Research On Fractal Patch Antenna

In today's world, the development of science and technology is very rapid, and so does the wireless communication technology. So, the wireless communication equipments are under the ever-increasing demands. As one of the most important sections in the wireless communication equipments, antenna technology is facing new demands as miniaturization and multiband. The fractal antenna based on space self-filling ability and self-similarity ability, presents some characteristic such as electrically small size, wideband and multi-frequency. However, the research on fractal antenna is focused on the characteristics and the structures of the fractal elements, and the polarization form is very single. But, the circular polarization antennas have a very wide range of applications in practice, therefore, how to apply the concept of fractal antenna to design circular polarization antenna is very worthwhile to research.In this thesis, the author firstly expounds the design theory of microstripe antenna, summarizes the commonly used methods of circular polarization, then selects the aperture-coupled technique for fractal antenna to achieve the circular polarization mode. The aperture-coupled structure is modeled and analyzed by the transmission line method. Then, two fractal patch antenna based on this structure are proposed. The two antennas are fabricated using the Koch island patch and the FRC (Rectangular Fractal Curve) patch respectively. The result shows that these two antennas have ideal circular polarization performance. In addition, this thesis uses tow ordinary patch antennas to compare with the two fractal antennas, and the result shows that both of the fractal antennas possess good characteristics of miniaturization.A novel hybrid-fractal microstrip antenna with broadband multiple frequency characteristics is proposed in this thesis, too. The antenna is feed by a Coplanar Waveguide (CPW) feed line, and have two radiation patchs. The driving patch and the parasitic patch are stacked-Sierpinski patch but with different element loaded. The result shows that this is a multi-frequency and frequency easy-selecting antenna, and it has ideal radiation pattern and gains. At last, we use the idea of the hybrid-fractal to design an antenna to accomplish the communication demands of 2G and 3G, and obtained an ideal result.