A Molecular Resonance AFC System for Millimeter Oscillators

An investigation was made of a millimeter-wave oscillator AFC system utilizing the inherent stability of a molecular rotational transition as a reference. A unique frequency discriminator, based on Stark modulation of the J=1→2 transition of methyl fluoride, CH₃F, was used to stabilize a reflex klystron. The stabilized frequency was approximately 102.2 GHz. Experimental data indicate that a closed-loop stability of about one part in 10⁷ per hour was achieved. The long-term stability thus obtained is comparable to that of a phase-locked oscillator utilizing a low-frequency quartz crystal oscillator as a reference.