A novel polygonal spiral antenna

In this paper, we present a novel 2-18 GHz polygonal spiral antenna that approximates a circular spiral in its highest frequencies and gradually transforms itself into a square spiral antenna at its lowest frequencies of operation. The design has successfully addressed the problem of high axial ratios associated with UWB rectangular spiral antenna systems. Our results demonstrate that the polygonal spiral antenna demonstrates excellent axial ratio and gain-bandwidth performance with ≤3 dB axial ratio over 93.5% of its operational bandwidth.