An Active Retro-Directive Array with Different Transmit and Receive Frequencies

This paper presents an active retro-directive array (RDA) for satellite calibration. In contrast to other approaches, the RDA system uses two different frequencies, received and transmit frequencies being 2.51 GHz and 2.68 GHz, respectively. The active phase conjugate circuit uses two mixers and heterodyne principle. Circularly polarized antennas are used to avoid polarization problem due to propagation through ionosphere. Detail design of the RDA system is presented. Finally, a prototype is fabricated and tested. Measurement results agree well with the desired performance.