VHF Adaptive Array Test Results

Abstract

A four-element Anti-Jam Antenna Array (AJAA) system has been built to provide protection for U.S. Marine Corps inter-command post communications in the 30-76 MHz band. A unique and important feature of the AJAA system is its ability to spatially null jammers down to a level below that of the desired signal. This capability and the prevention of accidental cancellation of the desired signal is achieved by using the desired signal's direction-of-arrival (DOA) in a prebeamformer located ahead of the adaptive beamformer. A positive S/J at the array output is required to prevent capture by a co-channel interference in standard FM field radios. Antenna range tests were performed on the AJAA system using AN/PRC-77 radios as far-field signal and jamming sources. Results of these tests show that the AJAA provides an intelligible FM voice signal at its output while simultaneously suppressing three jammers.