a passive instantaneous microwave signal frequency identifying and angle of arrival identifying system employing a beam steering multiple element antenna coupled through a butler matrix to a plurality of simplified fourier transformation radio receivers wherein unit value or near unit value magnitudes of the kernel function  - j2   π   kn n in the receivers &# 39 ; fourier transformations are used to elude transformation computation complexity and resulting radio receiver size and cost penalties . limiting amplifiers , a video signal path and direction finding encoding logic are also employed . airborne military application of the system in electronic warfare direction finding , radar frequency determination and other activities is included .