Design Of CPW-fed Multiband Miniaturized Antenna For WLAN/WiMAX

With the continuous advancement of wireless communication technology,antennas are gradually developing toward multi-function,miniaturization,and high spectrum utilization.The researchers began a series of studies on multi-band antennas,miniaturized antennas,and MIMO antenna systems.In order to meet the needs of modern wireless communication equipment,the antenna is required to have characteristics of multiple frequency bands,miniaturization,and high spectrum utilization.This thesis will mainly focus on co-planar waveguide-fed multi-band,miniaturized,and MIMO antennas applied to Wireless Local Area Network(WLAN)and Worldwide Interoperability for Microwave Access(WiMAX).Finally,two triple-band miniaturized antennas,a quad-band miniaturized antenna and a four-port dual-band MIMO antenna were designed.The main work of the thesis is as follows:(1)The basic parameters of the printed antenna and the specific parameters of the MIMO antenna are introduced,and then the principle and method of realizing multi-band,miniaturization and decoupling of the MIMO antenna are summarized.(2)For the problem of incomplete coverage of the existing antenna bandwidth applied to WLAN / WiMAX,two miniaturized triple-band antennas with coplanar waveguide feeding were designed.The first antenna is a miniaturized triple-band notch slot antenna fed by a coplanar waveguide.The antenna is based on the bandwidth advantage of a planar rectangular monopole.The triple-band antenna can completely cover the WLAN/WiMAX bands by adding radiation branch and notch structure.The second is a miniaturized triple-band multi-branch monopole antenna fed by a coplanar waveguide.Using the method of adding radiating branches,a triple-band monopole antenna with a very small size that can independently adjust each frequency band is designed.The evolution process of the two antennas is introduced,and the influence of the branch on each resonance frequency is analyzed through the surface current distribution.The simulation results show that the two antennas have reached the expected operating bandwidth,have good omnidirectional radiation characteristics,and reasonable resonance frequency gain.(3)In order to meet the multi-functional requirements of the wireless communication system,a quad-band printed monopole antenna with a multi-branch structure applied to the WLAN / WiMAX / X bands was designed based on the second antenna.This chapter introduces the evolution of the antenna,analyzes in detail the key parameters of the resonance frequency of each branch,studies the effect of patch length on the reflection coefficient,and gives the optimal parameters.The actual measurement results show that the antenna has reached the expected operating bandwidth,has good omnidirectional radiation characteristics,and has a reasonable gain at each resonance frequency.This shows that the antenna is suitable for WLAN / WiMAX / X-band wireless access equipment.(4)In order to meet the needs of wireless equipment for large information communication capacity,a miniaturized dual-band four-element MIMO antenna designed for coplanar waveguide feeding in the WLAN / WiMAX bands is designed.We give the size structure of the antenna and the evolution process of the antenna,and analyze the influence of the branch on each resonance frequency through the surface current distribution.The measured results show that the antenna has reached the required operating bandwidth,has good omnidirectional radiation characteristics and appropriate gain.Compared with other similar products,the antenna has the advantages of moderate size,simple structure,good omnidirectional radiation characteristics,and complete frequency band coverage.This makes it ideal for small portable WLAN / WiMAX equipment.