A Compact Forward Coupler Using Coupled Composite Right/Left-Handed Transmission Lines

Abstract

A novel forward coupler using coupled composite right/left-handed (CRLH) transmission lines (TLs) is presented. Forward coupling is enhanced by the CRLH TLs, which have a considerable difference between the effective phase constants in the even and odd modes. A 10-dB forward coupler using the coupled CRLH TLs is simulated and experimentally demonstrated in the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -band. Its coupled-line length is reduced to half that of the conventional right-handed forward coupler with the same coupling.