A Scheme for Hardware Reduction in Wireless Retrodirective Transponders

Typical transponders operate with an omnidirectional response to interrogation, with a single antenna element, resulting in inefficient use of available power. Conventional retrodirective array architectures require phase-conjugators at each element, placing a heavy burden on the amount of active circuitry required and limited real estate. In this paper, a switching feed network is integrated into a retrodirective array architecture to offer an N to 1 reduction in the amount of required phase-conjugating hardware, and therefore cost, while offering the directivity of an array architecture and maintaining omni-directional receive and transmit coverage. A four-element retrodirective transponder array is realized under this switching configuration. The introduced switching network can also serve as a built-in modulator for simple data transfer tasks