Scattering characteristics of a 1D array of cavity-backed cylindrical holes in a PEC ground plane

We examined the scattering characteristics of a canonical rod/hole system. We found that the holes could simply be modeled as sections of cylindrical waveguides with short-circuit terminations. Comparisons with fundamental quantities such as the guided wavelength and cutoff frequency yielded results that agreed quite well. The notion of an effective single-hole efficiency was introduced, implicitly accounting for inter-element coupling. We found that it asymptotically tends to a constant value as the number of holes increases. We also concluded that the proximity of the rod to the grating plays an important role in the coupling phenomenon, a result of the traveling-wave nature of the rod field. Finally, we compared a computed array far-field pattern with one based on a simple array-factor expression that includes an HFSS (a commercial 3D finite-element EM simulator) computed leakage constant. The results lead to the conclusion that use of the effective efficiency as an array synthesis parameter will yield the predicted antenna characteristics.