Abstract: In an antenna array of N elements in a circle around a large through mast, direction finding capabilities are enhanced for an incoming signal where fewer elements are needed compared to standard quasi-Doppler or pseudo-Doppler methods. Azimuth detection takes advantage of the scattered wave from the through mast where measurements of amplitude and relative phase shift shows an induced distortion pattern from through mast scattered waves. Analyzing the amplitude and phase measurements determines the azimuth angle of the arrival of the incoming signal.

Abstract: A system using two magnetic quadrupole antennas, two magnetic dipole antennas and means for processing the respective antenna signal outputs provides unambiguous estimates of elevation and polarization for an incident RF signal. The system uses an efficient procedure to process the signals from a small aperture array of fixed loop elements for the purpose of providing radio direction of arrival information that is free of intrinsic polarization error. The directional information is developed by performing a simultaneous arctangent operation on signals output from the antennas or as the measured phase difference between a quadrature summed quadrupole output and a quadrature summed dipole output compensated by a phase offset between the dipole antennas and the quadrupole antennas.

Abstract: A sky wave DF antenna system is disclosed. It is able to respond to an incoming transmitted signal and define the direction of the transmitter. It utilizes six or more simple loops connected and arranged to form a spaced loop antenna system which indicates the incoming direction of the transmitted signal without regard to the polarization or the elevational angle of the sky wave.