Cassegrain antenna

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

Double reflector antenna with feed horn protection

Abstract: A double reflector antenna mounted on a terrestrial mount with Azimuth and elevation shafts in which a primary field radiating and detecting horn is mounted within a housing behind a central opening of the main reflector dish so as to radiate and receive energy from a sub-reflector mounted at the focal point of the main reflector dish and such that the lead supplying energy to and from the horn can be very short and the horn can be substantially shielded from snow and rain.

Cassegrain antenna with improved subreflector for terrestrial communication systems

Abstract: A Cassegrain antenna for use in terrestrial communication systems. The antenna has the conventional subreflector including a central area which provides tapered illumination of the entire main reflector, and a peripheral area which directs spillover from the central area onto the peripheral portion of the main reflector to improve the uniformity of illumination of the main reflector, thereby improving illumination efficiency and reducing gain loss due to spillover. The central and peripheral areas of the subreflector are preferably both surfaces of revolution of conic sections of the same kind, such as hyperboloids, ellipsoids or paraboloids, although the peripheral area may be a frustoconical surface if desired. The virtual focal points of the two conic sections of the subreflector are both coincident with the phase center of the feed horn.

Adjustable antenna mount for parabolic antennas

Abstract: An antenna mount for aiming a parabolic antenna towards a geosynchronous satellite characterized by four, pivotal sub-assemblies, each of which is rotatable around its own axis. The mount can be quickly adjusted to point the antenna at a particular geosynchronous satellite, or may be caused to sweep across the satellite belt in a scanning manner. The antenna mount can be attached to a support post of virtually any orientation ranging from vertical to horizontal.

Reflector arrangement for attachment to a wireless communications terminal

Abstract: A reflector arrangement (20, 22) is configured for attachment to a wireless communications terminal (4) having a patch antenna. The patch antenna includes a patch radiator(28)in a substantially parallel relationship with a ground plane(42), and the patch antenna produces a radiation beam of a predetermined beamwidth. The reflector arrangement is configured, when attached to the terminal, to produce a radiation beam of reduced beamwidth relative to the predetermined beamwidth. The reflector arrangement comprises a main reflector(20)and a sub-reflector (22) for reflecting radiation towards the main reflector(20), and the reflector arrangement is configured such that, when attached to the terminal, the patch antenna acts as a feed antenna for the sub-reflector(22). The sub-reflector (22) is arranged to collect the radiation from the patch antenna and to reflect the beam towards the main reflector (20) such that the main reflector (20) produces the radiated beam of reduced beamwidth.

Offset-fed multi-beam tracking antenna system utilizing especially shaped reflector surfaces

Abstract: A reflector antenna system is described suitable for ground stations used in communication with geostationary satellites. Dual beams or multi-beams can be directed at several satellites spaced angularly from 5° to 20° apart and these beams are scanned by feed motion keeping a single main reflector surface fixed. Offset feed geometry is used for low aperture blocking and shaping of subreflectors and main reflector results in very high aperture efficiencies, low sidelobes and symmetric low cross-polarization patterns needed for satellite links. A novel method for shaping subreflectors using the ratios of ray lengths squared and variable focal lengths is applied in the optimally tilted offset geometry results in almost uniform aperture power distributions. A new general procedure for shaping doubly curved surfaces intercepting a known population of rays such that these rays are focused to a point or reflected in a given direction is used to shape the main reflector for elimination of aperture phase errors and to shape a second subreflector which focuses perfectly to the apex of a second feed horn.