Active microwave delay line for reducing the dead time in electron-spin echo spectrometry

A simple active microwave delay line to be used with an electron-spin echo spectrometer to reduce the dead time is described. The delay line employs a microwave amplifier and two PIN diode switches as its active components. Tests with a coal sample at room temperature show that the dead time could be reduced from 140 ns without to 60 ns with the active delay line.