Measurement of electric-field intensities using scanning near-field microwave microscopy

In this paper, we propose methods for the measurement of electric intensities of a microwave field above the surface of microwave circuits. Using miniaturized coaxial antennas, we measure all spatial components of the induced field above device-under-test. A special position/signal difference method is used to better localize the measured field and increase the spatial resolution of the field mapping. During the scanning process, the antenna is driven at the defined distance above the sample surface according to previously acquired topographic data. For measurement of the tangential-field components parallel to the sample surface, the antenna is tilted by approximately 45° relative to the sample surface. By its rotation about the vertical axis, various components of the field are measured, and vertical and horizontal electric-field intensities are recalculated. The probes are calibrated in a well-defined field standard and allow good quantitative characterization of the measured field.