A Planar Quasi Yagi-Uda Antenna Designed For Liquid Crystal Based End-Fire Phased Arrays

This paper presents a planar quasi Yagi-Uda antenna based on liquid crystal (LC) technology for millimeter-wave applications. The antenna is built on the inner surfaces of two parallel glass substrates, with thin layer of LC filled in the feed part. It is fed by a two-step coaxial-to-microstrip transition. The antenna achieves a measured bandwidth of 31 % with a VSWR <; 2, better than 15 dB front-to-back ratio, better than -13 dB cross polarization and 9.0 dBi gain at 28 GHz. Measured scattering parameters, as well as far field patterns agree very well with the simulation results. The planar quasi Yagi-Uda antenna is compatible with existing planar reconfigurable feed network based on LC technology, complementary to the broadside radiating array.