Wide-Base Doppler Very-High-Frequency Direction Finder

Although it is quite well known that bearing errors occurring with multipath propagation can be reduced by using widebase antenna arrays, only systems operating with phase or frequency modulation have come into practical use. A method of progressively scanning a circular antenna array is described. This scanning which produces a frequency modulation in which the frequency deviation is a function of the bearing information, is accomplished by a rotating capacitive switch, and no vacuum tubes or crystal diodes are employed. Moreover, a special light indicator replaces the usual cathode-ray tube. Designed primarily for the very-and ultra-high frequencies, the equipment is quite simple and of high reliability.