Scan independent phased arrays

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Abstract
This paper discusses a derivation of the scan impedance for a phased array consisting of arbitrarily oriented planar elements with arbitrary current distribution located in a general stratified media. It is shown that the scan impedance will remain scan independent if and only if the product of the element power pattern and the transformation function for the stratified dielectric media varies as the cosine to the scan angle. An entire class of scan independent phased arrays is defined in this fashion. As simple examples of this class, we discuss arrays of slots or dipoles bounded by a single dielectric slab with ϵ = 1.3. The scan impedance has VSWR < 1.5 for scan angles up to ±80° in both principal planes, and further improvements appear possible. These designs are quite different and superior to earlier phased array designs (Magill and Wheeler, 1966; Campbell and Popovich, 1972; Chen, 1973).