Complex Effective Dielectric Permittivity and Characteristic Impedance of Tunable Coplanar Line

An analysis of complex dielectric permittivity and characteristic impedance of micromechanically tunable coplanar line is presented. The coplanar line parameters tuning is achieved by signal line electrode movement above the substrate or the dielectric plate above the surface of line electrodes. A reconfiguration of electromagnetic field with complex nature occurs as a result of such movement in the line. It is described in terms of effective permittivity and characteristic impedance. We studied an influence of physical and geometrical parameters of the line on characteristics of effective permittivity tuning and change in characteristic impedance and line loss. It is found that proposed method for line tuning parameters allows us to obtain a high sensitivity to movement for effective parameters, wherein the level of losses in the line is not deteriorated, and under certain conditions are reduced. These results make it possible to design high-quality tunable resonant elements and phase shifters based on micromechanically controlled coplanar line.