Transmission-loss measurements made on two Knife-edge diffraction paths over the andes

Feasibility experimental tests were carried out with a view to the establishment of a 60-channel radio link between Argentine and Chile over the Andes to back up the existing telephone circuits, so liable to breakdown due to natural conditions. The path profile over the Andes ruled out a beyond-the-horizon radio link as presenting a prohibitive loss. Transmission loss measurements at a frequency of 891 MHz were made on two different diffraction paths. This method of propagation is based on the fact that under certain conditions mountain ranges act as diffracting knife-edges for radio waves. Details are given of two paths selected and the equipment used for the measurements. Curves are shown comparing the results of the loss measurements. Analysis of the results indicated that a 60 channel system would be possible over one of the paths and should give a propagation reliability greater than 99.9% using a transmitted power of 1 kW, 30 ft diameter antennas and fourfold diversity.