Gregorian Antenna Based on Metasurface

Abstract

The invention provides a Gregorian antenna based on a super surface, and aims to reduce the phase compensation error of the antenna and simplify the antenna structure at the same time. The Gregorian antenna comprises a slab waveguide, a main reflector, an auxiliary reflector and a feed source, wherein the main reflector, the auxiliary reflector and the feed source are clamped between two metal plates of the slab waveguide, both the main reflector and the auxiliary reflector adopt a phase sudden change super surface structure constructed based on a generalized Snell's law, the size of a metal ring microstructure on a phase control layer of the main reflector is decided by the electromagnetic wave incident angle and the scattering parameter phase at the location so as to realize an electromagnetic wave phase compensation characteristic similar to that of a paraboloid, the size of a metal ring microstructure on a phase control layer of the auxiliary reflector is decided by the electromagnetic wave incident angle and the scattering parameter phase at the location so as to realize an electromagnetic wave phase compensation characteristic similar to that of an ellipsoid; and the feed source is located at the midpoint of the main reflector which is opposite to the phase control layer of the auxiliary reflector, a near focus of the auxiliary reflector is overlapped with a focus of themain reflector, and a far focus of the auxiliary reflector is overlapped with a phase center of the feed source.

Description

technical field [0001] The invention belongs to the technical field of antennas, and relates to a Gregorian antenna, in particular to a Gregorian antenna with a planar structure realized by a phase mutation metasurface based on generalized Snell's theorem, which can be used in the microwave field. [0002] technical background [0003] The microwave reflector antenna is mainly a parabolic antenna, which uses the collimation effect of the parabolic reflector to form a highly directional radiation pattern. The Gregorian antenna adds an elliptical sub-reflector to the parabolic antenna. Electromagnetic waves pass through the sub-reflector and are reflected by the main reflector to form a highly directional radiation pattern. Compared with ordinary parabolic antennas, on the one hand, the added sub-reflector is easier to design the surface field distribution and can optimize the radiation performance of the antenna; on the other hand, since the feed source is placed close to the ...

AI Technical Summary

Problems solved by technology

The reflective surface of a typical Gregorian antenna is composed of a metal surface processed into a curved profile. Although the design is simple, it requires high processing requirements.

[0004] In order to solve the problem of inconvenient processing and assembly of curved reflective surfaces designed to regulate electromagnetic waves by contour design, existing research uses metamaterials to regulate electromagnetic waves, and realizes planar Gregorian antennas by printing microstrip plates.

Such as the Chinese patent, the application publication number is CN 102800995 A, the invention titled "a Cassegrain type metamaterial antenna" discloses a Cassegrain type metamaterial antenna, the invention passes through the middle of the ground dielectric plate A planar snowflake-like cross-shaped metal microstructure is set, and the metal reflective surface is covered with a metamaterial with a gradient change in refractive index to approximate the reflection characteristics of a curved reflector, and a Gregorian antenna with a flat plate structure is realized, but its phase compensation method is electromagnetic wave successively. After passing through the metamaterial twice, the wavefront is calibrated by using the different constitutive parameters of the metamaterial on the propagation path to change the electrical wavelength at the same physical distance. On the one hand, the premise of the phase path design based on the metamaterial layer is to assume that the electromagnetic wave is vertical The incident reflective surface does not consider the change of the incident angle when the electromagnetic wave is obliquely incident. In theory, only when the refractive index is infinite can the refracted wave be perpendicular to the reflective surface. There is a large phase compensation error, and with the incident angle increases, the phase error will increase, which limits the radiation characteristics and application range of the Gregorian antenna based on metamaterials; on the other hand, because the phase compensation of the reflected wavefront is based on the fact that the electromagnetic wave passes through the metamaterial layer twice On the above, different electromagnetic parameters have different matching degrees between metamaterials and free space, so the matching between metamaterial layers and free space will also affect the wavefront calibration results of the antenna, and the resulting phase compensation error will further increase

Finally, the required metamaterials are realized by loading metal microstructures in multilayer dielectric plates, which is relatively complicated.

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