| In recent years,metal case phones have been widely accepted by consumers because of their better structural stability and better appearing looks.However,the electromagnetic shielding effect caused by metal case will worsen antenna working bandwidth and radiation efficiency and other performance indicators largely,which makes it difficult and also attractive to the vast researchers to overcome the shortness of implying metal environment on antennas and further improve the antenna performances.At the same time,the urgent need for MIMO(Multiple-Input MultipleOutput)technology in mobile communication,which can be used to increase the reliability and reusability of mobile communication systems,makes the design of MIMO antenna and its related research become one of the populates research topics.Due to the compact space insides the mobile phone,there are strong electromagnetic couplings between the antenna elements,which affects the antenna performance largely.So far,there has no 4-element MIMO antennas used in mobile terminals,which makes it highly demanded for researches in mobile terminal MIMO antenna demagnetization coupling theory.Based on the previous researches in mobile phone antenna,4-unit LTE MIMO antenna in metal environment is investigated with details in this paper.Two mobile phone antennas are designed and fabricated.The experimental measured results match well with the theoretical ones.The envelope correlation coefficient,the multiplexing efficiency and the channel capacity of the LTE MIMO system are also simulated.The main contents of this paper are as follows:1.The background and status of researches in all metal mobile phone antenna and MIMO technology are introduced in in this chapter.Then it clarifies the purpose and significance of the research and forecasts the development trends and challenges of mobile phone antenna in the future.2.This chapter introduces the basic principle of slot antenna,monopole antenna,IFA antenna,PIFA antenna and LOOP antenna.It also briefly describe the measuring and debugging method of mobile phone antenna,which is the preparation of theoretical and engineering practice of the antenna design.3.This chapter proposed a compact GPS/WLWAN antenna for metal-housing phone,using techniques like loading the ground structure for suppressing cavity resonances,loading the resonant circuit of capacitance and inductance for reducing the antenna size,applying coupling feed and adding extra radiate strip to increase the bandwidth.Finally,the simulated and measured results both meet the requirement of engineering very well.4.Based on demands of MIMO antenna design for mobile terminal,this chapter proposed a 4 elements MIMO LTE antenna array with high isolation and small size.This antenna design is simulated and fabricated,the measure results shows that both the antenna efficiency and bandwidth can meet the communication requirements.5.This chapter introduces the basic parameters in MIMO communication system.Then the proposed 4 elements LTE MIMO system is simulated and its correlation coefficient,channel capacity,multiplexing efficiency are calculated,which basically satisfies the requirement of engineering applications. |
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