Electromagnetic shock waves from transmission lines

We have observed subpicosecond electrical pulses to propagate on 5m coplanar transmission lines at velocities faster than the phase velocity in the underlying dielectric. This situation produces an electromagnetic shock wave in a manner similar to Cherenkov radiation and electro-optic Cherenkov radiation. Using time-domain spectroscopy we have measured the strong frequency-dependent loss of energy in the propagating electrical pulse due to this radiation. © 1987 The American Physical Society.