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.