Calibration of a waveguide-below-cutoff attenuator using a voltage doubler

The design and operation of an automatic precision attenuator using a laser interferometer and a method for utilizing the new National Bureau of Standards (NBS) 1.25 MHz voltage doubler calibration system have been discussed previously [1], [2]. The purpose of this paper is to provide the technique required to determine corrections for multimode propagation and leakage in a waveguide below cutoff attenuation standard. Sufficient details are given to enable several orders of accuracy improvement near the attenuation limits. Calibrated values for skin-depth correction vary from prior publications [6]. Several areas requiring further research which were identified using these techniques are discussed.