The Research On The Electromagnetic Characteristic Of Fractal Antennas

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 antenna is useful in military and civil application.In this thesis, the concept of 'fractal' and the recursive algorithm of fractal structure are depicted. The wavelength-independent character of Archimedean spiral antenna and the space filled property of Koch monopole are analyzed by the Method of Moment. For the case of microstrip patch antenna structure with dielectric, the FDTD based commercial software EMPIRE is used. A coaxial probe-fed microstrip patch antenna and a coaxial probe-fed stack patch antenna have been analyzed for checking its validity. On the base of that, the multi-band property of microstrip fractal patch antenna is carefully studied, and the effect of antenna's property by the permittivity, the size of patch, the order of the fractal and the metal box is depicted.