Patent ID: 7102456

Claim:
A transmission line with a controllable characteristic impedance, the transmission line comprises a signal strip and a return conductor spaced apart a predetermined distance, the characteristic impedance comprises a characteristic inductance part and a characteristic capacitance part, the characteristic inductance part is dependent on a distance between longitudinal currents of the signal strip and longitudinal currents of the return conductor, the characteristic capacitance part is dependent on transverse currents on effective facing areas of the signal strip and the return conductor, characterized in that the characteristic impedance of the transmission line is controlled by varying a nearest distance between longitudinal currents of the signal strip and longitudinal currents of the return conductor, thereby controlling the characteristic inductance part, while keeping the same predetermined distance between the signal strip and the return conductor by an introduction of at least two non-conducting discontinuities in the return conductor, the at least two discontinuities extend from parts of the return conductor closest to the signal strip and away from the signal strip a length sufficient to controllably increase the nearest distance between the longitudinal currents of the signal strip and the longitudinal currents of the return conductor due to a movement of the longitudinal currents of the return conductor away from the longitudinal currents of the signal strip, the at least two discontinuities extend in such a way as to allow transverse currents between the discontinuities and in that the transmission line comprises a plurality of non-conducting discontinuities distributed along the return conductor, the non-conducting discontinuities are of a width and are spaced apart a center to center distance such that losses due to radiation through the non-conducting discontinuities are avoided or minimized.