The dual-aperture counter wound log-spiral antenna direction-finder system

One of the problems of the spiral-antenna direction finder (DF) is the alteration of phase reference with logarithm of the frequency [1]. Compensation would require a special network operating over the bandwidth of the DF antenna. This communication describes a technique using two antenna apertures which are identical except for the sense of winding of the antenna arms. The frequency dependent error is canceled with signal averaging after phase detection of each antenna. The same measurement technique could be used to measure elevation angle by phase comparison.