Miniaturization Of Broadband Microstrip Antenna Design

With the development of the mobile communication technology, the terminal communication equipment performance is improved. The terminal communication equipment is not only required to combine a variety of functions, but also required to have a small size. Therefore, the antenna of the terminal communication system must be provided with a smaller size and a wider bandwidth. So many miniaturization technologies and broadband technologies must be used to improve the performance of the conventional antenna. These technologies can reduce the size of the antenna and extend the bandwidth of the antenna as much as possible on the basis of reaching the requirements of gain and direction. The microstrip antenna has a low profile. Therefore, the process of the miniaturization can just reduce the area of the radiating element, and the microstrip antenna becomes the first choice for the miniaturization broadband antenna.In this article, three miniaturization broadband microstrip technologies, fractal, loading and winding radiator, are used to design four miniaturization broadband microstrip antennas.The first antenna is designed with the planar monopole with top loading and two G shaped rings.The top loading reduces the sizes of the planar monopole, and two G shaped rings are used to extend the bandwidth of the high-frequency band of the antenna. So, the antenna can cover all WLAN and WiMAX bands in addition to the3.5GHz band of the WiMAX. In order to further improve the performance of the antenna, the antenna is mended:the G shaped rings are replaced by the circular rings, and the width of the planar monopole is adjusted. The modified antenna can cover all frequency bands of WLAN and WiMAX.The second antenna gets the miniaturization antenna through using a planar monopole with the top loading and a winding planar monopole and is consisted by two branches. The left branch is constituted by planar monopole with the top loading, and the right branch is composed of a winding planar monopole. The left branch and right branch generate the high-frequency band and the low-frequency band respectively.The third antenna and the fourth antenna are both the modified Sierpinski carpet fractal antennas, but they use the different iteration factor. The third antenna gets wider bandwidth than the Sierpinski carpet fractal antenna significantly. The fourth antenna indicates that the bandwidth of the fractal antenna does not change when the sizes of the antenna change proportionally. At the same time, the paper provides detailed evaluation parameters of these four antennas, and some key parameters of these four antennas are also discussed.