Page 23 - SPECTRUM

stacking have been proposed. Apart from bandwidth improvement this ap-

proach also provides the benefit of high gain. Stacked T- and Z-shaped DRA
designs have been proposed. Measured impedance bandwidth of 110.5% in

stacked T-shaped DRA, and 114.5% in case of stacked Z-shaped DRA has been
achieved. The simulated results of both the antennas have been validated.

In the third approach, two novel DRA designs using a hybrid configuration based

on the combined concept of fractal geometry and stacking have been proposed.
This approach helps in achieving all three benefits of wide bandwidth, high

gain, and antenna miniaturisation. Stacked fractal Maltese Cross and Triangular

Prism-shaped DRA designs have been proposed. UWB of 111% covering 3.6–
12.6 GHz and 120.9% covering 3.3–13.4 GHz have been achieved in stacked

fractal Maltese Cross- and Triangular Prism-shaped DRA designs, respectively.

Finally, the aspect of mutual coupling reduction has been addressed by
the use of different defected ground structures. Mutual coupling reduc-

tion is the most essential factor for the use of antennas in multiple-input
multiple-output (MIMO) applications. Four DRA array designs with novel

DGS structures have been proposed. In the first two designs namely, fractal
Tree- and stacked fractal Maltese Cross-shaped DRA array, periodic defect-

ed ground structure (PDGS) of C-shape has been incorporated to achieve

mutual coupling reduction (< -15 dB). Elliptical-shaped DGS is used to re-
duce mutual coupling in the Triangular Prism-shaped fractal DRA array (third

design). The fourth design is a Surya Yantra-shaped fractal DRA array with
rectangular loop-shaped DGS for better isolation between DR elements.

In all, ten novel designs have been proposed along with their detailed study.

SPECTRUM Pg. 18 ISSUE 1