EFFECT OF REFLECTING STRUCTURES ON CIRCULARLY POLARIZED TV BROADCAST TRANSMISSION

Much discussion has centered on the potential benefits of circularly polarized transmission of TV signals to the viewing public. One of these proposed benefits is the possibility of ghost reduction when both the transmitter and the receiver are equipped with CP antennas. While there has been much conjecture and a limited amount of testing, no definitive discussion has appeared on the conditions required and the extent to which ghosts may be expected to be reduced. It is the purpose of this paper to explore these questions from a theoretical point of view. It will be shown that there are, in fact, situations in which ghost reduction should be expected, considering practical transmitting antennas, receiving antennas, and the characteristics of typical reflecting structures. While this discussion is theoretical in nature, it is hoped that it will be useful to the broadcaster contemplating CP transmission so that he can evaluate his market in terms of possible benefit. In addition, this theoretical treatment should serve to guide further field studies to verify that the predicted conditions for ghost reduction are actually observed in practice. Finally, the characteristics required of CP receive antennas to maximize the benefits of CP to the viewer will be discussed. Copyright © 1978 by the Institute of Electrical and Electronics Engineers, Inc.