Metasurface-based transmissive Cassegrain antenna

Abstract

The invention provides a metasurface-based transmissive Cassegrain antenna for solving the technical problem that effective radiation of electromagnetic waves is hindered due to the fact that a secondary reflector of a reflective Cassegrain antenna shields a main reflector in the prior art. The metasurface-based transmissive Cassegrain antenna comprises a parallel planar waveguide, a secondary reflector, a main transmitting mirror and a feed source, wherein the secondary reflector, the main transmitting mirror and the feed source are located between two metal plates of the parallel planar waveguide; multiple uniformly arranged annular metal patches are printed on one side surface of the secondary reflector and a metal bottom plate is printed on the other side surface; the main transmittingmirror is of a multilayer dielectric layer structure; multiple uniformly arranged annular gaps are etched at the front sides of an odd number of dielectric layers; multiple uniformly arranged metal strips are printed at the front sides of an even number of dielectric layers; multiple uniformly arranged annular gaps are etched at the back side of the last dielectric layer; a rectangular horn antenna structure is adopted by the feed source; and a phase jump metasurface structure constructed on the basis of a generalized Snell's theorem is adopted by the main transmitting mirror and the secondary reflector.

Description

technical field [0001] The invention belongs to the technical field of antennas, and relates to a Cassegrain antenna, in particular to a transmission type Cassegrain antenna with a planar structure realized by a phase mutation metasurface based on the generalized Snell theorem, which can be used in the microwave field. technical background [0002] The Cassegrain antenna adds a hyperboloid secondary reflector on the basis of a parabolic antenna. Electromagnetic waves pass through the secondary reflector and are reflected by the primary 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-reflector makes it easier to design the surface field distribution, which can optimize the antenna radiation performance; on the other hand, sin...

AI Technical Summary

Problems solved by technology

The reflector 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 mirrors with contour design to regulate electromagnetic waves, existing research uses metamaterials to regulate electromagnetic waves, and realizes flat structure Cassegrain antennas by printing microstrip plates

For example, the application publication number is CN102800994 A, and the patent application titled "a Cassegrain-type metamaterial antenna" discloses a Cassegrain-type metamaterial antenna. The sub-reflector and the main reflector of the Segren antenna, the electromagnetic wave is reflected by the sub-reflector and the main reflector to form a highly directional radiation pattern. This invention is easier to manufacture and process, and the cost is lower, but its defects Yes: On the one hand, due to the shielding effect of the sub-reflector on the radiated electromagnetic wave, the side lobe of the antenna is relatively high, especially the small-aperture main reflection surface will be difficult to radiate effectively due to the influence of the sub-mirror; on the other hand, the sub-reflector of the invention The premise of the phase error compensation of the mirror and the main mirror is to assume that the electromagnetic wave is vertically incident, and does not consider the influence of the phase change of the sub-mirror and the main mirror when the electromagnetic wave is obliquely incident. In theory, it can only be used when the refractive index is infinite. The refracted wave is perpendicular to the reflective surface, so there is a large phase compensation error, and as the incident angle increases, the phase error will increase. At the same time, 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 metamaterials and free space is different, so the matching between metamaterial layers and free space will also affect the wavefront calibration results of the antenna, resulting in a further increase in phase compensation errors. A large phase compensation error with the primary mirror will cause the antenna sidelobe to further increase

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