INFLUENCE OF SUPPORTING DIELECTRIC LAYERS ON THE TRANSMISSION PROPERTIES OF FREQUENCY SELECTIVE SURFACES

Single layer arrays of linear dipole slots and patches symmetrically embedded in a dielectric layer or bonded to its surface illustrate dielectric tuning effects in this mainly computer aided but partly experimental study. After its initial rapid decline as the layer thickness increases, the resonant frequency of the slots varies cyclically about the limiting value for the patches. Contours of transmission level on a frequency/thickness plot illustrate this frequency pulling effect and lead to a discussion of passband shaping and the sensitivity to angle of incidence. Equivalent circuit concepts account for the observed bandwidth and resonant frequency variations. The performance of two experimental surfaces is described, including the influence of trapped waves in the dielectric.