CN117353000B - Novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna - Google Patents

Abstract

The present invention discloses a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna, which is manufactured by CNC all-metal processing technology, and the antenna includes an antenna layer and a feeding layer. The antenna layer includes a radiation layer, a coupling layer and a resonant cavity layer, and can actually be processed into one layer. The radiation unit on the radiation layer is used to change the phase of the electric field under different polarizations, and the coupling layer is provided with longitudinally centrally arranged oblique grooves, which can produce 45° linear polarization. The resonant cavity layer is provided with a rectangular resonant cavity and a metal bump; the feeding layer is provided with a standard rectangular waveguide WR12, which is used to feed the resonant cavity layer. The present invention uses a multi-layer metallized structure antenna to achieve circular polarization and highly symmetrical and smooth radiation patterns.

Description

A new type of circularly polarized antenna for 3D millimeter-wave vehicle-mounted radar

Technical Field

The present invention relates to the technical field of vehicle-mounted antennas, and in particular to a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna.

Background technique

At present, millimeter-wave vehicle-mounted radar antennas basically transmit horizontally polarized and vertically polarized signals. In real life, poor antennas and some obstacles often affect the propagation characteristics of radio electromagnetic waves, thereby reducing the reliability and effectiveness of information transmission. Circular polarization can solve these problems. Circularly polarized antennas can receive linearly polarized waves in any direction, and the circularly polarized waves they generate can also be received by any linearly polarized antenna. In addition, according to the characteristics of the propagation direction of the electric field, the rotation direction of circular polarization is divided into left and right, which can reduce the selective weakening of signals caused by multipath effects. When the linearly polarized wave reaches a certain height, the Faraday effect will cause signal loss, but for circularly polarized antennas, the impact is very small.

Summary of the invention

The purpose of the present invention is to solve the above-mentioned defects in the prior art and provide a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna.

The purpose of the present invention can be achieved by adopting the following technical solutions:

A novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna, the polarized antenna comprising an antenna layer located at the top and a feeding layer 4 located at the bottom, wherein the antenna layer comprises a radiation layer 1, a coupling layer 2, and a resonant cavity layer 3 arranged in sequence from top to bottom, the feeding layer 4 is used to feed the resonant cavity layer 3, the resonant cavity layer 3 couples and feeds the radiation layer 1 through the coupling layer 2, and finally the radiation layer radiates into space and forms a fan-shaped beam;

The radiation layer 1 is provided with a radiation unit 1A with a hollow structure and an opening upward;

The coupling layer 2 is provided with four hollow structures, which are longitudinally arranged and centrally symmetrically arranged at an angle of 45°, namely, a first slant 2AA, a second slant 2AB, a third slant 2AC and a fourth slant 2AD. The first slant 2AA and the second slant 2AB are respectively symmetrical with the third slant 2AC and the fourth slant 2AD about the center of the coupling layer; the upper surface of the coupling layer 2 is seamlessly bonded to the lower surface of the radiation layer 1;

The resonant cavity layer 3 is provided with a rectangular resonant cavity 3A with a hollow structure, and the two long sides of the rectangular resonant cavity 3A are respectively provided with a first metal bump 3AA, a third metal bump 3AC, a second metal bump 3AB, and a fourth metal bump 3AD; the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC, and the fourth metal bump 3AD are staggered and symmetrical about the center of the resonant cavity 3A; the upper surface of the resonant cavity layer 3 and the lower surface of the coupling layer 2 are seamlessly bonded;

The feeding layer 4 is provided with an L-shaped rectangular waveguide 4A with a hollow structure, which is located at the center of the feeding layer. The L-shaped rectangular waveguide 4A includes a first waveguide port 4AA, a second waveguide port 4AB, and a matching block 4AC is provided at a right angle. The upper surface of the feeding layer 4 and the lower surface of the resonant cavity 3A are seamlessly bonded, wherein the first waveguide port 4AA is used as a feeding input port and is arranged on the side of the feeding layer 4, and feeds the resonant cavity 3A through the second waveguide port 4AB which is used as a feeding output port. The second waveguide port 4AB is arranged on the upper surface of the feeding layer 4 and is located directly below the center of the resonant cavity 3A.

Furthermore, the first oblique slot 2AA, the second oblique slot 2AB, the third oblique slot 2AC and the fourth oblique slot 2AD are located below the radiation unit 1A and above the rectangular resonant cavity 3A, and the oblique slots cut the current of the rectangular resonant cavity 3A and couple to the radiation unit 1A in phase.

Furthermore, the shapes of the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC and the fourth metal bump 3AD are rectangular, triangular, elliptical or irregular, which changes the position of the electric field standing wave point in the rectangular resonant cavity 3A, so that the four oblique grooves can be arranged in a colinear manner.

Furthermore, the distance between every two adjacent oblique grooves in the four oblique grooves ranges from λg/2 to λg, so as to avoid the appearance of grating lobes in the antenna radiation pattern; the distance between the first metal bump 3AA and the third metal bump 3AC, and the distance between the second metal bump 3AB and the fourth metal bump 3AD ranges from λg/2 to λg, where λg is the waveguide wavelength of the rectangular resonant cavity 3A at the target frequency, and all hollow structures of the antenna are centrally symmetrical with the same center point to ensure that the main beam of the antenna is facing forward.

Furthermore, the shape of the radiation unit 1A is rectangular, trapezoidal, triangular or rhombus. When electric fields of different polarizations pass through the radiation unit 1A, the phase velocities are different. Therefore, by changing the height of the radiation unit 1A, the phase difference between the vertical electric field vector and the horizontal electric field vector is adjusted.

Furthermore, the L-shaped rectangular waveguide 4A is provided with a stepped matching block 4AC at the right angle, and the impedance of the L-shaped rectangular waveguide changes suddenly at the right angle, so the matching block is used to change the impedance value of the L-shaped rectangular waveguide at the right angle, thereby adjusting the reflection coefficient of the L-shaped rectangular waveguide 4A.

Furthermore, the first oblique slot 2AA, the second oblique slot 2AB, the third oblique slot 2AC and the fourth oblique slot 2AD are rectangular or L-shaped in shape, cutting the current of the rectangular resonant cavity 3A to achieve a 45° polarized electric field.

Furthermore, the radiation layer 1, the coupling layer 2 and the resonant cavity layer 3 in the antenna layer are processed and formed as a layer, and the cross-sectional thickness of the antenna layer is [2.2mm, 3mm], which can reduce the number of steps, reduce costs, and improve the antenna processing yield.

Compared with the prior art, the present invention has the following advantages and effects:

1. A novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna disclosed in the present invention can radiate a right-hand circularly polarized wave in the 77GHz frequency band, and the bandwidth covers 76-81GHz, which is used for millimeter-wave vehicle-mounted radar.

2. A novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna disclosed in the present invention uses a waveguide transmission line at the bottom for central feeding, thereby avoiding the adverse effects of the feeding structure on the antenna radiation performance.

3. A new type of 3D millimeter-wave vehicle-mounted radar circularly polarized antenna disclosed in the present invention adopts a multi-layer all-metal structure, which is conducive to the antenna obtaining broadband and excellent radiation performance; it is conducive to controlling the excitation current of the radiation unit, better satisfying the Chebyshev distribution, and achieving low side lobes.

4. The novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna disclosed in the present invention has a simple structure. Although the antenna adopts a multi-layer structure, it can be integrated into one by integrating the radiation layer, coupling layer and feeding layer, thereby reducing the processing procedures and processing costs.

5. The novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna disclosed in the present invention realizes circularly polarized waves, has strong anti-interference capability, and makes radar detection more accurate in harsh environments.

6. The present invention discloses a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna, wherein the concave-convex structure of the resonant cavity enables the oblique slots to be arranged in a colinear manner.

7. The present invention discloses a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna, which generates a 45° polarized electric field through an oblique slot and designs a radiation unit with different phase velocities for the vertically polarized electric field and the horizontally polarized electric field, thereby realizing circularly polarized waves; by rotating the oblique slot 90°, circularly polarized waves with opposite hand direction can be realized accordingly.

8. The novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna disclosed in the present invention takes processing tolerance into consideration and reduces the risk of antenna mass production.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

FIG1 is a schematic diagram of the overall structure of a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna in Example 2 of the present invention;

2 is a schematic diagram of the overall structure of a novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna in Example 3 of the present invention;

FIG3 is a top view of the radiation layer 1 of the novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna in Example 2 of the present invention;

FIG4 is a top view of the radiation layer 1 of the novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna in Example 3 of the present invention;

FIG5 is a top view of the coupling layer 2 of the novel 3D millimeter wave radar circularly polarized antenna in Example 2 of the present invention;

FIG6 is a top view of the coupling layer 2 of the novel 3D millimeter wave radar circularly polarized antenna in Example 3 of the present invention;

FIG7 is a top view of the resonant cavity layer 3 of the novel 3D millimeter wave radar circularly polarized antenna of the present invention;

FIG8 is an oblique view of the feed layer 4 of the novel 3D millimeter wave radar circularly polarized antenna of the present invention;

9 is a side view of an L-shaped rectangular waveguide 4A having a hollow structure of a feeding layer of a novel 3D millimeter wave radar circularly polarized antenna according to the present invention;

10 is a simulation curve diagram of |S11| of the novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna in Example 2 of the present invention;

11 is a curve diagram of the axial ratio bandwidth simulation of the novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna in Example 2 of the present invention;

12 is a 78.5GHz directional pattern simulation curve diagram of the novel 3D millimeter-wave vehicle-mounted radar circularly polarized antenna in Example 2 of the present invention;

13 is a simulation curve diagram of |S11| of the novel 3D millimeter wave radar circularly polarized antenna in Example 3 of the present invention;

14 is a curve diagram of the axial ratio bandwidth simulation of the novel 3D millimeter wave radar circularly polarized antenna in Example 3 of the present invention;

15 is a 77.5 GHz directional pattern simulation curve diagram of the novel 3D millimeter wave radar circularly polarized antenna in Example 3 of the present invention;

Figure numerals: 1-radiation layer, 1A-radiation unit, 2-coupling layer, 2AA-first oblique slot, 2AB-second oblique slot, 2AC-third oblique slot, 2AD-fourth oblique slot, 3-resonance cavity layer, 3A-rectangular resonant cavity, 3AA-first metal bump, 3AB-second metal bump, 3AC-third metal bump, 3AD-fourth metal bump, 4-feeding layer, 4A-L-type rectangular waveguide, 4AA-feeding input end, 4AB-feeding output end, 4AC-matching block.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

This embodiment discloses a wide-band, low-sidelobe all-metal circularly polarized antenna for a 77GHz millimeter-wave vehicle-mounted radar, comprising an upper and lower layer, which are an antenna layer and a feed layer 4. The antenna layer includes a radiation layer 1, a coupling layer 2, and a resonant cavity layer 3 arranged in sequence from top to bottom. The radiation layer 1 is provided with a radiation unit 1A with an opening upward; the coupling layer 2 is provided with 45° inclined grooves arranged longitudinally; the inclined grooves include a first inclined groove 2AA, a second inclined groove 2AB, a third inclined groove 2AC and a fourth inclined groove 2AD, the inclined grooves are located below the radiation unit 1A, seamlessly connected to the bottom of the radiation unit 1A, and the upper surface of the coupling layer 2 is the lower surface of the radiation layer; the resonant cavity layer 3 is provided with a rectangular resonant cavity 3A, a first metal bump 3AA, a second metal bump 3AB, a third metal bump 3AC and a fourth metal bump 3AD; the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC and the fourth metal bump 3AD are symmetrical about the center of the rectangular resonant cavity 3A; the distance range between adjacent inclined grooves is λg/2~λg, and the distance range between adjacent metal bumps is λg/2~λg (λg is the waveguide wavelength of the rectangular resonant cavity 3A at the target frequency).

The feeding layer 4 is provided with an L-shaped rectangular waveguide 4A; wherein the feeding input terminal 4AA is coplanar with the side surface of the feeding layer, the long side of the feeding input terminal 4AA is perpendicular to the upper surface of the feeding layer, and the short side is parallel to the upper surface of the feeding layer; the feeding output terminal 4AB is coplanar with the upper surface of the feeding layer, the waveguide port 4AB of the feeding output port is directly below the center of the rectangular resonant cavity 3A, the long side of the feeding output terminal 4AB is perpendicular to the long side of the rectangular resonant cavity 3A, and the L-shaped rectangular waveguide is provided with a matching block 4AC at a right angle, and the matching block 4AC is a stepped protrusion for reducing the reflection coefficient of the L-shaped rectangular waveguide 4A.

The feeding layer 4 is used to feed the resonant cavity layer 3, and the resonant cavity layer 3 couples and feeds the radiating layer 1 through the coupling layer 2; wherein, the radiating layer 1, the coupling layer 2 and the resonant cavity layer 3 can be processed as one layer, and the cross-section of the antenna layer is only 2.5 mm, which meets the single-layer processing requirements, while reducing the processing cost and reducing the processing error.

The novel 3D millimeter-wave vehicle-mounted radar antenna disclosed in this embodiment uses a resonant cavity layer 3 to achieve the effect of one-to-four unequal power division. The interior of the resonant cavity layer 3 is a rectangular resonant cavity, a first metal bump 3AA, a second metal bump 3AB, a third metal bump 3AC and a fourth metal bump 3AD. Power is fed at the center of the bottom of the resonant cavity layer. By changing the sizes of the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC and the fourth metal bump 3AD, the electric field distribution and power distribution inside the rectangular resonant cavity 3A are achieved; the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC and the fourth metal bump 3AD can all be replaced by triangles, trapezoids or irregular shapes.

The first oblique slot 2AA, the second oblique slot 2AB, the third oblique slot 2AC and the fourth oblique slot 2AD are longitudinally distributed along the center line of the rectangular resonant cavity 3A, and the spacing between adjacent rectangular oblique slots is 0.5λg~λg. According to the current distribution on the upper surface of the rectangular resonant cavity 3A, the position where the current direction is in phase is selected to achieve in-phase excitation; the first oblique slot 2AA, the second oblique slot 2AB, the third oblique slot 2AC and the fourth oblique slot 2AD cut the current on the upper surface of the rectangular resonant cavity 3A at an angle of 45° respectively, and the electric field is perpendicular to the long sides of the first oblique slot 2AA, the second oblique slot 2AB, the third oblique slot 2AC and the fourth oblique slot 2AD, and can be decomposed into a vertical electric field vector and a horizontal electric field vector with equal amplitude and phase. After passing through the radiation layer 1, the vertical electric field vector leads the horizontal electric field vector by 90°, thereby realizing a right-handed circularly polarized wave. The circumference of the first oblique groove 2AA, the second oblique groove 2AB, the third oblique groove 2AC and the fourth oblique groove 2AD is 0.51λ ₀ , and the spacing between two adjacent oblique grooves is 0.82λ _g , where λ ₀ is the operating wavelength in free space at the target frequency (such as 77 GHz corresponds to a working wavelength of 3.9 mm), and λ _g is the waveguide wavelength of the electromagnetic wave in the rectangular resonant cavity 3A.

When the resonant cavity layer 3 of the polarized antenna is excited, by adjusting the sizes of the rectangular resonant cavity 3A, the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC and the fourth metal bump 3AD, the first bevel 2AA, the second bevel 2AB, the third bevel 2AC and the fourth bevel 2AD, the excitation current distribution required by the bevel can better meet the Chebychev distribution, thereby achieving the purpose of low side lobe of the beam.

The present invention uses a multi-layer all-metal structure antenna to achieve circular polarization, and realizes 15dB side lobes in the wide frequency band of 74.19GHz-81.76GHz and the full bandwidth; due to the odd symmetry of the antenna structure and the center feeding method from bottom to top, the radiation pattern under circular polarization is highly symmetrical and smooth; while having excellent performance, the structure is simple, easy to process and has a low profile, and the three layers of the radiation layer, coupling layer and feeding layer are combined into one to achieve integrated processing.

Example 2

Considering the harsh environment in real life, circularly polarized waves are less affected than single linearly polarized waves, and the reliability and effectiveness of information transmission are higher. At the same time, under the premise of ensuring the excellent performance of the antenna, in order to reduce the number of layers of the all-metal structure, reduce the impact of the actual layer gap, reduce the antenna profile, and reduce materials, this embodiment discloses a wide-band, low-sidelobe all-metal circularly polarized antenna for 77GHz millimeter-wave vehicle-mounted radar.

Figure 1 is a schematic diagram of the overall structure of the antenna. The 3D millimeter wave vehicle-mounted radar antenna of the present invention includes a radiation layer 1, a coupling layer 2, a resonant cavity layer 3 and a feeding layer 4. Adjacent layers are seamlessly connected, and the coupling layer 2, the resonant cavity layer 3 and the feeding layer 4 can be processed as one layer to avoid gaps between layers during installation.

FIG. 3 of the present embodiment is a top view of the antenna radiation layer 1, wherein the radiation layer 1 includes a radiation unit 1A with an opening upward, and the radiation unit 1A is a horn-shaped unit with an opening upward. The shape of the radiation unit 1A in FIG. 2 is rectangular, but is not limited to a rectangle, and may also be a trapezoidal, triangular or irregular shape, etc. By changing the height of the radiation unit 1A, the phase difference between the vertical electric field vector and the horizontal electric field vector may be adjusted, and the axial ratio may be changed. A suitable height may be selected according to different situations.

FIG. 5 in this embodiment is a radiation diagram of the coupling layer 2. The coupling layer 2 includes four longitudinally distributed oblique grooves, 2AA-first oblique groove, 2AB-second oblique groove, 2AC-third oblique groove, and 2AD-fourth oblique groove. In this embodiment, the shape of the oblique groove is rectangular, but not limited to a rectangle, and can be of any diameter, but its axis must be 45° with the axis of the rectangular resonant cavity 3A. In order to ensure the beam is viewed positively, the simplest central symmetrical arrangement is selected. It is also possible to achieve beam viewing by changing the arrangement, the position and size of the oblique grooves, and the size of the rectangular resonant cavity 3A; the long sides of the four longitudinally distributed oblique grooves are at an angle of 45° to the central axis of the resonant cavity layer (-45° is also acceptable, and the placement angles of all oblique grooves must be consistent), respectively corresponding to a single cavity inside the resonant cavity layer, as shown in FIG. 4. The width of the four oblique grooves is 1 mm (the recommended processing size is 0.5 mm-1.2 mm. If the width is too small, it is easily affected by the processing accuracy. The simulation can reduce the short side size of the oblique groove at will).

FIG7 is a schematic diagram of the hollow structure inside the resonant cavity layer, where the resonant cavity layer 3 includes a rectangular resonant cavity 3A, a first metal bump 3AA, a second metal bump 3AB, a third metal bump 3AC, and a fourth metal bump 3AD; the total length of the rectangular resonant cavity 3A is 12 mm (for four units, the total length range is 10-15 mm), the width is 3.3 mm (3 mm-4 mm), and the height is 0.5 mm (0.2-1 mm). By adjusting the size of the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC, and the fourth metal bump 3AD, the power and current distribution in the corresponding cavity are changed.

Fig. 8 is an oblique view of the feeding layer, and Fig. 9 is a side view of the L-shaped rectangular waveguide 4A of the hollow structure of the feeding layer. The feeding layer 4A includes a rectangular waveguide input end 4AA, a rectangular waveguide output end 4AB and a matching block 4AC. The matching block 4AC is. The wave port feeding method is adopted. The cross-sectional length of the rectangular waveguide input end 4AA is 2.8mm, and the width is 1mm. The cross-sectional length of the rectangular waveguide output end 4AB is 3.1mm, and the width is 1mm. The single-mode transmission condition of the rectangular waveguide in the 76-81GHz frequency band is met. According to the required impedance matching, the appropriate cross-sectional size can be selected.

The present invention realizes one-to-four power distribution with one feeding layer. When the resonant cavity layer is fed from the bottom center by a rectangular waveguide, the presence of the metal bump is conducive to the distribution of power in the cavity; the current cutting in the axial direction is realized by placing the long side of the skew groove at a 45° angle with the axis of the resonant cavity layer, and 45° polarization is realized. Finally, the vertical electric field vector is 90° ahead of the horizontal electric field vector through the radiation layer to realize right-handed circularly polarized waves. Then, by optimizing the size of the first metal bump 3AA, the second metal bump 3AB, the third metal bump 3AC, and the fourth metal bump 3AD, and optimizing the position of the first skew groove 2AA, the second skew groove 2AB, the third skew groove 2AC, and the fourth skew groove 2AD, the current distribution on the first skew groove 2AA, the second skew groove 2AB, the third skew groove 2AC, and the fourth skew groove 2AD is close to the Chebyshev weighted distribution, thereby achieving a low side lobe of -16dB.

The millimeter-wave vehicle-mounted radar circularly polarized antenna of this embodiment is simulated and calculated to obtain a simulated S11 curve, as shown in Figure 10. As shown in Figure 10, the simulated -10dB impedance bandwidth of the antenna is 74.67GHz-83.73GHz. As shown in Figure 11, the simulated 3dB axial ratio bandwidth of the antenna is 72.29GHz-83.86GHz. Figure 12 is a simulated radiation pattern of the horizontal plane Phi=0° and the vertical plane Phi=90° of the antenna at the frequency of 78.5GHz. The realized and dotted lines represent the directional patterns of the horizontal plane and the vertical plane, respectively. It can be seen from the figure that the antenna gain is 13dBi, the 3dB beam width displayed on the E plane is 21.6°, and the 3dB beam width displayed on the H plane is 79°. The sub-class level is lower than -16dB, and there is no in the frequency band. The circularly polarized antenna disclosed in this embodiment has excellent performance such as wide bandwidth, high gain, and wide beam. Furthermore, the antenna structure of this embodiment is designed based on the domestic CNC processing accuracy requirements, and has a simple structure, is easy to process, and has a small number of layers.

Example 3

In this embodiment, there are four layers, which are radiation layer 1, coupling layer 2, resonant cavity layer 3 and feeding layer 4 from top to bottom, wherein the principles of feeding layer 4 and resonant cavity layer 3 are the same as those in embodiment 1. The difference from embodiment 1 is that in this embodiment, the shape of the inclined slots 2AA, 2AB, 2AC, and 2AD in embodiment 1 is L-shaped rectangular inclined slots, as shown in FIG4; in this embodiment, the radiation layer 1 includes a radiation unit 1A, and the radiation unit 1A is four rhombus open waveguides arranged linearly in the longitudinal direction, as shown in FIG6; the antenna structure of this embodiment can also play the effect of generating circularly polarized waves.

As shown in Fig. 4, in this embodiment, the radiation unit 1A can make the phase velocities of the vertical polarization electric field and the horizontal polarization electric field different. In this embodiment, the vertical polarization electric field of the electromagnetic wave lags behind the horizontal polarization electric field by 90° through the radiation unit 1A, thereby realizing a left-hand circularly polarized wave. The aperture size and depth size of the radiation unit 1A directly affect the phase difference between the vertical polarization component and the horizontal polarization component, so it is sufficient to control the phase difference to be around 90°.

As shown in Figure 6, the first slanted slot 2AA, the second slanted slot 2AB, the third slanted slot 2AC, and the fourth slanted slot 2AD can respectively cut the current on the upper surface of the rectangular resonant cavity 3A, and the generated electric fields are perpendicular to each other. The first slanted slot 2AA, the second slanted slot 2AB, the third slanted slot 2AC, and the fourth slanted slot 2AD are all rotated 90° around themselves to change the direction of rotation of the circularly polarized wave. The axial length of the first slanted slot 2AA, the second slanted slot 2AB, the third slanted slot 2AC, and the fourth slanted slot 2AD is about λ/2, the slot width is about 1mm (it is recommended to be more than 0.5mm for easy processing), and the slot depth is unlimited. The placement positions of the first slanted slot 2AA, the second slanted slot 2AB, the third slanted slot 2AC, and the fourth slanted slot 2AD can be adjusted at will, but the direction of the electric field in each slanted slot must be consistent.

The millimeter-wave vehicle-mounted radar circularly polarized antenna of this embodiment is simulated and calculated to obtain a simulated S11 curve, as shown in Figure 13. As shown in Figure 13, the simulated -10dB impedance bandwidth of the antenna is 76.69GHz-78.38GHz. As shown in Figure 14, the simulated 3dB axial ratio bandwidth of the antenna is 75.19GHz-78.59GHz. Figure 15 is a simulated radiation pattern of the horizontal plane Phi=0° and the vertical plane Phi=90° of the antenna at the frequency of 77.5GHz. The realized and dotted lines represent the directional patterns of the horizontal plane and the vertical plane, respectively. It can be seen from the figure that the antenna gain is 15dBi, the 3dB beam width displayed on the vertical plane is 17.1°, and the 3dB beam width displayed on the H plane is 57°. The sub-class level is lower than -16dB, and there is no high gain, wide beam and other excellent performances in the frequency band disclosed in this embodiment.

The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims (8)

1. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna is characterized by comprising an antenna layer positioned at the upper part and a feed layer (4) positioned at the lower part, wherein the antenna layer is sequentially arranged from top to bottom and comprises a radiation layer (1), a coupling layer (2) and a resonant cavity layer (3), the feed layer (4) is used for feeding power to the resonant cavity layer (3), the resonant cavity layer (3) carries out coupling power feeding on the radiation layer (1) through the coupling layer (2), and finally the radiation layer radiates to space and forms a fan-shaped wave beam;

The radiation layer (1) is provided with 1 radiation unit (1A) with an upward opening and a hollow structure;

The coupling layer (2) is provided with 4 longitudinally arranged 45-degree inclined grooves which are distributed in a hollowed-out structure and are symmetrical in center, wherein the 45-degree inclined grooves are respectively a first inclined groove (2 AA), a second inclined groove (2 AB), a third inclined groove (2 AC) and a fourth inclined groove (2 AD), and the first inclined groove (2 AA) and the second inclined groove (2 AB) are respectively symmetrical with the third inclined groove (2 AC) and the fourth inclined groove (2 AD) with respect to the center of the coupling layer; the upper surface of the coupling layer (2) is in seamless fit with the lower surface of the radiation layer (1);

The resonant cavity layer (3) is provided with a rectangular resonant cavity (3A) with a hollowed-out structure, and two long sides of the rectangular resonant cavity (3A) are respectively provided with a first metal lug (3 AA), a third metal lug (3 AC), a second metal lug (3 AB) and a fourth metal lug (3 AD); the first metal bumps (3 AA), the second metal bumps (3 AB), the third metal bumps (3 AC) and the fourth metal bumps (3 AD) are arranged in a staggered manner and are symmetrical about the center of the rectangular resonant cavity (3A); the upper surface of the resonant cavity layer (3) is in seamless fit with the lower surface of the coupling layer (2);

The utility model provides a rectangular waveguide structure L type that feed layer (4) are equipped with one hollow out construction, be located feed layer central point put, L type rectangular waveguide (4A) are including first waveguide mouth (4 AA), second waveguide mouth (4 AB), and be equipped with at right angle department and match piece (4 AC), the upper surface of feed layer (4) and the seamless laminating of lower surface of rectangular resonant cavity (3A), wherein first waveguide mouth (4 AA) are as the feed input port, set up in the side of feed layer (4), and feed rectangular resonant cavity (3A) through second waveguide mouth (4 AB) as the feed delivery outlet, second waveguide mouth (4 AB) set up in the upper surface of feed layer (4), and be located rectangular resonant cavity (3A) center below.

2. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna according to claim 1, wherein the first chute (2 AA), the second chute (2 AB), the third chute (2 AC) and the fourth chute (2 AD) are positioned below the radiating unit (1A), are in seamless connection with the bottom of the radiating unit (1A), and the upper surface of the coupling layer (2) is the lower surface of the radiating layer.

3. The novel 3D millimeter wave vehicle radar circularly polarized antenna according to claim 1, wherein the first metal bump (3 AA), the second metal bump (3 AB), the third metal bump (3 AC) and the fourth metal bump (3 AD) are rectangular, triangular, elliptical or irregular in shape.

4. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna according to claim 1, wherein the distance between every two adjacent inclined grooves in the 4 inclined grooves ranges from λg/2 to λg, the distance between the first metal bump (3 AA) and the third metal bump (3 AC), the distance between the second metal bump (3 AB) and the fourth metal bump (3 AD) ranges from λg/2 to λg, λg is the waveguide wavelength of the rectangular resonant cavity (3A) under the target frequency, and the radiation layer, the coupling layer, the resonant cavity layer and the feed layer in the antenna are all centrosymmetric with respective center points.

5. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna according to claim 1, wherein the radiating element (1A) is rectangular, trapezoidal, triangular or diamond-shaped, and the phase difference between the vertical electric field vector and the horizontal electric field vector is adjusted by changing the height of the radiating element (1A).

6. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna according to claim 1, wherein the L-shaped rectangular waveguide (4A) is provided with a stepped matching block (4 AC) at a right angle for adjusting the reflection coefficient of the L-shaped rectangular waveguide (4A).

7. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna according to claim 1, wherein the first chute (2 AA), the second chute (2 AB), the third chute (2 AC) and the fourth chute (2 AD) are rectangular or L-shaped.

8. The novel 3D millimeter wave vehicle-mounted radar circularly polarized antenna according to claim 1, wherein the radiation layer (1), the coupling layer (2) and the resonant cavity layer (3) in the antenna layer are used as one layer for processing and forming, and the section thickness of the antenna layer is [2.2mm,3mm ].