| A 'fractal' is a recursively generated structure having a fractional dimension and self-similarity property. The concept of a 'fractal' has been applied to antenna design in order to reduce the size of antenna and obtain multi-band frequency operation. Fractal antennas have broad application prospect in military and civil application.In this thesis, the concept of 'fractal' and the recursive algorithm of fractal structure are depicted. For the case of microstrip fractal patch antenna structure, the MoM based EM tool Momentum of commercial software ADS is used for analysis and research. Firstly a microstrip-fed microstrip patch antenna has been emulated and validated. On the base of this, the multi-band property of Sierpinski equilateral triangle and squareness microstrip fractal patch antennas are carefully studied, and the effect of antenna's property by the permittivity, the size of patch, the order of the fractal and the decrease of fractal patches is depicted; secondly on the base of analysis and comparison of performance of microstrip-fed semicircle and rectangle double-band microstrip patch antennas, warranty of dimension curtailment is offered; finally expansion of band of those antennas above is discussed.
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