Abstract: A simplified and compact electron paramagnetic resonance (EPR) spectrometer is constructed by putting a self-detecting microwave marginal oscillator, as a wave source, a sample and a detector in one cavity-structure on the basis of small magnetic modulation, computer control and data superimp osing. The final sensitivity is 3×10⁸ spins/T.

Key words: EPR spectrometer, a small magnetic modulation field, se lf-detection of microwave marginal oscillation, computer control