Abstract :
The characteristics of metallized-glass-vane attenuators in rectangular waveguide are briefly reviewed. Resetting accuracies of 0.004 and 0.012 dB in 40 dB are achieved at 3 and 10 Gc/s, respectively. The glass vanes are unaffected by extreme climatic conditions, and laboratory attenuators in the 10 Gc/s band have retained their calibration to within 0.03 dB over a five-year period. The attenuators are calibrated with reference to the accurately constructed piston attenuator of a 60 Mc/s signal generator. The microwave signal is amplitude modulated and is converted to 60 Mc/s in a linear mixer. The signal generator output is also amplitude modulated, and the two 60 Mc/s signals are compared in a phase-sensitive detector. Methods are described for the determination of the errors of calibration, and it is concluded that the total inaccuracy does not exceed 0.03 dB in the range 0¿50 dB in the 3 and 10 Gc/s bands.
