AN IMPROVED SCANNING AUTOMATIC TRACKING ANTENNA FOR TELEMETRY APPLICATIONS

Abstract

The generation of scanned offset beams for producing error signals to track targets is an old and well proven technology which has been improved over the years with innovative techniques directed at specific mission capabilities. The various techniques of generating offset beams, sequential lobing, conical scan, and single channel monopulse, have proven to be acceptable, cost effective means of autotracking. These techniques and a new, generalized electronic scanned beam configuration will be discussed with their inherent advantages and disadvantages for various mission applications. A new electronic scanning, autotrack technique, ESCAN, will be developed mathematically and its performance demonstrated through analysis and measured antenna radiation pattern data. The ESCAN tracking antenna concept will be shown to have superior side lobe characteristics to previous electronic scanned beam approaches due to its capability to control side lobes in both the scanned, offset beam plane and the orthogonal plane. ESCAN offers improved capability in reducing crosstalk between the two orthogonal tracking channels, offset beam control vs frequency, and wider frequency bandwidth. ESCAN retains the flexibility of simultaneous generation of a separate unmodulated data channel and a modulated tracking channel. Since ESCAN is an electronic scanning technique the rate of scan can be controlled at any fixed rate or for variable rates (including random variations in rate) within the capabilities of solid state switches. This capability allows the antenna system to acquire and track spin stabilized vehicles as well as other vehicles such as polar orbiting satellites and airplanes.