3:1 Bandwidth Sinuous Antenna for Direction Finding Applications

This paper discusses the design and performance of an eight-arm sinuous antenna for analog and digital direction finding (DF) systems. The multimode and dual-polarized capabilities of the eight-arm sinuous are utilized to achieve wideband angle of arrival estimation independent of the incoming signal polarization. The performance is evaluated for the classical analog amplitude/phase comparison and the importance of mode 3 to achieve more accurate estimation is highlighted. Also, the Cramér-Rao lower bound (CRLB) is used to evaluate the performance of the proposed design in the context of a digital receiver backend. The performance of the antenna is experimentally verified over the 1.5-4.5GHz frequency band and low estimation errors are demonstrated over wide field of view.