Signal and noise measurement techniques using magnetic field probes

Magnetic loops have long been used by EMC personnel to "sniff" out sources of emissions in circuits and equipment. Additional uses of such probes are presented here that can be very useful to both EMC personnel and circuit designers. Methods are shown for measuring crosstalk and inductive voltage drop along conductors, trace current paths on conducting planes, measure currents, and inject precisely controlled amounts of noise into a circuit. Data is presented in this paper to illustrate usage of some of these methods.