Generalised design method of broadband array antennas using curved geometry

Abstract

Curved array antennas offer increased degrees of freedom when antenna elements are configured in non-uniform geometries. This permits increased flexibility over control of pattern structure and increase in the bandwidth of operation. In this study, the authors present a generalised design method for broadband antenna arrays using such curved structures. Following this design process, two types of array structures evolved: pseudo-curved array (PCA), with the array apertures parallel to one another and the fully curved array (FCA), with the outer element apertures oriented radially outwards. These antenna arrays were designed, analysed and measured on five and seven element structures at a centre frequency of 18 GHz. Both PCA and FCA performance showed a broader frequency response as compared with the uniform array; additionally, it was determined that the variation in array geometry permits them to control the number of beams and nulls in the far-field pattern, as well as the beamwidth of the array. Overall, it was observed that curved arrays showed a narrowing of multibeam positions and conversely a broader frequency response as compared with uniform arrays.