A novel 3D millimeter wave vehicle-mounted radar 45° polarization antenna

Abstract

The application discloses a novel 45-degree polarization antenna of a 3D millimeter wave vehicle radar, which comprises a radiation layer, a resonant cavity layer and a feeding layer which are sequentially attached; the radiation layer comprises four radiation units and a metal bottom plate, the four radiation units are arranged on the metal bottom plate, each of the radiation units is provided with a rectangular inclined groove, and the rectangular inclined groove penetrates through the metal bottom plate; the resonant cavity layer is internally hollowed to form a rectangular hollow structure, and the radiation layer and the feeding layer are the upper surface and the lower surface of the rectangular hollow structure, so that a rectangular resonant cavity is formed in the resonant cavity; and the feeding layer is provided with a rectangular waveguide which penetrates through the feeding layer in the up-down direction. The application realizes the 45-degree polarization antenna of the full-metal structure, and the bandwidth covers the golden frequency band 76-81GHz of the millimeter wave vehicle radar.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, and in particular to a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna. Background Technology

[0002] Vehicle-mounted imaging millimeter-wave radar achieves its detection function by emitting electromagnetic waves and receiving the reflected waves after they pass through a target object. Currently, the two most commonly used millimeter-wave radar antenna structures are horizontally polarized and vertically polarized antenna structures. Horizontal and vertical polarization each have their advantages and disadvantages for object detection. For example, in radar, horizontally polarized signals are more suitable for detecting aerial targets, while vertically polarized signals are more suitable for detecting ground targets. 45° polarization can be considered as the vector sum of horizontal and vertical polarization, combining the performance of both, and can be used to detect areas with both ground and aerial targets. This makes it suitable for detection in a wider range of scenarios.

[0003] In addition, the all-metal waveguide antenna has lower loss compared to traditional mainstream microstrip antennas, allowing for lower costs in mass production. Furthermore, the stacked design significantly reduces the radar's area. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a novel 3D millimeter-wave vehicle radar 45° polarized antenna.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna includes a radiating layer, a resonant cavity layer, and a feeding layer that are sequentially bonded together.

[0007] The radiation layer includes four radiation units and a metal base plate. The four radiation units are disposed on the metal base plate, and each radiation unit has a rectangular inclined groove that penetrates the metal base plate.

[0008] The resonant cavity layer is hollowed out to form a rectangular hollow structure. The radiation layer and the feed layer are the upper and lower surfaces of the rectangular hollow structure, thereby forming a rectangular resonant cavity inside the resonant cavity.

[0009] The feed layer has a rectangular waveguide that runs vertically through the feed layer.

[0010] Furthermore, metal bumps are provided on the side of the rectangular resonant cavity to ensure that the electric fields on each rectangular inclined slot are in phase.

[0011] Furthermore, two stepped waveguide ridges are provided on the upper surface of the feed layer to improve the resonant frequency and antenna impedance matching within the rectangular resonant cavity.

[0012] Furthermore, the rectangular slant slots and the radiating elements are arranged collinearly, and the long sides of the rectangular slant slots and the radiating elements are inclined at a 45° angle to the array direction to generate 45° polarization.

[0013] Furthermore, the spacing between adjacent radiating elements is between half a waveguide wavelength and one waveguide wavelength.

[0014] Furthermore, the four radiating units have similar and independent structures with certain gaps, which helps to reduce the cross-polarization ratio.

[0015] Furthermore, the height of each of the four radiating elements is one-quarter of the working wavelength, meaning that the radiating surface is one-quarter of the wavelength away from the floor. This allows the floor-reflected wave to be positively superimposed on the main radiating beam, achieving high gain and beam smoothing.

[0016] Furthermore, the dimensions of the rectangular oblique slot satisfy the fundamental mode transmission conditions, and the length of the long side is half the operating wavelength of the antenna.

[0017] Furthermore, the centers of the radiating layer, the resonant cavity layer, and the feed layer are all located on the normal line of the antenna.

[0018] Furthermore, the rectangular waveguide is located at the center of the feed layer, enabling the antenna beam to be viewed directly.

[0019] Furthermore, the two stepped waveguide ridges are rectangular or cylindrical in shape.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] (1) The present invention discloses a novel 3D millimeter-wave vehicle radar 45° polarization antenna that can radiate a 45° polarization wave in the 77GHz frequency band and has a bandwidth covering 76-81GHz, which is used for millimeter-wave vehicle radar.

[0022] (2) The novel 3D millimeter-wave vehicle radar 45° polarized antenna disclosed in this invention uses a waveguide transmission line for center feeding at the bottom, which avoids the adverse effects of the feeding structure on the antenna radiation performance.

[0023] (3) The novel 3D millimeter-wave vehicle radar 45° polarized antenna disclosed in this invention adopts a multi-layer all-metal structure, which is conducive to the antenna obtaining broadband and excellent radiation performance; and facilitates mass production to reduce costs.

[0024] (4) The novel 3D millimeter-wave vehicle radar 45° polarized antenna disclosed in this invention has a simple structure. Although the antenna adopts a multi-layer structure, it can be integrated into one processing by combining the radiation layer and the resonant cavity layer, thereby reducing processing steps and processing costs.

[0025] (5) The present invention discloses a novel 3D millimeter-wave vehicle radar 45° polarization antenna that realizes 45° polarization wave and integrates the detection capabilities of vertical polarization and horizontal polarization antennas.

[0026] (6) The present invention discloses a novel 3D millimeter-wave vehicle radar 45° polarized antenna with a concave-convex resonant cavity that allows the slanted slots to be arranged collinearly and has low sidelobes.

[0027] (7) The novel 3D millimeter-wave vehicle radar 45° polarized antenna disclosed in this invention takes into account the processing tolerance and reduces the risk of mass production of antennas.

[0028] (8) The novel 3D millimeter-wave vehicle radar 45° polarized antenna disclosed in this invention takes into account the influence of the coplanarity of the radiating surface and the ground plane of the traditional all-metal waveguide antenna. Therefore, the radiating element is designed as an independent structure on the metal plate, and the distance between the radiating surface and the ground plane is set to one-quarter of the working wavelength to ensure that the main beam of the antenna can be stable without depression.

[0029] (9) The present invention discloses a novel 3D millimeter-wave vehicle radar 45° polarized antenna, which combines a concave-convex resonant cavity and a stepped waveguide ridge, greatly improving the antenna impedance matching. Attached Figure Description

[0030] Figure 1 This is an overall schematic diagram of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention;

[0031] Figure 2 This is a top view of the radiating layer of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention.

[0032] Figure 3 This is a top view of the radiating layer of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention.

[0033] Figure 4 This is a top view of the resonant cavity layer of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention;

[0034] Figure 5 This is a top view of the feed layer of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention;

[0035] Figure 6 This is the simulation result of |S11| of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by this invention;

[0036] Figure 7 This is a simulation result of the 77GHz radiation pattern of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention;

[0037] Figure 8 This is the gain simulation result of a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna structure provided by the present invention.

[0038] The diagram shows:

[0039] 1-Radiating layer, 1C-Metal base plate, 1AA-First radiating unit, 1AB-Second radiating unit, 1AC-Third radiating unit, 1AD-Fourth radiating unit, 1BA-First rectangular skew slot, 1BB-Second rectangular skew slot, 1BC-Third rectangular skew slot, 1BD-Fourth rectangular skew slot, 2-Resonant cavity layer, 2A-Rectangular resonant cavity, 2AA-First metal bump, 2AB-Second metal bump, 2AC-Third metal bump, 2AD-Fourth metal bump, 3-Feed layer, 3A-Rectangular waveguide, 3C-Metal base plate, 3BA-First stepped waveguide ridge, 3BB-Second stepped waveguide ridge. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0041] Example

[0042] like Figures 1-5 As shown, a novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna comprises a radiating layer 1, a resonant cavity layer 2, and a feeding layer 3, which are tightly bonded together in this order from top to bottom.

[0043] The radiating layer 1 includes four radiating units 1AA, 1AB, 1AC, and 1AD, and a metal base plate 1C. The four radiating units are mounted on the metal base plate. Each radiating unit is an independent square all-metal structure with four rectangular inclined slots 1BA, 1BB, 1BC, and 1BD inside. One end of each rectangular inclined slot penetrates the metal base plate 1C to cut the resonant cavity current and generate radiation. The long sides of both the radiating units and the rectangular inclined slots are inclined at a 45° angle to the array direction to generate 45° polarization.

[0044] The rectangular slant slots and radiating elements are all collinearly arranged. Controlling the spacing between adjacent radiating elements can optimize antenna cross-polarization and provide a suitable beamwidth. Preferably, the spacing between adjacent radiating elements is 3.2 mm, which is less than one waveguide wavelength and greater than half a waveguide wavelength (corresponding to the target frequency).

[0045] The height of the first radiating element 1AA, the second radiating element 1AB, the third radiating element 1AC, and the fourth radiating element 1AD is one-quarter of the working wavelength (corresponding to the target frequency), thereby reducing cross-polarization; preferably, the height is 1mm and the width is 1.8mm.

[0046] The antenna uses an independent directional all-metal structure as the radiating element on the radiating layer 1, with slots cut inside it. The height of the radiating element is about one-quarter of the working wavelength (λ = 3.89 mm), which reduces the reflected electromagnetic waves caused by the metal base plate 1C on the radiating layer 1. In addition, there are certain gaps between adjacent radiating elements, which can enhance radiation and effectively reduce the cross-polarization ratio and control the azimuth beamwidth. If there are no requirements for the cross-polarization ratio and beamwidth, the radiating element can be completely replaced by a metal plate with the same length and width as the radiating layer.

[0047] The rectangular skew slots 1BA, 1BB, 1BC, and 1BD of the antenna are of the same size and are arranged collinearly to form an array antenna. These rectangular slots differ from gaps. The dimensions of the rectangular slots satisfy the conditions for the establishment of a waveguide aperture, i.e., the fundamental mode transmission conditions. However, using gaps instead of rectangular skew slots can also allow the antenna to radiate normally. In this invention, rotating the radiating element by 90° can produce -45° polarization, with the same mechanism as 45°.

[0048] The dimensions of the first rectangular slant 1BA, the second rectangular slant 1BB, the third rectangular slant 1BC, and the fourth rectangular slant 1BD meet the fundamental mode transmission conditions, and the length of the long side is approximately half the working wavelength (corresponding to the target frequency), preferably 2.1 mm for the long side and 1 mm for the short side, so as to achieve better radiation performance in the target frequency band.

[0049] The resonant cavity layer is a metal plate of a certain thickness, hollowed out to form a rectangular hollow structure. The bottom surface of the metal base plate 1C of the radiating layer 1 serves as the upper surface, and the upper surface of the metal base plate 3C of the feeding layer 3 serves as the lower surface, thus forming a rectangular resonant cavity 2A inside the resonant cavity. Four metal bumps 2AA, 2AB, 2AC, and 2AD are added to this structure, ensuring that the electric fields on each rectangular slot are in phase and that the rectangular slots and radiating units are collinearly arranged. The preferred dimensions of the rectangular resonant cavity are 11.6 mm on the long side, 3.3 mm on the wide side, and 1 mm in height.

[0050] Furthermore, four metal bumps are located on the two long sides of the rectangular resonant cavity, with two bumps on each long side.

[0051] The feed layer 3 has a rectangular waveguide 3A that runs vertically through it, and first and second stepped waveguide ridges 3BA and 3BB are provided on the upper surface of the feed layer 3 to improve the resonant frequency in the rectangular resonant cavity 2A and improve the antenna impedance matching.

[0052] The rectangular waveguide 3A is located at the center of the feed layer and is sized according to the standard wr12 waveguide size. It is used for waveguide feeding to ensure that the antenna can achieve beam frontal view.

[0053] Furthermore, the first stepped waveguide ridge 3BA and the first stepped waveguide ridge 3BB are rectangular or cylindrical in shape. Controlling the dimensions of the stepped waveguide ridges can change the internal distribution parameters of the rectangular resonant cavity 2A, thereby enabling it to resonate within the target frequency band. Preferably, the height dimensions are 0.4 mm and 0.8 mm, and the width is 1.4 mm.

[0054] Simulation experiments were conducted to verify the provided novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna, and the results were obtained. Figures 6-8 The test results shown are described below:

[0055] Specifically, Figure 6 The simulation results show the reflection coefficient of the 45° polarized antenna of the novel 3D millimeter-wave vehicle radar shown in the figure. Figure 7 The horizontal axis represents frequency, and the vertical axis represents the reflection coefficient |S11|.

[0056] Depend on Figure 7 It can be seen that in the 74.1–84 GHz range, the reflection coefficient |S11| is less than -10 dB, indicating a better matching effect.

[0057] Figure 8 The gain simulation results are for the novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna provided in this embodiment. The antenna's in-band gain ranges from 13.8 dBi to 14.8 dBi in the 74.1–84 GHz frequency band.

[0058] Simulation results show that the novel 3D millimeter-wave vehicle-mounted radar 45° polarized antenna provided by this invention has significant advantages such as wide bandwidth, low sidelobe, and high gain.

[0059] The radiating layer of this invention adopts a group of rectangular slots arranged collinearly, with each rectangular slot at a 45° angle to the longitudinal direction, in order to radiate electromagnetic waves polarized at 45°. The resonant cavity layer adopts a closed metal enclosed structure with concave and convex structures, and has stepped ridges inside, which can effectively improve the resonance in the resonant cavity. For ease of processing, the stepped ridges are set on the upper surface of the feed layer. The feed layer is equipped with a waveguide feed line for single-mode transmission, with a standard WR12 aperture, for feeding the resonant cavity layer.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A novel 3D mmWave vehicular radar 45° polarized antenna, characterized by, The antenna comprises a radiation layer, a resonant cavity layer and a feed layer which are sequentially attached; The radiation layer comprises four radiation units and a metal base plate, the four radiation units are arranged on the metal base plate, each radiation unit is an independent square full-metal structure, each radiation unit is provided with a rectangular inclined slot, the rectangular inclined slot penetrates the metal base plate, the height of each radiation unit is one quarter of the working wavelength, the long side of the rectangular inclined slot and the radiation unit is at an angle of 45° with the array direction for generating 45° polarization, the rectangular inclined slot and the radiation unit are arranged in a line, and the spacing between adjacent radiation units is controlled to optimize the cross-polarization of the antenna; The resonant cavity layer is internally hollowed to form a rectangular hollow structure, and the radiation layer and the feed layer are the upper surface and the lower surface of the rectangular hollow structure, thereby forming a rectangular resonant cavity inside the resonant cavity; The feed layer is provided with a rectangular waveguide which penetrates the feed layer from top to bottom; Metal bumps are arranged on the side surface of the rectangular resonant cavity, so that the electric field on each rectangular inclined slot is in phase; The size of the rectangular inclined slot satisfies the base mode transmission condition, and the long side size is half of the working wavelength of the antenna.

2. The novel 3D mm-wave vehicular radar 45° polarized antenna according to claim 1, characterized in that, The upper surface of the feed layer is provided with two stepped waveguide ridges for improving the resonant frequency in the rectangular resonant cavity and the impedance matching of the antenna.

3. The novel 3D mm-wave vehicular radar 45° polarized antenna according to claim 1, characterized in that, The spacing between adjacent radiation units is between half of the waveguide wavelength and one waveguide wavelength.

4. The novel 3D mm-wave vehicular radar 45° polarized antenna according to claim 1, characterized by, The centers of the radiation layer, the resonant cavity layer and the feed layer are on the normal line of the antenna.

5. The novel 3D mm-wave vehicular radar 45° polarized antenna according to claim 1, characterized by, The rectangular waveguide is located at the center of the feed layer to realize the normal view of the antenna beam.

6. The novel 3D mm-wave vehicular radar 45° polarized antenna according to claim 2, characterized by, The shape of the two stepped waveguide ridges is cuboid or cylindrical.

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