Large Area Millimeter Wave Dosimetry

A large area absorbing screen is proposed to measure the power density of millimeter wave signals. The screen has metalization that is 188ohms/square so that at least 50% of the incident millmeter wave power is absorbed by the screen. The power density that is absorbed by the screen is read via an infrared camera. It is expected that the time constant of the absorbing screen will be much faster than the previously used cabon loaded teflon screens so that near real time measurements can be carried out. Calibration of the power density as it relates to the infrared image is acomplished via a millimeter wave radiometer. The radiometer can calibrate both CW and pulsed sources. The absorbing screen is novel and is based upon work carried out on frequency selective surfaces. The approach achieves a wide bandwidth that extends from 26GHz to 100GHz. The sensitivity of the approach is anticpated to be better than 1mw per square centimeter.