Experimental comparisons of sky wave DF algorithms using a small circular array of loop antennas

A large quantity of array responses to skywave signals has been recorded by an automated data acquisition system and has been processed using several fundamentally different algorithms for estimating azimuth angle of arrival. The skywave signals incident on the array were generated by a controlled transmitter positioned at ranges varying from 278 to 1379 km, and operating at frequencies from 2 to 15 MHz. The data were processed to compare the experimental performance of a synthesized spinning spaced loop system, a synthesized system of magnetic dipoles and symmetric magnetic quadrupoles, and a form of sum-and-difference mode DF. To provide comparative results from a system having well understood polarization error, the data were also processed with a conventional simple loop DF algorithm