Full Evolution of the 6 and 20 Centimeter Radio Emission from SN 1980K

First detected at 6 cm in 1980 November, only 1 month after optical maximum, and several months later at 20 cm in 1981 March, SN 1980K has now dropped below reasonable monitoring limits of the VLA at these two frequencies. It thus represents the first Type II radio supernova to have been well-studied at centimeter wavelengths from "turn-on" to "turn-off." It also represents one of the few radio supernovae to have such an extensive, decade-long, multiple-frequency data set. We present new observations of SN 1980K made with the VLA at 20 and 6 cm from 1984 November through 1990 December. Unless the radio emission strengthens again in the future, this completes our monitoring of the supernova at these wavelengths. The study of these "complete" light curves shows that the "minishell" model of Chevalier still provides the best representation of the data at both wavelengths. The similarities between the behavior of the radio emission from SN 1980K and SN 1979C argue that these two objects represent a distinct class of radio supernovae which is distinguishable from the radio emission from Type Ib supernovae, such as SN 1983N and SN 1984L, or the radio emission from the presumed Type II supernova SN 1986J. The implication is that there exist several classes of radio- emitting supernovae whose differing radio properties probably arise from different mass-loss rates and therefore different zero-age main-sequence masses of progenitor stars.