Design and fabrication of a new micromachined interdigital coplanar waveguide

In this paper, a new micromachined interdigital coplanar waveguide (CPW) structure has been developed and its characteristics have been studied as a function of transmission line parameters. In interdigital CPW, the ground conductor is thickened by micromachining techniques which is helpful for reducing the interference between the adjacent center conductors while microwave transmits along it. Within the frequency range from 5 to 20 GHz, the return loss of this structure has two minimal values whose positions change with the structural parameters. The relative bandwidths reached 23.5% and 9.97% at 8.3 and 16.55 GHz while the insertion losses are about 0.33 and 0.5 dB/cm, respectively. The interdigital CPW is useful for designing bandpass filter and phase shifter and minimizing the whole size of microelectromechanical system (MEMS) devices.