Thin-film multilayered electrode, high-frequency transmission line,

Abstract

A thin-film multilayered electrode has a dielectric substrate; a ground conductor provided on a back surface of the dielectric substrate; and a plurality of thin-film conductive layers and dielectric layers alternately stacked on a front surface of the dielectric substrate. In one example, the ground conductor, one of the thin-film conductive layers in contact with the dielectric substrate and the dielectric substrate interposed therebetween form a TEM mode principal transmission line, and each thin-film dielectric layer and a pair of thin-film conductive layers sandwiching the thin-film dielectric layer form a TEM mode sub-transmission line. A thickness and a dielectric constant of each thin-film dielectric layer is set such that phase velocities of TEM waves which propagate through the TEM mode principal transmission line and the TEM mode sub-transmission lines are substantially identical with each other. A thickness of each thin-film conductive layer is set at a predetermined value which is smaller than a skin depth at a predetermined operating frequency such that electromagnetic fields between the TEM mode principal transmission line and its adjacent TEM mode sub-transmission line, and between each adjacent pair of TEM mode sub-transmission lines, are coupled with each other. At least one of the thin-film dielectric layers which is closest to the dielectric substrate has a thickness greater than that of the other thin-film dielectric layers.