A coupled-line coupler based on two coupled artificial composite right/left-handed transmission lines (CRLH TLs) fabricated on high resistivity silicon substrate using coplanar waveguides (CPW) is designed, fabricated and on-wafer experimentally characterized. The CRLH TL consists of series CPW interdigital capacitors and parallel short-ended CPWs. For this four-port circuit, the on-wafer experimental results have been obtained using a two-port vector analyzer following a method which is also presented.