Abstract: A method for electromagnetic imaging of containers receives uncalibrated first data corresponding to signals of a first plurality of different frequencies associated with an antenna array residing in a container having contents. The method estimates of a second data based on a computer model and simulation of signals of a second plurality of different frequencies associated with the antenna array, the second plurality of different frequencies including a subset of the first plurality of different frequencies. The method compares magnitudes, without corresponding phase comparisons, of the first and second data at each frequency of the second plurality of different frequencies. The method updates the second data based on the comparing. The method provides information about the contents within the container based on the updated second data.