040] like Figure 3 As shown, the slit structure of the radiating structure 11 achieves radiation by cutting the electric field of the radiating serpentine double-ridge waveguide, similar to the radiation principle of a narrow-side slit in a rectangular waveguide. The radiation of the narrow-side slit in the double-ridge waveguide mainly depends on the slit length, slit width, and slit depth. In this embodiment, since a double-ridge waveguide offset scheme is used instead of an inclined radiating slit, the slit radiation is also related to the offset of the double-ridge swing. In this embodiment, the slit width takes into account the manufacturing process requirements, and the slit length and slit depth take into account the half-wavelength resonance of the slit, manufacturing, and simulation optimization. The slit length L_slot, slit width w_slot, slit depth deep_cut, and slit spacing period p_slot are 2.5mm, 0.5mm, 0.5mm, and 2.2mm, respectively. The slit period is around 0.6 wavelengths. By controlling the offset of the ridge swing corresponding to each slit, sidelobes are suppressed, achieving low sidelobes.

[0041] like Figure 3As shown, the adapter structure 13 connects the fed double-ridged waveguide to the test interface or the chip transmitter interface. The test interface is a standard WR10 waveguide interface with dimensions of 1.27mm × 2.54mm. To achieve matching between the waveguide interface and the fed double-ridged waveguide, a matching structure is added, including the double-ridged waveguide and a matching block; the air width Rdige_wr10 of the double-ridged 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 vertically packaged chip transmitter interface.

[0043] like Figure 4 The radiating element structure of the dual-ridge waveguide slot array antenna includes a radiating serpentine dual-ridge waveguide and narrow-side slots. This element structure allows for analysis of the resonant state achieved by the slot length and slot depth under different dual-ridge oscillation offsets.

[0044] like Figure 5 (a) and Figure 5 As shown in (b), the dual-ridge waveguide slot array antenna can be divided into three layers: a radiating layer, a feeding layer, and a transition layer, which are processed separately and then assembled. The processing technology can employ machining and injection molding; injection molding offers a cost advantage for mass production.

[0045] Please refer to the simulation results of the dual-ridge waveguide slot array antenna in this embodiment. Figures 6-8 .

[0046] Figure 6 The graph shows the return loss, with the horizontal axis representing frequency and the vertical axis representing return loss. As can be seen from the graph, the return loss |S11| is better than 10dB in the 76GHz-81GHz range, indicating excellent matching performance.

[0047] Figure 7 The gain curves within the frequency band show that the antenna gain is higher than 16dBi in the 76GHz-81GHz range, exhibiting stable high-gain characteristics.

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

[0049] The simulation results show that the dual-ridge waveguide slot array antenna in this example has significant advantages such as wide bandwidth, low sidelobes, high gain, and extremely low cross-polarization.

[0050] Example 2

[0051] like Figure 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 lower sidelobes and lower cross-polarization pattern performance. At the same time, compared with the standing wave array, the traveling wave array has a simpler structure and design optimization procedure.

[0052] Example 3

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

[0054] The above is only one specific embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be deemed as infringing the protection scope of the present invention.

Claims

1. A double-ridged waveguide slot array antenna, characterized in that: This includes radiating structures, double-ridge waveguide feeding structures, and transition structures; The radiation structure is composed of multiple symmetrically collinearly arranged slot structures, used to radiate electromagnetic waves with indicators of beamwidth and sidelobe level. The dual-ridge waveguide feeding structure includes a fed dual-ridge waveguide, a dual-ridge waveguide power divider, and a radial serpentine dual-ridge waveguide, wherein the fed dual-ridge waveguide is connected to the dual-ridge waveguide power divider. The double-ridged waveguide power divider distributes the signal to each radiating serpentine double-ridged waveguide with a specific power ratio and phase difference; the radiating serpentine double-ridged waveguide has radiating slots. The adapter structure is used to connect the fed double-ridge waveguide to a rectangular waveguide and a transmission line, which is connected to a test interface or chip. The slot structure is a narrow-side slot of the waveguide, and the parameters of the slot structure include slot length, slot width, and slot depth. The parameters of the fed double-ridge waveguide include double-ridge waveguide height, double-ridge waveguide width, ridge width, and ridge height. The double-ridge waveguide power divider structure includes a matching double-ridge waveguide, the ridge width of which is different from that of the fed double-ridge waveguide. The waveguide width and ridge width of the radial serpentine double-ridge waveguide are different from those of the fed double-ridge waveguide. All waveguide heights and ridge heights are the same in the double-ridge waveguide feeding structure.

2. The dual-ridge waveguide slot array antenna according to claim 1, characterized in that, The number of the slit structures is even.

3. The dual-ridge 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.

4. The dual-ridge waveguide slot array antenna according to claim 1, characterized in that, The dual-ridge waveguide slot array antenna is divided into three layers: a radiating layer, a feeding layer, and a transition layer. These layers are processed separately and then assembled.

5. A vehicle-mounted millimeter-wave radar device, characterized in that, Including the dual-ridge waveguide slot array antenna as described in any one of claims 1-4.

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