Mode-Selective MIMO OTH Radar: Demonstration of Transmit Mode-Selectivity on a One-Way Skywave Propagation Path

This paper reports results of an experimental program called the Mode Selection Experiment that was designed to demonstrate ionospheric mode selectivity on transmit over a one-way skywave propagation path. This corresponds to the transmitter-to-target part of the two-way propagation path used in an Over-the-Horizon Radar. The purpose of the experiment was to show that multiple-input multiple-output radar techniques can be used to construct the required multiple simultaneous adaptive range-dependent transmitter beams needed in a ModeSelective Over-the-Horizon Radar, which is a new class of skywave radar designed for Maritime Domain Awareness applications. The results comprehensively show that a beam can be created and applied to selectively illuminate desirable ionospheric propagation paths while simultaneously nulling undesirable propagation paths. It is possible to simultaneously create a different such beam for each range cell in the range coverage and so achieve mode-selectivity throughout the full range extent of the radar.