Microwave brightness temperatures across C band during the growth of a saline ice sheet are presented. The data were collected with the Stepped Frequency Microwave Radiometer (SFMR) as part of a cooperative experiment at the U.S. Army Cold Regions Research and Engineering Laboratory, CRRELEX '88. Data at the six frequencies of the SFMR exhibited oscillatory behavior as the ice sheet developed, which indicates a coherent effect in the emission. Ice thickness and angle of incidence were monitored continuously, making it possible to solve for the dielectric constant of the sheet at ice thickness corresponding to local brightness temperature maxima and minima. The resulting values for dielectric constant are large for extremely thin ice but then decrease to approach the accepted first-year ice value as the ice becomes optically thick. ¿ American Geophysical Union 1993