Radiation from a short dipole or monopole near a thick conducting cylinder of resonant length

Using a theoretical-numerical technique involving the magnetic field integral equation, the radiation fields are determined for configurations comprised of a centrally located dipole and a thin quarter-wave monopole near conducting cylinders of finite lengths. Such configurations are important since they give measures of the radiation effects of fuselages of aircraft or other structures which the cylinders may model. The radiation fields are determined in the three principal planes for wavelengths passing through the resonant length of the cylinder, i.e.,L \approx \lambda. The radiation patterns for both the dipole and monopole sources when normalized with respect to one another are similar to within approximately 1 dB. The vertically polarized patterns in the horizontal plane (the plane orthogonal to the dipole axis and containing the cylinder axis) show small deviations from their near omnidirectional characteristics for cylinder electrical lengths of 0.5, 1.0, and1.5\lambda. On the other hand, the cross polarized component (the horizontal component) in the same plane shows a substantial enhancement of the intensity of the lobe structure at resonance. The patterns are compared to those acquired experimentally in an anechoic chamber and close agreement is demonstrated.