Propagation of ultrashort electrical pulses on microstriplines with submicron dielectrics

We present and analyze a new waveguide structure for the transmission of ultrashort electrical pulses over relatively long distances. By using the method proposed in the present work, microstrip waveguides with submicron dielectric thickness can be formed with III-V semiconductors on highly conducting (metallic) substrates for the first time. In order to minimize signal attenuation, three conventional superconducting materials have been considered to form the metallization. At 4.2 K it is found that pulse propagation is best when the lines are formed with Nb3Sn although NbN performs only slightly less well, with Nb giving the poorest performance. Such waveguides are shown to be extremely good media for the transmission of signals with components in the range 1011–1012 Hz.