Via-Less CPW-based composite right/left-handed transmission line

This paper presents a design for a left-handed coplanar waveguide (LHCPW) transmission line without vias or lumped elements. The introduced LHCPW consists of two CPW in two planes. They are mutually coupled by two parallel plate capacitive elements which function as series capacitance elements. Also, the grounded inductive elements are implemented by shorted CPW lines. The proposed LHCPW was simulated using a full-wave Finite Element Method (FEM) solver. Based on the general circuit model of the LH structures, an equivalent circuit of the unit cell of the proposed structure was derived by fitting its scattering parameters to those calculated by the solver. Using the obtained circuit model and calculating the dispersion diagram, we show the anti-parallel directions of the group and the phase velocities below 2.6 GHz, which shows the LH characteristic of the proposed CPW transmission line.