A Planar Four-Element UWB Antenna Array with Stripline Feeding Network

This paper proposes a four-element ultrawideband (UWB) planar antenna array with elliptical-shaped radiators and a stripline excitation network designed for the 6-8.5 GHz UWB frequency band allowed in Europe by the European Commission. The designed antenna array has a symmetrical structure in which the radiators are placed along one line in the central conducting layer, arranged between two layers of a dielectric. Radiating elements are fed by the stripline excitation network that provides uniform power distribution. The dimensions of the elliptical radiators' axes are 14 mm x 16 mm. Two variants of array are proposed. The distance between the radiators' centers is L = 19 mm for a shorter variant and L = 24 mm for a longer one. The presented antenna array structures have a size of 81 mm x 41 mm and 96 mm x 41 mm. These arrays present a measured gain of 6.4-10.6 dBi for the shorter variant and 8.5-10.8 dBi for the longer one and a fair impedance matching. The measured |S-11| is less than -8.7 dB and -9.7 dB for the shorter and longer corresponding variants.