The present invention includes phase shifters, interrogators, methods of shifting a phase angle of a signal, and methods of operating an interrogator. One aspect of the present invention provides a phase shifter including a first power divider configured to receive a signal and provide plural quadrature...http://www.google.de/patents/US7091828?utm_source=gb-gplus-sharePatent US7091828 - Interrogators, methods of operating a coherent interrogator, backscatter communication methods, interrogation methods, and signal processing methods
