Imaging Microwave Electric Fields Using a Near-Field Scanning Microwave Microscope

TL;DR

This paper demonstrates a near-field scanning microwave microscope capable of imaging local electric fields at microwave frequencies with high spatial resolution, providing detailed insights into microwave device behavior.

Contribution

It introduces a method for imaging microwave electric fields using a fine coaxial probe and a simple interpretive model, enabling detailed field component visualization.

Findings

Achieved ~200 μm spatial resolution in electric field imaging.

Successfully imaged electric field components above a copper microstrip at 8 GHz.

Demonstrated the probe's sensitivity to the electric flux normal to its face.

Abstract

By scanning a fine open-ended coaxial probe above an operating microwave device, we image local electric fields generated by the device at microwave frequencies. The probe is sensitive to the electric flux normal to the face of its center conductor, allowing different components of the field to be imaged by orienting the probe appropriately. Using a simple model of the microscope, we are able to interpret the system's output and determine the magnitude of the electric field at the probe tip. We show images of electric field components above a copper microstrip transmission line driven at 8 GHz, with a spatial resolution of approximately 200 $\mu$m.