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Abstract
The wireless revolution is creating a flood of new wireless devices that dramatically increase the availability of voice, video and data services nearly anywhere in the world. While this revolution is significantly expanding the opportunity for new, smaller and better wireless communication terminals, it also is creating new performance demands for antennas to fulfill the need to miniaturize communication devices.
Antenna Engineers Dijemma
“Bandwidth and Antenna Size are Inversely Related”
The bandwidth of a small antenna can be increased by decreasing the efficiency. thereby
reducing the gain.
“Antenna Gain and Size are Directly Related”
The maximal gain of an antenna can be enhanced somewhat by varying the geometry and
the bandwidth can be similarly increased.
In this thesis the research is intended to propose small antennas structures for most wireless applications by implementing fractal geometry for simple wire structures. The main motivation is to consider fractal antennas for wireless applications are that it is possible to:
• Design effective antennas
• Miniaturize antennas
• Improve input impedance matching
• Improve directivity
• Design frequency-independent or multiband antennas
Important problems in design are the cost, size, bandwidth and the quality factor. If one wants both an effective and small antenna, a trade-off is needed since small antennas are generally poor radiators. Today there are also different frequency bands allocated for wireless applications. The goal in this thesis is to reduce the size of the antenna while still providing efficient radiation and allow operation at several frequencies.
Fractal antenna structures are simulated using computer aided design tools implementing MoM for numerical analysis, in order to find new promising designs. Regardless of the traditionality of this method it still gives reasonably good results with simple calculation and moderate processing time. In order to find good fractal antenna structures, attempts to correlate their characteristics with their unique mathematical properties are also made.