Rectangular Dielectric Resonator Antennas by Rajveer S. Yaduvanshi & Harish Parthasarathy

Author:Rajveer S. Yaduvanshi & Harish Parthasarathy
Language: eng
Format: epub
Publisher: Springer India, New Delhi

(7.10)

where

(7.11)

(7.12)

(7.13)

7.4 Top-Loading RDRA

This chapter is developed based on new approach using a top-loading excited RDRA as shown in Fig. 7.9, for generating higher-order modes. The even as well as odd modes can be generated even with ground plane. It has also been studied that even modes (in z-direction) were short-circuited, when RDRA was placed on a ground plane. Short magnetic dipoles are basis for generation of these resonant modes . Nearly, λ/3, λ/2, and λ heights of the dielectric resonator generated TEδ11, TEδ13 and TEδ15 (0 < δ ≤ 1) modes. The gain is found to be increasing in higher modes . This is also evident from the findings that gain of RDRA starts decreasing or reducing even in higher modes, when magnetic dipoles start overlapping. This overlapping of dipoles can be seen when the wavelength used is very small.

Top loading excited both even and odd modes . Simulations have shown that 1st and 3rd resonances got shifted toward 2nd resonance, when the space ‘s’ between top and bottom RDRAs varies. Merging of neighboring resonance modes could be done using this method. This is an excellent phenomenon, which can be used for bandwidth enhancement. This merging of bands helped to increase the antenna bandwidth. Thus, existing patch antenna gain and bandwidth can also be increased by using the concept of higher-order modes. Blocking or shifting of any modes has become possible in RDRA.

E and H fields perturbations in RDRA can be introduced by carrying out small changes in the structure, or this can be obtained by input excitation currents. This perturbation gets converted into eigenvector or eigenvalues . The perturbations are proportional to eigenvector and resonant mode. The number of modes is directly related to number of lobes occuring in radiation patterns . There are two ways in which the number of modes can be increased in RDRA: One is by increasing the RDRA dimensions a, b, and d, and the other is by increasing the input excitation frequency.

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