Investigations of metamaterials for microwave frequency in time-domain

Summary form only given. Metamaterials, specially, metamaterials for microwave by composite right-left-handed transmission line (CRLH-TL), are studied frequency in frequency-domain. For example, it was studied by transmission-reflection characteristics from S-parameter. But it is difficult to know clearly the relationship of phases, of group velocity, of phase velocity, and the wave propagation process. In this paper, the investigations of metamaterials for microwave in time-domain are presented: 1. The experimental set-up and the experimental method are presented for the microstrip transmission line protocol. For a simple CRLH-TL, it shows directly that the phase velocity is toward the source and is consequently antiparallel to the group velocity. 2. For the electric beam controlled CRLH-TL leaky wave antenna, it shows clear that there are two left-handed frequency ranges, but only one range can be used for electric beam controlled radiation. 3. For the asymmetric RH-CRLH coupler, which composed of a conventional right-handed (RH) transmission line and a CRLH transmission, the time-domain experimental results show that the phase velocities of the two lines to be equal and move toward the same direction. A vortex-like interface mode exists at the interface of a RH-CRLH coupler and the vortex-like interface mode can lead to slow propagation from the CRLH TL across the interface to the RH TL. 4. For the ENG/MNG pairs, the experiments in time-domain can show clear the distribution of evanescent wave in ENG/MNG pairs by transmission line, and the phase relationship between the input and output of the pair while the tunneling occurs. 5. For the photonic crystal transmission line, the experimental results can show the dispersive relation directly, and show there is no any left-handed transmission relationship. 6. For the coupler composed of CRLH-TL and PC-TL, the time-domain experiments show that it is similar to the coupler composed CRLH-TL and normal transmission line.