A comparison of antenna problems at UHF & VHF TV

Television transmitting and receiving antennas are components of a major intelligence transfer system only small portions of which are subject to man´s control. The information is carried between antennas by propagating waves which are affected by the propagation media. The main propagation phenomena are considered briefly, but not in detail, to point up how wavefront variations occur. These usually are greater at UHF than at VHF and make the large capture area UHF receiving antenna impractical in many cases. The design and effective application of receiving antennas is quickly discussed in the light of these problems. UHF transmitting antenna design is then reviewed. It is approached from the standpoint of requiring an effective Size near the VHF antenna, in order to partly offset the inapplicable receiving antenna. The resulting many wavelength UHF apertures then require new feeding techniques. These are briefly described. It is also pointed out how the resultant high gains require care in application, with perhaps necessary contouring. The manner in which the same FCC curves are used to predict coverage for channels 14-83 as for channels 2-6 despite differences in propagation characteristics is explained. A single set of measured UHF field intensities is shown. In conclusion, adequate-signal UHF results in superb picture quality because of less selective distortion because of the smaller percent bandwidth. Man-made noise is almost nil. It is only necessary for the receiving end economically to approach as near VHF performance as the transmitting end has, and many of the UHF problems will vanish.