Analysis of simultaneously recorded 1.5- and 4-GHz scintillations at Tangua, Brazil, has shown that the scintillation index varies approximately as the wavelength between 1.5 and 4 GHz under weak scattering conditions. The amplitude distributions, especially those of the 1.5-GHz data, are somewhat irregular in shape and cannot be represented by a simple mathematical expression. The power spectra of the amplitude fluctuations on a log-log plot show a slope of −3 and have low wave number rolloffs near 10−2 m−1. This paper discusses some possible implications of these findings. Half of the 4-GHz power spectra show the minima which are predicted by the thin-screen weak scattering theory. The l/e falloff of the autocorrelation corresponds to irregularities between 100 and 200 m. The cross correlation between the 1.5- and 4-GHz scintillations is about 0.3.