Design Of Composite Right/Left-Handed Transmission Line And Applications

With the rapid development of information technology, all the communication equipments are required to be small, wideband and multiband in modern communications systems. And in some cases, it has pushed communication equipments design beyond the capabilities of current technologies. The composite right/left-handed transmission line, which have novel physical properties such as low-loss, wide bandwidth and balance, has opened up a highly promising research field in electromagnetics. Currently, with the validation of the physical characteristics of the CRLH TL in theory and experiment, its novel design and applications has drawn the attentions of physicists and electromagnetic scientists. In the thesis, the theory of CRLH transmission line is deduced, novel CRLH TLs are designed and the applications in leaky-wave antennas and medicine and biology are explored.The main work of the thesis can be summarized as follows:1)The working mechanism of the double negative property of CRLH TL is studied thoroughly. Furthermore, the principle and characteristics of the ideal CRLH TL and LC networking CRLH TL are researched methodically.2) A CRLH TL composed of a substrate and X-shaped metal patches is proposed and investigated theoretically as well as experimentally. Moreover, the required equations and the dispersion diagram derived from the equivalent circuit model to analyze the proposed CRLH structure give strong support to the interpretation of all EM phenomena. It is found that the structure works as a dual band CRLH TL having the first right-handed passband and the second balanced CRLH frequency band at the frequency ranges of6.27GHz-6.56GHz and11GHz-16.5GHz, respectively. 3) A CRLH TL composed of four units’X-shaped metal patches is proposed. During the electrical simulation, the corresponding parameters of the equivalent circuit model are extracted based on magnitude/phase fitting technique. Moreover, the constitutive parameters are extracted to demonstrate the left-handed band and right-handed band. The CRLH-TL is fabricated with printed circuit board, and a parallel-plate waveguide (PPW) measurement system is employed to study the characteristics of the CRLH TL. The proposed structure works as a broad band CRLH-TL and the frequency region from9.3GHz to10.08GHz are presented as right-handed band, while from10.08GHz-10.9GHz as right-handed band.4) A novel CRLH TL composed of a parallel-plate capacitor and a bent microstrip line is employed to to achieve balanced CRLH structure from0.9GHz to7.5GHz. Thus a novel leaky-wave antenna based on the proposed CRLH TL is designed. It is found that the leaky-wave antenna attains the balance fashion at2.25GHz and the broadside radiation from-380to250.5) The application to reduce the body’s absorption of radiant energy is intruduced. Simulation results show that with the impedance matching CRLH TL as a shield plate in the mobile phone system, the SAR are reduced significantly. However, the shield plate has little impact on the performance of the antenna radiation.