Pure left-handed transmission line

The pure left-handed transmission line (PLH TL) for a broad left-handed (LH) band is presented. It consists of a defected ground structure (DGS) and a wire bonded inter-digital capacitor (WBIDC). The bridged connection of vias to ground makes the components of inductance and capacitance effectively negative. These negative components exclude a parasitic right-handed branch so that the transmission line has only a pure left-handed branch. The equivalent circuit of a bridge type is provided to analyse the structure. The dispersion and S-parameter characteristics of the PLH TL are analysed by circuit analysis, Bloch-Floquet theory, and full-wave simulation. The measured results of dispersion curves and frequency behaviours have good agreements with those of theory and simulation. An optimised PLH TL with wide LH fractional bandwidth of 140% is also designed.