Abstract: Apparatus and method having a probe and readout for taking electromagnetic field measurements by acquiring raw data and linearizing the data either during processing or after processing by using a curve-fitting equation to non-linearly interpolate between calibration data points. A curve-fitting equation of the form V/m=a+bxc is used for selected segments of the data and the invention requires only the retention of numerical values for the coefficients a, b, and c for each data segment. The coefficient values are stored in the probe and used either by the probe or the readout to construct calibrated data in volts per meter (V/m).