Determining the Operational Patterns of Directional TV Antennas

In January, 1959, the Television Allocations Study Organization authorized its Committee on Directional Antennas to conduct field tests on directional TV antennas looking toward development of a means whereby the operational antenna pattern could be determined and to explore the effect of reflections and anomalous propagation on the degree of directivity actually obtained as compared with that calculated. Tests were subsequently carried out at WBZ-TV in Boston, Massachusetts, and at WKY-TV in Oklahoma City, Oklahoma, with special directional antenna systems possessing various degrees of directivity. Measurements were made at distances varying from a few miles from the transmitter to well over 100 miles from the transmitter. Within the limits imposed upon the tests by the choice of sites, nature of the terrain, and a limited period of observation, it was found that propagation conditions did not materially affect the directivity of the array, even at distances where the scatter fields were of appreciable magnitude. In the course of these measurements and tests, a procedure was developed whereby the operational antenna pattern could not only be determined, but also rechecked at suitable intervals thereafter.