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.