摘要:
An antenna for communicating with a satellite from a moving vehicle. The antenna comprises a transmitter for generating a transmission signal, main and sub reflectors, and a waveguide associated with the transmitter for conducting the transmission signal toward the sub reflector. The sub reflector is configured for redirecting the transmission signal toward the main reflector; the main reflector is configured for projecting the redirected transmission signal as an antenna beam toward the satellite.
摘要:
An antenna for communicating with a satellite from a moving vehicle. The antenna comprises a transmitter for generating a transmission signal, main and sub reflectors, and a waveguide associated with the transmitter for conducting the transmission signal toward the sub reflector. The sub reflector is configured for redirecting the transmission signal toward the main reflector; the main reflector is configured for projecting the redirected transmission signal as an antenna beam toward the satellite.
摘要:
A dual offset reflector system is disclosed. The system comprises a main reflector, a subreflector, a first gimbal mechanism for positioning of the subreflector. The system includes at least two feeds for receiving beams from the main reflector and the subreflector. One of the feds is at a focal point of the system and the other beam is displaced from the focal point. Accordingly, a simple solution to restore antenna gain reduction and avoid beam distortion due to the scan loss for a reflector system is provided that utilizes multiple feeds at different frequencies and polarizations. By placing the feeds at focal point trajectory of the subreflector whose positioning is controlled by a gimbal mechanism, a system is provided that minimizes distant and scan loss in a dual reflector system. The gimbal mechanism positions the subreflector so that a desired feed is in the focal point of the subreflector.
摘要:
An antenna for communicating with a satellite from a moving vehicle. The antenna comprises a transmitter for generating a transmission signal, main and sub reflectors, and a waveguide associated with the transmitter for conducting the transmission signal toward the sub reflector. The sub reflector is configured for redirecting the transmission signal toward the main reflector; the main reflector is configured for projecting the redirected transmission signal as an antenna beam toward the satellite.
摘要:
An antenna system includes an antenna feed aligned with a subreflector and a main reflector. The subreflector has a concave surface defining a vertex. A main reflector having a concave surface is aligned with the subreflector to define an antenna focal area at the vertex of the subreflector. The antenna feed may be a phased array or fixed antenna feed. The antenna system may further include a controller cooperating with the phased array antenna feed for beamsteering or beamforming. The controller may cooperate with the phased array antenna feed to define and steer multiple beams, at different frequencies, for example.
摘要:
A multi-band reflector antenna having a main reflector, a sub reflector, a first feed and a second feed. The first feed, the sub reflector and the main reflector positioned in a Gregorian optic configuration wherein an output of the first feed is directed to the sub reflector, from the sub reflector to the main reflector and from the main reflector into a first beam. The sub reflector may be shaped to distribute the output of the first feed reflecting off the sub reflector onto the main reflector whereby a central area of the main reflector has a lower illumination than a surrounding outer area of the main reflector and or elongated vertically. The second feed projecting from a hole in the sub reflector is oriented whereby an output of the second feed is directed to the main reflector and from the main reflector into a second beam.
摘要:
A radar surveillance system includes a plurality of satellites a plurality of medium earth orbit satellites to provide continuous, long dwell coverage of a region of interest. Each satellite has an antenna having a main reflector and a subreflector electromagnetically coupled to the main reflector. A phased array generates multiple electromagnetic beams positioned so the electromagnetic beams reflect from the subreflector onto said main reflector. The system may be used in determining slow moving targets using a combination of monopulse anomaly and target spectral width measurements. The system also performs synthetic aperture radar imagery and focussed area fast moving target detection using alternating slope linear frequency modulated pulses. The plurality of medium Earth orbit satellites include a self-contained communications system consisting of high bandwidth self-relay crosslinks, high bandwidth downlink, and direct broadcast downlinks for processed data.
摘要:
A satellite-based communications system operating at high data rates in a broadcasting (multicasting) mode enables the use of mobile ground terminals with low profile antennas whose areas are significantly smaller than previous embodiments not using this invention. The invention can be applied to existing (in-orbit) or new satellites (including those in non-geostationary orbits) operating with linearly polarized downlink transponders. Important embodiments include the use of Ku FSS satellites providing service within the continental U.S. (nullCONUSnull), and the use of Ku BSS satellites operating within Europe. Transponder pairs on board the satellite with opposite linear polarization, but overlapping frequency bands, receive a specially processed uplink waveform from an uplink facility. Service may be optimized for (1) a particular geographical area by using receiving sensors located in that area, monitoring the polarization of the broadcast signal; or (2) a particular location with the satellite operating in a unicasting mode (delivery of Internet data or nulllocalnull video/audio broadcasts). A spread-spectrum waveform can also be used on the downlink, with the resultant processing gain applying directly to antenna area reduction and improved interference. Redundancy or increased capacity can be achieved by locating a second satellite in the same orbital location broadcasting the orthogonal circular (as received on the ground) polarization.
摘要:
An antenna includes a feed generating a communication signal. A sub-reflector is positioned to reflect the communication's signal to form a sub-reflective signal. A main reflector is positioned to reflect the sub-reflective signal. The sub-reflector has an elliptical rim.
摘要:
An antenna feed system capable of simultaneously transmitting and receiving in multiple frequency bands. In one embodiment, the feed system comprises a non-collimating lens attached to the emitting end of a broad-band antenna feed. The lens is positioned to receive and focus the broad-band wireless signals from any reflector configuration to any antenna feed. It is also positioned to transmit and focus the broad-band wireless signals from any antenna feed to any reflector configuration. A method for illuminating a reflector configuration through an antenna feed with the lens is disclosed. A wireless sensor system is also disclosed. In one embodiment, the non-collimating lens may be used as part of a wireless signal sensor unit used to increase or decrease the angular aperture of the sensor unit.