Scan independent phased arrays

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 def'med in this fashion. As simple examples of this class, we discuss arrays of slots or dipoles bounded by a single dielectric slab with e = 1.3. The scan impedance has VSWR < 1.5 for scan angles up to _+80 ø 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).

Input Impedance of an Infinite Linear Scanned Array of Flat Rectangular Strips Inside a Dielectric Loaded Parallel Plate Waveguide

“…It can readily be seen from (24a) to (24c) and (26a) to (26c) that the argument of the summation with respect to n associated with the input impedance Zin becomes then a function of (2n+1) 2 . If it is assumed that G is a function of (2n+1) 2 , then it can be shown easily that…”

“…This can le done, in principle, by solving an integral equation, which involves a tedious task of numerical computations. In order to alleviate this difficulty, it has become common to assume a sinusoidal current distribution along a current element [2]- [7]. This, one of the simplifying assumptions used here, is Manuacipt approved May 27, 1986.…”

“…Since the width of the probe is very small compared to the wavelength in the medium in which the probe is embedded, the current in the probe oan be assumed to he confined to the y-dlrection (along the lenjth of the probe) only. (2) where YO is the unit vector in the y-direction. The relative dielectric constant ei is a piecewise constant having different values, in general, in different regions of the z-dimension.…”

“…Different configurations and techniques have been proposed for this purpose. For instance, Magill and Wheeler [1], and also Munk with his co-workers [2] proposed different dielectric loading for achieving wide-angle impedance match. The geometry of the problem can play an important role in satisfying some requirements.…”

Broadband Metallic Radome.

“…To determine the transmission through this structure, the procedure is similar to that of an earlier report (7]. This consists of the following three parts:…”