High efficiency and broadband excitation of leaky mode in microstrip structures

This paper reports a novel technique for high efficiency and broadband excitation of the first higher order leaky mode in microstrips. A uniplanar microstrip-to-CPS transition is employed to launch the odd leaky mode, and the mode purity is enhanced by suppressing the even fundamental mode using an optimized mode suppressor. An X-band prototype demonstrates excellent mode conversion efficiency as predicted by simulations. A record bandwidth of 20.2% is achieved for a microstrip leaky-wave source based on this newly proposed structure.