Moment Method Computation of Miniaturized Rectangular Hard Waveguide with Passband and Stopband

A numerical moment-method for treating the dipole-FSS loaded hard rectangular waveguide has been presented. The results obtained from it agree with CST simulations. An unusual upper modal cutoff-frequency, not present in the conventional bare-slab loaded waveguide, was found in the dipole-loaded one. Modes of such waveguides thus possess band-pass properties. If appropriately designed, a stopband is possible. This suggests that when these waveguides are used as the lower frequency elements of a multi-band interlaced array, the operation of the higher frequency elements within the stopband allows the two functions to be performed simultaneously without interference. Measurements on a manufactured dipole-loaded waveguide were also made. The experimentally-obtained dispersion diagrams concur well with CST simulations and with a third independent approach based on network theory (Maci, S. et al., IEEE Trans. Antennas Propag., vol.53, no.1, 2005).