Amplitude scintillation spectra and statistics obtained simultaneously at VHF (257.55 MHz), L band (1541.5 MHz), and C band (3945.5 MHz) from the MARISAT communications satellite (15¿W) are presented. The measurements were made at Ascension Island (7¿58'S, 14¿25'W, 30¿S DIP) over a high elevation propagation path within a few degrees of the magnetic meridian plane. The multi-frequency data and the unique propagation geometry enable us to study the structures of the equatorial ionospheric irregularities closely. Numerical simulation is used to model a specific event. Comparisons between the modeling results and the observations indicate that the data are consistent with the recently measured (in situ) two-component power law irregularity spectrum with a shallow large-scale regime and a steeper small-scale regime, and a spectral break at about 1-km scale size.