Comparison between incoherent and coherent measurements

Several laboratories have demonstrated the superiority of coherent measurements for EMI/EMC (electromagnetic interference/compatibility) test and evaluation over conventional incoherent methods. The author presents an overview of these two methods. After discussing the conventional method and its shortcomings, he describes the advanced coherent method based on the network analyzer and lists its advantages over the conventional method. Beside its distinct advantages, the coherent method is shown to have a much higher integrity and wider dynamic range in tests. Finally, an example is given to compare these two methods