Using periodicity to control spectral characteristics of an array of narrow slots

We consider a frequency selective surface (FSS) consisting of a thin perfectly conducting sheet periodically perforated with narrow slot apertures. For wavelengths greater than the periodicity, such a surface performs similarly to a bandpass filter since the periodic elements within the FSS possess resonance characteristics. The effects on the spectral characteristics of varying the periodicity of a narrow slot array (or its complementary dipole array) was studied by Ott et al. (1967) and Munk et al. (1971). By changing the periodicity, they found it possible to change the location of the resonant wavelength and the bandpass width of the transmission/reflection spectrum. With advances in computational technology, we are able to study these effects of periodicity in narrow slot arrays in much more detail. In this study we used the methods described by Chen (1970) to predict the spectral characteristics of narrow slot arrays designed for use in the middle infrared spectral region. An algorithm was written in FORTRAN for use on either a PC or workstation. Although our work presented is limited to a normally incident plane wave, the approach can be extended to the case of oblique incidence.