Patent ID: 7774034

Claim:
A signal switching device including a plurality of transmission paths connected to an input path, said signal switching device outputting a signal from the input path through one of the transmission paths, comprising: a first variable impedance unit connected to a first transmission path, said first variable impedance unit including a first section formed from a superconducting material, said first section being set to a non-superconducting state when the signal is to be output through a second transmission path, wherein said input path and each of said plurality of transmission paths are formed by a wave guide including a central conductor and a coplanar grounding conductor, the ground conductor being spaced from the central conductor, and said first section includes a first portion at an input end of the first section and a second portion at an output end of the first section, an output end of the first portion being connected to an input end of the second portion, and a width of the second portion increases from the input end of the second portion to an output end of the second portion.