Abstract:
Microstrip patch antennas are extensively used due to their desirable characteristics of
being low profile, light weight, robust and easy fabrication. Among patches triangular
patch is smaller in size than other patch geometries which make it a favorable choice for
applications such as wireless communication and positioning system. On the other hand
triangular patch antenna also has few limitations such as low gain and narrow bandwidth.
For most applications it is desirable to improve both the VSWR and gain of the antenna.
Several approaches have been reported in the literature in order to improve the gain and
VSWR. These include making modifications into the surface of the patch geometry,
stacking of patches, use of superstrates and exciting higher order modes. For high gain
higher order modes can be excited in the patch antenna by the use of fractal geometry.
Application of fractal boundaries to the antennas result in antenna miniaturization,
broadside directive patterns, multiband behavior and high gain. These fractal geometries
when applied to the patches produce higher order localized modes in which currents with
higher amplitudes are concentrated in certain regions of the patch causing improvement
in the gain of antenna.
Based on the above mentioned concepts this thesis is based on the improvement in the
performance of triangular microstrip patch antenna. A simple equilateral triangular
microstrip patch antenna with air gap at resonant frequency of 3.5GHz is designed and
simulated in High Frequency Structure Simulator (HFSS). Simple triangular patch
antenna is then modified by introducing partial Koch fractal boundaries. Size of the
applied partial Koch fractal boundary and feed point is optimized in HFSS in order to
achieve improved VSWR and relatively high gain. Simple equilateral triangular
microstrip patch antenna and modified triangular patch antenna are fabricated and tested.
Measured gain and return loss of simple equilateral triangular microstrip patch antenna is
found out to be 7.3dB and -27.8dB respectively while that of modified antenna is 9.44dB
and -44.07dB respectively. Modified geometry has shown an improvement of 2.14dB in
gain and 16.27dB in return loss over the simple triangular microstrip patch antenna hence
making it favorable to be used for many applications in S band
