A non-contacting probe for measurements on high-frequency planar circuits

A novel magnetic-field probe for internal measurements on high-frequency planar circuits has been designed and tested. It requires no electrical contact with the circuit and has little or no effect on the circuit under test. Using this probe, circuit operation can be verified, and S-parameters of embedded passive and active components can be measured. Amplitudes and phases of currents at arbitrary positions can be measured. Using microfabrication techniques, working probes have been constructed for measurements in the 26.5-40.0-GHz band. Performance characteristics and typical measurements are described. Direct measurements obtained with these probes provide new information on internal circuit operation. The technique can be applied to rapid production testing.<>