Dual-Frequency Retrodirective Antenna Array With Wide Dynamic Range for Wireless Power Transfer

This letter presents a dual-frequency heterodyne retrodirective antenna (RDA) array with relatively large frequency ratio between receiving and transmitting for adaptive tracking in far-field wireless power transfer systems. The proposed RDA consists of an eight-channel radio frequency mixing, amplify chain and two 1 × 8 circularly polarized arrays with different operation frequency and orthogonal polarizations, receiving at 3.8 GHz with right-hand circular polarization and transmitting at 5.8 GHz with left-hand circular polarization, respectively. For received power levels from −80 to −40 dBm, each chain outputs with consistent phase and stable power about 29 dBm brought by automatic gain control and compensation phase shifter. It can transmit reversely along the direction of beacon signal from near to far distance. High system isolation is achieved through inherent isolation of different frequencies and orthogonal polarizations of the T/R arrays. Monostatic and bistatic measurements are taken, and measured results verify that the proposed RDA is of far-field tracking capability to receive and transmit from −40° to 40°.