Low sidelobe radar antenna and vehicle-mounted radar antenna

Abstract

The present invention provides a low sidelobe radar antenna and a vehicle-mounted radar antenna, wherein the low sidelobe radar antenna comprises: a dielectric substrate; N 45° polarized linear arrays, laid on the dielectric substrate; the 45° polarized linear array comprises a feeder and a plurality of array elements arranged on the feeder; the angle between each array element and the feeder is 45°; and N is a positive integer greater than or equal to 3. When the low sidelobe radar antenna of the present invention is opposite to the same 45° polarized radar, the ±45° polarization orthogonality can provide sufficient antenna isolation, thereby greatly reducing interference from oncoming vehicles or oncoming radar antennas.

Description

Technical Field

[0001] The invention belongs to the field of radar technology and relates to an antenna, in particular to a low sidelobe radar antenna and a vehicle-mounted radar antenna. Background Art

[0002] Radar is a device used to radiate and receive electromagnetic waves and determine the direction of detection. When transmitting, the radar must concentrate the energy to radiate in the direction required; when receiving, it should only receive the echo in the detection direction as much as possible, and distinguish the azimuth and elevation of the target, or one of the two. Among the three coordinates (azimuth, elevation and distance) of the target position measured by radar, the measurement of two coordinates (azimuth and elevation) is directly related to the performance of the antenna. Therefore, antenna performance is more important for radar equipment than for other electronic equipment (such as communication equipment).

[0003] The vehicle-mounted radar antenna used for forward collision warning needs to have high gain, low sidelobe and other characteristics. Although the traditional microstrip array antenna can provide sufficient high gain and low sidelobe characteristics, its polarization mode is generally horizontal polarization or vertical polarization. When the oncoming vehicle is also equipped with horizontal polarization or vertical polarization radar, it is easy to cause interference. In addition, in order to meet the MIMO radar system, the antenna feed line is usually very long. Too long feed line will bring higher loss, and its bend will generate strong radiation to the outside, thereby deteriorating the antenna pattern and affecting the radar performance.

[0004] Therefore, how to provide a low sidelobe radar antenna and a vehicle-mounted radar antenna to solve the defects of the existing technology such as easy interference and feeder radiation seriously affecting radar performance has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a low sidelobe radar antenna and a vehicle-mounted radar antenna, which are used to solve the defects of the prior art that the prior art is prone to cause interference and the feeder radiation seriously affects the radar performance.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a low sidelobe radar antenna, comprising: a dielectric substrate; N 45° polarized linear arrays laid on the dielectric substrate, the 45° polarized linear array comprising a feed line and a plurality of array elements arranged on the feed line; the angle between each array element and the feed line is 45°; N is a positive integer greater than or equal to 3.

[0007] In an embodiment of the present invention, each of the array elements is rotated counterclockwise with a designated angle as a rotation base point, so that the array element and the feed line where the array element is located are at 45 degrees.

[0008] In an embodiment of the present invention, a plurality of the array elements are alternately distributed left and right relative to the feed line.

[0009] In one embodiment of the present invention, when the number of the array elements is an odd number M, the sizes of the array elements distributed on both sides of the feed line are symmetrical with the (M+1) / 2th array element as the center; the (M+1) / 2th array element is arranged in the middle of the feed line.

[0010] In one embodiment of the present invention, the array elements all adopt rectangular patches; the width of the rectangular patches decreases gradually toward the two ends of the feed line, and the length of the rectangular patches and the spacing between two adjacent rectangular patches are equal to half the equivalent wavelength in the medium.

[0011] In one embodiment of the present invention, the N 45° polarization linear arrays are arranged at equal intervals.

[0012] In one embodiment of the present invention, the 45° polarized linear array further includes a quarter impedance transformer and a 50Ω microstrip line disposed at the head of the feed line; the feed line is connected to the 50Ω microstrip line via the quarter impedance transformer.

[0013] In one embodiment of the present invention, the low sidelobe radar antenna also includes a power division network connected to the 45° polarized linear array; the power division network is an unequal power divider for feeding the 45° polarized linear array; the unequal power divider includes a plurality of output ports; the plurality of output ports are centrally symmetrical, and the horizontal spacing between the output ports is equal; wherein the output ports use 50Ω microstrip lines.

[0014] In one embodiment of the present invention, the low sidelobe radar antenna also includes a gradually widening microstrip-substrate integrated waveguide structure, which is arranged at both ends of the substrate integrated waveguide structure, and is used to propagate in TEM mode after receiving energy, and then convert the TEM mode into TE mode to propagate in SIW, and then convert the TE mode into TEM mode, and distribute the energy to each linear array through a power division network.

[0015] In one embodiment of the present invention, the low sidelobe radar antenna also includes a substrate integrated waveguide structure connected to the microstrip-substrate integrated waveguide structure; used to feed the 45° polarized linear array; wherein the substrate integrated waveguide structure is a closed structure connected by metal walls on the upper and lower surfaces through periodic metal through holes at both ends.

[0016] On the other hand, the present invention provides a vehicle-mounted low sidelobe radar antenna, comprising: a dielectric substrate; a 45° polarized linear array, laid on the dielectric substrate, for forming an orthogonal direction with the polarization direction of the vehicle-mounted radar antenna mounted on an oncoming vehicle; wherein the 45° polarized linear array comprises a feed line and a plurality of array elements arranged on the feed line; the angle between each array element and the feed line is 45°.

[0017] As described above, the low sidelobe radar antenna and vehicle-mounted radar antenna of the present invention have the following beneficial effects:

[0018] First, the array antenna provided by the present invention has a compact structure and has the characteristics of high gain and low side lobe;

[0019] Second, the design of the power division network provided by the present invention can not only expand the array aperture and reduce the coupling between the linear arrays, but also enable the power division ratio design and phase correction to be performed independently, thus simplifying the design of the power division network;

[0020] Third, when facing the same 45° polarization radar, the ±45° polarization orthogonality can provide sufficient antenna isolation, greatly reducing the interference from oncoming vehicles or radar antennas;

[0021] Fourthly, the present invention utilizes the advantages of SIW such as low transmission loss and low radiation to improve the problems of antenna pattern deterioration and gain reduction caused by the excessive length and external radiation of traditional microstrip lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. 4 is a schematic diagram of a planar structure of a low sidelobe radar antenna according to an embodiment of the present invention.

[0023] Figure 2 It is a schematic structural diagram of a 45° polarized linear array in one embodiment of the present invention.

[0024] Figure 3 FIG. 4 is a schematic diagram showing the structure of a power division network in an embodiment of the present invention.

[0025] Figure 4 FIG. 4 is a schematic diagram of a planar structure of a microstrip-SIW structure of the present invention in one embodiment.

[0026] Figure 5 FIG. 1 is a schematic diagram of a planar structure of a SIW structure of the present invention in one embodiment.

[0027] Figure 6 Shown is the radiation pattern of the low sidelobe radar antenna of the present invention.

[0028] Figure 7 Shown is a graph of return loss for the low sidelobe radar antenna of the present invention.

[0029] Figure 8 Shown is a schematic diagram comparing the elevation pattern of the low sidelobe radar antenna of the present invention and the elevation pattern of a traditional feeder.

[0030] Fig. 9 FIG. 1 is a schematic structural diagram of a vehicle-mounted low sidelobe radar antenna according to an embodiment of the present invention.

[0031] Component number description

[0032] 1 Low sidelobe radar antenna

[0033] 11 Dielectric substrate

[0034] 12 45° polarized linear array

[0035] 13 Power Distribution Network

[0036] 14 Microstrip-substrate integrated waveguide structure

[0037] 15 Substrate Integrated Waveguide Structure

[0038] 121 Feeder

[0039] 122 Array

[0040] 123 Quarter Impedance Transformer

[0041] 124 50Ω microstrip line

[0042] 131 Output Port

[0043] 151 Upper Metal Wall

[0044] 152 Lower Metal Wall

[0045] 153 Metal Holes

[0046] 91 Vehicle-mounted radar antenna

[0047] 92 Vehicle sensor chip DETAILED DESCRIPTION

[0048] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0049] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0050] Embodiment 1

[0051] This embodiment provides a low sidelobe radar antenna, including:

[0052] dielectric substrate;

[0053] N 45° polarized linear arrays are laid on the dielectric substrate, and are used to form an orthogonal polarization direction with the opposite 45° polarized linear array; wherein the 45° polarized linear array comprises a feed line and a plurality of array elements arranged on the feed line; the angle between each array element and the feed line is 45°; and N is a positive integer greater than or equal to 3.

[0054] The low sidelobe radar antenna will be described in detail below with reference to the figures. The low sidelobe radar antenna described in this embodiment can be applied to vehicles (eg, cars, tanks, armored vehicles, etc.) or guide devices. Figure 1 , which is a schematic diagram of a planar structure of a low sidelobe radar antenna in one embodiment. Figure 1 As shown, the low sidelobe radar antenna 1 includes a dielectric substrate 11, N 45° polarized linear arrays 12, a power division network 13, a microstrip-substrate integrated waveguide structure 14 (microstrip-SIW structure) and a substrate integrated waveguide structure 15 (SIW structure).

[0055] In this embodiment, the dielectric constant of the dielectric substrate 11 is 3.04, the thickness is 0.127 mm, and the copper foil is rolled copper with a thickness of 18 um.

[0056] The 45° polarized linear array 12 laid on the dielectric substrate 11 is used to form an orthogonal polarization direction with the opposite 45° polarized linear array. In this embodiment, from the perspective of the low sidelobe radar antenna 1 in one direction, the polarization direction of the opposite low sidelobe radar antenna 1' is -45°, which is exactly orthogonal to the polarization direction of the low sidelobe radar antenna 1. According to the antenna polarization theory, the low sidelobe radar antenna 1 cannot receive orthogonal polarized waves, so it can suppress interference from the opposite direction.

[0057] The 45° polarized linear array 12 includes a feed line 121 , a plurality of array elements 122 , a quarter impedance transformer 123 and a 50Ω microstrip line 124 .

[0058] In this embodiment, the number N of the 45° polarized linear arrays 12 is a positive integer greater than or equal to 3. In order to simplify the design of the power division network, the power division network is made bilaterally symmetrical. Therefore, the number of the 45° polarized linear arrays 12 is an even number. In this embodiment, the value of the number N of the 45° polarized linear arrays 12 is 6. Six 45° polarized linear arrays 12 form a planar array. Six 45° polarized linear arrays 12 can meet the gain and beam requirements, save space, and facilitate integration. In this embodiment, the arrangement of the 45° polarized linear arrays 12 adopts a uniform array arrangement, for example, an equal spacing arrangement.

[0059] The present invention requires the antenna to have a higher gain and a narrower beam. The more antennas there are, the higher the gain and the narrower the horizontal beam.

[0060] A plurality of array elements 122 arranged on each feed line 121 form a polarized linear array. In this embodiment, each array element 122 rotates counterclockwise with a specified angle as a rotation base point, so that the array element and the feed line where the array element is located are 45 degrees. The array elements 122 on each feed line 121 are alternately distributed left and right relative to the feed line 121.

[0061] Since the number of array elements is an odd number, it is easier to control the sidelobe level in the elevation direction. Therefore, when the number of array elements is an odd number M, the sizes of the array elements distributed on both sides of the feeder are symmetrical with the (M+1) / 2th array element as the center. The (M+1) / 2th array element is set in the middle of the feeder.

[0062] Preferably, the number M of the array elements is 19, and the sizes of the array elements arranged on each feed line 121 are symmetrical with the 10th array element as the center.

[0063] Since the current amplitude of each patch obeys Taylor distribution, the patch impedance can be controlled by controlling the patch width, thereby changing the current distribution to obey Taylor distribution, which can reduce the side lobe level in the pitch direction. Therefore, the array elements 122 all use rectangular patches. Figure 2 The width Wi of the rectangular patch decreases toward the two ends of the feed line 121, and the length Li of the rectangular patch and the spacing di between two adjacent rectangular patches are equal to (approximately equal to) half the equivalent wavelength (λg) in the medium.

[0064] The quarter impedance transformer 123 and the 50Ω microstrip line 124 are disposed at the head of the feed line 121. The feed line 121 is connected to the 50Ω microstrip line 124 via the quarter impedance transformer 123.

[0065] The power division network 13 connected to the 45° polarized linear array 12 is used to feed the 45° polarized linear array 12. Figure 3 , which is a schematic diagram of the structure of a power division network in one embodiment. Figure 3 As shown, the power division network 13 uses an unequal power divider to feed the series structure arranged on both sides thereof in parallel. In order to reduce the sidelobe level, the unequal power divider includes a plurality of unequal output ports 131. Among them, m1, m2, m3, m4, and m5 represent quarter impedance transformers, whose lengths are one quarter of the wavelength in the medium, and the power division ratio of each port can be adjusted by adjusting the width.

[0066] The multiple output ports 131 are centrally symmetrical, and their lengths gradually decrease toward both sides. The horizontal spacing between the output ports is equal, and the quarter impedance transformer 123 at each output port 131 is adjusted to achieve the best power division ratio, and the length of the 50Ω microstrip line is adjusted for phase compensation.

[0067] Preferably, the output port 131 adopts a 50Ω microstrip line.

[0068] Continue reading Figure 1 , arranged at both ends of the substrate integrated waveguide structure 15, and the microstrip-SIW structure 14 connected to the power division network 13 and the chip is used for the energy to propagate in TEM mode after entering, and then pass through the substrate integrated waveguide structure to convert the TEM mode into TE mode to propagate in SIW, and then pass through the substrate integrated waveguide structure to convert the TE mode into TEM mode, and distribute the energy to each linear array through the power division network. In this embodiment, for impedance matching, the microstrip-SIW structure 14 adopts a gradually widening type. Please refer to Figure 4 , which is a schematic diagram of a planar structure of a microstrip-SIW structure in one embodiment. Figure 4 As shown, the height n1 of the microstrip-SIW structure 14 is 1.5 mm, and the widest part of the port is n2 = 1 mm.

[0069] Continue reading Figure 1 The substrate integrated waveguide structure 15 connected to the microstrip-substrate integrated waveguide structure 14 is used to feed the 45° polarized linear array 12. In order to reduce the deterioration of the antenna direction, the substrate integrated waveguide structure is a closed structure connected by metal walls on the upper and lower surfaces through metal through holes at both ends.

[0070] Specifically, the substrate integrated waveguide structure 15 adopts the following Figure 5In the structure shown, the substrate integrated waveguide structure 15 is a closed structure consisting of an upper metal wall 151, a lower metal wall 152, and two rows of metal holes 153 that are periodically distributed and connect the upper and lower metal walls 151 / 152. The radius r of the metal hole 153, the hole spacing ds between the two rows of metal holes, and the hole spacing d between adjacent metal holes satisfy a certain relationship (in this embodiment, the certain relationship refers to an empirical formula in the art) to form a waveguide structure. In this embodiment, the SIW structure 15 has good sealing and transmission performance. Using the SIW structure 15 to replace the traditional microstrip feeder can improve the problem of pattern deterioration caused by excessive feeder length and feeder radiation.

[0071] See also Figure 6 , which shows the radiation pattern of a low sidelobe radar antenna. Figure 6 As shown, the gain of the 45° polarized array antenna to which the SIW feed line can be added is 22 dB, the horizontal beam width is 13.6°, the elevation beam width is 9.8°, and the sidelobe level SLL = -20.9 dB. Figure 6 The horizontal axis is the angle, and the vertical axis corresponds to the gain at that angle. This is the directional diagram.

[0072] See also Figure 7 , which shows the return loss plot of a low sidelobe radar antenna. Figure 7 As shown, the center frequency of the low sidelobe radar antenna is 77 GHz, S11 = -29.3 dB. The horizontal axis is the frequency, and the vertical axis is the return loss S11.

[0073] See also Figure 8 , which shows a comparison diagram of the elevation pattern of a low sidelobe radar antenna and the elevation pattern of a traditional feeder. Figure 8 As shown, the solid line is the elevation pattern of the present invention, and the dotted line is the elevation pattern of the traditional feeder. It can be seen that the low sidelobe radar antenna of the present invention can improve the deterioration of the antenna pattern caused by the traditional feeder.

[0074] The low sidelobe radar antenna of this embodiment has the following beneficial effects:

[0075] First, the array antenna provided in this embodiment has a compact structure and has the characteristics of high gain and low side lobe;

[0076] Second, the design of the power division network provided in this embodiment can not only expand the array aperture and reduce the coupling between the linear arrays, but also enable the power division ratio design and phase correction to be performed independently, thus simplifying the design of the power division network;

[0077] Third, when facing the same 45° polarization radar, the ±45° polarization orthogonality can provide sufficient antenna isolation, greatly reducing the interference of the opposing radar antenna;

[0078] Fourthly, this embodiment utilizes the advantages of SIW such as low transmission loss and low radiation to improve the problems of antenna pattern deterioration and gain reduction caused by the excessive length and external radiation of the traditional microstrip line.

[0079] Embodiment 2

[0080] This embodiment provides a vehicle-mounted radar antenna, including:

[0081] dielectric substrate;

[0082] N 45° polarized linear arrays are laid on the dielectric substrate, and are used to form an orthogonal direction with the polarization direction of the vehicle-mounted radar antenna mounted on the oncoming vehicle; wherein the 45° polarized linear array includes a feed line and a plurality of array elements arranged on the feed line; and the angle between each array element and the feed line is 45°.

[0083] The vehicle-mounted radar antenna will be described in detail below. The vehicle-mounted radar antenna of this embodiment is applied to vehicles, such as cars, tanks, armored vehicles, etc., to eliminate interference caused by radar antennas mounted on oncoming vehicles. Fig. 9 , which is a schematic diagram of the structure of a vehicle-mounted radar antenna in one embodiment. Fig. 9 As shown, the vehicle-mounted radar antenna 91 described in this embodiment is connected to the vehicle-mounted sensor chip 92.

[0084] The vehicle-mounted radar antenna includes a dielectric substrate, a 45° polarized linear array, a power division network, a microstrip-substrate integrated waveguide structure (microstrip-SIW structure) and a substrate integrated waveguide structure (SIW structure).

[0085] In this embodiment, the dielectric constant of the dielectric substrate is 3.04, the thickness is 0.127 mm, and the copper foil is rolled copper with a thickness of 18 um.

[0086] The 45° polarized linear array laid on the dielectric substrate is used to form an orthogonal polarization direction with the 45° polarized linear array mounted on the oncoming vehicle. In this embodiment, from the perspective of the radar antenna of the vehicle in one direction, the polarization direction of the radar antenna measured in the oncoming direction is -45°, which is exactly orthogonal to the polarization direction of the radar antenna. According to the antenna polarization theory, the radar antenna cannot receive orthogonal polarized waves, and therefore, the interference from the oncoming direction can be suppressed.

[0087] In this embodiment, the 45° polarized linear array includes a feed line, a plurality of array elements, a quarter impedance transformer and a 50Ω microstrip line.

[0088] In this embodiment, the number N of 45° polarized linear arrays is a positive integer greater than or equal to 3. In order to simplify the design of the power division network, the power division network is made bilaterally symmetrical. Therefore, the number of 45° polarized linear arrays is an even number. In this embodiment, the number N of the 45° polarized linear arrays is 6. Six 45° polarized linear arrays form a planar array. Six 45° polarized linear arrays can meet the gain and beam requirements, save space, and facilitate integration. In this embodiment, the arrangement of the 45° polarized linear arrays adopts a uniform array arrangement, for example, an equal spacing arrangement.

[0089] The present invention requires the antenna to have a higher gain and a narrower beam. The more antennas there are, the higher the gain and the narrower the horizontal beam.

[0090] A number of array elements arranged on each feeder line form a polarized linear array. In this embodiment, each array element rotates counterclockwise with a specified angle as a rotation base point, so that the array element and the feeder line where the array element is located are 45 degrees. The array elements on each feeder line are distributed alternately left and right relative to the feeder line.

[0091] Since the number of array elements is an odd number, it is easier to control the sidelobe level in the elevation direction. Therefore, when the number of array elements is an odd number M, the sizes of the array elements distributed on both sides of the feeder are symmetrical with the (M+1) / 2th array element as the center. The (M+1) / 2th array element is set in the middle of the feeder.

[0092] Preferably, the number M of the array elements is 19, and the sizes of the array elements arranged on each feeder line are symmetrical with the 10th array element as the center.

[0093] In this embodiment, the array elements are all rectangular patches. The width Wi of the rectangular patches decreases toward the two ends of the feed line, and the length Li of the rectangular patches and the spacing di between two adjacent rectangular patches are equal to (approximately equal to) half of the equivalent wavelength (λg) in the medium.

[0094] The quarter impedance transformer and the 50Ω microstrip line are arranged at the head of the feeder line. The feeder line is connected to the 50Ω microstrip line through the quarter impedance transformer.

[0095] The power division network connected to the 45° polarized linear array is used to feed the 45° polarized linear array. In this embodiment, the power division network uses an unequal power divider to feed the series structure arranged on both sides thereof in parallel. In order to reduce the sidelobe level, the unequal power divider includes a plurality of unequal output ports.

[0096] The multiple output ports are centrally symmetrical, and their lengths gradually decrease toward both sides. The horizontal spacing between the output ports is equal, and the quarter impedance transformer at each output port is adjusted to achieve the best power division ratio, and the length of the 50Ω microstrip line is adjusted to perform phase compensation.

[0097] Preferably, the output port adopts a 50Ω microstrip line.

[0098] The microstrip-SIW structure disposed at both ends of the substrate integrated waveguide structure and connected to the power division network and the chip is used to propagate in TEM mode after energy enters, and then convert the TEM mode into TE mode through the substrate integrated waveguide structure to propagate in SIW, and then convert the TE mode into TEM mode through the substrate integrated waveguide structure, and distribute the energy to each linear array through the power division network. In this embodiment, for impedance matching, the microstrip-SIW structure adopts a gradually widening type. The height of the microstrip-SIW structure n1 = 1.5 mm, and the widest part of the port n2 = 1 mm.

[0099] The substrate integrated waveguide structure connected to the microstrip-substrate integrated waveguide structure is used to feed the 45° polarized linear array 12. In order to reduce the deterioration of the antenna direction, the substrate integrated waveguide structure is a closed structure connected by metal walls on the upper and lower surfaces through metal through holes at both ends.

[0100] Specifically, the substrate integrated waveguide structure is a closed structure consisting of an upper metal wall, a lower metal wall, and two rows of periodically distributed metal holes connecting the upper and lower metal walls. The radius r of the metal hole, the hole spacing ds between the two rows of metal holes, and the hole spacing d between adjacent metal holes satisfy a certain relationship to form a waveguide structure. In this embodiment, the SIW structure has good sealing and transmission performance. Using the SIW structure 15 to replace the traditional microstrip feeder can improve the problem of pattern deterioration caused by the excessive length of the feeder and the radiation of the feeder.

[0101] In summary, the low sidelobe radar antenna and vehicle-mounted radar antenna of the present invention have the following beneficial effects:

[0102] First, the array antenna provided by the present invention has a compact structure and has the characteristics of high gain and low side lobe;

[0103] Second, the design of the power division network provided by the present invention can not only expand the array aperture and reduce the coupling between the linear arrays, but also enable the power division ratio design and phase correction to be performed independently, thus simplifying the design of the power division network;

[0104] Third, when facing the same 45° polarization radar, the ±45° polarization orthogonality can provide sufficient antenna isolation, greatly reducing the interference from oncoming vehicles or radar antennas;

[0105] Fourth, the present invention utilizes the advantages of low transmission loss and low radiation of SIW to improve the problems of antenna pattern deterioration and gain reduction caused by the excessive length and external radiation of traditional microstrip lines. The present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0106] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A low sidelobe radar antenna, characterized in that: include: dielectric substrate; N 45° polarized linear arrays are laid on the dielectric substrate, the 45° polarized linear arrays include a feeder and a plurality of array elements arranged on the feeder; the angle between each array element and the feeder is 45°; N is a positive integer greater than or equal to 3; the array elements are all rectangular patches; the width of the rectangular patches decreases toward the two ends of the feeder, and the length of the rectangular patch and the spacing between two adjacent rectangular patches are equal to half of the equivalent wavelength in the medium; The 45° polarized linear array further includes a quarter impedance transformer and a 50Ω microstrip line arranged at the head of the feeder; the feeder is connected to the 50Ω microstrip line through the quarter impedance transformer; The low sidelobe radar antenna also includes a power division network connected to the 45° polarized linear array; the power division network is an unequal power divider for feeding the 45° polarized linear array; the unequal power divider includes a plurality of output ports; the quarter impedance transformer at each output port is adjusted to achieve an optimal power division ratio, and the length of the 50Ω microstrip line is adjusted to perform phase compensation; The low sidelobe radar antenna also includes a gradually widening microstrip-substrate integrated waveguide structure, which is arranged at both ends of the substrate integrated waveguide structure, and is used to propagate in TEM mode after receiving energy, and then convert the TEM mode into TE mode to propagate in SIW, and then convert the TE mode into TEM mode, and distribute the energy to each linear array through a power division network.

2. The low sidelobe radar antenna according to claim 1, characterized in that: Each of the array elements rotates counterclockwise with a specified angle as a rotation base point, so that the array element and the feed line where the array element is located are at 45 degrees.

3. The low sidelobe radar antenna according to claim 1, characterized in that: A plurality of array elements are distributed alternately left and right relative to the feed line.

4. The low sidelobe radar antenna according to claim 3, characterized in that: When the number of the array elements is an odd number M, the sizes of the array elements distributed on both sides of the feeder are symmetrical with the (M+1) / 2th array element as the center; the (M+1) / 2th array element is arranged in the middle of the feeder.

5. The low sidelobe radar antenna according to claim 1, characterized in that: The N feed lines are arranged at equal intervals.

6. The low sidelobe radar antenna according to claim 1, characterized in that: The multiple output ports are centrally symmetrical, and the horizontal spacing between the output ports is equal; wherein the output ports use 50Ω microstrip lines.

7. The low sidelobe radar antenna according to claim 1, characterized in that: The substrate integrated waveguide structure is connected to the microstrip-substrate integrated waveguide structure; it is used to feed the 45° polarized linear array; wherein the substrate integrated waveguide structure is a closed structure connected by upper and lower surface metal walls through periodic metal through holes at both ends.

8. A vehicle-mounted radar antenna, characterized in that: include: N 45° polarized linear arrays are laid on a dielectric substrate to form an orthogonal polarization direction with the vehicle-mounted radar antenna mounted on the oncoming vehicle; wherein the 45° polarized linear array comprises a feeder and a plurality of array elements arranged on the feeder; the angle between each array element and the feeder is 45°; the array elements are all rectangular patches; the width of the rectangular patches decreases toward the two ends of the feeder, and the length of the rectangular patch and the spacing between two adjacent rectangular patches are equal to half of the equivalent wavelength in the medium; The 45° polarized linear array further includes a quarter impedance transformer and a 50Ω microstrip line arranged at the head of the feeder; the feeder is connected to the 50Ω microstrip line through the quarter impedance transformer; The vehicle-mounted radar antenna also includes a power division network connected to the 45° polarized linear array; the power division network is an unequal power divider for feeding the 45° polarized linear array; the unequal power divider includes a plurality of output ports; the quarter impedance transformer at each output port is adjusted to achieve an optimal power division ratio, and the length of the 50Ω microstrip line is adjusted to perform phase compensation; The vehicle-mounted radar antenna also includes a gradually widening microstrip-substrate integrated waveguide structure, which is arranged at both ends of the substrate integrated waveguide structure. After receiving energy, it is first propagated in TEM mode, and then the TEM mode is converted into TE mode for propagation in SIW, and then the TE mode is converted into TEM mode, and the energy is distributed to each linear array through a power division network.

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