A retrodirective array (RDA) capable of retransmitting predictable polarization with respect to any received polarization state is presented. RDAs have the unique ability to scatter the received signal back to the interrogator without prior knowledge of the source location. In addition to this unique feature, the proposed system can receive any polarization and always retransmits the signal that is orthogonally polarized with respect to the received polarization state. This added feature helps to maintain a more stable communication link between the RDA and the interrogator by mitigating the polarization mismatch loss. The proposed system shows excellent retrodirectivity for various received linear and circular polarizations. © 2013 IEEE.

This paper presents an all-passive phased-array feed network based on composite right/left handed (CRLH) transmission lines (TLs). A CRLH TL enables systematic engineering of the phase response providing phase advance in addition to phase delay. When utilized in a phased-array feed network, an all-passive 1-D frequency-scanning array can be designed with a large scanning angle range toward both positive and negative elevation angles. This unique feature cannot be realized using conventional delay lines or dispersive lines that do not contain left-handed properties. Also, unlike the previously studied CRLH-based leaky-wave antennas that provide similar 1-D continuous frequency-scanning functionality, the proposed method completely decouples the radiating antenna element from the array factor; thereby providing extra design freedom and enhanced radiation performance. To validate the added advantage, we use the proposed CRLH-based phased-array feed network to demonstrate simultaneous controllability of the radiated polarization and array current amplitude distribution. © 1963-2012 IEEE.