Quadrant switching PLL phase conjugator for retrodirective antenna applications

A new method for producing phase conjugation is presented. This is the essential component of a retrodirective array. This architecture, for the first time, addresses virtually all of the shortcomings of the previously used mixer approaches to this problem. The requirement for a frequency component at 2x F_RF to be present is dispensed with. The architecture here does not require any frequency component higher than FRF, and also exhibits other advantages such as excellent conversion gain, and the re-transmission of a low phase noise high power carrier. Our solution involves the addition of a standard power combiner, used for vector summation, to a standard PLL. By using a novel four quadrant switching method, we can obtain reliable conjugation over a 360deg phase range. Our circuit is ideally suited to low cost point to point self steered wireless applications such as video streaming.