High Efficiency Excitation of Dielectric Rods Using a Magnetic Ring Current

We describe a theoretical analysis of the excitation of the fundamental surface wave mode on an infinite dielectric rod by a magnetic ring current that is interior to the rod. Earlier work has provided results for an external ring source. Results obtained by us show that for an interior source excitation efficiencies close to 100% are possible for high permittivity dielectrics and launching efficiencies greater than 90% can be achieved over bandwidths greater than 20%. This is a higher efficiency than is possible with an exterior source. Simulation results verifying the theoretical analysis are presented for the practical case of a coaxial waveguide exciting the dielectric rod.