A Study Of Dual And Wideband Microstrip Antennas And Fractal Antennas

In recent years, there has been increasing interest in the dual frequency and wideband operation of microstrip antennas, due to the development of larger capacity, multi-functions and intelligence communication systems. Microstrip antennas have been used in many fields for their inherent advantages such as lightweight, thin profile , manufacturing, packaging and installing.The radiation theory and analysis method of microstrip antenna are presented in the first part of this thesis. The design technique of dual frequency microstrip antenna and wideband microstrip antenna are analyzed detailedly. A novel design of dual and wideband microstrip antenna is presented. The dual frequency operation is achieved by load rectangle notch in each edges of rectangle antenna and the wideband operation is achieved by aperture-stacked coupling feed. The return loss and radiation patterns of this antenna have been simulated by the Ansoft HFSS, which is found on Finite Element, and the bandwidth of antenna is 12.0% at lower resonant frequency and 57.9% at upper resonant frequency, which is wider than commonly microstrip antenna. The antenna has similar radiation patterns at lower resonant frequency and upper resonant frequency.The conception and some common structure of fractal are presented in the second part of this thesis. Because of the shape self-similarity property of fractal antennas between part to whole and part to part, it's easy to form dual-frequency and multi-frequency radiation. The Sierpinski fractal antenna with two iterations and modified the flare angle is simulated by the Ansoft HFSS. Return losses and far fields radiation pattern are gotten in different conditions.