Cassegrain antenna

About: Cassegrain antenna is a research topic. Over the lifetime, 3207 publications have been published within this topic receiving 28278 citations.

Shaped-beam or scanned beams reflector or lens antenna

Abstract: Multiple shaped-beam or scanned beams reflector or lens antenna configured so as to have the radiating elements outside the focal plane (imaging) with improved characteristics in terms of gain and coverage area Said antenna (Fig 1) essentially consists of a reflector or a lens (1), a certain number of radiators (3) positioned outside the focal plane, a Beam Forming Network (BFN) It classifies in the technical field of multiple shaped-beam antennae and is applicable to radars, telecommunications in general and to space telecommunications in particular Its most significant advantage consists in its use as transmitter antenna since in it the electric performance/complexity ratio is improved

3-D Printed Wideband Cassegrain Antenna With a Concave Subreflector for 5G Millimeter-Wave 2-D Multibeam Applications

Abstract: A novel wideband planar Cassegrain beam-former with a three-layered folded parallel plate waveguide geometry is investigated. By replacing the convex subreflector of the conventional design with a concave one, a 20% reduction in the size in boresight direction of the planar Cassegrain beam-former can be achieved, while its operating characteristics are not degraded. The direction of the radiation beam can be adjusted independently in the H- or E-plane by laterally offsetting the feed waveguide or bending the waveguide linking with the metallic flare that operates as a radiating structure. By this means, five Cassegrain subarrays with multiple waveguide inputs and different bending angles are stacked to build a high-gain wideband 2-D multibeam antenna array in the Ka -band, whose 3 dB beams cover angular ranges of ±60° in the E-plane and ±18° in the H-plane. A bandwidth of more than 40%, stable multibeam radiation with cross polarization of less than −25 dB, a gain of higher than 20 dBi, and a radiation efficiency of more than 90% are confirmed experimentally by a metallic 3-D printed subarray. With the compact printable geometry and the good operating performance, the presented 2-D multibeam antenna fed by the planar Cassegrain beam-formers is an attractive candidate for millimeter-wave multiple-input multiple-output (MIMO) applications in the fifth-generation (5G) mobile communications.

Gaussian beam techniques for illuminating reflector antennas

Abstract: Simple design procedures are presented for use when a Gaussian beam is used to illuminate a classical reflector antenna. Displacement of the location of the beamwaist toward the focusing element in the case of electrically small antennas where the aperture is in the near field of the feed was calculated together with modification of the required beamwaist radius. Dual reflector antennas were discussed and design procedures appropriate for systems with large and small focal length to diameter ratio developed. Cases where a reflector or subreflector is electrically small, or in the near field of a feed, are readily treated. For elliptical beam antennas, a simple illumination system using only a scalar horn and a single cylindrical lens can generally be found; this has no ray optics analogue. A configuration of this type is discussed, with a practical case study of a 28-by-80- lambda elliptical Cassegrain antenna operating at a wavelength of 3 mm. The design process for designing the feed system is discussed in detail. Despite the small size and relatively large aperture blockage, an aperture efficiency of 0.48 was measured, which compared quite well with the expected efficiency of 0.53, thus verifying the validity of the Gaussian beam design approach. >

A compact offset gregorian antenna system for providing adjacent, high gain antenna beams

Abstract: An antenna system comprising a feed array, a subreflector and a main reflector which are oriented to define a offset gregorian antenna geometry. The feed array is comprised of a plurality of separate feeds which are aligned on a predetermined contour. Each feed array is coupled to a feed network which acts to combine the illumination beams of clusters of a preselected number of feeds to produce a plurality of composite illumination beams. Each composite illumination beam is directed to be incident upon a separate predetermined location on the subreflector which directs the composite illumination beams and directed towards the main reflector. Each composite illumination beam is reflected by the main reflector in a preselected direction so that each composite illumination beam forms an antenna beam that impinges a predetermined coverage area on the Earth. Each antenna beam defines a separate coverage cell in the coverage area, wherein the position and orientation of the feeds, the subreflector and the main reflector provides antenna beams over a full Earth field of view coverage area where each antenna beam is approximately symmetrically shaped.