The Calibration of Microwave Attenuators by an Absolute Method

A bridge method by means of which microwave attenuators can be calibrated absolutely is described, with a consideration of the main possible sources of error. A bridge was set up at lambda₀ = 3.2 cm to test the principle of the method. It was shown that, using nonspecialized equipment, a high degree of accuracy was obtainable. An attenuator was calibrated over a range of 20 db, with an accuracy of the order of +-0.02 db. This accuracy is within the accuracy of other methods of calibration in current use, and there seems no reason why, with suitable precautions, the order of accuracy should not be improved still further, if required.