Ultrawideband Frequency-Diverse Array Antennas: Range-Dependent and Autoscanning Beampattern Applications

Unlike phased-array antennas, which provide both rangeindependent and time-independent beampatterns, frequency-diverse array (FDA) antennas produce rangeangle and time-dependent beampatterns and, accordingly, autoscanning transmit beampattern (TB) characteristics due to the employment of a small frequency increment across its array elements. This article introduces the FDA antenna in the background of ultrawideband (UWB) radar and communication applications. The FDA range-dependent and autoscanning beampattern characteristics are analyzed for both continuouswave and pulsed signals. The FDA beampattern characteristics in narrow-band (NB) and UWB cases are illustratively compared. Potential applications in multipath mitigation and secure communications and low probability of interceptor (LPI) are discussed, along with their technical challenges, especially in antenna and propagation aspects, e.g., transmit beamforming and optimal array design.