An autonomous antenna for aerospace applications

A compact shipboard antenna array that provides full hemispherical electronic scan and tracking is described. Using surface acoustic wave (SAW) devices and microstrip variable power combiners (VPCs), the autonomous array can track and receive telemetry data from a submarine-launched Trident II missile just as well as a large mechanically scanned dish antenna. The tracking antenna consists of three-element microstrip patch antenna panels located every 60 degrees around the periphery of the antenna. There are two adjacent patch radiators for both azimuth and elevation angle-of-arrival direction-finding. The tracking information from the SAW is fed into a microprocessor which selects the optimum patch polarization and chooses which high-gain helix radiator to turn on to point to the missile. The energy is transferred from one helix to another by means of VPCs and switches via microprocessor commands. When the VPC has energy equal to that of two adjacent helices, there is a 3-dB increase in gain due to the two-element array factor.<>