Analysis of Cross- and X-Shaped Spiral Antenna Arrays for Amplitude-Comparison DF Systems

This paper presents a performance analysis of cross- and X-shaped arrays of cavity-backed spiral antennas for amplitude-comparison direction finding (ACDF) systems. First, an effective calibration strategy for the ACDF system is proposed, which uses the embedded element patterns to improve the accuracy of the evaluated calibration coefficients. As will be seen, both cross- and X-shaped arrays show calibration residual error values lower than 1° rms. Finally, the ACDF system angular error values are quantified for sources which are not polarization matched to the spiral antennas. Full-wave simulations are run to estimate the arrays radiation performances in the range from 1 to 18 GHz.