Anandrao B. Kakade

Mode Excitation in the Coaxial Probe Coupled Three-Layer Hemispherical Dielectric Resonator Antenna

In this paper, a coax-probe excited multilayer dielectric resonator antenna (DRA) structure is rigorously analyzed from the modal perspective. The full-wave Greens function approach is presented for the analysis of such multilayer structures with an arbitrary number of layers with greatly reduced computational overhead. Additional reduction in computation time is demonstrated for a centered probe. Also, the modes of the multilayer DRA can be identified from the analysis, which can be used to explain the broadband nature of the coupling. The layer permittivities are optimized for broadband operation of the coax-fed DRA. The bandwidth enhancement for a centered and offset probe is seen to be due to a combination of several DRA modes and the probe resonance. Frequency tuning of the antenna structure is also demonstrated by exciting the antenna at a higher order mode, maintaining the broadband characteristics. The radiation characteristics of the antenna are also investigated.

Efficient Technique for the Analysis of Microstrip Slot Coupled Hemispherical Dielectric Resonator Antenna

In this letter, a novel method for the numerical evaluation of the Greens function for the microstrip slot coupled hemispherical dielectric resonator is presented. The proposed technique is very fast as compared to the conventional method of fourfold integration. In this technique, the homogeneous part of the dielectric resonator antenna (DRA) Greens function is manipulated in such a manner that its source and field terms are expressed in the absolute product form. Then, using method of moments (MoM), the absolute product form is numerically integrated by the product of two double integrations. The input impedance calculation using the proposed technique is almost 48 times faster than conventional technique. The method is very rigorous and general and should find applications in the other hemispherical DRA configurations.

Guided Modes in a Metamaterial-Filled Circular Waveguide

Abstract In this article, characteristics of circular waveguides filled with metamaterials are studied. Also, for the first time, hybrid modes are investigated, and several new conclusions in hybrid mode behavior are drawn. Particularly, conditions under which the hybrid mode separates into the transverse electric and transverse magnetic (n = 0) modes are obtained. This condition eases mode excitation in the waveguide without power being coupled to the undesired modes. Frequency dispersive behavior of the modes under isotropic conditions is addressed with potential applications. The anisotropic implementation, which offers a good technique for the practical realization of metamaterial-filled circular guides, is also investigated.