Radio wave blind zone in a duct: an analytical approach

Electromagnetic (EM) waves propagate through the atmosphere where they are refracted depending on the composition of the atmosphere. This refraction highly influences the propagation of the EM-waves. Certain atmospheric conditions can cause EM-waves to get trapped within a duct. In these ducts blind zones may occur, where there is no EM-wave coverage. These blind zones show up in the results of ray tracing simulations. However, these codes provide no insight into the dependence of the blind zone on the atmospheric conditions and the transmitter height. In this research analytical expressions are derived for the range of these blind zones. The expressions have been verified by ray trace simulations for several transmitter heights under ducting conditions. Results show that the blind zone range can be accurately predicted.