On the Time-Range Dependency of the Beampatterns Produced by Arbitrary Antenna Arrays: Discussions on the Misplaced Expectations from Frequency Diverse Arrays

TL;DR

This paper clarifies that range-dependent time-invariant beampatterns cannot be achieved with frequency diverse arrays, challenging recent claims and highlighting the limitations of FDA-based spatial focusing in the farfield.

Contribution

It demonstrates the fundamental impossibility of creating range-dependent time-invariant beampatterns with arbitrary antenna arrays, correcting misconceptions in recent literature.

Findings

Time-invariant spatial beampatterns with FDAs are feasible.

Range-dependent time-invariant beampatterns are impossible to construct.

Misapplications of FDAs in recent studies are discussed.

Abstract

In the recent years constructing time-invariant spatial-focusing beampatterns by using frequency diverse arrays (FDAs) is conveyed in several papers. Further than time-invariant spatial-focusing beampatterns, the unfeasibility of constructing range-dependent time-invariant beampatterns is demonstrated in this paper. It is indicated that the beampatterns produced by antenna arrays including FDAs are not independently controllable in time, t, and range, r, dimensions, in the farfield. Inappropriate applications of the FDAs having time-invariant spatial-focusing beampatterns in two recent papers are also discussed.