Phase-Only Beam Shaping for Transmitting Array Antennas in Radar Applications

TL;DR

This paper introduces two phase-only beam shaping methods for radar array antennas, with the novel TPT method leveraging pulse-to-pulse phase variation to achieve low side lobes and effective beam shaping.

Contribution

It proposes a new time-varying phase tapering method for radar antennas that improves beam shaping and reduces side lobes compared to traditional phase tapering optimization.

Findings

TPT achieves lower side lobe levels than PTO.

Dimensionality reduction simplifies radiation pattern optimization.

TPT effectively shapes beams using pulse-to-pulse phase variations.

Abstract

Two beam broadening methods for active electronically scanned array (AESA) antennas with uniform amplitude excitation are proposed and compared: phase tapering optimization (PTO) and a novel time-varying phase tapering (TPT). The PTO is a simple and efficient approach assuming continuous polynomial phase distribution and requiring optimization of only few parameters. The TPT is valid mainly for radar applications, taking advantage of the fact that radars typically transmit pulse trains for coherent integration. By varying the array elements' phases from pulse to pulse, the TPT achieves effective amplitude tapering, thus providing a method of beam shaping, occasionally with a simple analytic form. The TPT also makes it possible to produce beam shaping with very low side lobe levels in comparison to the PTO. As a preliminary step, the dimensionality of the radiation pattern characterization for all scan directions is reduced from five to only two variables. This is crucial for efficient optimization of the radiation pattern which needs to be evaluated over a judiciously specified two-dimensional domain.