Leaky Wave Antennas: Theory and Design

We review old and recent developments on leaky wave antenna theory and design. A leaky wave is treated mathematically as a complex plane wave and the radiation pattern is derived in terms of the complex propagation constant. Several leaky wave antenna structures are introduced and analyzed. An example of a one dimensional leaky wave antenna is a planar surface waveguide with a partially reflecting screen (PRS) made of periodic thin metal strips placed on the dielectric /air interface. This particular configuration has been treated theoretically and experimentally by the present authors. Radiation occurs in this antenna by the spatial harmonic mode with n= -1. The two dimensional (2-D) leaky wave structures depend on radially travelling waves and they produce pencil beams in the broadside direction and conical beams otherwise. Examples of such antennas include a stack of dielectric layers of contrasting alternate high/low permittivities. Results obtained on an antenna of this type are presented as well as some results on new types of planar structures. Future trends and applications for these type of antennas are also featured.