Symmetric Unit Cell Models for Composite Right/Left-handed Transmission Lines (CRLH-TL) Metamaterials

摘要

Based on the homogeneous composite right/left-handed transmissions lines (CRLH-TL) equivalent circuit model, an symmetric unit cell model for CRLH-TL metamaterials having left-handedness (LH), right-handedness (RH) at different frequencies presented. The CRLH TL unit model is a meta-structured TL composed of a series capacitance and a shunt inductance as well as a series inductance and a shunt capacitance. The series capacitance and the shunt induc-tance provide the LH nature at lower frequencies, whereas the series inductance and the shunt capacitance provide the RH nature at higher frequencies, an unique characteristic of CRLH-TL. We can obtain [S21]=1 at a desired center frequency and also make a desired phase shift over a unit cell possible. The unit cell model for CRLH-TL is analyzed using S-parameter formulations resulting in some useful closed-form expressions for design purposes. These results provide some useful references in facilitating the design of CRLH-TL.