The Double-Kelvin Bridge Transmission Line and Some Applications

The double-Kelvin transmission line is formed when two layers of dielectric and two layers of resistive material of uniform width and thickness are placed on top of a conductive layer. The open-circuit impedance function and voltage transfer function for the two-port formed by this device are derived. The conditions for real-frequency zeros in the transfer function are developed and a locus of line parameters yielding lines with real-frequency zeros is given. The general case for the transfer function of the double-Kelvin twoport when connected in series with a linear and passive impedance is considered. Experimental verification of the analytical results are shown for three physical realizations of the double line using lumped-element circuits, thin-film circuits and parallel-plate circuits.