A high directivity-wideband metamaterial multisection directional coupler

In this paper, a novel uni planar directional coupler using left-handed TL is proposed. Short microstrip parallel coupled lines and asymmetrical delay line pairs make multisectioned coupler enhance the directivity as well as the coupling. Each delay line pair consists of a right-handed TL and a lumped left-handed TL. Furthermore, a 2/12 coupled line section makes the design area compact. The designed 3-section 18 dB coupler is measured at center frequency of 2.0 GHz, It shows good agreement with the simulation result.