Compact Antipodal Vivaldi Array With UWB Beam Steering and Element AMC Inclusions for Scattering Reduction

A compact antipodal Vivaldi antenna array (AVAA) with ultra-wideband (UWB) beam steering capabilities is presented. The fabricated and measured array prototype has good matching from about 1.5 GHz to 11 GHz (147%) for all ports and can achieve wide angle steering, with low side-lobe and cross-pol levels, within that range. The compact 118.6 mm
$ \times 81$
mm design also has a maximum gain of 13.5 dBi and the 13.6 mm E-Plane element spacing allows the array to be steered across this matching range with no grating lobes present. The AVAA is further enhanced by the introduction of artificial magnetic conductors (AMCs) onto the surface of the array elements themselves to reduce broadside scattering, without increasing aperture size, and this approach is non-conventional. Moreover, the small rectangular AMC cells reduce the scattering from 5.7 to 18.4 GHz (105%) for both horizontal and vertical polarisations and this scattering reduction approach, which is also critical for compact implementations, is verified through measurements as is the absence of any performance degradations caused by these AMC inclusions. Applications of the compact AVAA include imaging, new UWB radar systems, and whenever UWB beamsteering is required with reduced scattering.