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Abstract:
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With the recent progress and rapid increase in mobile terminals, the design of
antennas for small mobile terminals is acquiring great importance. In view of this
situation, several design concepts are already been addressed by the scientists and
engineers. Compactness and efficiency are the major criteria for mobile terminal
antennas. The challenging task of the microwave scientists and engineers is to device
compact printed radiating systems having broadband behavior, together with good
efficiency. Printed antenna technology has received popularity among antenna
scientists after the introduction of microstrip antenna in 1970s. The successors in this
kind such as printed monopoles and planar inverted F are also equally important.
Scientists and Engineers are trying to explore this technology as a viable coast
effective solution for forthcoming microwave revolution. The transmission line
perspectives of antennas are very interesting. The concept behind any
electromagnetic radiator is simple. Any electromagnetic system with a discontinuity
is radiating electromagnetic energy. The size, shape and the orientation of the
discontinuities controls the radiation characteristics of the system such as radiation
pattern, gain, polarization etc. It can be either resonant or non resonant structure.
Microstrip antennas are suitable for wireless applications due to their low cost,
high gain and ease of fabrication. But the major disadvantage of micro strip antennas is
their inherent narrow bandwidth. A lot of techniques are introduced by the researchers
all over the world to enhance the bandwidth of micro strip patch antennas. The thesis
addresses an attempt to enhance the bandwidth of micro strip patch antennas by
incorporating impedance matching strip as a part of the micro strip patch antenna. The
first part of the thesis deals with the broadband operation of the tilted square slot and
polygonal slot loaded square micro strip patch antennas. The resonant mechanisms are
clearly mentioned using the simulation and experimental studies. The bandwidth of the
polygonal slotted broadband patch antenna is again enhanced by implementing an Lstrip
feed mechanism. In the second major part of the thesis, a novel gain enhancement
technique for single band and broadband square micro strip patch antennas is achieved
by implementing offset stacked configurations. |