Microstrip Array Antenna

Abstract

The embodiment of the present invention discloses a microstrip array antenna, wherein the microstrip array antenna is an M×N array antenna, the microstrip array antenna is composed of T m×n array antennas connected by a microstrip-waveguide converter and a waveguide combiner, the m×n array antenna is composed of m 1×n linear array antennas connected by a microstrip power divider, and the 1×n linear array antenna is composed of n antenna units, wherein M is an integer multiple of m, N is an integer multiple of n, T is a positive even number, and m and n are both integers. The technical solution of this embodiment achieves the performance of high gain, narrow beam, and wide bandwidth by combining microstrip feeding and waveguide feeding.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of antenna technology, and in particular to a microstrip array antenna. Background Art

[0002] Antenna is an important radio device in the communication system, and its performance will directly affect the performance of the radio device. In the millimeter wave K band radar system, in order to achieve high gain and narrow beam, especially when the detection distance exceeds 3000m, waveguide slot antennas or other large and irregular antennas are usually used, which will make the entire radar system bulky and not conducive to product miniaturization and cost reduction.

[0003] Microstrip array antennas have attracted extensive attention due to their small size, light weight, low profile, and easy commonality. They also have the advantages of low cost, easier integration, and mass production. However, the unit gain of microstrip antennas is generally 6dBi to 8dBi, but it is difficult to achieve high gain and narrow beam, especially to achieve a gain higher than 30dB and a beam less than 1.5° using microstrip array antennas. Summary of the invention

[0004] The embodiment of the present invention provides a microstrip array antenna, which achieves the performance of high gain, narrow beam and wide frequency bandwidth.

[0005] In a first aspect, an embodiment of the present invention provides a microstrip array antenna, which is an M×N array antenna. The microstrip array antenna is composed of T m×n array antennas connected by a microstrip-waveguide converter and a waveguide combiner. The m×n array antenna is composed of m 1×n linear array antennas connected by a microstrip power divider. The 1×n linear array antenna is composed of n antenna units, wherein M is an integer multiple of m, N is an integer multiple of n, T is a positive even number, and m and n are both integers.

[0006] Furthermore, the antenna unit includes an antenna patch unit and a dielectric substrate; wherein the antenna patch unit is a rectangular patch, and the rectangular patch is fed by side feeding; the thickness of the dielectric substrate is 0.254 mm, the dielectric constant is 2.2, and the material is Rogers 5880 plate.

[0007] Furthermore, every two 1×n linear array antennas are arranged symmetrically.

[0008] Furthermore, the feed width between two adjacent antenna units from the middle to the right constitutes a first geometric progression, and the feed width between two adjacent antenna units from the middle to the left constitutes a first geometric progression.

[0009] Furthermore, the common ratio of the first geometric progression is a first value, and the first value is any value between 0.95 and 1.

[0010] Furthermore, the unit widths between two adjacent antenna units from the middle to the right constitute a second geometric progression, and the unit widths between two adjacent antenna units from the middle to the left constitute a second geometric progression.

[0011] Furthermore, the common ratio of the second geometric progression is a second value, and the second value is any value between 0.9 and 1.

[0012] Furthermore, the length of the main feed line in the 1×n linear array antenna is 2.2 mm, and the width is any value between 0.4 mm and 1.2 mm.

[0013] Furthermore, the microstrip array antenna includes at least 4 microstrip line output ends, and the microstrip line output ends first change the impedance of the main feed line to 100 ohms through a quarter-wavelength impedance, and then change 100 ohms to 50 ohms through a quarter-wavelength impedance.

[0014] Specifically, n is 30.

[0015] The microstrip array antenna provided in the above embodiment, wherein the microstrip array antenna is an M×N array antenna, the microstrip array antenna is composed of T m×n array antennas connected by a microstrip-waveguide converter and a waveguide combiner, the m×n array antenna is composed of m 1×n linear array antennas connected by a microstrip power divider, and the 1×n linear array antenna is composed of n antenna units, wherein M is an integer multiple of m, N is an integer multiple of n, T is a positive even number, and m and n are both integers. The technical solution of this embodiment achieves the performance of high gain, narrow beam, and wide bandwidth by combining microstrip feeding and waveguide feeding. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a microstrip array antenna provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of the overall antenna structure of an 8×60 microstrip array antenna provided by an embodiment of the present invention with a feeding waveguide added;

[0018] Figure 3 is a schematic diagram of a 1×60 array antenna provided by an embodiment of the present invention;

[0019] Figure 4 is a schematic diagram of an antenna unit provided by an embodiment of the present invention;

[0020] Figure 5 is a graph of S11 of an 8×60 microstrip array antenna provided in an embodiment of the present invention;

[0021] Figure 6 It is the overall two-dimensional radiation pattern of the 8×60 microstrip array antenna provided by the embodiment of the present invention;

[0022] Figure 7 This is the overall three-dimensional radiation pattern of the 8×60 microstrip array antenna and the overall three-dimensional radiation pattern of the 8×8 microstrip array antenna. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0024] In one embodiment, Figure 1 A schematic diagram of a microstrip array antenna provided in an embodiment of the present invention, Figure 2 The overall antenna structure diagram of the 8×60 microstrip array antenna provided by the embodiment of the present invention with the feeding waveguide added. Figure 1 and Figure 2 As shown, the microstrip array antenna is an M×N array antenna, which is composed of T m×n array antennas 11 connected by a microstrip-waveguide converter and a waveguide combiner, and the m×n array antenna is composed of m 1×n linear array antennas 12 connected by a microstrip power divider, and the 1×n linear array antenna is composed of n antenna units 13, wherein M is an integer multiple of m, N is an integer multiple of n, T is a positive even number, and m and n are both integers. Specifically, the M×N array antenna is composed of M 1×N linear array antennas.

[0025] Wherein, M can be understood as the number of transverse antenna units in the microstrip array antenna, and N can be understood as the number of longitudinal antenna units in the microstrip array antenna. The values ​​of M and N can be determined according to the design requirements of the microstrip array antenna, and are not limited in this embodiment. Further, in this embodiment, n is preferably 30.

[0026] The microstrip array antenna provided in this embodiment is mainly used in radar systems, and is mainly used in radar systems in the millimeter wave K band. Specifically, the above-mentioned microstrip array antenna is mainly a flat microstrip array antenna for anti-UAV radar.

[0027] It should be noted that Figure 1 In the figure, T=4, M=8, N=60, m=4, and n=30 are used as an example for illustration. In this embodiment, the specific values ​​of the parameters T, M, N, m, and n are not limited.

[0028] Specifically, in this embodiment, the M×N array antenna is an 8×60 array antenna. The 8×60 microstrip array antenna is an array element that is equivalent to a 1×30 linear array antenna. The 1×30 linear array antenna is first combined into a 4×30 array, and then combined into an 8×60 array. The connection method is to first use a microstrip power divider to connect to form a 4×30 array, and then pass through a microstrip-waveguide converter, and then a waveguide combiner to combine four 4×30 arrays into an 8×60 microstrip array antenna. Specifically, the 8×60 array antenna is composed of 8 1×60 linear array antennas.

[0029] Among them, the microstrip power divider generally includes a microstrip line, a microwave dielectric substrate and a ground plate. The microstrip line is processed on one side of the microwave dielectric substrate through printed circuit board technology, and the other side is a ground plate. The microstrip line is connected into a square, and each side of the square is composed of 2 sections of equivalent 1 / 4 wavelength microstrip lines. The intersection of the 2 sections of equivalent 1 / 4 wavelength microstrip lines on the left and right sides of the square is connected by an equivalent 1 / 2 wavelength microstrip line; at the four corner points of the square and at the intersection of the 2 sections of equivalent 1 / 4 wavelength microstrip lines on the upper and lower sides; the equivalent 1 / 4 wavelength or 1 / 2 wavelength microstrip line is formed by a microstrip line with a length less than 1 / 4 wavelength or 1 / 2 wavelength connected to a grounding capacitor through capacitor loading technology.

[0030] Among them, microstrip-waveguide converter refers to an electrical component or circuit that converts a microstrip line into a waveguide. The commonly used microstrip-waveguide converter is to insert a microstrip probe from the center of the waveguide wide side. One is that the dielectric surface is perpendicular to the waveguide transmission square, called the H-plane probe, and the other is that the dielectric surface is parallel to the waveguide transmission direction, called the E-plane probe.

[0031] The waveguide combiner can be a two-way combiner, a three-way combiner, and a 2 p ×3 q Wherein, p and q are non-negative integers. In this embodiment, only the waveguide combiner is described, but not limited.

[0032] Furthermore, according to theory, if the number of antenna units is doubled, the antenna gain increases by about 3dBi. It can be roughly inferred that excluding the feed loss, the gain of the 8×60 array antenna is about 32dBi.

[0033] Among them, the microstrip antenna is an antenna unit composed of a thin metal layer attached to one side of a thin dielectric substrate as a ground plane, a metal patch of a certain shape made by photolithography and etching on the other side, and a microstrip line used to feed the patch.

[0034] Furthermore, each of the two 1×n linear array antennas are bilaterally symmetrically arranged. Specifically, Figure 3 is a schematic diagram of a 1×60 array antenna provided by an embodiment of the present invention, such as Figure 3As shown, the 1×60 microstrip linear array antenna is composed of two 1×30 array antennas, which are mainly used to design horizontal beams and horizontal side lobes. Among them, the two 1×30 array antennas are symmetrically arranged.

[0035] The feed widths between two adjacent antenna units from the middle to the right constitute a first geometric progression, and the feed widths between two adjacent antenna units from the middle to the left constitute a first geometric progression. The common ratio of the first geometric progression is a first value, and the first value is any value between 0.95 and 1.

[0036] Specifically, the feeding width between adjacent antenna units satisfies the following formula:

[0037] H i =K×H i-1 ;

[0038] Among them, H i is the feed width between the ith antenna element and the i+1th antenna element, H i-1 is the feed width between the i-1th antenna unit and the i-th antenna unit, i is an integer greater than or equal to 2, and K is any value between 0.95 and 1. Starting from the middle, the first antenna unit on the right is the 1st antenna unit, and then to the right are the 2nd antenna unit, the 3rd antenna unit, ..., the i-1th antenna unit, the i-th antenna unit, the +1th antenna unit, ..., the nth antenna unit. Starting from the middle, the first antenna unit on the left is the 1st antenna unit, and then to the left are the 2nd antenna unit, the 3rd antenna unit, ..., the i-1th antenna unit, the i-th antenna unit, the +1th antenna unit, ..., the nth antenna unit.

[0039] Specifically, the feeding width between the first antenna unit and the second antenna unit is H1, the feeding width between the second antenna unit and the third antenna unit is H2, the feeding width between the third antenna unit and the fourth antenna unit is H3, and so on. The feeding width between the 29th antenna unit and the 30th antenna unit is H29, and their relationship is H30=K×H29, H29=K×H28, H28=K×H27, and so on. H2=K×H1, and K is in the range of 0.95 to 1.

[0040] The unit widths between two adjacent antenna units from the center to the right constitute a second geometric progression, and the unit widths between two adjacent antenna units from the center to the left constitute a second geometric progression. The common ratio of the second geometric progression is a second value, and the second value is any value between 0.9 and 1.

[0041] Specifically, the unit width between two adjacent antenna units satisfies the following formula:

[0042] W i =S×W i-1

[0043] Among them, W i is the feed width of the ith antenna element, W i-1 is the feed width of the i-1th antenna unit, i is an integer greater than or equal to 2, and S is any value between 0.9 and 1.

[0044] Among them, starting from the middle, the first antenna unit on the right is the 1st antenna unit, and then to the right are the 2nd antenna unit, the 3rd antenna unit, ..., the i-1th antenna unit, the i-th antenna unit, the +1th antenna unit, ..., the nth antenna unit. Starting from the middle, the first antenna unit on the left is the 1st antenna unit, and then to the left are the 2nd antenna unit, the 3rd antenna unit, ..., the i-1th antenna unit, the i-th antenna unit, the +1th antenna unit, ..., the nth antenna unit.

[0045] Specifically, the unit width of the first antenna unit is W1, the unit width of the second antenna unit is W2, the unit width of the third antenna unit is W3, and so on. The unit width of the 30th antenna unit is W30. The near-and-far tapered distribution method is adopted. W2=W1×S, W3=W2×S, W4=W3×S, and so on. W30=W29×S. S is any value between 0.9 and 1.

[0046] Furthermore, Figure 4 is a schematic diagram of an antenna unit provided by an embodiment of the present invention, such as Figure 4 As shown, the feed width between the two adjacent antenna units is Figure 4 The width of the left rectangle in the figure, the unit width of the above antenna unit is Figure 4 The width of the right square.

[0047] Furthermore, the antenna unit includes an antenna patch unit and a dielectric substrate; wherein the antenna patch unit is a rectangular patch, and the rectangular patch is fed by side feeding; the thickness of the dielectric substrate is 0.254 mm, the dielectric constant is 2.2, and the material is Rogers 5880 plate.

[0048] Specifically, the dielectric substrate is a Rogers 5880 dielectric substrate with a thickness of 0.254 mm and a dielectric constant of 2.2; the antenna patch unit is a rectangular patch, the preliminary size of the rectangular patch is calculated according to the transmission line model method and the resonant cavity model method, and the rectangular patch is fed by side feeding.

[0049] The above antenna unit is also called a microstrip antenna unit, wherein the basic structure of the microstrip antenna unit is a metal patch attached to an electrically thin, grounded dielectric substrate, and the metal patch has various shapes, such as rectangular, circular, ring, pentagonal, etc., and in order to meet the performance required for a specific application, more complex structural changes are usually made on the basic graphics. The microstrip antenna unit has the advantages of low profile, small size, light weight, easy conformality, low cost, good integration, and diversified electrical performance; however, the microstrip patch antenna also has some disadvantages that limit its application, such as narrow impedance bandwidth, poor polarization purity, low radiation efficiency, poor power handling capacity, poor scanning characteristics, and easy to excite surface waves.

[0050] Furthermore, the length of the main feed line in the 1×n linear array antenna is 2.2 mm, and the width is any value between 0.4 mm and 1.2 mm.

[0051] Specifically, the length is 2.2 mm and the width is between 0.4 and 1.2 mm. The input impedance of the 1×30 array antenna is optimized to pure impedance for power divider design. By changing the width of the main feed line, the pure impedance of the antenna input can be changed, which can facilitate the design of antennas with different power division ratios.

[0052] Furthermore, the microstrip array antenna includes at least 4 microstrip line output ends, and the microstrip line output ends first change the impedance of the main feed line to 100 ohms through a quarter-wavelength impedance, and then change 100 ohms to 50 ohms through a quarter-wavelength impedance.

[0053] Specifically, the four microstrip lines of the 8×60 microstrip array antenna first output a quarter-wavelength impedance to change the main feed to 100 ohms, making the line thinner, reducing coupling and facilitating routing. Then, the 100 ohms are changed to 50 ohms through a quarter-wavelength impedance.

[0054] Furthermore, the specific parameters of the microstrip array antenna are: the size of the entire 8×60 microstrip array antenna is 500mm×50mm×5mm, the gain of the 8×60 microstrip array antenna is 30.5dBi, the E-plane 3dB beamwidth of the 8×60 microstrip array antenna is 1.4°, the H-plane 3dB beamwidth of the 8×60 microstrip array antenna is 26°, the E-plane sidelobe level of the 8×60 microstrip array antenna is -22.6dB, and the H-plane sidelobe level of the 8×60 microstrip array antenna is -24.7dB.

[0055] Among them, the beam width is divided into horizontal beam width and vertical beam width. The horizontal beam width refers to the angle between the two directions where the radiation power drops by 3dB on both sides of the maximum radiation direction in the horizontal direction; the vertical beam width refers to the angle between the two directions where the radiation power drops by 3dB on both sides of the maximum radiation direction in the vertical direction. In radar meteorology, the beam width refers to the angle between the two half-power points of the beam, which is related to the antenna gain. Generally, the greater the antenna gain, the narrower the beam and the higher the detection angle resolution.

[0056] Antenna gain refers to the ratio of the power density of the signal generated by the actual antenna and the ideal radiating unit at the same point in space under the condition of equal input power. It quantitatively describes the degree to which an antenna radiates the input power. The gain is closely related to the antenna pattern. The narrower the main lobe of the pattern, the smaller the side lobe, and the higher the gain. Antenna gain is used to measure the ability of an antenna to send and receive signals in a specific direction. It is one of the most important parameters for selecting base station antennas.

[0057] Among them, the E plane of the antenna refers to the plane passing through the maximum radiation direction of the antenna and parallel to the electric field vector; the H plane of the antenna refers to the plane passing through the maximum radiation direction of the antenna and parallel to the magnetic field vector.

[0058] The sidelobe level refers to the logarithmic value of the ratio of the power density in the maximum radiation direction of the sidelobe to the power density in the maximum radiation direction of the main lobe, expressed in dB. Usually, the sidelobe level close to the main lobe is higher than that far away, so the sidelobe level usually refers to the first sidelobe level. Generally, the sidelobe level is required to be as low as possible.

[0059] Figure 5 The S11 curve of the 8×60 microstrip array antenna provided by the embodiment of the present invention, wherein the parameter S11 is one of the S parameters, indicating the return loss characteristics, generally through the network analyzer to see the loss dB value and impedance characteristics, this parameter is used to indicate the transmission efficiency of the antenna, the larger the value, the greater the energy reflected back by the antenna itself, and the worse the efficiency of the antenna. Figure 5 As shown, it can be seen from the curve of parameter S11 that the bandwidth range of the 8×60 microstrip array antenna provided in this embodiment is 24.18 GHz-25.62 GHz, and the bandwidth is about 500 MHz.

[0060] Figure 6 is the overall two-dimensional directional pattern of the 8×60 microstrip array antenna provided by an embodiment of the present invention, Figure 7It is the overall three-dimensional radiation pattern of 8×60 microstrip array antenna × the overall three-dimensional radiation pattern of 8 microstrip array antenna, where the antenna radiation pattern is also called the radiation pattern (radiation pattern) and the far-field radiation pattern (far-field pattern), which refers to the graph of the relative field strength of the radiation field changing with the direction at a certain distance from the antenna, usually represented by two mutually perpendicular plane radiation patterns in the direction of the maximum radiation of the antenna; ultra-high frequency antennas are usually represented by two planes parallel to the field vector, namely the E plane radiation pattern and the H plane radiation pattern; in order to facilitate the comparison of the radiation pattern characteristics of various antennas, it is necessary to specify some characteristic parameters, mainly including: main lobe width, side lobe level and other parameters; the main lobe width is a physical quantity that measures the sharpness of the maximum radiation area of ​​the antenna, usually taken as the width between the two half-power points of the main lobe of the antenna radiation pattern; the side lobe level refers to the level of the first side lobe closest to the main lobe and with the highest level, generally expressed in decibels. Such as Figure 6 and Figure 7 As shown, the E-plane 3dB beamwidth of the 8×60 microstrip array antenna is 1.4°, the H-plane 3dB beamwidth of the 8×60 microstrip array antenna is 26°, the E-plane sidelobe level of the 8×60 microstrip array antenna is -22.6dB, and the H-plane sidelobe level of the 8×60 microstrip array antenna is -24.7dB.

[0061] In one embodiment, the microstrip array antenna is manufactured in the following manner:

[0062] S1. Select the substrate material of the microstrip array antenna unit, and obtain the best microstrip array antenna unit by calculating the antenna size and simulation optimization;

[0063] S2. Use the High Frequency Structure Simulator (HFSS) antenna simulation tool to simulate the 1×60 microstrip linear array antenna model, and adjust the feed line width and length of each unit to achieve the requirements of high gain, narrow beam, high efficiency, and strong directivity.

[0064] Among them, HFSS is a three-dimensional electromagnetic simulation software and the world's first commercial three-dimensional structural electromagnetic field simulation software. HFSS provides a simple and intuitive user design interface, a precise and adaptive field solver, and a powerful post-processor with unprecedented electrical performance analysis capabilities. It can calculate the S parameters and full-wave electromagnetic fields of three-dimensional passive structures of any shape. HFSS software has powerful antenna design functions. It can calculate antenna parameters such as gain, directivity, far-field pattern profile, far-field 3D diagram and 3dB bandwidth; draw polarization characteristics, including spherical field components, circular polarization field components, Ludwig third definition field components and axial ratio. S3, using series feeding, microstrip-waveguide converter and waveguide to form an 8×60 microstrip array antenna, while satisfying the same phase of excitation of each array element, reducing feeder loss and reducing antenna size.

[0065] The microstrip array antenna provided in the embodiment of the present invention adopts a 30-unit array as a serial-fed subarray, and realizes high gain and narrow beam through different feeding widths H and unit widths W. Then, the left 30-unit subarray and the right 30-unit subarray are equivalent to a 1×60 horizontal array, and finally high gain, narrow beam and wide bandwidth performance are obtained by combining microstrip feeding and waveguide feeding.

[0066] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A microstrip array antenna, wherein the microstrip array antenna is an M×N array antenna, characterized in that: The microstrip array antenna is composed of T m×n array antennas connected by a microstrip-waveguide converter and a waveguide combiner, the m×n array antenna is composed of m 1×n linear array antennas connected by a microstrip power divider, and the 1×n linear array antenna is composed of n antenna units, wherein M is an integer multiple of m, N is an integer multiple of n, T is a positive even number, and m and n are both integers; The feed width and unit width adopt near and far tapered distribution mode; The microstrip array antenna includes at least 4 microstrip line output ends, and the microstrip line output ends first change the impedance of the main feeder line to 100 ohms through a quarter-wavelength impedance, and then change 100 ohms to 50 ohms through a quarter-wavelength impedance; Every two 1×n linear array antennas are set symmetrically on the left and right; The feed widths between two adjacent antenna units from the middle to the right constitute a first geometric progression, and the feed widths between two adjacent antenna units from the middle to the left constitute a first geometric progression; The unit widths between two adjacent antenna units from the center to the right form a second geometric progression, and the unit widths between two adjacent antenna units from the center to the left form a second geometric progression.

2. The microstrip array antenna according to claim 1, characterized in that: The common ratio of the first geometric progression is a first value, and the first value is any value between 0.95 and 1.

3. The microstrip array antenna according to claim 1, characterized in that: The common ratio of the second geometric progression is a second value, and the second value is any value between 0.9 and 1.

4. The microstrip array antenna according to claim 1, characterized in that: The antenna unit includes an antenna patch unit and a dielectric substrate; wherein the antenna patch unit is a rectangular patch, and the rectangular patch is fed by side feeding; the dielectric substrate has a thickness of 0.254 mm, a dielectric constant of 2.2, and is made of Rogers 5880 plate.

5. The microstrip array antenna according to claim 1, characterized in that: The length of the main feed line in the 1×n linear array antenna is 2.2 mm, and the width is any value between 0.4 mm and 1.2 mm.

6. The microstrip array antenna according to claim 1, characterized in that: n is 30.

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