INVESTIGATION OF VHF PROPAGATION BEYOND LINE-OF-SIGHT

Abstract

In this investigation the main problem studied iis the propagation of VHF TV Signals beyond L-O--S. In normal TV broadcast, this service is given by L-O-S propagation. But due to various conditions in the atmosphere, it is possible for a VHF radio signal to propagate to much U. large distance than radio horizon. When such propagation taken place then there are mainly two factors which are of importance. These are (a) Some sort of grade B service can be given by TV transmission to distance larger than L-0-S path. This increase the coverage of a T-V transmitter., .4:lthough the a service beyond L-O-S cannot be called satisfactorily. (b) !,•hen large distances are covered by TV transmission, tIhi is always a possibility of interfering with other services (including any other TV transmission at locations beyond the primary coverage). It is,therefore, of practical importance to investi-gate the problem of VHF propagation beyond L-O-S. Moreover the investigation also yields results on the effect of refractive index gradient upon the propaga-tion of a TV signal....