Iterative Fourier Transform Phased Array Radar Pattern Synthesis

Abstract

Many Adaptive Phased Array Radar (APAR) techniques provide farfield signal power and location. Once this information is known, placing nulls at these locations to cancel jammers can be accomplished through a proper choice of antenna weights. The weight and angular domains are related through Fourier transformation. To obtain a fine sampling in the angular domain to accurately specify the desired nulls, it is required to extend the weight aperture by padding it with zeros. However, in the final weight vector applied to the antenna output, the contribution of these extra elements must be zero since they do not correspond to available antenna elements. This provides two sets of constraints on the solution, the set of desired nulls in the angular domain and the available aperture in the weight domain. A method of finding a solution which matches constraints in both the time and frequency domains is the Gerchberg-Saxton error reduction algorithm, which is often applied to image reconstruction. This paper will describe the investigation into the behavior of this algorithm as applied to the discrete antenna pattern synthesis case. The algorithm is presented in matrix/vector form and its transient and steady state response is derived. To assist in this analysis, we introduce a new matrix operator which greatly simplifies the required derivations. Computer simulation and numerical evaluations of the analytical results are included to demonstrate the applicability of the algorithm to pattern synthesis.© (1987) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.