A method based on the 4-port S parameters of the unit cell and the Bloch theory is proposed to analyze planar 2-D Left-handed structures.The Left/Right-handed frequency bands are identified by the Bloch wave number and the Bloch impedance.Compared to the previous unit cell analysis methods

the new method is suitable for analysis of more flexible structures

can give better consideration to the distributed elements’ dispersion

can determine the Left/Right-handed frequency bands more easily and accurately

and can be used to analyze anisotropic and lossy structures.As an example

a capacitance-enhanced Left-handed structure is designed and analyzed with the new method.FDTD simulation is also performed to illustrate the backward wave propagation in the periodic structure with infinite arrays in Left-handed frequency band.This demonstrates the effectiveness of the new method.