High-gain dual-frequency circularly polarized patch antenna with wide axial ratio

Abstract

The invention relates to a high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio, which belongs to the technical field of antennas, and comprises a dielectric substrate, a radiation patch, a rectangular metal plate ring group and a grounding plate, the radiation patch is composed of an upper radiation patch and a lower radiation patch; the upper radiation patch and the lower radiation patch are respectively positioned on the upper surface and the lower surface of the dielectric substrate; the grounding plate is located below the lower radiation patch, and an air dielectric layer is arranged between the grounding plate and the lower radiation patch; the rectangular metal plate ring group is positioned on the upper surface of the grounding plate; the rectangular metal plate ring group comprises a plurality of rectangular metal plate groups; each rectangular metal plate group consists of two rectangular metal plates; and the two rectangular metal plates of the same rectangular metal plate group are positioned on the same diameter. The air dielectric antenna is an ideal choice for high gain, wide axial ratio beam width and miniaturization.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio. Background Art

[0002] With the rapid development of the global satellite navigation industry, the comprehensive use of the four major satellite positioning systems (i.e., GPS, COMPASS, GLONASS, and Galileo) is a solution to improve the reliability of satellite navigation, measurement, and positioning. The Global Navigation Satellite System (GNSS) broadcasts signals in two frequency bands: a low-frequency band of 1164 to 1300 MHz and a high-frequency band of 1559 to 1610 MHz. All signals transmitted by satellite antennas are right-hand circularly polarized (RHCP). Therefore, in order to minimize polarization mismatch and obtain high-quality satellite signals, GNSS terminal antennas should have the same polarization. In addition, in order to miniaturize the terminal antenna covering the four systems, the miniaturized low-profile dual-frequency circularly polarized (CP) microstrip antenna is more focused on GNSS terminal applications.

[0003] At present, the miniaturization of dual-frequency GNSS antennas mainly relies on high dielectric constant loading, which is costly. The application of high dielectric constant substrates or metamaterials to miniaturize antennas has been studied, but the miniaturization of antennas comes at the expense of their gain and bandwidth.

[0004] The use of miniaturized high-gain antennas with a wide 3dB axial ratio (AR) beamwidth helps to better receive satellite signals. The axial ratio (AR) beamwidth of GNSS antennas developed in recent years has become wider and wider. Some proposed antennas achieve wide AR beamwidth by installing multiple pairs of folded dipole antennas on a virtual square, and achieve a 3dB AR beamwidth of 142° at 1.6GHz by subtracting the radiation pattern. A 3dB AR beamwidth of 180° is achieved by using rectangular radiating patches and a resistor-free series feeding network. Some have proposed a design method for a circularly polarized antenna with a wide AR beamwidth, in which two pairs of curved patch dipole antennas are vertically distributed on the cross-section of a hemispherical shell, achieving an axial ratio (AR) beamwidth of 202°.

[0005] A dual-band stacked annular slot patch antenna was proposed, which consists of a main radiator patch, a parasitic radiator patch located below the main radiator, and a coaxial feeding probe. The antenna achieves a wider 3dB axial ratio (AR) beamwidth of 145° on two GNSS bands. Jovic et al. proposed a ring-shaped CP dielectric resonator antenna for GNSS. The dielectric resonator is loaded by printing a metal structure on the sidewall and fed by four coplanar strips. It achieves a 3dB axial ratio (AR) beamwidth of 120° and 165° in the lower and upper bands, respectively. However, these designs cannot achieve a better balance between structural simplification and key performance indicators, and cannot better meet the needs of mainstream dual-frequency high-precision navigation and positioning terminals. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio, which is an ideal choice for high-gain, wide axial ratio beamwidth and miniaturized air dielectric antennas.

[0007] The present invention adopts the following technical solutions to achieve the above technical effects:

[0008] A high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio, comprising a dielectric substrate, a radiation patch, a rectangular metal plate ring group and a ground plane; the radiation patch is composed of an upper radiation patch and a lower radiation patch; the upper radiation patch and the lower radiation patch are respectively located on the upper surface and the lower surface of the dielectric substrate; the ground plane is located below the lower radiation patch, and an air dielectric layer is provided between the two;

[0009] The rectangular metal plate ring group is located on the upper surface of the grounding plate; the rectangular metal plate ring group includes a plurality of rectangular metal plate groups; each rectangular metal plate group is composed of two rectangular metal plates; the two rectangular metal plates in the same rectangular metal plate group are located on the same diameter.

[0010] The centers of the ground plate, the rectangular metal plate ring group, the dielectric substrate and the radiation patch are all located on the same central axis.

[0011] Furthermore, the plurality of rectangular metal plate groups in the rectangular metal plate ring group are arranged in an array around the center circumference of the grounding plate.

[0012] Furthermore, the upper radiation patch includes a main body patch, and the edge array of the main body patch has rectangular branches; the main body of the lower radiation patch is a circular patch, and the center of the circular patch is provided with a hollow projection of the upper radiation patch on the lower radiation patch.

[0013] Furthermore, there are 8 rectangular branches in total.

[0014] Furthermore, the height of the rectangular metal plate is lower than the thickness of the air dielectric layer.

[0015] Furthermore, plastic screws are arranged on the grounding plate to support the dielectric substrate.

[0016] Furthermore, in the same rectangular metal plate group, the rectangular metal plates close to the center of the rectangular metal plate ring group are all connected to the edge of the lower radiation patch; and the rectangular metal plates are perpendicular to the ground plate.

[0017] Furthermore, the radiation patch is fed by four probes, and the four probes are excited at different phases of 90°, 180°, 270° and 360° to achieve circular polarization.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0019] The antenna consists of a main dual-frequency coplanar metal frame radiator, radiating elements and some coaxial feeding probes. Due to the use of air dielectric, the maximum right-hand circularly polarized gain of the antenna can reach 6.2dBic in the low frequency band and 6.3dBic in the high frequency band. By adopting dual-frequency coplanar patches and metal loading technology, the opening size of this common circularly polarized antenna is only 0.38λ×0.38λ×0.04λ. In order to expand the 3dB axial ratio beamwidth, a novel vertical ground short-circuit plate is introduced. At 1.227GHz, the 3dB axial ratio beamwidth is -120° to 100°, and at 1.575GHz, the 3dB axial ratio beamwidth is -90° to 95°. Therefore, this antenna is an ideal choice for high-gain, wide axial ratio beamwidth and miniaturized air dielectric antennas.

[0020] The invention has a miniaturized ground plane. The antenna has excellent cross-polarization suppression, wide AR beamwidth and small phase center offset (PCO) in two operating frequency bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 A top view of the present invention;

[0023] In the figure: 1. upper radiation patch, 2. dielectric substrate, 3. rectangular metal plate, 4. ground plane. DETAILED DESCRIPTION

[0024] Below, the present invention is further described in conjunction with the accompanying drawings.

[0025] In order to facilitate the technical personnel in this field to understand the technical solution of this patent, and at the same time, to make the technical purpose, technical solution and beneficial effects of this patent clearer and to fully support the scope of protection of the claims, the technical solution of this patent is further and more detailed in the form of specific cases.

[0026] The structure of the proposed antenna is as follows Figure 1 and Figure 2 As shown. The antenna consists of an outer sawtooth circular patch (upper radiation patch), an inner sawtooth annular patch (lower radiation patch) and a ground plane. The outer sawtooth circular patch is printed on the lower surface of a polytetrafluoroethylene (PTFE) dielectric substrate (εr = 2.65, loss tangent = 0.0015) as a radiation patch for the upper frequency band. The inner sawtooth annular patch is a radiation patch for the lower frequency band. The rectangular metal plate at the outer edge of the sawtooth annular patch is perpendicular to the ground plane to connect to the ground plane. On the ground plane, 24 vertically grounded rectangular metal plates are evenly distributed around the antenna to form a capacitor coupled with the rectangular teeth on the outer edge of the sawtooth. The coupling capacitor can reduce the size of the antenna. The radiation patches of the upper and lower frequency bands are fed by 4 feeding probes, which are excited at different phases of 90°, 180°, 270° and 360° to achieve circular polarization. Plastic screws are used to support the radiation patch part and fix the antenna part to the ground.

[0027] By using single air dielectric coplanar technology, the upper band radiation patch of the antenna can be embedded in the central hollow area of ​​the lower band radiation patch. In order to reduce the operating frequency, the sawtooth structure of the outer periphery of the upper band radiation patch and the inner part of the lower band radiation patch is designed respectively, and the path of the equivalent current is increased while keeping the antenna size unchanged. The rectangular metal plates are connected to the outer edge of the lower radiation patch. These rectangular metal plates (inner ring) are perpendicular to the ground plane and form a capacitive load with the rectangular metal plates (outer ring) on ​​the ground plane. The introduction of capacitive load can reduce the resonant frequency of the radiation patch, thereby realizing the miniaturization design of the antenna.

[0028] In order to broaden the antenna's axial ratio (AR) beamwidth, 24 vertically grounded rectangular metal sheets are loaded around the antenna, and the circularly polarized (CP) wave is composed of vertical linear polarized waves and horizontal linear polarized waves. At low elevation angles of the antenna with a poor circular polarization axis ratio, the vertical linear polarized wave will not be reflected by its parallel rectangular metal sheets, while the horizontal linear polarized wave is superimposed and enhanced by its vertical rectangular metal sheets through one or more reflections, making the low elevation angle axial ratio (AR) smaller.

[0029] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio, comprising a dielectric substrate, characterized in that: It comprises a radiation patch, a rectangular metal plate ring group and a grounding plate; the radiation patch is composed of an upper radiation patch and a lower radiation patch; the upper radiation patch and the lower radiation patch are respectively located on the upper surface and the lower surface of the dielectric substrate; the grounding plate is located below the lower radiation patch, and an air dielectric layer is provided between the two; The rectangular metal plate ring group is located on the upper surface of the grounding plate; the rectangular metal plate ring group includes a plurality of rectangular metal plate groups; each rectangular metal plate group is composed of two rectangular metal plates; the two rectangular metal plates in the same rectangular metal plate group are located on the same diameter; The centers of the ground plate, the rectangular metal plate ring group, the dielectric substrate and the radiation patch are all located on the same central axis.

2. A high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 1, characterized in that: A plurality of rectangular metal plate groups in the rectangular metal plate ring group are arranged around the central circumference of the ground plate.

3. The high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 1, characterized in that: The upper radiation patch comprises a main body patch, the edge array of which has rectangular branches; the main body of the lower radiation patch is a circular patch, the center of which is provided with a hollow for the projection of the upper radiation patch on the lower radiation patch.

4. The high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 3, characterized in that: There are 8 rectangular branches in total.

5. The high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 1, characterized in that: The height of the rectangular metal plate is lower than the thickness of the air medium layer.

6. The high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 1, characterized in that: The grounding plate is provided with plastic screws to support the dielectric substrate.

7. The high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 1, characterized in that: In the same rectangular metal plate group, the rectangular metal plates close to the center of the rectangular metal plate ring group are all connected to the edge of the lower radiation patch; and the rectangular metal plates are perpendicular to the ground plate.

8. The high-gain dual-frequency circularly polarized patch antenna with a wide axial ratio according to claim 1, characterized in that: The radiating patch is fed by four probes, and the four probes are excited at different phases of 90°, 180°, 270° and 360° to achieve circular polarization.

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