Metamaterial Based Electronically-Scanned Circularly-Polarized LWA

An electronically-scanned circularly-polarized leaky-wave antenna (LWA) designed for ETC system is proposed in this paper. Based on the theory of composite right/left-handed (CRLH) transmission line (TL), the proposed antenna can fulfill the beam-scan from
$-{\hbox{6}}^{\circ}$
to
$-{\hbox{21}}^{\circ}$
in the half plane continuously at the fixed frequency of 5.8 GHz by tuning the bias voltage of varactors loaded on the CRLH TL. By loading corner-cut square patches, a circularly-polarized radiation is obtained at the main beam, and the maximum gain in the main beam direction keeps above 11 dB.