Directivity enhancement and characteristics of space‐wave, leaky‐wave and creeping‐waves for an impedance cylinder coated with dielectric

Abstract

The dielectric-coated impedance cylinder configuration is investigated thoroughly with respect to the space-wave, leaky-wave and creeping-wave excitations for all source polarizations. A very high directivity is achieved for the space- and leaky-wave radiation for the antenna structure compared to that from a dielectric cylindrical rod investigated earlier. It is also observed that such high directivity for the dominant-mode leaky-wave is accompanied by higher-order azimuthal harmonics with low attenuation constant contributing to the leaky-wave pole, instead of the n = 0 harmonic for the previous configuration. A large enhancement in the space-wave directivity is also achieved, contributed by higher space-wave harmonics compared to lower-order azimuthal harmonics for the cylindrical dielectric rod antenna. The space-wave and leaky-wave directivities are examined with variation in the design parameters and azimuthal harmonics. The phase and attenuation characteristics of the leaky-wave are used to evaluate the optimized leaky-wave structure parameters and appropriate azimuthal harmonics that result in high directivity for the configuration. The creeping-wave characteristics for the configuration are also investigated, with a relatively stronger creeping-wave excitation observed for an inductive surface-impedance.