Propagation and Field Excitation in Metal-Strip Grating Waveguides: Homogeneous Model and Full-Wave Analysis

Partially filled parallel-plate waveguides (PPWs) loaded with parallel metal strips arranged periodically [i.e., metal strip gratings (MSGs)] are studied by means of both an approximate homogeneous model and a rigorous full-wave analysis. Bloch modes supported by the waveguide are first considered in different propagation regimes. Full-wave results for the fields excited by an electric line source are also obtained via the array scanning method (ASM) so that the limits of validity of classical homogeneous models (based on a transverse network representation of the structure) can be assessed in the presence of finite sources and for observation and source points close to the actual periodic metallic loading.