I've posted the abstract to my dissertation below. You can also download (or view) my Dissertation Proposal (1.1 MB) and Dissertation (3.5 MB) entitled Frequency Selective Surfaces with Multiple Periodic Elements. They are both in Adobe Acrobat 3.0 format so you must have the Acrobat Reader 3.0 installed to view them.
It has been brought to my attention that I left out the listing for the function CRECT in the program listing for the FSS code in my dissertation. I've included a copy of the listing for the function here, along with the circular modal function data file CIRMODE that the program uses.
FREQUENCY SELECTIVE SURFACES WITH MULTIPLE PERIODIC ELEMENTS
Jeffrey A. Reed, Ph.D.
The University of Texas at Dallas, 1997
Supervising Professor: Dale M. Byrne
A thorough computer design study using the method of Chen1,2,3 was undertaken for bandpass filters constructed from frequency selective surfaces (FSSs). The FSSs, modeled as thin, perfectly conducting surfaces with periodically arranged apertures, were designed to produce a transmission profile with a bandpass characteristic centered at 10.6 mm and to have various specified bandwidths. The effects of aperture shape and dimensions, configuration and periodicity of the aperture array, and presence of a dielectric substrate were examined in-depth. For comparison purposes, a complimentary array of metallic patches was also examined. The successful design (a thin, planar sheet of aluminum perforated with narrow rectangular apertures in a triangular array configuration on a thick zinc selenide substrate) provided a preliminary set of basic design rules for creating bandpass filters from FSSs.
Dual resonance transmission profiles were generated by considering a FSS with a group of apertures as the periodic element. Chens method1,2,3 was modified to work with periodic groups of up to four rectangular or circular shaped apertures (or metallic patches). Combinations of different length narrow slot apertures, combinations of square and narrow slot apertures, and variation of periodicity along alternating rows of narrow slot apertures, all produced a dual resonance transmission profile in the computer model. For the combination of different length narrow apertures, the dual resonance resulted from the natural resonance associated with the two different length narrow apertures, while for the combination of squares and narrow slots, an enhancement of the Woods anomaly at the diffraction edge created the second resonance peak. Variation of the periodicity along alternating rows produced a dual resonance because each of the "superimposed arrays" had a different periodicity. The presence of Woods anomalies in the transmission profile was also examined.
Finally, "proof of concept" investigations were performed in using a FSS as a beamsplitter and a narrowband Ha astronomy filter.