On The Research And Design Of The Multi-frequency Microstrip Antenna Applied To The Wireless LAN

In a small wireless communication device with multiple communication functionsintegrated, the requirements for its built-in antenna are as follows: be miniaturized, be etchedon the PCB board or be the same type with equipment components, be easy to drive, and beeasy to realize multi-frequency omnidirectional radiation. Microstrip antenna, due to its ownadvantages, can meet the requirements mentioned above for the antenna performance. Todayit is widely used in multi-functional, high-performance portable communication devices. Inthe thesis, based on the researches on microstrip antenna technological knowledge of themicrostrip antenna feed method, the radiation theory, multi-frequency radiation method, smallmulti-frequency microstrip antenna is researched and designed to be applied to WLAN andWIMAX. And on the basis of grasping the microstrip antenna multi-frequency radiation,further study is made on the method of extending microstrip antenna bandwidth in the hope ofresearching and designing a small ultra-broadband microstrip antenna which can be applied tothe ultra-wideband communication technology.The thesis is divided into three parts; the first part, firstly, introduces the purpose andsignificance of this thesis, and then follows the detailed introduction to the important contentsinvolved in the research on the microstrip antenna;The second part, after the study in the microstrip antenna the feed method, theimpedance matching technology, the radiation theory and the multi-frequency radiation,proposes five models of small multi-frequency microstrip antenna with a novel structure, astable performance. They are:1. based on a coplanar waveguide feed method, the dual-bandmonopole microstrip antenna used in WLAN;2. based on the microstrip line feed, thetri-band monopole multi-radiation minor microstrip antenna used in WLAN and WIMAX slystructure;3. based on the coupled feed, the tri-band monopole resonance unit microstripantenna used in WLAN and WIMAX;4. based on a combination of feed, loaded parasiticpatch tri-band monopole microstrip antenna used in the WLAN and WIMAX;5. themicrostrip balun feedline dipole multi-frequency antenna applied to WLAN. Among them thefourth one--multi-frequency microstrip antenna based on the mixed feed is a comprehensiveimprovement one on the basis of the first three antenna designs; it has a brand new antennadesign structure, and the parameters of its important antenna performances are better than those of the first three antenna designs.The third part, on the basis of the microstrip antenna multi-frequency radiation, furtherstudies each narrow-band bandwidth correspondence to the extended microstrip antennamulti-frequency radiation; through the introduction of a new kind of DSG and the use of themulti-frequency radiation technology, the design is proposed of the ultra-wideband microstripantenna with a novel structure, a stable performance, and a relative bandwidth of more than110%.