Calibration and Stability of a Millimeter Confocal Wavemeter

The construction and calibration of a confocal wavemeter for the 94 GHz region is described. Material selection was predicated upon obtaining a frequency stability of 1 part in 105 per °C over a 34°C temperature range. The system uses a 94 GHz signal generated from a crystal reference and phase-lock loop to calibrate the wavemeter. Several readout techniques are discussed. 1) the conventional dip indication, 2) the pip obtained from the resonator used in the transmission mode, and 3) the measurement of the pip phase. The latter technique permits the resolution of 100 KHz at a center frequency of 100 GHz or 1 part in 106.