Abstract: A system for probing a circuit is disclosed. In particular, a system for monitoring power levels close to the tip of a measurement probe in order to more accurately monitor the power applied to a circuit is contemplated. Microwave and millimeter wave signals are monitored through the use of a directional coupler which is mounted proximate the probe tip of a measurement probe. Power delivered to the probe tip is then detected by a signal created in the directional coupler. Connected to the directional coupler is a diode. The voltage across the diode is monitored and is indicative of the power delivered to the probe tip. A control signal resulting from the diode voltage may provide feedback control to a power source which delivers power to the measurement probe. Thus, utilizing feedback control a more accurate power delivery system is provided.