The perturbation approach is presented here for the first time for the analysis of an inhomogeneous circularly polarized rectangular dielectric resonator (DR) antenna (DRA). The inhomogeneous permittivity is created by perturbing a rectangle-shaped region of different material inside the rectangular dielectric resonator antenna (RDRA). The orthogonal degenerate modes with a phase difference of ${\mathrm{TE}}_{111}^{\mathrm{x}}$, and ${\mathrm{TE}}_{111}^{\mathrm{y}}$, are excited simultaneously for achieving circular polarization. A simple expression for the calculation of the resonant frequency and optimal axial ratio point for a circularly polarized (CP) inhomogeneous RDRA is presented here. Theoretical results obtained from the proposed theory are compared with theoretical, simulated, and experimental data available in the literature. The proposed analysis results show optimal axial ratio point calculations within a 1% range of the simulated and experimental data, which is better than the previous transverse transmission line reported method, having an error of approximately 4%. The advantages, accuracy, and simplicity of perturbation theory for DR are discussed in detail. The proposed theory can be easily extended for higher order modes and other shapes of material perturbation and anisotropic DRAs. The proposed technique will help in incorporation of the perturbation in the DR so that CP radiation can be obtained in an easy way.

The paper presents a concept of cylindrical shaped material perturbation in rectangular dielectric resonator antenna (RDRA) which can be used for gain and bandwidth enhancement over original DRA. Material perturbation of cylindrical shape in two orthogonal directions will result in change of resonance of isotropic rectangular dielectric resonator antenna. The Effect of change of radius of cylinder for different dielectric materials is investigated. The proposed RDRA with centered cylindrical shape perturbation (PRDRA_CC) is analyzed theoretically using perturbation theory and simulated on 3D EM simulator HFSS. Theoretical and simulated results are compared and good agreement between two is obtained. Material perturbation provide wide tuning range, improved degree of freedom and hence more flexibility in designing antenna for given frequency range of application. Further, material perturbation and wall perturbation can be combined for obtaining polarization diversity in DRAs.

Dielectric resonator antennas (DRAs) operating in higher order modes provide wideband, enhanced gain, and circularly polarized performance. This paper presents a simple perturbation theory for predicting the resonant frequency of higher order modes in perturbed rectangular DRAs (RDRAs). The proposed theory has been validated for isolated RDRA, two‐layer DRA, and RDRA with rectangular‐ and cylindrical‐shaped perturbations. To determine the accuracy of the proposed theory, the frequency computed from it is compared to simulated and measured results of higher order mode perturbed antennas available in the literature. The proposed theory can be easily applied to the design of perturbed DRAs that operate at higher order modes. Also, the theory can be extended to compute other antenna parameters.