Cassegrain antenna based on super surface

Abstract

The invention provides a Cassegrain 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 Cassegrainantenna 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 metalring 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 on 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 a hyperboloid; and the feedsource is located at the midpoint of the main reflector which is opposite to the phase control layer of the auxiliary reflector, a virtual focus of the auxiliary reflector is overlapped with a focus of the main reflector, and a real 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 Cassegrain antenna, in particular to a Cassegrain antenna based on a generalized Snell theorem phase mutation metasurface to realize a planar structure, which can be used in the microwave field. technical background [0002] 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 Cassegg antenna adds a hyperboloid secondary reflector on the basis of the parabolic antenna. The electromagnetic wave passes through the secondary reflector and is reflected by the main reflector to form a highly directional radiation pattern. Compared with ordinary parabolic antennas, its dual-mirror design can achieve the radiation performance of long-focus paraboloids with short-focus paraboloids, which is more advantageous in practical applications. On the one hand, the added sub...

AI Technical Summary

Problems solved by technology

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

[0003] 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 flat structure Cassegrain antennas by printing microstrip plates

Such as the Chinese patent, the application publication number is CN 102800994 A, the invention titled "a Cassegrain-type metamaterial antenna" discloses a Cassegrain-type metamaterial antenna. 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 Cassegrain antenna with a flat structure is realized, but its phase compensation method is electromagnetic wave After passing through the metamaterial twice successively, the wavefront calibration is performed by using different constitutive parameters of the metamaterial on the propagation path at the same physical distance as the electrical wavelength changes differently. On the one hand, the premise of the phase path design based on the metamaterial layer is to assume that the electromagnetic wave The vertical 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 , the phase error will increase, which limits the radiation characteristics and application range of the metamaterial-based Cassegrain antenna; 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 basis of different electromagnetic parameters, the degree of matching between the metamaterial and the free space is different, so the matching between the metamaterial layer and the 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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