CN110444867B

CN110444867B - Circularly polarized patch antenna

Info

Publication number: CN110444867B
Application number: CN201910773237.6A
Authority: CN
Inventors: 吕文俊; 吴志芳; 郁剑; 吴汉; 赵志宾; 王见远; 李司杰; 李小慧; 朱洪波
Original assignee: Nanjing University of Posts and Telecommunications
Current assignee: Nanjing University of Posts and Telecommunications
Priority date: 2019-08-21
Filing date: 2019-08-21
Publication date: 2020-12-08
Anticipated expiration: 2039-08-21
Also published as: CN110444867A

Abstract

The invention discloses a circularly polarized patch antenna, which is designed on a medium substrate with any dielectric constant, wherein one side of the medium substrate is a metal ground, the other side of the medium substrate is a fan-shaped radiation patch, one radius edge of the radiation patch is connected with the metal ground through a short circuit wall, the surface of the patch is connected with the metal ground through a short circuit nail, and meanwhile, a rectangular groove is formed in the surface of the radiation patch. The invention can keep the inherent low profile property of the antenna, has good circular polarization characteristic, and the maximum radiation direction and the vertical plane of the antenna have a certain included angle, namely the antenna presents the radiation characteristic of the inclined circular polarization wave beam; the antenna adopts coaxial feed, has the advantages of simple structure, small volume, low profile, large bandwidth and the like, and can realize good circular polarization performance of oblique wave beams.

Description

Circularly polarized patch antenna

Technical Field

The invention belongs to the technical field of Internet of things and microwaves, and particularly relates to a circularly polarized patch antenna.

Background

The circularly polarized antenna can receive incoming waves in any direction, the radiation waves can be received by the antenna with any polarization, and the circularly polarized waves can reduce the influence of reflected signals, so that the circularly polarized antenna has important application in the aspects of communication, radar, electronic countermeasure and point detection, broadcast and television and the like.

The conditions for realizing circular polarization are two linear polarized waves with equal amplitude, orthogonality and 90-degree phase difference, so that the modes for realizing the circular polarization antenna can be divided into two types: (1) a loop current; (2) two line currents placed orthogonally, provided that they are of equal amplitude and 90 deg. out of phase.

Small-sized circular polarized antennas are quadrifilar helix antennas and microstrip circular polarized antennas. Compared with the conventional microwave antenna, the microstrip antenna has the advantages of small size, low cost, easy implementation of circular polarization and linear polarization, and the like, and thus, has been widely used in a wide frequency band from about 100MHz to about 50 GHz. The circular polarization technology of the microstrip antenna is mainly realized by three methods: single feed, multi feed, and multivariate.

Circularly polarized antennas with tilted beams are well suited for use in various wireless systems, such as mobile and satellite communication systems. On the premise of not using mechanical rotation, the following methods are mainly used for realizing the inherent oblique circularly polarized wave beam: the first is to use a combination helical antenna; the second technique is to use a complementary oscillator structure; the third technique employs a corner cut microstrip line of traveling wave characteristics. These techniques all require the use of traveling wave structures, which are bulky.

Disclosure of Invention

The purpose of the invention is as follows: in view of the above problems, the present invention provides a circular polarized patch antenna, which has a small volume, a simple structure, and good radiation characteristics of tilted circular polarized beams.

The technical scheme is as follows: in order to achieve the design purpose, the technical scheme adopted by the invention is as follows: a circularly polarized patch antenna comprises a metal ground plate and a fan-shaped radiation patch, wherein the fan-shaped radiation patch is parallel to the metal ground plate, the fan-shaped radiation patch is connected with the metal ground plate through a short-circuit wall with a long radius, and the short-circuit wall is vertical to the metal ground plate; the metal grounding plate is connected with the fan-shaped radiation patch through the short circuit nail, and the fan-shaped radiation patch is provided with a plurality of rectangular grooves; the coaxial feed element is located on a different radius from the shorting wall.

Further, a medium with any dielectric constant is filled between the fan-shaped radiation patch and the metal ground plate.

Further, the distance between the fan-shaped radiation patch and the metal grounding plate is less than 0.1 wavelength.

Furthermore, the angle range between the short circuit nail and the short circuit wall is 20-140 degrees, and the distance between the center of the short circuit nail and the center of the fan-shaped radiation patch is 0.2-0.6 times of the radius of the fan-shaped radiation patch.

Further, the arc length of the circumference of the fan-shaped radiating patch is an odd multiple of the 1/4 wave length corresponding to the resonant frequency of the antenna.

Further, the coaxial feeding unit includes a coaxial line inner conductor and a coaxial line outer conductor.

Furthermore, the distance between the center of the coaxial feed unit and the center of the fan-shaped radiation patch is 0.1-1 times of the radius of the fan-shaped radiation patch.

Further, the number and location of the rectangular slots depends on the higher order resonant mode employed by the antenna.

Has the advantages that: the antenna has the positive circular polarization or inclined circular polarization wave beam in the pitching plane, namely the radiation direction with the lowest axial ratio appears in the range of positive and negative 30 degrees of the pitching angle, and has the advantages of simple structure, low section, large bandwidth, small volume and the like.

Drawings

FIG. 1 is a schematic diagram of the front structure and reference coordinates of an antenna;

FIG. 2 is a schematic three-dimensional view of an antenna and a schematic reference coordinate;

FIG. 3 is a radiation pattern of the antenna in the XZ and YZ planes;

FIG. 4 is a graph of antenna reflection coefficient characteristics;

fig. 5 is an axial ratio diagram of the antenna at different elevation angles in the ZX plane.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

As shown in fig. 1 and 2, the present invention provides a small circularly polarized patch antenna, which includes a sector radiation patch 2, a rectangular slot 4, a coaxial feed unit, a short circuit pin 3, a metal ground plate 1, and a short circuit wall 7; the fan-shaped magnetic dipole forming the antenna is of a semi-closed structure and comprises a fan-shaped radiation patch 2, a metal grounding plate 1 and a short circuit wall 7 with a long radius, wherein the metal grounding plate and the fan-shaped radiation patch are connected through a short circuit nail 3, and the angle between the short circuit nail and the short circuit wall is 20-140 degrees.

The fan-shaped radiation patch 2 is parallel to the metal grounding plate 1, the fan-shaped radiation patch 2 is connected with the metal grounding plate 1 through a short-circuit wall 7 with a long radius, and the short-circuit wall 7 is vertical to the metal grounding plate 1; a plurality of rectangular grooves 4 are formed in proper positions of the fan-shaped radiation patches; the coaxial feed element is on a different radius from the shorting wall 7.

The coaxial feed unit comprises a coaxial inner conductor 5 and a coaxial outer conductor 6, and the distance between the center of the coaxial feed unit and the center of the fan-shaped radiation patch is 0.1-1 times of the radius of the radiation patch.

The fan-shaped radiation patch is positioned above the metal grounding plate, and a plurality of rectangular grooves are formed in the proper position of the fan-shaped radiation patch. The radiation direction having a circularly polarized or tilted circularly polarized beam in the elevation plane, i.e. the lowest axial ratio, occurs within plus or minus 30 ° of the elevation angle. The circumference arc length of the fan-shaped radiation patch is odd times of 1/4 corresponding to the resonance frequency of the antenna, and the central angle range is 30-360 degrees. The resonance modes of the antenna are controlled by the central angle and the circumferential arc length of the fan-shaped radiation patch, and each resonance mode can be described by a uniform closed analytical expression. The number and location of the rectangular slots depends on the mathematical expression for the higher order resonant mode employed by the antenna. Circular polarization is achieved by adjusting the phase difference between the two orthogonal resonant modes with the shorting pin.

A medium with any dielectric constant is filled between the upper surface and the lower surface of the antenna. The ratio of the distance between the short-circuit nail and the circle center to the radius of the patch is 0.2-0.6. The distance between the fan-shaped radiation patch and the metal grounding plate is less than 0.1 time of wavelength. The circular polarization rotation direction of the circular polarization rotation device is changed by mirror mapping of a short circuit wall, a feed point and a slot on the angular bisector of a fan.

Compared with the traditional patch, the novel circular patch structure is adopted on the antenna structure, so that the size of the antenna can be reduced, and the practical range of the antenna is enlarged. The bandwidth is increased by adjusting the frequency of the higher-order mode by adding the rectangular groove. This antenna structure easily adjusts, can reduce return loss and improve impedance matching characteristic to a certain extent through the relative position that changes coaxial feeder and short-circuit nail for resonant frequency and bandwidth change, satisfy specific requirement.

The technical solution of the present invention is further illustrated by the following specific examples.

In the embodiment, an air medium is adopted, the distance between the fan-shaped radiation patch 2 and the nearly ground plate 1 is 4 mm, the radius of the fan-shaped radiation patch is 15mm, the radius of the ground plate is 60mm, the degree of a central angle 8 is 200 degrees, the size of an angle 9 is 133 degrees, and the angle 10 is 100 degrees. The distance between the center of the short-circuit nail 3 and the center of the radiation patch 2 is 6.6mm, the distance between the rectangular groove and the center of the radiation patch is 8.8mm, and the radius of the coaxial feeder line is 0.65 mm.

Fig. 3 is a radiation pattern of the antenna in the XZ plane, with the antenna operating frequency at 5.3GHz, with the dashed line indicating left hand circular polarization and the solid line indicating right hand circular polarization. Fig. 4 is a reflection coefficient characteristic of an antenna having an impedance bandwidth covering a 4.73-6.08GHz band and a center frequency of 5.56GHz, and it can be seen that the antenna has a wide bandwidth. Fig. 5 is a graph of axial ratio of different angles of the antenna, the solid line shows the graph of axial ratio with a pitch angle of 5 °, the dotted line shows the graph of axial ratio with a pitch angle of 10 °, and the dotted line shows the graph of axial ratio with a pitch angle of 15 °, and it can be seen from the results of fig. 5 that the oblique circular polarization angle of the antenna has an axial ratio bandwidth of less than 3dB within 0-15 °.

Claims

1. A circularly polarized patch antenna is characterized by comprising a metal grounding plate (1) and a fan-shaped radiation patch (2), wherein the fan-shaped radiation patch (2) is parallel to the metal grounding plate (1), the fan-shaped radiation patch (2) is connected with the metal grounding plate (1) through a short-circuit wall (7) with a long radius, and the short-circuit wall (7) is vertical to the metal grounding plate (1); the metal grounding plate is connected with the fan-shaped radiation patch through a short-circuit nail (3), and the fan-shaped radiation patch is provided with a plurality of rectangular grooves (4); the coaxial feed element is located on a different radius from the shorting wall (7).

2. The circularly polarized patch antenna of claim 1, wherein a medium of any dielectric constant is filled between the sector radiating patch and the metal ground plate.

3. The circularly polarized patch antenna of claim 1, wherein the spacing between the sector radiating patch and the metallic ground plate is less than 0.1 wavelengths.

4. The circularly polarized patch antenna of claim 1, wherein the short-circuit pin has an angle with the short-circuit wall ranging from 20 ° to 140 °, and the distance between the center of the short-circuit pin and the center of the sector-shaped radiation patch is 0.2 to 0.6 times the radius of the sector-shaped radiation patch.

5. The circularly polarized patch antenna of claim 1, wherein the sector shaped radiating patch circumferential arc length is an odd multiple of the 1/4 wavelengths corresponding to the antenna resonant frequency.

6. The circularly polarized patch antenna according to claim 1, wherein the coaxial feed unit comprises a coaxial inner conductor (5) and a coaxial outer conductor (6).

7. The circularly polarized patch antenna of claim 1, wherein the distance between the center of the coaxial feed unit and the center of the sector-shaped radiating patch is 0.1-1 times the radius of the sector-shaped radiating patch.

8. The circularly polarized patch antenna of claim 1, wherein the number and location of the rectangular slots is dependent on the higher order resonant mode employed by the antenna.