Effect of Target Motion on Equivalent Transmit Beamforming for the Frequency Diverse Array

Conventional antenna-array beamforming along a selected direction cannot discriminate between different far-field subranges. To select a particular subrange in the far-field, a distance-specific multiantenna transmission architecture known as the frequency diverse array along with amatching receiver architecture knownas equivalent transmit beamforming (ETB) has been recently proposed. However, these breakthroughs have not explicitly addressed the effects of target motion, which is ubiquitous in radar applications. These effects are analyzed in this article, leading to the conception of a range-direction-Doppler version of the "direction cosine" which is used to develop analytical formulas for the ETB beampattern characteristics in terms of the ETB system parameters along with insights for system design.