Design Of Arbitrary Polarization And Full Scanning Retrodirective Antenna Arrays

The rapid development of the wireless communication system calls for better characteristic and performance of antenna arrays, such as low cost, high link gain and the capability of adaptive beam tracking. A retrodirective array(RDA) is a class of antenna that can automatically transmit a signal along the direction between the interrogator and the RDA without prior knowledge of the incoming signal direction. In addition, it does not rely on any phase shifter or complex digital signal processing. It has applications in both military and commercial communications systems.Polarization characteristics have been previously studied in conjunction with the RDAs, however, these RDAs only work for certain polarizations, and therefore, it always has polarization mismatch in complex communication environment. In addition, full angular coverage is often preferred or required for some applications such as radar and satellite communications. However, most of the retrodirective arrays reported are in 1-D linear and 2-D rectangular configurations. Thus, these problems have constrained the development and application of the retrodirective arrays.Based on the current research status both at home and abroad, various kinds of realization methods and the key technology of RDAs are theoretically studied. The influencing parameters on the beam pointing error for judging the performance of a retrodirective array are analyzed in theory.A polarization friendly rectrodirective array is presented. The proposed RDA can receive any polarization and always retransmit the signal back to the interrogator with the predictable(orthogonal) polarization. This added feature can mitigate polarization mismatch loss and provide a more secure communication link. The proposed polarization friendly RDA shows excellent retrodirectivity for various received polarization states.A cylindrical conformal retrodirective array is proposed for a full 360° scanning range. The impact of some factors on the conformal array, such as the number and spacing of antenna elements and the radius of the curved metal ground is analyzed. Then, combining the independent transmitting and receiving antennas with a phase conjugated circuit, the whole retrodirective array was implemented with full range coverage. In addition, a novle wideband antenna is proposed for the wideband RDAs, extending the application of the RDAs.