Synthesis of a steerable frequency-invariant radiation pattern for broadband scalable antenna arrays

Abstract

This paper discusses the synthesis of a steerable frequency-invariant radiation pattern for broadband scalable antenna arrays (SAAs). The proposed method allows to achieve constant beamwidth and beam direction over a 3:1 bandwidth and is based on an appropriate radiating elements’ placement in the SAA and a proper amplitude and phase excitation of the array. Both amplitudes and phases of signals exciting the radiating elements are varied with frequency to ensure the radiation pattern invariance. Additionally, the paper proposes solutions to problems occurring in SAAs i.e., the problem of overlapping radiating elements and the problems of sidelobe and grating lobe reduction. To verify the proposed synthesis method, a set of radiating elements, which operate over a 3−9 GHz frequency range, has been manufactured and measured. The overall radiation pattern of the antenna array has been obtained by a summation of the radiation patterns produced by each of the radiating elements.