Frequency-scanning phased-array feed network based on composite right/left-handed transmission lines

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.