Abstract:
Miniaturization has become a requirement of modern wireless systems. Majority of applications
require low profile and wideband antennas. The reduction in size of antenna decreases its efficiency.
Fractal shape antennas present the solution to design wideband and compact antennas without
compromising the antenna efficiency. The Fractal geometry with properties like self similarity, jagged
shapes, long electrical lengths provide the benefits of multiband behavior, effective radiation and
miniaturization. Many Fractal geometries are available for wideband applications. The investigation of
conventional fractal shapes like Koch, Minkowski, Sierpinski, Pythagorean Tree structures is made to
find out new Fractal shapes.
Ultra wideband (UWB) technology presents many advantages like immunity to multipath
interference, security, low interference and high data rates. Antenna for UWB applications requires
wideband impedance matching characteristic and compactness. This requirement resulted in a trend
to design wideband and compact antennas for wireless systems. Long electrical lengths of patches are
encapsulated in a small area which reduces efficiency. Fractal antennas present solution for designing
compact and wideband antennas. Available fractal geometries for wideband applications are
Sierpinski, Koch, Minkowski and Pythagorean tree.
Various polygonal shape antennas are designed in HFSS to find desired polygonal geometry with
wideband property. Proposed solution with heptagonal fractal antenna gives desired performance.
Thesis work presents a comparison of novel heptagonal fractal monopole antenna design for two
different substrates. A super wideband heptagonal fractal monopole antenna with coplanar waveguide
feed is designed and fabricated. Fractal geometry has base shape of heptagon. Base shape is iterated
four times. FR4 and Rogers RT/ Duroid 5880 substrates are used for antenna design and fabrication.
Monopole configuration of antenna provides omni-directional radiation pattern. Simulated and
measured results analysis shows that monopole fractal antenna with Rogers RT/ Duroid 5880
substrate has better performance than fractal antennas fabricated on FR4 substrate.
