Ka-band low-cost dual circularly polarized wide-angle scanning microstrip array antenna

Abstract

The application discloses a Ka-band low-cost double-circular polarization wide-angle scanning microstrip array antenna and belongs to the field of mechanically aided scanning antenna arrays. The antenna comprises a lower metal plate, a dielectric layer and an upper metal plate. The lower metal plate is provided with a feed network. The dielectric layer comprises a dielectric disc located in the middle and two dielectric substrate flat waveguides symmetrically arranged on the left and right sides of the dielectric disc. The dielectric disc is used for realizing double-circular polarization radiation and can rotate to realize mechanical auxiliary scanning. The upper metal plate is used for fixing the dielectric layer and is provided with a circular through hole for placing a shielding radiation aperture. The antenna solves the problems of the traditional VICTS antenna design, i.e. linear polarization, great influence of multipath interference, disadvantage for satellite communication, the traditional Pillbox antenna design, i.e. limited beam coverage range and scanning angle, and has the characteristics of wide beam scanning range, circular polarization, low profile and low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of mechanically assisted scanning antenna array, and relates to a large-angle scanning and dual-circularly polarized antenna array, in particular to left-handed circular polarization and right-handed circular polarization applied to left feed port and right feed port antennas respectively. BACKGROUND

[0002] Vehicle-mounted satellite communication needs an antenna solution with a wide beam scanning range, circular polarization, low profile and relatively low cost. In satellite communication, circularly polarized waves are less affected by multipath effects and polarization distortion, and have no strict placement attitude requirements for receiving antennas, so circularly polarized antennas are generally used in satellite communication systems. Dual circular polarization can adapt to various signal polarizations, avoid signal reception difficulties, and effectively improve the channel capacity of the system by providing two orthogonal polarization modes. Compared with single circularly polarized antennas, dual circularly polarized antennas have greater advantages in satellite communication.

[0003] Advanced electrically scanned phased arrays have the characteristics of large-angle scanning and low profile, but the cost is relatively high; mechanical scanning is a lower-cost option, but has a high three-dimensional profile and slow scanning speed. Therefore, a planar mechanically assisted scanning that combines the advantages of electrically scanned phased arrays and mechanical scanning becomes an ideal low-profile, low-cost solution.

[0004] Common planar mechanically assisted scanning antennas include planar lens antennas, Pillbox-type antennas and VICTS antennas. Planar lens antennas are end-fire antennas, so they are not suitable for vehicle-mounted satellite communication antennas. Pillbox antennas have a lower profile, are more conducive to integration, and are suitable for multi-polarization design, but their scanning angle is usually small due to the influence of the metal box, and they cannot be continuously scanned, so the beam coverage range of the antenna is small. VICTS antennas have the characteristics of continuous large-angle scanning, but their overall profile is very high due to the separation of the radiation layer and the feed layer, which is not conducive to integration on the roof of a vehicle, and traditional VICTS antennas are mostly linearly polarized or single-polarized, which are not suitable for multi-polarization design. SUMMARY

[0005] In view of the problems of the traditional VICTS antenna design that the polarization is linear polarization, which is greatly affected by multipath interference and is not conducive to satellite communication, and the limited beam coverage range and small scanning angle of the traditional Pillbox antenna design, the application provides a dual-circularly polarized large-angle scanning low-cost microstrip antenna working at Ka. The antenna works at 27.0GHz-31.0GHz, and can fully meet the working needs of Ka-band low-orbit satellite communication and mobile communication.

[0006] The specific technical solutions adopted by the application are as follows:

[0007] A dual circularly polarized wide-angle scanning low-cost microstrip antenna operating at Ka band, characterized in that the antenna is left-right mirror-symmetrical and comprises, from bottom to top, a lower metal plate, a dielectric layer, and an upper metal plate;

[0008] The lower metal plate is provided with a feed network comprising two feed branches arranged left-right symmetrically, and the two feed branches are used for converting input signals into Quasi-TEM modes and feeding the input ports of the left and right dielectric substrate slab waveguides, respectively; meanwhile, the upper surface of the lower metal plate is provided with a groove matching the shape of the dielectric layer for accommodating and fixing the dielectric layer.

[0009] The dielectric layer comprises a dielectric disc in the middle and two dielectric substrate slab waveguides symmetrically arranged on the left and right sides of the dielectric disc; wherein the dielectric substrate slab waveguides are used for transmitting the fed Quasi-TEM modes to the dielectric disc; the dielectric disc is used for realizing circularly polarized radiation, and when the dielectric disc receives the Quasi-TEM modes of the left feed branch, right circular polarization is realized, and when the dielectric disc receives the Quasi-TEM modes of the right feed branch, left circular polarization is realized; meanwhile, the dielectric disc can rotate left and right under external driving, thereby changing the beam pointing direction and realizing mechanical auxiliary scanning.

[0010] The upper metal plate is used for pressing and fixing the dielectric layer, and the middle area is provided with a circular through hole with a radius smaller than that of the direct disc and larger than that of the radiation aperture of the dielectric disc.

[0011] Preferably, the dielectric disc comprises a circular dielectric substrate and copper layers on the upper and lower surfaces thereof, wherein the middle part of the copper layer on the upper surface is provided with a radiation structure; the radiation structure comprises a plurality of parallel microstrip transmission lines and a plurality of radiation units; the radiation units are arranged in a triangular lattice, and each radiation unit is composed of four rectangular radiation patches on both sides of the microstrip transmission line, each rectangular radiation patch has one top corner connected to the microstrip transmission line, and the spacing between the top corners in the electromagnetic wave propagation direction is one-quarter of the working wavelength; meanwhile, the rectangular radiation patches are rotated by 90° in sequence to realize dual circular polarization.

[0012] Preferably, the middle part of the radiation patch is provided with a U-shaped groove to reduce the volume of the radiation patch.

[0013] Preferably, the two ends of the microstrip transmission line are provided with trapezoidal transition structures to optimize the matching.

[0014] Preferably, the medium substrate flat plate waveguide comprises a medium substrate and its upper and lower copper-coated layers, the outer side of the medium substrate is arc-shaped, the inner side is semicircular, and a stepped structure is arranged along the electromagnetic wave transmission direction; the outer edge of the lower copper-coated layer of the medium substrate is etched with an arc-shaped groove matching the shape of the output port of the feed network as the input port of the medium substrate flat plate waveguide, and the output port of the medium substrate flat plate waveguide is a cylindrical surface close to the medium disc.

[0015] Preferably, the feed network is divided into left and right parts, wherein the left part comprises a stepped matching waveguide, a planar horn, a trapezoidal planar waveguide, and a planar wave transition structure, and the right part is mirror-symmetric to the left part; wherein the stepped matching waveguide is vertically arranged, its input port is a standard waveguide port and is located at the bottom of the lower metal plate, and is used for feeding the input signal into the planar horn; the planar horn is horizontally arranged in the lower metal plate, and is used for converting the input signal into TE10 mode and feeding it into the trapezoidal planar waveguide; the trapezoidal planar waveguide is horizontally arranged in the lower metal plate, and is used for converting the TE10 mode into Quasi-TEM mode and feeding it into the planar wave transition structure; and the planar wave transition structure is used for feeding the Quasi-TEM mode into the medium substrate flat plate waveguide above.

[0016] Preferably, the planar wave transition structure is realized by a special-shaped stepped waveguide, which is composed of a planar waveguide and a convex parabolic special-shaped waveguide, and a stepped matching transition structure is arranged at the connection between the planar waveguide and the parabolic special-shaped waveguide, and the lower side of the planar waveguide is cut at an angle to optimize the matching; the planar waveguide is used for guiding the Quasi-TEM mode to be transmitted to the parabolic special-shaped waveguide through the stepped matching transition structure, and then the Quasi-TEM mode is input into the medium substrate flat plate waveguide above through the parabolic special-shaped waveguide.

[0017] Preferably, the upper surface of the upper metal plate directly above the medium layer and the lower surface of the lower metal plate directly below the medium layer are both provided with a plurality of uniformly distributed circular groove arrays for suppressing energy leakage.

[0018] Preferably, the lower metal plate is composed of an upper cover plate and a lower cover plate.

[0019] Preferably, the outer region of the medium disc is provided with a positioning hole, a pin is inserted into the positioning hole, the lower end of the pin is fixedly connected to a driving device in the lower cover plate, and under the driving of the driving device, the pin drives the metal disc to rotate left and right; at the same time, the lower metal plate is provided with a sliding rail for the movement of the pin.

[0020] The antenna feeds input signals through two waveguide ports on the lower metal plate, and the two waveguide ports correspond to the left-handed circular polarization state and the right-handed circular polarization state of the antenna respectively, and when one waveguide port feeds, the other waveguide port exists as a matching port. The input signal fed by the waveguide port enters the plane horn through the stepped matching waveguide and is converted into a TE10 mode, and then the TE10 mode is converted into a Quasi-TEM mode through the trapezoidal plane waveguide. Next, unlike the traditional VICTS antenna, the application does not have a separate flat waveguide layer, but combines the radiation layer and the flat waveguide layer, and uses a double-sided single-layer dielectric plate to replace the flat waveguide layer. The Quasi-TEM mode is fed to the dielectric substrate flat waveguide through the special-shaped stepped waveguide as a plane wave transition structure, and then the electromagnetic wave travels to the dielectric disc through the dielectric substrate flat waveguide and is radiated. The application can realize left-handed circular polarization and right-handed circular polarization by switching different feed ports, and the dielectric disc can realize mechanical auxiliary scanning of the beam by rotating.

[0021] The application provides a Ka-band double circularly polarized wide-angle scanning low-cost microstrip antenna, which solves the problems of the traditional VICTS antenna, i.e., linear polarization, great influence of multipath interference, and being not conducive to satellite communication, and the problems of the traditional Pillbox antenna, i.e., limited beam coverage range and scanning angle. The basic working principle of the application is similar to that of the traditional VICTS antenna, and the application can be directly used to replace the existing VICTS antenna without changing the related control and servo technology. The application has the characteristics of wide beam scanning range, circular polarization, low profile and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 FIG. 1 is a structural diagram of the upper metal plate of the Ka-band low-cost double circularly polarized wide-angle scanning microstrip array antenna.

[0023] Figure 2 FIG. 2 is an exploded view of the overall structure of the Ka-band low-cost double circularly polarized wide-angle scanning microstrip array antenna.

[0024] Figure 3 FIG. 3 is a structural diagram of the upper metal plate of the Ka-band low-cost double circularly polarized wide-angle scanning microstrip array antenna.

[0025] Figure 4 FIG. 4 is a structural diagram of the dielectric layer and the placement position of the Ka-band low-cost double circularly polarized wide-angle scanning microstrip array antenna.

[0026] Figure 5 FIG. 5 is a structural diagram of the radiation of the Ka-band low-cost double circularly polarized wide-angle scanning microstrip array antenna.

[0027] Figure 6 FIG. 6 is a structural diagram of the upper cover plate of the lower metal plate of the Ka-band low-cost double circularly polarized wide-angle scanning microstrip array antenna.

[0028] Figure 7 Structure diagram of the lower metal plate lower cover plate of the Ka low-cost dual circularly polarized large-angle scanning microstrip array antenna of the application.

[0029] Figure 8 Partial structure explosion view of the Ka low-cost dual circularly polarized large-angle scanning microstrip array antenna of the application.

[0030] Figure 9 Right-hand circularly polarized scanning result of the Ka low-cost dual circularly polarized large-angle scanning microstrip array antenna of the application.

[0031] Figure 10 Left-hand circularly polarized scanning result of the Ka low-cost dual circularly polarized large-angle scanning microstrip array antenna of the application.

[0032] Explanation of reference numerals: 1100. upper metal plate, 1200. circular slot array on the lower surface of the upper metal plate, 1300. circular through hole, 2100. left dielectric substrate slab waveguide, 2200. dielectric disc, 2300. right dielectric substrate slab waveguide, 2210. microstrip transmission line, 2220. trapezoidal transition structure, 2230. rectangular radiation patch, 2231. U-shaped slot, 2240. positioning hole, 2400. lower metal plate upper cover plate, 2410. circular slot array on the upper surface of the lower metal plate upper cover plate, 2420. sliding rail, 3100. lower metal plate lower cover plate, 3110. stepped matching waveguide, 3120. planar horn, 3130. trapezoidal planar waveguide, 3140. feed waveguide. DETAILED DESCRIPTION

[0033] The application will be further described in detail below in combination with the drawings and examples.

[0034] The embodiment provides a dual circularly polarized large-angle scanning low-cost microstrip antenna working at Ka, as shown in Figure 1 and Figure 2 The antenna is left-right mirror image symmetry, and comprises, from bottom to top, a lower metal plate, a dielectric layer and an upper metal plate; wherein the lower metal plate is composed of an upper cover plate and a lower cover plate.

[0035] The lower metal plate is provided with a feed network, as shown in Figure 7 , Figure 8As shown, the feeding network is divided into two parts, the left part includes a step-matching waveguide, a planar horn, a trapezoidal planar waveguide, and a plane wave transition structure, and the right part is mirror-symmetrical to the left part; wherein, the step-matching waveguide is vertically arranged, and its input port is a standard waveguide port and is located at the bottom of the lower metal plate, for feeding the input signal into the planar horn; the planar horn is horizontally arranged in the lower metal plate, for converting the input signal into TE 10 mode and feeds it into a trapezoidal planar waveguide; the trapezoidal planar waveguide is laterally arranged in the lower metal plate, and is used to convert the TE10 mode into a Quasi-TEM mode and feed it into a plane wave transition structure; the plane wave transition structure is realized by a special-shaped stepped waveguide, which is composed of a planar waveguide and a raised parabolic shaped waveguide, and a step-matching transition structure is provided at the connection between the planar waveguide and the parabolic shaped waveguide, and the lower side cutting angle of the planar waveguide is set to optimize the matching; the planar waveguide is used to guide the Quasi-TEM mode to be transmitted to the parabolic shaped waveguide through the step-matching transition structure, and then input the Quasi-TEM mode into the upper dielectric substrate slab waveguide through the parabolic shaped waveguide.

[0036] The dielectric layer, such as Figure 4 As shown, it includes a dielectric disk located in the center and two dielectric substrate slab waveguides symmetrically arranged on the left and right sides of the dielectric disk. The dielectric substrate slab waveguide is used to transmit the fed Quasi-TEM mode to the dielectric disk. The dielectric disk is used to achieve circularly polarized radiation. When the dielectric disk receives the Quasi-TEM mode from the left feed branch, it achieves right-handed circular polarization, and when the dielectric disk receives the Quasi-TEM mode from the right feed branch, it achieves left-handed circular polarization. The dielectric disk is also provided with a positioning hole in the outer area, into which a pin is inserted. The lower end of the pin is fixedly connected to a drive device located in the lower cover plate. Driven by the drive device, the pin drives the metal disk to rotate left and right. Simultaneously, a sliding track for the pin is provided on the lower metal plate. The dielectric disk rotates left and right under the external drive, thereby changing the beam direction and achieving mechanically assisted scanning.

[0037] Specifically, the dielectric substrate slab waveguide includes a dielectric substrate and copper cladding layers on its upper and lower surfaces. The outer side of the dielectric substrate is arc-shaped, the inner side is semicircular, and a stepped structure is provided along the direction of electromagnetic wave transmission. The outer edge of the copper cladding layer on the lower surface of the dielectric substrate is etched with an arc-shaped groove that matches the shape of the output port of the feed network, serving as the input port of the dielectric substrate slab waveguide. The output port of the dielectric substrate slab waveguide is a cylindrical surface close to the dielectric disk.

[0038] Specifically, if Figure 5As shown, the medium disc includes a circular medium substrate and copper layers on its upper and lower surfaces, wherein the central part of the copper layer on the upper surface is provided with a radiation structure; the radiation structure includes 24 parallel microstrip transmission lines and 192 radiation units; the two ends of the microstrip transmission line are provided with trapezoidal transition structures to optimize matching; the radiation units are arranged in a triangular grid, and each radiation unit is composed of four rectangular radiation patches on both sides of the microstrip transmission line, and a U-shaped groove is arranged in the middle of the radiation patch to reduce the volume of the radiation patch; each rectangular radiation patch has one top corner connected with the microstrip transmission line, and the spacing of the top corners in the direction of electromagnetic wave propagation is one quarter of the working wavelength, and the rectangular radiation patches are rotated by 90° in turn to realize dual circular polarization.

[0039] As shown in the figure, Figure 3 The upper metal plate is used for pressing and fixing the medium layer, and the central region is provided with a circular through hole with a radius smaller than that of the disc and larger than that of the radiation aperture of the medium disc.

[0040] The lower surface of the upper metal plate directly above the medium layer and the upper surface of the lower metal plate directly below the medium layer are both provided with a plurality of uniformly distributed circular groove arrays for suppressing energy leakage.

[0041] When the medium disc rotates by a certain angle during operation of the antenna, the planar wave propagating through the medium substrate slab waveguide enters the medium disc and forms an inclination angle with the microstrip radiation structure, at this time, a phase difference is generated between each linear array in the radiation structure, thereby realizing beam scanning. The radiation structure introduces additional rotary feeding through triangular arrangement and coupling between adjacent double circular polarization units, so that the antenna can maintain better axial ratio during scanning. At the same time, based on the scanning principle of VICTS structure and the design of the medium substrate slab waveguide with step structure and the trapezoidal transition structure at both ends of the microstrip transmission line to optimize matching, large angle scanning can be easily realized.

[0042] Figure 9 The right-handed circular polarization scanning result of the Ka low-cost dual circular polarization large-angle scanning microstrip array antenna of the embodiment is shown in the figure, Figure 10 The left-handed circular polarization scanning result of the Ka low-cost dual circular polarization large-angle scanning microstrip array antenna of the embodiment is shown in the figure. It can be seen that the low-cost antenna can realize large-angle scanning of ±60° through mechanical auxiliary scanning, and the axial ratios of dual circular polarization can be maintained below 3dB, which indicates that the structure has excellent performance.

Claims

1. A low-cost dual circularly polarized, large-angle scanning microstrip antenna operating in the Ka band, characterized in that: The antenna is mirror-symmetrical from left to right, and includes a lower metal plate, a dielectric layer, and an upper metal plate arranged in sequence from bottom to top; The lower metal plate is provided with a feeding network, including two feeding branches arranged symmetrically on the left and right sides, which are used to convert the input signal into a Quasi-TEM mode and feed it to the input ports of the dielectric substrate slab waveguide on the left and right sides, respectively; at the same time, the upper surface of the lower metal plate is provided with a groove matching the shape of the dielectric layer, which is used to accommodate and fix the dielectric layer; The dielectric layer includes a dielectric disk located in the middle and two dielectric substrate slab waveguides symmetrically arranged on the left and right sides of the dielectric disk; wherein the dielectric substrate slab waveguide is used to transmit the fed Quasi-TEM mode to the dielectric disk; the dielectric disk is used to achieve circularly polarized radiation, and when the dielectric disk receives the Quasi-TEM mode of the left feeding branch, it achieves right-handed circular polarization, and when the dielectric disk receives the Quasi-TEM mode of the right feeding branch, it achieves left-handed circular polarization. At the same time, the dielectric disk can rotate left and right under external drive, thereby changing the beam direction and achieving mechanically assisted scanning; The upper metal plate is used to press and fix the dielectric layer. A circular through hole is provided in the central region thereof. The radius of the circular through hole is smaller than the radius of the direct disk and larger than the radiation opening of the dielectric disk.

2. A low-cost dual circularly polarized, large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 1, characterized in that: The dielectric disk includes a circular dielectric substrate and copper clad layers on its upper and lower surfaces, wherein a radiation structure is provided in the middle of the copper clad layer on the upper surface; the radiation structure includes a plurality of parallel microstrip transmission lines and a plurality of radiation units; the radiation units are arranged in a triangular grid, and each radiation unit is composed of four rectangular radiation patches located on both sides of the microstrip transmission line, each rectangular radiation patch has a vertex connected to the microstrip transmission line, and the spacing between the vertex corners along the direction of electromagnetic wave travel is one-quarter of the working wavelength. At the same time, the rectangular radiation patches are rotated 90 degrees in sequence to achieve dual circular polarization.

3. A low-cost dual circularly polarized large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 2, characterized in that: A U-shaped groove is provided in the middle of the radiation patch.

4. A low-cost dual circularly polarized, large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 2, characterized in that: Trapezoidal transition structures are provided at both ends of the microstrip transmission line.

5. The low-cost dual circularly polarized large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 2, characterized in that: The dielectric substrate slab waveguide includes a dielectric substrate and copper cladding layers on its upper and lower surfaces. The outer side of the dielectric substrate is arc-shaped, the inner side is semicircular, and a stepped structure is provided along the electromagnetic wave transmission direction. The outer edge of the copper cladding layer on the lower surface of the dielectric substrate is etched with an arc-shaped groove that matches the shape of the output port of the feed network, serving as the input port of the dielectric substrate slab waveguide. The output port of the dielectric substrate slab waveguide is a cylindrical surface close to the dielectric disk.

6. A low-cost dual circularly polarized, large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 5, characterized in that: The feeding network is divided into two parts, the left part includes a step-matching waveguide, a planar horn, a trapezoidal planar waveguide, and a plane wave transition structure, and the right part is mirror-symmetrical to the left part; wherein the step-matching waveguide is arranged vertically, and its input port is a standard waveguide port and is located at the bottom of the lower metal plate, which is used to feed the input signal into the planar horn; the planar horn is arranged horizontally in the lower metal plate, which is used to convert the input signal into a TE10 mode and feed it into the trapezoidal planar waveguide; the trapezoidal planar waveguide is arranged horizontally in the lower metal plate, which is used to convert the TE10 mode into a Quasi-TEM mode and feed it into the plane wave transition structure; the plane wave transition structure is used to feed the Quasi-TEM mode into the dielectric substrate planar waveguide above.

7. A low-cost dual circularly polarized large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 6, characterized in that: The plane wave transition structure is implemented using a special-shaped stepped waveguide, which is composed of a planar waveguide and a raised parabolic special-shaped waveguide. A step-matching transition structure is provided at the connection between the planar waveguide and the parabolic special-shaped waveguide, and the lower side cutting angle of the planar waveguide is set. The planar waveguide is used to guide the Quasi-TEM mode through the step-matching transition structure and transmit it to the parabolic special-shaped waveguide, and then input the Quasi-TEM mode into the dielectric substrate slab waveguide above through the parabolic special-shaped waveguide.

8. The low-cost dual circularly polarized large-angle scanning microstrip antenna operating in the Ka band according to claim 6, characterized in that: A plurality of evenly distributed circular groove arrays are provided on the lower surface of the upper metal plate located directly above the dielectric layer and the upper surface of the lower metal plate located directly below the dielectric layer.

9. A low-cost dual circularly polarized large-angle scanning microstrip antenna operating in the Ka band as claimed in claim 8, characterized in that: The lower metal plate is formed by processing and assembling an upper cover plate and a lower cover plate.

10. The low-cost dual circularly polarized large-angle scanning microstrip antenna operating in the Ka band according to claim 9, characterized in that: A positioning hole is provided in the outer area of ​​the medium disc, into which a pin is inserted. The lower end of the pin is fixedly connected to a driving device located in the lower cover plate. Driven by the driving device, the pin drives the metal disc to rotate left and right; at the same time, a sliding track for the pin to move is provided on the lower metal plate.

Images