<title>Photorefractive phased array antenna beam-forming processor</title>

Abstract

A high bandwidth, large degree-of-freedom photorefractive phased-array antenna beam-forming processor which uses three-dimensional dynamic volume holograms in photorefractive crystals to time integrate the adaptive weights to perform beam steering and jammer-cancellation signal-processing tasks is described. The processor calculates the angle-of-arrival of a desired signal of interest and steers the antenna pattern in the direction of this desired signal by forming a dynamic holographic grating proportional to the correlation between the incoming signal of interest from the antenna array and the temporal waveform of the desired signal. Experimental results of main-beam formation and measured array-functions are presented in addition to beam-propagation computer simulations demonstrating the spatio-temporal evolution of the holographic index grating and the resulting processor output. keywords: adaptive phased-array antennas, photorefractive signal processing, optoelectronic signal processing.

Efficient Adaptive Optical Processing for Sonar Arrays

“…This is the reason that most DSP approaches utilize techniques that reduce the problem size, such as subarray adaptation. In this way the number of adaptive parameters are reduced at the expense of sacrificing optimal processing, thus diminishing their ability to process data from complex signal environments with large numbers of targets.As an alternative, in this proiject we investigated a class of optical processors that we have previously employed[1,2,3,4] for adaptive phased-array radar jammer-nulling and beamsteering operations. This architecture is fully adaptive, with the full ml degress of freedom, but requires only 1 feedback delay line and one additional delay line per adaptively formed beam.…”