Microstrip array antenna of millimeter wave radar

Abstract

The invention discloses a microstrip array antenna of a millimeter wave radar, which belongs to the technical field of vehicle-mounted radars, and comprises a dielectric substrate, a microstrip radiation patch, a grounding layer, a metalized through hole and a coaxial feed structure, one surface of the dielectric substrate is provided with the microstrip radiation patch, and the other surface is covered with the grounding layer; the microstrip radiation patch comprises an antenna unit rectangular array and a hybrid feed network, the hybrid feed network comprises a power divider and a main feeder, the antenna unit rectangular array comprises a plurality of linear arrays which are connected in parallel through the power divider, and each linear array comprises a plurality of antenna units which are connected in series through the main feeder; one end of an inner conductor of the coaxial feed structure is connected with the center of the microstrip radiation patch, and the other end of the inner conductor of the coaxial feed structure penetrates through the dielectric substrate and the grounding layer; the metalized through holes are through holes of a quasi-coaxial structure, the multiple through holes of the quasi-coaxial structure are annularly distributed around the inner conductor of the coaxial feed structure, and the through holes of the quasi-coaxial structure penetrate through the dielectric substrate.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle-mounted radars, and in particular relates to a microstrip array antenna for millimeter-wave radars. Background Art

[0002] As the total number of cars continues to grow, travel safety and reducing traffic accidents have become a major focus of public attention. Improving driving safety has become a challenge that automakers are constantly striving to overcome. Cars perceive the external environment through sensors, including ultrasonic radar, infrared radar, and millimeter-wave radar. Millimeter-wave radar is widely used due to its all-weather operation and low sensitivity to external interference.

[0003] Millimeter-wave wavelengths lie between microwaves and infrared. Millimeter-wave radars offer high angular resolution. Compared to optical and infrared devices, they experience minimal atmospheric absorption and attenuation within their transmission window, offering superior penetration through rain, smoke, and fog. These radars are more suitable for inclement weather and battlefield environments, and can more accurately measure the speed, distance, and angle of targets. Millimeter-wave microstrip array antennas, due to their narrow beamform, low sidelobes, and high gain, are widely used in millimeter-wave radar applications. To avoid interference, civilian automotive radars typically use the 24 GHz or 76-79 GHz frequency bands. The 35 GHz band is generally considered a military band for automotive radars.

[0004] As an active safety defense system in areas such as automotive driving, collision avoidance radar systems can effectively prevent traffic accidents. Millimeter-wave antennas are key communication components in radar systems, but their high cost hinders widespread adoption. To overcome these limitations, there is an urgent need to develop low-cost, high-performance millimeter-wave radar antenna technology. This technology can promote the legal application of the 35GHz frequency band in civilian automotive radar applications and enhance the radar system's environmental adaptability and target recognition capabilities. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of the lack of 35GHz frequency band for application in civilian automotive radar. A microstrip array antenna for millimeter-wave radar is proposed to solve the problems of high cost, limited frequency band and insufficient performance in the existing technology, and to achieve low-cost, high-precision, all-weather automotive radar detection.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a microstrip array antenna for millimeter-wave radar includes a dielectric substrate, a microstrip radiation patch, a ground layer, a metallized through hole, and a coaxial feed structure; One side of the dielectric substrate is a microstrip radiation patch, and the other side of the dielectric substrate is covered with a ground layer; The microstrip radiation patch includes a rectangular array of antenna units and a hybrid feed network, the hybrid feed network includes a power divider and a main feed line, the rectangular array of antenna units includes a plurality of linear arrays connected in parallel via a power divider, and a single linear array includes a plurality of antenna units connected in series via a main feed line; One end of the inner conductor of the coaxial feeding structure is connected to the center of the microstrip radiation patch, and the other end of the inner conductor of the coaxial feeding structure passes through the dielectric substrate and the ground layer; The metallized through hole is a quasi-coaxial structure through hole, and a plurality of the quasi-coaxial structure through holes are provided. The plurality of quasi-coaxial structure through holes are distributed in a ring shape around the inner conductor of the coaxial feeding structure, and the quasi-coaxial structure through holes are provided through the dielectric substrate.

[0007] Furthermore, a conductive metal is provided on the surface of the through hole of the quasi-coaxial structure.

[0008] Furthermore, the main feeder includes a multi-stage impedance transformation section, the length of each stage of the multi-stage impedance transformation section is a quarter of the medium wavelength, and the impedance value of each stage of the multi-stage impedance transformation section decreases along the feeder direction.

[0009] Furthermore, the polarization mode of the antenna is linear polarization.

[0010] Furthermore, the hybrid feeding network adopts Chebyshev distribution.

[0011] Furthermore, the dielectric substrate is a double-sided copper clad plate.

[0012] Furthermore, the linear array is a traveling wave series-fed array antenna.

[0013] Furthermore, the antenna unit is a rectangular microstrip patch.

[0014] Furthermore, the length of the rectangular microstrip patch is:

[0015]

[0016]

[0017] in, L is the length of the microstrip radiation patch, is the waveguide wavelength, is the length of the equivalent gap, is the effective dielectric constant, W is the width of the microstrip radiation patch, h is the thickness of the dielectric substrate, is the speed of light, f is the resonant frequency of the antenna unit, is the relative dielectric constant of the dielectric substrate.

[0018] In a second aspect, a vehicle-mounted radar is characterized by using a microstrip array antenna of the millimeter-wave radar.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention proposes a microstrip array antenna for millimeter-wave radar. In terms of radiation performance, the rectangular array of antenna elements is combined with a hybrid feed network. By connecting the linear array in parallel with a power divider and the antenna elements in series with the main feed line, this significantly improves gain and directivity, enabling more accurate radar detection at longer distances. The antenna also offers flexible control of beam shape and directionality to meet the needs of different scenarios. Regarding feeding, the inner conductor of the coaxial feed structure penetrates the dielectric substrate and ground layer, providing a stable path for signal transmission. Furthermore, the surrounding annular quasi-coaxial structure can be adjusted to achieve good impedance matching with the microstrip radiating patch, improving signal transmission efficiency and ensuring the antenna can operate efficiently in the 35GHz frequency band, meeting the stringent requirements of millimeter-wave radar for high-performance antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 Schematic diagram of a microstrip array antenna for a millimeter-wave radar in an embodiment.

[0021] Figure 2 2. It is a two-dimensional top view of a microstrip array antenna of a millimeter-wave radar in an embodiment.

[0022] Figure 3 It is a partial side perspective view of the center position of a microstrip array antenna of a millimeter wave radar in an embodiment.

[0023] Figure 4 This is a partial top view of the center position of a microstrip array antenna of a millimeter-wave radar in an embodiment.

[0024] Figure 5 It is a partial top-down perspective view of the center position of a microstrip array antenna of a millimeter-wave radar in an embodiment.

[0025] Figure 6 It is the basic structure of microstrip antenna.

[0026] Figure 7 The structure of the rectangular microstrip antenna and the electric field at the open end.

[0027] Figure 8 Side view of the microstrip antenna field distribution.

[0028] Figure 9 is the equivalent radiation gap of the microstrip antenna field distribution.

[0029] Figure 10 It is the equivalent circuit model of a one-dimensional linear array.

[0030] Figure 11 This is the structural principle diagram of the linear array antenna.

[0031] Figure 12 This is the simulation result of voltage standing wave ratio of array antenna structure.

[0032] Figure 13 The simulation results of the E-plane gain pattern of the array antenna structure at 35GHz.

[0033] Figure 14 The simulation results of the H-plane gain pattern of the array antenna structure at 35GHz.

[0034] Among them, 1 is a dielectric substrate; 2 is a microstrip radiation patch; 3 is a ground layer; 4 is a metallized through hole; 5 is a coaxial feeding structure, and 51 is an inner conductor. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions 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 embodiments described are only 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 making creative efforts should fall within the scope of protection of the present invention.

[0036] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be an element centered thereon. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an element centered thereon. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] Example 1 A microstrip array antenna for millimeter-wave radar includes a dielectric substrate 1, a microstrip radiating patch 2, a ground layer 3, a metallized through-hole 4, and a coaxial feed structure 5. The microstrip radiating patch 2 is disposed on one side of the dielectric substrate 1, and the ground layer 3 is covered on the other side. The microstrip radiating patch 2 includes a rectangular array of antenna elements and a hybrid feed network. The hybrid feed network includes a power divider and a main feed line. The rectangular array of antenna elements comprises several linear arrays connected in parallel via a power divider, and a single linear array comprises several antenna elements connected in series via a main feed line. The rectangular array of antenna elements is composed of several linear arrays connected in parallel via a power divider, and a single linear array is composed of several antenna elements connected in series via a main feed line. This array layout enables the antenna to concentrate energy and radiate in a specific direction, significantly improving the antenna's gain and directivity, enabling more accurate target detection and increasing detection range and accuracy. The power divider in the hybrid feed network rationally distributes power to each antenna element or linear array, while the main feed line transmits the signal. By adjusting the power distribution ratio of the power divider and the transmission characteristics of the main feeder, the antenna beam shape and direction can be flexibly controlled to meet the requirements of radar beams in different application scenarios.

[0040] One end of the inner conductor 51 of the coaxial feed structure 5 is connected to the center of the microstrip radiating patch 2, and the other end of the inner conductor 51 of the coaxial feed structure 5 passes through the dielectric substrate 1 and the ground layer 3. One end of the inner conductor of the coaxial feed structure is connected to the center of the microstrip radiating patch, and the other end passes through the dielectric substrate and the ground layer. This structure can provide a stable signal transmission path for the antenna, reduce signal loss and interference during transmission, ensure that the antenna can accurately receive and transmit signals, and improve the performance of the radar system. The coaxial feed structure can achieve good impedance matching with the microstrip radiating patch by adding quasi-coaxial through holes and adjusting the size of the microstrip line connected to the coaxial feed structure, thereby further improving signal transmission efficiency, reducing electromagnetic wave loss, and enabling the antenna to operate efficiently in the 35GHz frequency band.

[0041] The metallized through-holes 4 are quasi-coaxial through-holes. Several of these quasi-coaxial through-holes are arranged in a ring around the inner conductor 51 of the coaxial feed structure 5 and extend through the dielectric substrate 1. The quasi-coaxial through-holes are arranged in a ring around the inner conductor of the coaxial feed structure and extend through the dielectric substrate. Because the coaxial feed structure combined with the microstrip patch antenna generates inductive impedance, a ring of ground holes is added around the coaxial feed structure. These metallized through-holes 4 are located here to offset the inductive reactance, thereby achieving impedance matching and improving the antenna's anti-interference capability and radiation efficiency.

[0042] This embodiment demonstrates significant advantages in improving gain, directivity, beam control capability, signal transmission stability, impedance matching, and other aspects, and can meet the requirements of millimeter-wave radar for high-performance antennas in the 35 GHz frequency band.

[0043] The inner wall of the through-hole in the quasi-coaxial structure is coated with conductive metal. This conductive metal inner wall effectively reflects and absorbs electromagnetic waves, enhancing the electromagnetic shielding effect of the through-hole. It effectively isolates electromagnetic interference around the coaxial feed structure, reduces the impact of external signals on antenna performance, and reduces the leakage of electromagnetic waves radiated by the antenna itself. The main feed line includes multiple impedance transformation sections, each of which is one-quarter of the dielectric wavelength long. The impedance of each section decreases along the feed line. Each section is one-quarter of the dielectric wavelength long, and the impedance exhibits a Chebyshev distribution along the feed direction, achieving a high-gain, low-sidelobe, and narrow-beam radiation pattern. The antenna is linearly polarized. Linearly polarized antennas are relatively simple in structure, requiring minimal design and manufacturing effort. They can reduce the cost and complexity of radar systems, while also being compatible with other linearly polarized devices and facilitating system integration. The hybrid feed network utilizes a Chebyshev distribution. The Chebyshev distribution can effectively suppress the sidelobe level of the antenna array, improve the directivity coefficient of the antenna, enhance the mainlobe detection capability of the radar to the target, reduce sidelobe interference, and improve the radar's anti-interference performance and target recognition accuracy. The dielectric substrate 1 adopts a double-sided copper-clad laminate. The double-sided copper-clad laminate has good conductivity and processing performance, which is convenient for making microstrip radiation patches and grounding layers, can ensure the accuracy and consistency of the antenna structure, and improve the performance stability of the antenna. Preferably, the antenna array is 12×12. The array size of 12 rows and 12 columns can reasonably control the beam width while ensuring that the antenna has a high gain, so that the radar can achieve effective target detection in a larger range and meet the needs of different application scenarios. The antenna unit is a rectangular microstrip patch, and the linear array is a traveling wave series-fed array antenna. The rectangular microstrip patch antenna has a simple structure and is easy to integrate. The traveling wave series-fed array antenna can transmit the signal step by step between the antenna units to achieve traveling wave radiation, improve the radiation efficiency and bandwidth of the antenna, and enhance the radar's detection capability to the target. The length of the rectangular microstrip patch is:

[0044]

[0045]

[0046] in, L is the length of the microstrip radiation patch, is the waveguide wavelength, is the length of the equivalent gap, is the effective dielectric constant, W is the width of the microstrip radiation patch, h is the thickness of the dielectric substrate, is the speed of light, f is the resonant frequency of the antenna unit, is the relative dielectric constant of the dielectric substrate.

[0047] The inner wall of the through-hole in the quasi-coaxial structure provided in this embodiment is provided with conductive metal, which greatly enhances the electromagnetic shielding effect, effectively isolates external interference, reduces the leakage of its own electromagnetic waves, and improves anti-interference capabilities. The main feeder has a multi-stage impedance transformation section, and the length and impedance value of each stage are designed according to the Chebyshev distribution. This can reduce the sidelobe level, improve the directivity coefficient, enhance the mainlobe detection capability, reduce sidelobe interference, improve anti-interference and target recognition accuracy, and improve signal quality. The linear polarization method simplifies system design, reduces cost and complexity, and is also compatible with other linear polarization equipment. The double-sided copper-clad dielectric substrate is easy to process, ensures structural and precision consistency, and improves performance stability. The 12-row and 12-column array scale balances gain and beamwidth to meet the detection needs of multiple scenarios. The combination of rectangular microstrip patch units and traveling wave series and parallel feed line arrays achieves efficient radiation and improves bandwidth and detection capabilities.

[0048] Example 2 A vehicle-mounted radar uses the microstrip array antenna of the millimeter-wave radar in the first embodiment.

[0049] Example 3 A microstrip array antenna for 35GHz millimeter wave radar, see Figure 1 . Figure 1 This is a millimeter wave radar microstrip array antenna, comprising a dielectric substrate 1 with a thickness of 0.254 mm, using a Rogers 5880 dielectric substrate; a microstrip radiation patch 2; a ground layer 3; a metallized through hole 4; and a coaxial feed structure 5 using a 50Ω coaxial line. Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 , which is a two-dimensional graph structure.

[0050] Microstrip radiating patch 2 is printed on the front surface of dielectric substrate 1; ground layer 3 is printed on the back surface of dielectric substrate 1; inner conductor 51 of coaxial feed structure 5 passes through dielectric substrate 1 and is soldered to microstrip radiating patch 2; metallized through-hole 4 is embedded in dielectric substrate 1 to guide electromagnetic wave transmission. Coaxial feed structure 5 includes inner conductor 51, outer conductor, and insulation layer.

[0051] Microstrip radiating patch 2 adopts a hybrid feeding method of series and parallel connection. At the feeding port, 12 antenna units on both sides are connected in series through a main feed line, and the linear arrays on both sides are connected in parallel through a power divider. A main feed line and a power divider are connected in series and parallel to form a linear array 1×12. In order to meet the requirements of high gain and beam width, the number of arrays is increased and the main lobe width is reduced. The 12×12 microstrip array antenna is as follows: Figure 1 and Figure 2 As shown, the antenna array is fed from the reverse side of the dielectric substrate 1 through the inner conductor 51 of the coaxial probe.

[0052] The metallized through-hole 4 can be regarded as a quasi-coaxial structure for guiding the transmission of electromagnetic waves, which are input from the coaxial feeding structure 5 on one side and transmitted to the microstrip radiation patch 2. The setting of the quasi-coaxial structure can reduce the reflection and loss when the coaxial and microstrip lines are electrically connected.

[0053] When designing a microstrip antenna array, you first need to design microstrip antenna elements that meet the requirements, and then use these elements to form an array. This involves three operating principles: the design principle of microstrip patch elements, the equivalent circuit of a one-dimensional linear array, and the current weighting coefficient of the Chebyshev antenna array.

[0054] Microstrip patch unit design principle: A microstrip antenna is usually composed of a rectangular metal patch placed on the surface of a dielectric substrate 1 on a ground layer 3, such as Figure 6 This embodiment uses the transmission line theory to analyze the radiation principle of the rectangular microstrip antenna. The antenna structure is shown in the figure below. Figure 7 As shown in the figure, the length of the rectangular patch is L, the width is W, and the thickness of the dielectric substrate 1 is h. According to the transmission line theory, when the thickness of the dielectric substrate 1 is much smaller than the operating wavelength, the field distribution along h does not change. Assuming that the field distribution along W does not change, the field distribution of the transmission line under the main mode of excitation is as follows: Figure 8 shown.

[0055] The electric field at the two open ends can be decomposed into two components, one perpendicular to the floor and the other parallel to the floor. In the direction perpendicular to the ground plane 3, the two horizontal components of the electric field are the same, and the generated far-field fields are superimposed in phase, forming the maximum radiation direction. Therefore, the horizontal components of the electric field at the two open ends can be equivalent to two slits excited in the same direction on an infinite plane, such as Figure 9 As shown, the length of the gap is W and the width is , the distance between the two gaps is L, the tangent direction of the gaps is uniformly distributed along W, and the direction of the electric field is perpendicular to W.

[0056] If the resonant frequency of the antenna unit is f, then the width of its radiation patch is:

[0057] in, is the speed of light, is the relative dielectric constant of the dielectric substrate.

[0058] The length L of the radiating patch is usually ,in is the waveguide wavelength, and:

[0059] in, is the effective dielectric constant, and:

[0060] Due to the shortening effect of the edge, the actual length L of the radiating patch is:

[0061] Where is the length of the equivalent gap, and:

[0062] The equivalent circuit of a one-dimensional linear array is as follows Figure 10 As shown. Among them, Input admittance for each patch, and They are the characteristic admittances of the two quarter-wavelength impedance transformation sections. is the input admittance viewed from the i port to the right. The relative values of the currents of each patch are as follows:

[0063]

[0064] The feeding network uses To control the excitation of each unit in the waveguide wavelength impedance transformation section to achieve the purpose of reducing the side lobe, the spacing between each unit is .

[0065] The current weighting coefficient of the Chebyshev antenna array: The Chebyshev antenna array adjusts the current amplitude of each antenna unit to keep the sidelobe level of the radiation pattern consistent and lower than the main lobe, while the main lobe width is very narrow. The equiripple characteristics of the directional pattern are used to map the side lobes, and the main lobe corresponds to the polynomial in The peak value of the area.

[0066] Assuming the sidelobe level is SLL, the voltage ratio of the main lobe to the side lobe is:

[0067] satisfy ,in is the number of antenna elements.

[0068] Solve using hyperbolic functions:

[0069] Array Factor Corresponding Chebyshev polynomials:

[0070] in , , is the unit spacing.

[0071] Will Expanded into a cosine series, and the matrix factor expression:

[0072] Compare the coefficients to get the current amplitude of each unit .

[0073] for Element symmetrical array, current weighting coefficient By expanding And match the cosine term coefficient to determine the specific form and and Related, the formula is:

[0074] Before designing an array antenna, you need to determine the number of array elements and the spacing between them.

[0075] Assume that the total number of array antenna elements is , the 3dB beamwidth of the antenna H and E planes is known and The relationship between the directivity coefficient and beam width of the array antenna is:

[0076] According to the basic theory of uniform array, the number of known array elements is , the array element spacing is , then the 3dB beamwidth of the antenna can be expressed as

[0077] Using the above formula, given the half-power beamwidths of the antenna's H-plane and E-plane, the number of array elements required for the antenna can be calculated. After retaining a certain error margin, the final array size that meets the design requirements of this embodiment is 12×12.

[0078] The one-dimensional linear array in this embodiment belongs to a traveling wave series-fed array antenna. The terminal of the traveling wave series-fed network has a matching load. The incident wave is absorbed by the load, and the distribution of the electromagnetic wave on the feeder is a traveling wave distribution. The one-dimensional linear array has 12 units, namely , the feeding position is in the center and symmetrical, so only half of the linear array is studied and analyzed, such as Figure 11 The figure shows the principle diagram of the linear array structure. Taking the sidelobe level SLL = 20dB, the ratio of the current weighting coefficient calculated by the above formula is:

[0079] According to the one-dimensional linear array equivalent circuit model and formula, the relationship between the impedance matching characteristic impedance of the first quarter of each array element and the current amplitude can be obtained as follows:

[0080] By customizing the main feeder line impedance to 100Ω, the characteristic impedance of the first quarter impedance matching section of each array element can be calculated. The impedance of each matching section can be used to calculate the feeder line width and length for each matching section in the transmission line calculator, ensuring that the array element current excitation amplitude follows a Chebyshev distribution, thereby increasing the array antenna gain and reducing sidelobes.

[0081] This embodiment adopts a hybrid feeding method of series and parallel connection; uses Chebyshev distribution to reduce the sidelobe level of the array antenna; and adopts a coaxial-like feeding method to achieve impedance matching between the coaxial line and the microstrip line.

[0082] The simulation results of this embodiment are as follows Figure 12 、 Figure 13 、 Figure 14 shown.

[0083] Figure 12 VSWR stands for voltage standing wave ratio. When VSWR equals 1, the impedance of the feeder and antenna are perfectly matched. At this point, all high-frequency energy is radiated by the antenna, with no energy reflection loss, representing the ideal situation. The horizontal axis represents frequency, and the vertical axis represents VSWR. The impedance bandwidth for an VSWR less than 1.8 is 34.5-35.5 GHz, with a bandwidth of 1 GHz.

[0084] Figure 13 This represents the E-plane gain pattern at 35 GHz, with theta representing the elevation angle and phi representing the azimuth angle. The E-plane normal gain is 28.5 dBi, the 3 dB beamwidth is 7.1°, and the first sidelobe level is 22.4 dB.

[0085] Figure 14 This represents the H-plane gain pattern at 35 GHz, with theta being the elevation angle and phi being the azimuth angle. The H-plane normal gain is 28.5 dBi, the 3 dB beamwidth is 6.3°, and the first sidelobe level is 20 dB.

[0086] The impedance bandwidth of the antenna port standing wave ratio of this embodiment is less than 1.8, which is 1 GHz; the antenna polarization mode is linear polarization; the E-plane normal gain at the center frequency of the antenna is 28.5 dBi, the 3dB beamwidth is 7.1°, and the first sidelobe level is 22.4 dB; the H-plane normal gain at the center frequency of the antenna is 28.5 dBi, the 3dB beamwidth is 6.3°, and the first sidelobe level is 20 dB; the antenna adopts a hybrid feeding mode of series and parallel connection; and a quasi-coaxial feeding mode is adopted to achieve impedance matching between the coaxial and microstrip lines.

[0087] The millimeter-wave radar microstrip array antenna method of this embodiment has been verified by simulation and is completely feasible. It can meet the application requirements of 35GHz millimeter-wave radar and has good radiation performance.

[0088] The antenna array of this embodiment is linearly polarized, with a bandwidth of 1 GHz, a normal gain of 28.5 dBi, a first sidelobe level greater than 20 dB, and an E-plane and H-plane half-power beamwidth greater than 4°, with high gain, low sidelobe, and low-profile radiation performance. The array antenna is processed on a double-sided copper-clad plate through an etching and engraving process, and has the characteristics of high processing precision, simple process, and easy mass production. The array antenna structure of this embodiment can achieve high gain and strong directivity, has the characteristics of low profile and low cost, is easy to miniaturize and mass produce, and can be used in millimeter wave radar systems. This embodiment has a low profile and can be implemented with only one double-sided plate, which is easy to process, low cost, and easy to mass produce; the antenna has high gain and a narrow beamwidth, which can effectively achieve directional radiation; the antenna has low sidelobes, which can effectively improve the detection and positioning capabilities of the radar and help reduce signal interference.

[0089] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of the present teachings should be determined not with reference to the foregoing description, but rather with reference to the preceding claims, along with the full scope of equivalents to which such claims are entitled. For the purpose of completeness, all articles and references, including the disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the preceding claims is not a disclaimer of such subject matter, nor should it be interpreted that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0090] The above content is a further detailed description of the present invention, and it cannot be considered that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as belonging to the determined protection scope of the present invention submitted.

Claims

1. A microstrip array antenna for millimeter wave radar, characterized in that: It includes a dielectric substrate (1), a microstrip radiation patch (2), a ground layer (3), a metallized through hole (4) and a coaxial feeding structure (5); A microstrip radiation patch (2) is provided on one side of the dielectric substrate (1), and a ground layer (3) is covered on the other side of the dielectric substrate (1); The microstrip radiation patch (2) includes a rectangular array of antenna units and a hybrid feed network, the hybrid feed network includes a power divider and a main feed line, the rectangular array of antenna units includes a plurality of linear arrays connected in parallel via the power divider, and a single linear array includes a plurality of antenna units connected in series via the main feed line; One end of the inner conductor (51) of the coaxial feeding structure (5) is connected to the center of the microstrip radiation patch (2), and the other end of the inner conductor (51) of the coaxial feeding structure (5) passes through the dielectric substrate (1) and the ground layer (3); The metallized through hole (4) is a quasi-coaxial structure through hole, and a plurality of the quasi-coaxial structure through holes are provided. The plurality of quasi-coaxial structure through holes are distributed in a ring shape around the inner conductor (51) of the coaxial feeding structure (5), and the quasi-coaxial structure through holes are provided through the dielectric substrate (1).

2. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: Conductive metal is provided on the surface of the through hole of the quasi-coaxial structure.

3. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: The main feeder includes a multi-stage impedance transformation section, the length of each stage of the multi-stage impedance transformation section is a quarter of the medium wavelength, and the impedance value of each stage of the multi-stage impedance transformation section decreases along the feeder direction.

4. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: The polarization mode of the antenna is linear polarization.

5. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: The hybrid feeding network adopts Chebyshev distribution.

6. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: The dielectric substrate (1) is a double-sided copper-clad plate.

7. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: The linear array is a traveling wave series-fed array antenna.

8. The microstrip array antenna for millimeter wave radar according to claim 1, characterized in that: The antenna unit is a rectangular microstrip patch.

9. The microstrip array antenna for millimeter wave radar according to claim 8, characterized in that: The length of the rectangular microstrip patch is: in, L is the length of the microstrip radiation patch, is the waveguide wavelength, is the length of the equivalent gap, is the effective dielectric constant, W is the width of the microstrip radiation patch, h is the thickness of the dielectric substrate, is the speed of light, f is the resonant frequency of the antenna unit, is the relative dielectric constant of the dielectric substrate.

10. A vehicle-mounted radar, characterized in that: A microstrip array antenna for a millimeter-wave radar using the method described in any one of claims 1 to 9.

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