Analysis of a tubular monopole loaded with a shielded helical coil

An analysis of a shielded helical coil in a cylindrical tubular antenna is presented, based on a combination of aperture theory and a network model containing lumped RLC components, which is motivated by the desire to use this analysis in antenna-optimization routines. Measured input admittance data for an antenna loaded with a shielded helical coil are presented for comparison with computed data. Also, an experimental procedure by means of which one may measure the transverse electro-magnetic (TEM) input impedance of a coaxial guide loaded with helical coil is described.