A method of generating 200-990 MHz electric fields for electromagnetic susceptibility testing

A method for generating constant-amplitude electric fields used for swept-frequency electromagnetic susceptibility (EMS) testing in the frequency range 200-990 MHz is developed. The test equipment used to generate the fields has parameters which vary as a function of frequency, such as antenna factors, cable loss, reflection coefficient of the measurement site, amplifier gain, etc. The output voltage of the signal generator is increased or decreased as the frequency is swept to compensate for these parameters and produce a constant-amplitude electric field. The method is implemented using a programmable spectrum analyzer, in which the voltage corresponding to the electric field measured in a characterization run is stored in a data file. Another program compares this voltage with that corresponding to the desired field strength, and stores the difference in a second data file. Using a third computer program, this voltage difference is used to control the input to a programmable signal generator to generate a constant-amplitude electric field