Analysis of a directional antenna existing near a lossy dielectric cylinder

The electrical performance of an antenna located near a conductor or a dielectric material is affected by those obstacles. How the directional antenna can reduce the influence of the dielectric cylinder is investigated. First, an analysis method for the current distribution of an N-element dipole array located near the lossy dielectric cylinder is discussed. In this analysis, simultaneous integral equations, whose unknown functions are the currents on each element and whose kernels are the dyadic Green´s functions for the dielectric cylinder, are derived. Second, numerical calculations are performed in the case when the directional antennas are two-element Yagi arrays. The input impedance and radiation pattern of these directional antennas are compared to those of the single dipole, and it is shown that the change of input impedance and radiation pattern of the directional antenna located near the cylinder is much smaller than those of the single dipole.<>