Large Reductions of VHF Transmission Loss and Fading by the Presence of a Mountain Obstacle in Beyond-Line-of-Sight Paths

A detailed investigation of the probable mode of propagation in vhf operation over mountain obstacles has been made. Theory indicates that tremendous gains in received signal strength-above those obtained over a smooth spherical earth-may be expected from diffraction over an appropriate knife edge located in the path. Experimental verification of the principles involved is reported. In addition, the fading was found to be small and even essentially nonexistent on certain very long obstructed paths.