Research On Key Technologies Of Broadband And Multiband Antennas For Wireless Communication

With the rapid development of wireless communication technology,transmission rate of information becomes more and faster.Antenna,as an indispensable part of the transceiver system,whose performance will directly affect the whole wireless communication system.The high speed,large capacity and low delay required in the process of information transmission require higher requirements for antenna design.In order to meet the new requirements of wireless communication system,the research on broadband antenna,multiband antenna,dual polarization antenna and reconfigurable antenna are mainly carried out in this paper.The main research content is divided into the following parts.(1)Based on the coupling principle,three broadband antennas are designed in this subsection.The first wideband omnidirectional antenna is designed by using planar microstrip monopole antenna as main radiating structure and adjusting the impedance matching of the antenna by loading two different parasitic radiation patches.The relative bandwidth of the proposed antenna is 69.3%(2.66-5.48 GHz,S11<-10 dB).The second antenna is a wideband omnidirectional antenna as well,which is designed by directly loading periodic radiating elements on the microstrip feeding line.Under the condition of S11<-10 dB,the measured relative bandwidth of the antenna is 61.1%(2.16-4.06 GHz).Meanwhile,the antenna has stable omnidirectional radiation characteristics within the operating bandwidth.The third antenna is the broadband directional antenna which is designed according to the Yagi antenna principle.A broadband quasi-Yagi antenna without director is designed by cascading three reflectors.The relative bandwidth of the antenna is 83.8%(2.21-5.4 GHz)with the radiation efficiency above 32%in the effective bandwidth.(2)Based on the principle of multi-mode resonance,three antennas for different application scenarios are designed.The first antenna is a dual-beam antenna based on the TM02 mode.At 5.8 GHz,the maximum gain and radiation efficiency of the proposed antenna are 6.11 dBi and 71%,respectively.The structure of the proposed antenna is simple and easy to integrate,and meet the requirement of modem intelligent wireless communication system.The second antenna is designed based on TM02 and TMi2.At the first and second resonance points,the radiation characteristics are different,presenting bidirectional radiation characteristics and cross bidirectional radiation characteristics,respectively.The third multiband antenna is acquired based on the multi-mode coordination between patch antenna and slot antenna.(3)Based on the principle of orthogonal mode,two kinds of antennas are designed.Firstly,the resonant modes of rectangular radiation patch excited at 4.5-6 GHz are analyzed by characteristic mode theory,and then a dual-polarized antenna is proposed by using the required orthogonal modes.One is a dual-polarized antenna with dual-beam radiation characteristics.The other is a dual-function antenna.At 5.2 GHz and 5.8 GHz,it can be used as a vertically polarized antenna and a horizontally polarized antenna,respectively.The volumes of the two antennas are both 66.4×65×1 mm3,which is made of a single-layer dielectric substrate and fed by coplanar waveguide.It is quite easy to integrate into RF front-end with high design flexibility,thus it is suitable for wireless communication system.(4)Based on the principle of radiation field,two frequency reconfigurable antennas for specific scenarios are designed.One is frequency reconfigurable antenna,which has bidirectional radiation characteristic.Thus it is suitable for application in narrow and long area environment such as underground passage,subway tunnel,mine and so on.The size of the antenna is 46×34.3×1 mm3.The simulated maximum gain of the antenna is 3.49 dBi,3.06 dBi and 2.47 dBi at three resonant frequency points(5.2 GHz,5.31 GHz and 5.44 GHz),respectively.The other one is a bandwidth reconfigurable antenna with omni-directional radiation characteristics.The coverage bandwidth can be changed from 1.64-2.24 GHz to 1.65-2.68 GHz.