Recent improvements in instrumentation permit sufficient resolution in angular-deviation measurements to yield information on the shape of irregularities. The expected deviation imposed upon very high frequency signals from an orbiting satellite by an irregularity with a Gaussian electron-density distribution is modelled. The model predictions are fitted to experimental observations made at Churchill, Man. (59°N, 94°W geodetic). The data used are differential phase measurements of the coherent 150- and 400-MHz transmissions from satellites of the Navy Navigation Satellite System. Irregularities with both electron-density enhancements and depletions are found, with elongations in the direction of the magnetic field somewhat less than had been previously reported.