Analytical study of whispering gallery transmission in a non-uniform troposphere

An idealized two-dimensional cylindrical model of the earth with a troposphere whose refractive index varies both according to height and according to range is employed in the analysis of whispering gallery microwave transmission. The study of mode conversion phenomena is facilitated by the fact that the field for laterally uniform regions is expressed in the model as a discrete sum of modes orthogonal in the transverse plane. Mode conversion is also investigated for multisection structures, though at the cost of much additional computing time. However, a large step in height may often be used in the VHF and UHF regions to estimate mode conversion.