ANALYSIS OF PERIODIC ARRAYS OF ROTATED LINEAR DIPOLES, ROTATED CROSSED DIPOLES, AND OF BIPLANAR DIPOLE ARRAYS IN DIELECTRIC (SPATIAL FILTER, DICHROIC REFLECTOR, FREQUENCY SELECTIVE SURFACE)

In this investigation, scattering from periodic surfaces (Frequency Selective Surfaces) is analyzed. Many techniques are available for simply computing the scattering by these surfaces. However, the analysis presented here also allows a deeper understanding of the operation of these surfaces. This understanding greatly simplifies the design of periodic surfaces. Surfaces with arrays of dipoles are emphasized, but some results apply to surfaces with slots. The investigation is broken into three parts.; In the first part, a summary of the general theory used in the investigation is presented. The theory used was developed at The Ohio State University in 1977.; In the second part, the theory is applied to arrays of linear dipoles and arrays of crossed dipole elements. Arrays of elements rotated in the plane of the array are considered. Rotated elements are considered since this is a simple way to decrease the interelement spacing. Several interesting results of rotating the array elements are observed. Also, conditions for perfect reflection and transmission are found for arrays near their fundamental resonance. Through these conditions, array parameters which affect the scattering by the surface are identified. The effects are shown by examples and discussed in detail.; In the third part, the theory is applied to a complex Frequency Selective Surface. The surface consists of two linear dipole arrays embedded in three dielectric layers. The dipoles may be rotated in the plane of the array. Conditions for perfect reflection and transmission from this surface are found. The important array parameters are identified and studied. Several examples are given and discussed.