Page 22 - SPECTRUM

Ph. D. Studies

completed in EC

Kedar Trivedi (15EXTPHDE152)

Title of Thesis: Bandwidth Enhancement of Dielectric Resonator Antennas
using Stacked and Fractal Geometries

ABSTRACT: In recent times, the Dielectric Resonator Antennas (DRAs) have
shown great potential as an alternative to microstrip patch antennas in various

practical applications. Their inherent properties like wide bandwidth (BW),
high gain, low losses, high mechanical strength, high power handling capaci-

ty, three degrees of freedom, compatibility with diverse feeding techniques,
and many more make DRAs the preferred choice over microstrip antennas.

Various techniques have been employed by the researchers for bandwidth

improvement of Dielectric Resonator Antennas. This thesis focusses on the

concept of using fractal geometry, stacking and a hybrid of fractal geometry
and stacking for achieving wide bandwidth. Various novel DRA designs with

wideband and ultrawideband (UWB) performance have been proposed. The
proposed antennas have been analyzed using a FEM-based EM simulator An-

sys HFSS. The prototypes have been fabricated and their results compared
with simulated results to validate the designs. Further, it was found that very

little work had been carried out in the field of mutual coupling isolation in
ultrawideband DRA array. Using novel Defected Ground Structures (DGS), re-

duction in mutual coupling in different DRA array designs has been achieved.

In the first approach to enhance the bandwidth of DRAs, two novel frac-

tal-based DRA designs have been proposed. The use of fractal geometry
also offers the benefit of antenna miniaturisation. The first design is a Tri-

angular Prism-shaped DRA with Sierpinski Gasket fractal geometry. An im-
pedance bandwidth of 72.3% has been achieved in this prototype. Sec-

ondly, the design of the innovative Surya Yantra-shaped fractal UWB
DRA has been proposed. Measured impedance bandwidth of 113.3%

covering the frequency range from 2.6 to 9.4 GHz has been achieved.

In the second approach, two novel DRA designs based on the concept of

SPECTRUM Pg. 17 ISSUE 1