Exploiting advanced composite materials for lightweight shipboard SHF satellite communication antennas

Naval satellite communications and capacity requirements demand improved shipboard antenna performance. Extraordinary design features and the use of lightweight composite materials are necessary to meet the requirements of a shipboard antenna for SHF satellite communications. Advanced materials, modeling, and analysis techniques are used to produce high-efficiency antennas for operating in shipboard environments. The major requirements for the antenna are discussed. These are achieved using advanced technology in materials and design. Size and weight reductions are achieved using a gimbal structure employing advanced composite materials for the primary structural components. Lightweight composites in combination with stainless steel brackets provide the strength and stiffness required for a shipboard environment. Three axes support dynamic platform motion while reducing motor drive torque requirements. High gain and low noise temperature are achieved by an extremely high-efficiency Cassegrain antenna with low side and back lobes. Integration of redundant LNAs as part of the elevation housing reduces losses between the orthomode transducer (OMT) and LNA input. The orthomode transducer is a well-matched three-port waveguide junction. Orthogonal modes entering the common port of the transducer exit in individual, rectangular waveguides, one for the receive band and the other for the transmit band. By substantially reducing these losses, the antenna can achieve an impressive G/T ratio of 19.0 dB//spl deg/K. A complete description of the antenna, its design, and performance are described.<
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