Launching Efficiency of Wires and Slots for a Dielectric Rod Waveguide

This paper describes an experimental investigation of surface wave launching efficiency. Wires, rings, and slots are considered as exciters of the HE₁₁ mode on a dielectric rod image line. A formula is derived which relates the efficiency of a launcher to its impedance as a scatterer on the surface waveguide. Efficiency is obtained by using this formula and also by applying Deschamps´ method for determtimg the scattering matrix coefficients of a port junction. Graphs are presented which illustrate the variation of efficiency with the dimensions of the launchers and with the parameter lambda_g/lambda, the ratio of the guide wavelength to the free space wavelength.