IBC-MoM Model for Reactance Modulated Leaky-Wave Antennas

Two periodic leaky-wave antenna designs are presented using the n = -1 spatial harmonic. Both sinusoidal and square-wave modulations of the surface reactance are considered. An impenetrable impedance boundary condition (IBC) in conjunction with the method of moments (MoM) is used to obtain the radiation patterns for 2-D leaky-wave antennas of unite extent. The reactance variations are then physically realized by modulating the thickness of a grounded dielectric slab. This in turn is modeled in a full-wave 3-D simulator (CST). Aspects of the feed design for the 2-D and 3-D models are addressed to minimize contamination of the radiation pattern by direct radiation from the source. The resulting scan angles and beamwidths predicted by the CST model are found to agree with the 2-D IBC-MoM. The 2-D model is useful, because it can treat not only sinusoidal and square-wave modulations but any proule. Therefore, it becomes easy to rapidly predict in 2-D the key radiation characteristics (the scan direction and beamwidth) for impedance proules that are arbitrary.