ANALYSIS AND DESIGN OF WIDEBAND DIELECTRIC RESONATOR ANTENNAS IN ...

181 Pages·2015·8 MB·English

ANALYSIS AND DESIGN OF WIDEBAND DIELECTRIC RESONATOR
ANTENNAS IN FREQUENCY AND TIME DOMAINS
by
Mian Shahzad Iqbal
Dissertation submitted in fulfilment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
Department of Engineering
Faculty of Science and Engineering
Macquarie University
Sydney, Australia
August 2015

Copyright c 2015 Mian Shahzad Iqbal
(cid:13)
All Rights Reserved

ABSTRACT
DielectricResonatorAntennas(DRAs)areaclassofantennasthatofferpromising
solutions to many advanced wireless communication systems due to their high
radiation efficiency, compactness, light-weight and simple feed mechanisms. This
thesis presents the design and characterization of novel yet simple configurations
of DRAs for wideband and ultrawideband (UWB) applications. A multitude of
DRAs made by stacking multiple dielectric segments are considered since they
are simple to fabricate and offer wide impedance bandwidth.
This thesis proposes a DRA with a full ground plane to achieve contiguous
10-dB return-loss bandwidth of 115%, which fully encompasses the Federal Com-
munications Commission (FCC) UWB band. This antenna is composed of two
different dielectric segments and a full ground plane to produce realized mean
gain of 4-5 dBi. Unlike printed planar UWB antennas with partial ground planes,
the proposed DRA has a full ground plane to reduce unwanted radiation to the
lower hemisphere. When used in UWB-IR system, the antenna has to receive or
transmit pulsed signals. Therefore, investigating it only in the frequency domain
is not enough to fully assess its performance; time-domain characterization of the
antenna is essential to assess its pulse-preserving capabilities. Therefore, pulse-
preserving capabilities and effective isotropically radiated power (EIRP) spectra
of the tetrahedron DRA are rigorously investigated for several types of UWB
input pulses. The correlations between the input pulses and the radiated pulses
show that average correlation factors in elevation planes and azimuthal plane are

0.833 and 0.912, respectively. Nevertheless, EIRP spectrum calculations indicate
that none of those pulses efficiently fill the FCC UWB mask when applied to this
tetrahedron DRA. Hence, a third-order Rayleigh pulse is introduced and tuned in
to efficiently make use of the allowed spectrum limits whilst radiating highly cor-
related pulses. It is worth noting that spectrum efficiency of the DRA improves
from 40% to 52% as a result of the optimized input pulse.
The thesis also presents the design, implementation and testing of low-profile
multi-segment dielectric resonator antennas (MSDRAs) for wideband systems.
The paramount contribution of this design is to reduce the height of MSDRA for
high-data-rate wireless devices. Extensive exploitation of a multitude of different
dielectric segments, with respect to effective permittivity and Q factor, has pro-
vided the physical insight of the MSDRA, and led to a compact antenna design
with a wide impedance bandwidth. The bandwidth-to-volume ratio of MSDRA
is increased up to 73% as compared to the state-of-the-art design of a tetrahe-
dron DRA. The proposed design is tested with both a large ground plane (40 40
×
mm2) and a small rectangular ground plane (6 20 mm2). The measured results
×
of MSDRA with large ground plane show a 10-dB return-loss bandwidth of 83%
from 4.5-10.5 GHz, and the MSDRA with the small rectangular ground plane
show a a 10-dB return-loss bandwidth of 94% from 3.7-10.2 GHz.
These antenna configurations are good candidates for both impulse radio and
carrier-based UWB systems and they can be used in a myriad of portable wireless
applications such as wireless USB and personal area networks.

STATEMENT OF CANDIDATE
I certify that the work presented in this thesis entitled “Analysis and Design
of Wideband Dielectric Resonator Antennas in the Frequency and
Time Domains” has not previously been submitted for a degree nor has it
been submitted as part of the requirements for a degree to any other university
or institution other than Macquarie University..
I also certify that the thesis is an original piece of research andit has been written
by me.
In addition, Icertify that all informationsources andliterature used areindicated
in the thesis.
..................
Mian Shahzad Iqbal