Propagation studies over irregular terrain in Doon Valley

Abstract

Propagation measurements were conducted over a double knife-edge diffraction path between Roorkee and Dehradun at VHF band for a period of 18 months for mathematical modelling of basic transmission loss and fading characteristics. Though many theoretical formulations for predicting diffraction loss over multiple knife-edge diffraction paths have been reported, this experimental programme was undertaken as an order of discrepancy exists between the theoretical and experimental results. An attempt has also been made to correlate the basic transmission loss values with the surface refractivity (<i>N</i>_s) and the vertical refractivity gradient (D<i>N</i>). The results of these studies have been presented for planning communication links in similar terrains.