Study Of Novel Wireless Terminal Antennas Based On Electromagnetic Metamaterials

The next generation communication system is developing towards high-speed, high-quality, broadband and high-capacity. Multiple-input and multiple-output (MIMO) is a technology which uses diversity techniques to improve channel capacity. It utilizes multiple antennas both in base station and handset. The design of multiple antennas in handsets is a difficulty because of its limit space, which restricts the development of MIMO technology. Moreover, the existing communication technologies such as2G and3G even the coming4G will coexist for a long time which require the antennas of a handset to cover multiple communication bands. It makes the design of antenna much more difficult. Targeting at the requirement and trend of the next wireless communication system, the thesis researches the key techniques including the miniaturization, high-quality, multi-band, MIMO and high isolation design of antennas which can be used in wireless terminals by using metamaterials.This thesis first introduces the basic theory, the unique characteristics and the implementing form of the left handed materials. The comparative analysis of the two mainly implementing forms of the left handed materials is given, which is resonant structures and non-resonant structures. We pay our attention to the theory of the composite right and left handed transmission lines (CRLH-TL). In addition, the thesis introduces the basic theory of MIMO techniques, the diversity techniques and the parameters which are used to evaluate the performance of the diversity techniques in details.The theory of dual zero-order resonance (ZOR) is proposed to design a compact antenna with high performance, which can cover multiple communication bands of GSM850/900、DCS1800/1900and3G. The proposed antenna has a monopole-like radiation pattern and high efficiency. The measurement results of the manufacturing antenna confirm that its performance is satisfying the requirement of the handset. The effect of each part of the antenna on the performance is also analyzed. Finally, we optimize the height of the antenna holder, and the simulation results show the antenna optimized is also satisfying the requirement of the handset.The decoupling techniques of two antennas in handset for MIMO communication are studied in this thesis, especially for neutralization lines and ground slots techniques. On the basis of the proposed dual-ZOR metamaterial antenna, we design a MIMO dual antennas to cover GSM850/900、DCS1800/1900and3G. with high isolation. The proposed MIMO dual antennas have the monopole-like radiation patterns in the operational band with high efficiency. The simulation and experiment results show that the isolation (S21) of two antennas can achieve-13dB in the GSM850/900bands and-20dB in the DCS1800/1900and3G bands. The envelope correlation coefficient (ECC) with decoupling techniques is also analyzed, which can satisfy the requirement of MIMO diversity.This work has laid a good foundation for smart phone terminal antenna designs for next generation LTE wireless communication system.