A Novel Yagi-Uda Dipole Array Fed by A Microstrip-To-CPS Transition

We report the design and experiment of a novel Yagi-Uda dipole array fed by a MS-to-CPS transition. The Yagi-Uda array having one director on the same plane of the dielectric substrate as the driver element shows higher gain (9.1dB) than microstrip patch antennas and a much wider bandwidth (10.3%). The measured front-to-back ratio is about 15dB. This novel design should become an important alternative to tapered-slot type antennas for millimeter wave imaging array application.