Synthesis of Non-Mirror-Symmetrical Far-Field Patterns Using Two Parallel Current Sheets

Abstract

This paper shows that the radiation patterns and polarizations on the two sides of the source plane can be controlled separately if two parallel current sheets are used. An efficient algorithm is proposed to determine the propagation components of the currents on the two sheets directly from the specified radiation pattern. Numerical examples demonstrate that the algorithm is effective for synthesizing radiation patterns with complex footprints and beam-wise polarizations. Although the resultant continuous current distribution is not easy to implement in practical applications, it provides a useful base for further designs. If proper feeding techniques are developed, it will also be possible to spatially sample the continuous current distribution and realize the radiation pattern with large scale antenna arrays.

The Effective Number of Degrees of Freedom of the Far-Fields Radiated by Rectangular Current Sheets

“…While the derivation process remains consistent with prior works [22], [23], [24], we briefly review the derivation process for the convenience of readers' understanding. In free space, the electric field E at position r of a current source () Jr in source region s V can be generally expressed as:…”

“…The center of the upper current sheet locates at (0, 0, ) d , while that of the lower current sheet locates at (0, 0, ) d − . Similar to the case of one current sheet, the normalized far-field corresponding to the xpolarization can be expressed as As discussed in reference [24], an important issue is the impact of the distance between the two current sheets. We want to reveal the independent information that can be possibly carried in the far fields when the sizes of the two sheets and the distance between them are specified, with arbitrary current distributions on the two sheets, we consider all current distribution in the function space defined on the two sheets.…”

“…Two models are mainly involved in this paper: a singlelayer current sheet model and a double-layer current sheets model. The single-layer model is reasonable for modeling planar antenna arrays with symmetrical radiation patterns [22], [23], while the double-layer current sheets model is applicable for planar arrays with non-symmetrical radiation patterns [24]. We start directly from the expression of the radiation far-fields generated by the current sources.…”