Research On Microstrip Antenna Miniaturization And Frequency Tunable Techniques

Information transmission is an important part in human society, especially, in the modern society, the widely use of phone or mobile-phone smakes people communicating anytime and anywhere, People’s lives have been integrated with the communication technologies together. The rapid development and wide application of communication technologies, have greatly promoted the development of society, and have brought profound changes to the style of people’s life. The wireless communication is most widely used in the communication system, not depend on the visual transmission medium, wireless communication realized the purpose of rapid communication. Therefore it plays an increasingly important position in the modern communications. In numerous constituent components of the communication system, antenna plays an irreplaceable role. Antenna is the entrance and exit of the radio waves in wireless communication system, used to complete the transmitting and receiving functions. All radio communication, radio, radar, navigation and engineering systems use radio waves to carry out the work, the lack of access interface will lead to the system can not complete any functionsMicrostrip antenna is one of the most important manifestations of antenna, which has been widely used in Wireless communications system during the recent decade because its outstanding properties of low profile, low cost, light weight, easily fabricated and easily integrated with radio frequency and microwave circuit. This thesis presents a summary of the status of the microstrip antenna design. Based on this work, a widely range of research job was done on the technology of microstrip antenna miniaturization, broadband and frequency tunable. Combining with the full-wave analysis software, an optimization work was done for the model, impedance matching, gain of the antenna.The first major content of this thesis is to study the miniature and band exhibition problem of the Planar Inverted F Antenna. Ground plane and radiation patch slotted operation makes the antenna relative frequency band raised from21.9%to36.9%, an increase of68.5%was achieved, and special media loaded makes the size of the antenna reduce more effectively. Further exploration was done based on the previous work. The loaded of middle patch makes the resonant frequency decreased to the VHF band, which made the relative size of antenna decreased to28%of traditional Planar Inverted F Antenna, and the Impedance bandwidth over270MHZ can be larger than30%. Another main content of this thesis is the research of frequency tunable technology, especially the application of artificial electromagnetic media in antenna frequency tunable field. Based on the theory of Composite Right/Left Handed Transmission Line (CRLH TL), Varactor diode is loaded to realize the resonant frequency real-time tuned. The volume of the antenna is only15mm*15rnm*0.8mm, simulation results show that the resonant frequency can be tuned more than700MHz in S-band (S11parameter is better than-lOdB). The antenna has a simple structure, compact size, which has some theoretical significance and is attractive for applications in microwave system.