Generalisation of the concept of equivalent radius of thin cylindrical antennas

The concept of equivalent radius of electrically thin cylindrical antennas is well known in the case of metallic antennas in homogeneous dielectric media. It is possible, however, to define equivalent radius also in cases of thin cylindrical antennas in the presence of arbitrarily cylindrically shaped dielectric and/or magnetic materials. The approach is essentially a quasistatic energy approach. It enables a large number of complicated problems of such antennas to be reduced to the equivalent problem of a cylindrical antenna of circular cross-section with an appropriate single-type dielectric or (preferably) magnetic cover, which can be solved with ease. Illustrative examples, including those of strip antennas on a dielectric substrate, indicate high accuracy of the results obtained by the proposed theory.