Abstract

The concept of insertion loss as applied to microwave networks is discussed and methods of measurement are reviewed. It is concluded that superheterodyne substitution methods enable precise measurements of insertion loss to be made at frequencies for which no standard attenuators exist. Equipment of this type for use in the range 3.8–4.2 Gc/s uses a principle developed by C. M. Burrell.An intermediate frequency of 34.5 Mc/s is employed, and the 34.5 Mc/s output from the waveguide path, into which the network being measured is inserted, is compared with a signal at 34.5 Mc/s obtained from a crystal oscillator followed by a piston attenuator. Switching between the two signals is effected at a repetition rate of 1 kc/s, and detection of the composite 34.5 Mc/s signal yields a 1 kc/s output whose amplitude is proportional to the difference between the two 34.5 Mc/s signals; detection in a phase detector gives the sense of the difference. The piston attenuator is adjusted for zero output from the phase detector, and the difference of the attenuator readings, with and without the network inserted, gives the required insertion loss.The accuracy of measurement is ±0.05 and ±0.1 dB for losses of 6 and 30 dB, respectively, and losses of up to 60 dB, can be measured with decreased accuracy.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.