Design And Analysis Of MIMO Mobile Handset Antenna

With the rapid development of wireless communication,the demand for the higher communication quality and the bigger system capacity is becoming increasingly urgent.However,it is difficult to solve the above situation with the existing communication system and the shortage of spectrum resources.Multi-input and multi-output(MIMO)technology can improve the capacity and quality of the wireless system as also as the communication speed without exponentially increasing the transmission power and operation bandwidth.Therefore,the MIMO technology has attracted extensive attention around the world.In the MIMO antenna system,the receiving and transmitting terminals use the multi-antenna technology to achieve the good system diversity.The difficulty for the design of the MIMO antenna in the mobile phone is that how to place multiple antennas in such limited space and meanwhile generate the good isolation between the antenna elements so that the resultant performances are not degraded.Based on the above discussion,this paper proposed two MIMO antenna systems in the mobile phone.The thesis introduces the definition and performance parameters of the antenna,and also briefly describes the specific absorption rate(SAR).Moreover,the dielectric resonant antenna(DRA)has been discussed in four aspects,i.e.,the definition,the central frequency,the excitation methods and the approach of broadening the bandwidth.The basic concepts,parameters,diversity techniques,as well as the decoupling methods of MIMO antenna system are also described in this thesis.Meanwhile,the brief descriptions about the basic principle and performance of the characteristic mode theory(TCM)have been given.Based on the DRA theory,a MIMO antenna system for mobile terminals is proposed in this thesis.The operation frequency band of the proposed antenna covers multiple communication frequency bands,from 750 to 960 MHz and 1700 to 3600 MHz.The antenna system has good radiation characteristics in the operating frequency bands and the envelope correlation coefficient(ECC)also meets the engineering requirements.The proposed antenna system was fabricated and measured.The measured results agree well with the simulated ones.In addition,a MIMO antenna system is designed according to the TCM.This antenna system can operate in a bandwidth covering the LTE band 13(745-787MHz),GSM850/900(824-960MHz)and has a good isolation over the whole band.The two antennas have the completely orthogonal patterns,and the total efficiency of the two antennas are greater than 40% across the operating frequency bands.The ECC parameters and the SARs of the antenna system satisfy the engineering requirements.