This Phase I STTR proposal describes the development of a dual frequency millimeter-wave sun tracking radiometer designed to measure total atmospheric attenuation from ground level to the top of the atmosphere.The suns brightness temperature, which is on the order of 10,000K at millimeter-wavelengths, provides an ideal background reference allowing high dynamic range estimation of total atmospheric attenuation.By combining a narrow beam antenna with a compact radiometer mounted on a sun tracking pedestal, the proposed instrument will be able to measure total path attenuation with over 30 dB dynamic range. During Phase I, we will develop a detailed design of the sun tracking radiometer, resulting in detailed specification for the antenna, radiometer, sun tracking pedestal, and external in situ sensors.
