Cassegrain antenna

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

Deployable phased array of reflectors and method of operation

Abstract: A deployable phased-array-of-reflectors antenna includes individual reflectors and feed arrays. Each feed array is disposed above a corresponding individual reflector. The individual reflector antennas are preferably disposed adjacent to one another (e.g., on a hexagonal lattice) to form a phased array antenna using the individual reflectors antennas as elements. Phase and amplitude control electronics are coupled to each reflector antenna to provide steering for the signal energy coupled between the reflectors and the feed arrays. Switching electronics are coupled to the feed arrays and selectively activate and deactivate beam forming clusters of feeds in the feed arrays. A method for generating a steerable antenna pattern couples signal energy through a beamforming section to form steered signal energy. Next, the method couples the steered signal energy between a phased array of reflector antennas. The method selectively activates a first feed cluster for a first reflector, a second feed cluster for a second reflector, and so on, until feed clusters are activated in all of the reflectors in the array. The method then couples the steered signal energy between the first and second feed clusters. The method subsequently activates and deactivates the feed clusters to reduce the impact of grating lobes in the total antenna pattern, or when a particular cluster attenuation has been reached.

Scanning beam antenna with linear array feed

Abstract: The present invention relates to a scanning beam antenna comprising a doubly-curved main reflector, a doubly-curved subreflector and at least one linear array feed. The main reflector is doubly-curved in two planes to produce a separate first focus for each feed in a first plane in front of the subreflector and a separate second focus for each feed in a second orthogonal plane behind the subreflector. The subreflector is curved to refocus each second focus of the main reflector to coincide with the image line of a first axis on the reflecting surface of the main reflector in the first plane. Each feed array is disposed at a separate secondary focus of the combination of the main reflector and subreflector. The resulting antenna provides very little phase error due to aberrations as each beam is linearly scanned.

Imaging antenna systems with compensated optical aberrations based on unshaped surface reflectors

Abstract: An offfset imaging antenna system with compensated optical aberrations comprises a main a paraboloid reflector (4), a first paraboloid sub reflector (6), and a first feeding array (8) as an arrangement of first feed array elements to illuminate or to be illuminated by the first sub reflector. The main reflector (4) and the first sub reflector (6) are confocal by sharing a common focal point. The first feeding array (8) has a curved shape that corresponds to a first equivalent array (12) of magnified image feed elements (14) lying on a plane (16) crossing the main optical centre and perpendicular to the main bore-sight axis, all the first feed array elements (10) being positioned as to provide a planar distribution of the positions of the image feed elements (14) onto the first equivalent array (12) after a second reflection by the main reflector (4) with a central image point coinciding with the main reflector optical centre under a maximum illumination condition.

Reflector antenna with improved scanning

Abstract: A Cassegrainian antenna system has a planar array as the feed. An intermediate reflector is positioned in the near field of the array for substantially collimated illumination with all array elements operating in phase. Accordingly, an on-axis main beam is radiated from the main reflector upon illumination by energy from the intermediate reflector. By impressing a linear phase gradient across the array, the main beam is controllably tilted off-axis.

Excitation system for an antenna with a parabolic reflector and a dielectric radiator

Abstract: An excitation system which can be used with sector antennas which do not have circular reflectors is described. The reflector is designed as a rectangular strip which curves parabolically in the direction of its long axis to form a sector antenna. The end face of the radiator has four partial faces which form equal pairs and their opposing faces are arranged with respect to the central axis of the hollow conductor so that the surfaces of the two pairs extend at approximately right angles to each other. The partial faces of the radiator extending in the direction of the long axis of the reflector are large in relation to the two partial faces extending crosswise thereto.