Analysis of square spirals on planar dielectric and chiral slabs

n this thesis, the scattering characteristics of novel Frequency Selective Surfaces (FSSs) such as, L?shaped, One? and Two?turn square spiral elements are investigated theoretically on planar dielectric and chiral slabs for Transverse Electric (TE) and Transverse Magnetic (TM) incident plane waves. Assuming it to be infinitely thin and a perfect conductor, the FSS elements are placed periodically in the x?y plane. The Moment Method (MM) of Galerkin type is employed by expanding the current induced on the metallic surfaces in terms of overlapping Piecewise Sinusoidal (PWS) basis functions. The reflection and transmission coefficients due to FSS structures are obtained in terms of current coefficients. The numerical results of reflection and transmission coefficients are plotted against frequency for freestanding and dielectric backed FSS elements. The variation of reflection coefficient with respect to frequency is presented for different values of parameters such as incident angle, slab thickness and dielectric constant. The co? and cross?polarized field equations due to chiral medium are written separately for TE and TM incident waves. The co? and cross?polarized reflection and transmission coefficients are plotted with respect to frequency for different values of medium parameters such as chirality admittance, slab thickness, incident angle and dielectric constant. At resonant frequency a maximum current is excited on the elements; for this reason, the current amplitude induced on the metallic FSSs is plotted against the stretched out wire length at resonant frequency.