Obstacle Gain Measurements over Pikes Peak at 60 to 1,046 Mc

Radio transmission loss measurements made over four propagation paths approximately 100 miles in length show the effect of a large mountain obstacle on vhf and uhf ground-to-ground propagation. Recordings of transmission loss were obtained at four sites as a function of receiving antenna height and by mobile measurements along a route normal to the propagation path. Measurements for propagation directly over Pikes Peak exhibit the well defined lobing associated with four ray-path diffraction theory. Theoretical approximations based on the Fresnel-Kirchhoff scalar knife-edge diffraction theory predict values of transmission loss and lobe structures which are in good agreement with those observed. Measurements for propagation to the east and west of Pikes Peak are characterized by lower fields at all frequencies and large fading ranges.