Radiation from a Dipole near a Conducting Cylinder of Finite Length

Antennas radiating in free space or above a reflecting plane produce radiation patterns which are in general predictable. When these same antennas are mounted on bodies such as aircraft, submarines, or satellites, secondary currents may be induced on the fuselages and nearby conducting members. These secondary currents often result in unpredictable radiation in the forms of newly introduced polarizations or unwanted lobe structures which together may manifest themselves in the form of radio-frequency interference. As a model of the fuselage of either of the aforementioned conducting bodies, a cylinder of finite length is considered and the radiation fields of a radial dipole in the immediate vicinity of such a cylinder are determined by a theoretical-numerical technique. A cross- polarized field due to axial currents induced along the cylinder is found to represent a predominant feature of the radiation characteristics of the dipole-cylinder configuration.