The Design And Implementation Of Multi-band Microstrip Antennas Based On Fractal Structure

For the advantages of compact in total size, low profile, lightweight and able to be integrated with microwave circuits, microstrip antenna is broadly applied in the area of wireless communication. With the development of the communication, it is usual for the systems to work at the multi-network mode, and multi-band microstrip antenna is a good choice for the systems. In addition, an important character of the fractal antenna is that multi-band can be achieved. Therefore, it is a hotspot to introduce the fractal theory into antenna and to design a multi-band antenna with fractal structure.The basic concept, method of analysis and technique of multi-band microstrip antenna have been studied, analyzed and summarized. Fractal geometry and its mathematic description have been studied. Finally, by combining the fractal theory with the multi-band microstrip antenna, two multi-band microstrip antennas based on fractal structure are designed. One of which introduces a fractal structure as the radiating patch, with double U-shape slot loaded on the ground, multi-band is achieved. There are four band with return loss less than -10dB. Based on the technique of multi-stacked, arranging the parasitical patches by fractal free structure, the second antenna has been designed with five bands.The two antennas have been manufactured, and the resonant and the radiating characterization have been measured. The result indicates that the measured data and simulated data are essentially consistent. In the end, the future development of the study is presented.