Electromechanical parametric amplifier for measurement of electric fields

摘要

The disclosed device is an electromechanical parametric amplifier. It utilizes, as the required nonlinear mixing element, the square law force of an electric field on the surface of a conductor. In an exemplary device, a wire grid (10) is placed adjacent to a conducting diaphragm (11) . The diaphragm (11) is mechanically resonant at the local oscillator (LO) frequency. When a signal from the local oscillator (15) is applied to the grid (10), the diaphragm (11) experiences both the electrostatic force from the grid (10) and electrostatic force from the electric field to be measured. The amplitude of the vibration of the diaphragm (11) at the LO frequency is a measure of the electric field of interest. In an exemplary embodiment the vibration was measured by an electret microphone (12) and a lock-in amplifier (14). The measurement of electric field is important, for example, in industrial environments in which the buildup of static electricity is a problem.