Study And Design Of Multiband Monopole Patch Antenna

With the rapid development of wireless communications technology, the antennas as a key component in the wireless communications face lots of challenges, such as miniaturization, wide band, multi-band and so on. Microstrip antennas, which havethe advantages of small size, low profile, easy fabrication and easy integrationin circuits, are able to satisfy the requirements of the wireless communication systems.This thesis focuses on the design of multi-band antennas for WLAN/WiMAX applications.Based on the fundamental principles of microstrip antennas, researchers are conducted on the design and implementation of multi-band antennas. Finally, three types of novel multi-band monopole patch antennas are developed and investigated.Firstly, a brief introduction to the development, basic theory and analysis of the microstrip antennas is presented. Secondly,the feeding methods and theoretical model of the microstrip antennas are summarized. And then, an introduction to theory of the basic monopole patch antenna and WLAN / WiMAX communications protocol is given. At last, three types of multi-band antennas, which are suitable for WLAN / WiMAX applications, are investigated in detail. The proposed antennas include a tri-band planar monopole antenna with an asymmetric coplanar waveguide feeding structure, The asymmetric coplanar feed structure is only used in one side, and when the same frequency is generated in a trap, the gap will shrink to half of the original gap, which is more than the original size of the coplanar waveguide feed.a rectangular monopole antenna with a multi-branch radiator, This rectangular monopole antenna contains a dense multi branch structure, forming a different resonant current path, so the multi frequency operation is realized. and a compact dual notched-band ultra wideband antenna. The eight shape of the branch structure allows the antenna to match the impedance of the antenna in the ultra wideband frequency band and achieve the effect of the antenna. The antenna can be used to achieve the dual notch characteristics in the C band. The antenna can be used in the WiMAX frequency band.The model simulation and parameter analysis of the proposed antennas are obtained by using the electromagnetic simulation software HFSS from Ansoft.Besides, a protype of the tri-band monopole antenna with an asymmetric coplanar waveguide feeding structure have been fabricated and measured. The experimental results show that the antenna covers the WLAN / WiMAX operating bands and omnidirectional radiation patterns and hence it can be applied to wireless communication system.