THEORETICAL AND EXPERIMENT INVESTIGATION OF PARASITIC LOOP COUNTERPOISE ANTENNAS.

The radiation field produced by a single parasitic loop counterpoise antenna was investigated both theoretically and experimentally. Geometrical theory of diffraction was applied to obtain theoretical expressions for the far field produced by such an antenna. Within the range of approximation the agreement between theory and experiment was found to be very good. In the absence of mutual coupling between the parasitic elements, the present theory can be applied to double- and multiple-parasitic loop counterpoise antennas. The parasitic loops in general reduce the counterpoise edge diffraction effects on the far field patterns. The behavior of the parasitic loop counterpoise antenna pattern near the principal maximum is not appreciably different than the Alford loop counterpoise pattern near its maximum. Parasitic loops increase the response of the antenna in regions of space near the zenith theta 0 degrees. Detailed results of numerical and experimental investigations of various aspects of the parasitic loop counterpoise antenna have been given. These results bring out the effects of the different parameters of this new antenna system on the radiation patterns. The parasitic loop concept has been found to be capable of shaping the pattern produced by an Alford loop counterpoise antenna pattern in regions of space below the plane of the counterpoise. The investigation concludes that when suitably designed, the parasitic loop counterpoise antenna is potentially capable of minimizing the siting errors associated with existing VOR systems. Three new antenna systems are proposed which may find possible application in a VOR system. Author