Audio Modulation Substitution System for Microwave Attenuation Measurements

This paper describes an Audio Modulation Substitution System for high accuracy microwave attenuation measurements. In order to utilize the full advantages of a high-gain, narrow-band audio amplifier, problems of noise, hum, and instability had to be overcome. The techniques used to overcome these difficulties are discussed. The system is used over the frequency range of 240-40,000 mc and can measure up to 40 db.