Study of Surface Waves on Planar High-Gain Leaky-Wave Antennas

Much work has been devoted to gain enhancement of printed leaky antennas of multilayer resonant structure. However, little attention is paid to the excitation and characteristics of surface waves, which can reduce radiation efficiency and therefore the net antenna gain. We present a rigorous analysis for surface waves considering a three-dielectric-layer antenna configuration for which the radiation power and the surface-wave power are derived. It is shown that, for certain antenna parameters, surface-wave power can considerably reduce the antenna efficiency and antenna gain. Design consideration for efficient operation of these types of antennas is provided. The concepts and formulation described here can be adopted for application to similar configurations that employ different excitation and layered structures.