A Compact Parallel Coupled Meander Lines Shaped Composite Right/Left-Handed Transmission Line (Crlh-Tl) Based Symmetric Quasi-0 Db Coupler

In this paper, parallel coupled meander lines (PCML) composite right/left-handed transmission line (CRLH-TL) based symmetrical quasi-0 dB coupled-line coupler is presented. Proposed coupler shows measured backward wave coupling level of 0.81 dB at frequency of 6.17 GHz with 3 dB fractional bandwidth (FBW) of 12.64%. Throughout the 3 dB frequency range (5.78-6.56 GHz), isolation and insertion loss of the coupler is better than 24 dB. Overall size of the proposed coupler is 19.6 x 12.1 mm. An equivalent lumped LC circuit model of the coupler is demonstrated. Measured results of the coupler show good agreement with the electromagnetic (EM) simulated and lumped LC circuit model simulated results, which validates proposed coupler design and its performance.