INTERMODULATION DISTORTIONS IN KLYSTRONS AND TRAVELING-WAVE TUBES FOR MULTIPLE SIGNAL AMPLIFICATION

Multiresonator klystrons and travelling-wave tubes (TWT) are widely used in the output stages of transmitters in satellite earth stations and satellite repeaters. The transfer characteristic nonlinearity which is a characteristic property of these vacuum tube devices (the dependence of the instantaneous output voltage or current on the input voltage or current) and the nonuniformity of the phase-amplitude characteristics are primarily responsible for intermodulation distortions that arise in amplification of multiple signals at different frequencies. Odd-order intermodulation products appear in the transmission band of the output stage of the amplifier, and create interference for the amplified signals. Experimental data are used in this article to determine that the nonlinear distortions arising in klystrons can be described by a universal characteristic which can then be employed in preliminary calculation of satellite radio links.