A method of calibrating a measurement of electromagnetic (EM) signals. The method comprises separating at least one reference signal component from an EM signal, delaying at least one of the EM signal and the at least one reference signal component, extracting the EM signal after an interaction with a target object and the at least one reference signal component after at least one interaction with at least one reference element from different time slots in a reception, and calibrating a measurement of the interacted EM signal by a signal analysis of the extracted and interacted at least one reference signal component.