An Omnidirectional Circularly Polarized Planar Antenna

Abstract

The invention discloses an omnidirectional circularly polarized planar antenna, which includes a microstrip antenna, a dielectric substrate supporting the microstrip antenna, and a coaxial feed point located at the center point of the antenna; the microstrip antenna includes a microstrip antenna located on the upper and lower surfaces of the dielectric substrate The first and second metal rectangular patches and the first, second and third short-circuit walls connecting the first and second metal rectangular patches, the first and second metal rectangular patches have the same size, and the first and second metal rectangular patches are mutually Directly opposite and parallel, the first and second metal rectangular patches are respectively provided with parallel first and second slits, the vertical distance from the coaxial feed point to the first and second slits is equal, and the first and second slits are also connected to the The width directions of the first and second metal rectangular patches are parallel, and the heights of the first, second, and third short-circuit walls are equal to the thickness of the dielectric substrate; the three sides between the first and second metal rectangular patches are respectively connected with the first , Second, and third short-circuit walls, the fourth side of the first and second metal rectangular patch is in an open state.

Description

technical field [0001] The present invention relates to the technical field of antennas, and more specifically, to an omnidirectional circularly polarized planar antenna; the antenna is a millimeter-wave antenna with a working frequency of 5 GHz, and its radiation pattern in a vertical plane is omnidirectional, and its The polarization mode is circular polarization. Background technique [0002] With the development of modern wireless communication, the requirements and performance of the antenna are getting higher and higher, and circular polarization is one of the important index parameters. Circularly polarized antennas have the following important properties: 1. Circularly polarized waves are synthesized by two orthogonal linearly polarized waves with equal amplitude and a phase difference of 90 degrees, so it can receive radiation incoming waves in any polarization direction and avoid receiving blind spots ;2. Circularly polarized antennas are divided into left-handed ...

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Problems solved by technology

[0010] For the antenna structure mentioned above, literature [1] utilizes Babinet’s principle and the law of complementary antennas to form circular polarization in the far field by opening slots in the non-planar structure and array dipoles. In order to achieve the purpose of circular polarization, the The size of the antenna is placed in a secondary position, so it uses an antenna array of 81 elements, which makes the antenna section larger and the feed network complex; literature [2] and [3] use a combination of ring structure and vertical oscillator, through The orthogonal linear polarization formed by the two achieves the purpose of circular polarization in the far field

Since the main body of the antenna is a ring structure, and the input impedance of the loop antenna is relatively large, it is generally used as a receiving antenna, so the impedance characteristics of this structure are difficult to match

Secondly, although the antenna can achieve circular polarization, due to the energy coupling limitation of the ring structure, the angular coverage of circular polarization is only within ±45° of the end-fire direction; the antenna involved in literature [4] is based on a double-layer The dielectric plate is fed by slot coupling. Due to the limitation of the ground plate, it can only form radiation on the side of the antenna, so its circular polarization is also formed on the side of the far field of the antenna; the antenna described in [5] needs to be in a double-layer A ring passage is formed in the dielectric plate, and the middle is supported by a metal cylinder with a height of 15mm. Its non-planar structure requires a large section and is difficult to miniaturize

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