A self-steering array using power detection and phase shifting

Miniaturized Retrodirective Arrays for a Nanosatellite Platform

“…This technique was previously demonstrated in (5] , but had to operate in power-detection and retrodirection modes sequentially, rather than simultaneously. It was also only capable of half-duplex communication.…”

“…Our null-scanning RDA is an evolution of the beam-scanning RDA [5], in which a beam is scanned across a steering range, and the DOA is determined from the angle for which maximum power is detected. A drawback to this design is that constant target tracking cannot be achieved because the array must switch between power-detection and communication modes.…”

“…As a null is scanned throughout the angular range, the received power is recorded in the same manner as in [5]. In contrast to beam scanning, the DOA of the interrogator is determined by the angle for which the power received by the null-steering array is a minimum.…”

“…Compared to the analog phase shifters used in previous designs [5] , [17], [18] the discrete nature of digital phase shifters resulted in tolerance to small variations in control voltage, which are inherent in any control circuit. The analog phase shifters used previously were extremely sensitive at 221.4 degN [ 17], where commonly occurring variations in control voltages on the order of tenths and hundredths of volts would cause steering angle errors and instability.…”

“…Heterodyne mixing arrays use mixers on each element to conjugate the phase of the incoming wave [3]. Other architectures use phase shifters to direct the beam and either phase detectors or power detectors to determine the direction of arrival ofthe signal [4]- [5].…”