Investigation on Dielectric Resonator and Di- electric Loaded Antennas for Dual-Band and Wideband Applications
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Date
2021
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Abstract
In this thesis, an Equilateral Triangular shaped and a Rhombic shaped Dielectric
Resonator Antenna (DRA), and their potential for dual-band and wideband applications
have been investigated. Dielectric loading effects has been observed while designing
practical DRAs presented in this thesis and in the context of this, an investigation on
some of the aspects of dielectric loading effect is also presented. The investigations
reported in this thesis have resulted into several contributions. The quality factor of an
Equilateral Triangular shaped DRA operated in the dominant TM10δ mode has been
studied in detail. An expression for calculating the quality factor for this operating mode
is also developed for most commonly used aspect ratios and the dielectric constant
values used in the design of practical Equilateral Triangular shaped DRA. Further, this
investigation has been extended to study the bandwidth performance for this dominant
mode and relevant closed form expression for estimating the practical impedance
bandwidth for this antenna geometry in this dominant operating mode is also presented.
The Equilateral Triangular shaped DRA is also investigated for its potential as a dualband antenna for WLAN application in the frequency bands of 2.4-2.5 GHz and 5.75-
5.85 GHz. Two configurations of the dual-band Equilateral Triangular shaped DRAs are
proposed, and their performances are compared with other dual-band DRAs reported in
the literature. Based on various observations in the design of proposed dual-band
antenna configurations, some of the challenges in the design of dual-band/ multi-band
DRAs have also been highlighted. A Rhombic shaped DRA, having unequal diagonals,
has been investigated and presented in this thesis. The dominant and a few of the
higher order TE modes excited inside this basic antenna geometry have been identified
through Eigen mode analysis with the aid of Electromagnetic simulations performed
using CST Microwave Studio. Empirical formulae for calculating the resonant
frequencies of these modes have been developed separately for the x- and y- polarized
cases, through curve-fitting approximations. Suitable feeding techniques that can be
used for exciting these modes have also been presented. The nature of radiation
characteristics of these modes have been studied to get an insight into the behavior of
these modes excited inside such DRA. A prototype of this antenna has been fabricated
and its performance is verified experimentally. A preliminary investigation on the special
case of this antenna geometry with low profile configuration has also been presented.
Further, by fine-tuning the feed position, the proposed Rhombic DRA is also found to
exhibit wideband characteristics. Some aspects of dielectric loaded monopole antenna
has also been investigated and presented in this thesis. This investigation includes the
effect of size, shape, volume and dielectric constant of the dielectric load on the
impedance bandwidth and radiation characteristics of a monopole antenna. Dual-band
dielectric loaded monopole antennas for WLAN applications in the bands 2.4-2.5 GHz
and 5.75-5.85 GHz have been proposed. Appropriate mathematical model and a closed
form expression, useful in the design of such dual-band antennas have also been
discussed.
Description
Supervisor: Bhattacharjee, Ratnajit
Keywords
ELECTRONICS AND ELECTRICAL ENGINEERING