Research On Enhancement Gain Technique Of Omnidirectional Antenna

With the development of modern mobile wireless communications,radar and electronic systems,the research of omnidirectional antennas of base station antenna,which is utilized in indoor wireless communications,has gain more and more attention.How to reduce the size of omnidirectional antennas while improving its radiation gain has remain a study hotspot worldwide.Combining the research projects and research hotspots in antenna technology,proposed a design scheme for high-gain omnidirectional antennas is proposed in this thesis which is capable of maintaining their size simultaneously.The research results obtained are listed as following:1.Several kinds of design structures of commonly used omnidirectional antennas both domestic and foreign is proposed in this thesis,such as coaxial collinear antenna,serial feed coaxial oscillator antenna,omnidirectional antenna of microstrip structure and omnidirectional antenna based on rectangular waveguide slot.Based on the introduction of their basic principle of radiating omnidirectionality,we further analyzed the advantages and disadvantages of their structures.2.Designed a printed string-feed microstrip patch omnidirectional antenna that can be used for indoor and outdoor wireless communication.The simulations and optimizations based on the research of its unit are conducted,and the high gain is achieved by forming an antenna array with a series of cascaded feed structure.Furthermore,the fed balun is analyzed and designed.The bandwidth is extended by the quarter-wave turbulence sleeve,and the radiation performance of the high-gain omnidirectional antenna is improved.3.Designed two kinds of printed parallel double line omnidirectional antenna structures are designed in coaxial cascade feed way.One is a symmetric printed parallel double line omnidirectional antenna,and the other is an asymmetric printed parallel double line omnidirectional antenna.A microstrip-to-parallel bi-directional fed balun is used to feed the antenna.The miniaturized high-gain serial-fed omnidirectional antenna unit structure is obtained through simulation and optimization,and the two antenna structures are processed and tested..The test results are in good agreement with the simulation results.