Title: Miniaturized Receivers for Temperature and Humidity Sounding
Presenting Author: Pekka Kangaslahti
Organization: Jet Propulsion Laboratory
Co-Author(s): Steven Reising

Abstract:
Weather forecasting, hurricane science and a range of atmospheric science depend on temperature and humidity sounding of atmosphere. Current microwave instruments provide these measurements in all-weather conditions from ground based, airborne and LEO satellites by measuring radiometric temperature on the flanks of the 183 GHz water vapor line and the 60 or 118 GHz oxygen line. We have developed miniature low noise receivers that will enable these measurements from a geostationary thinned array sounder that operates as an interferometer. This geostationary instrument is based on hundreds of low noise receivers that convert the millimeter wave signal directly to baseband in-phase (I) and in-quadrature (Q) signals for digitization and correlation. The developed receivers provided a noise temperature of 350 to 450 K and had a mass of 3 g while consuming 24 mW of power. These are the most sensitive broadband I-Q receivers at these frequencies that operate at room temperature, and are significantly lower in mass and power consumption than previously reported receivers. Further benefit is the low LO power requirement of 0 to +3 dBm, an important feature for large arrays providing significant DC power savings. These DC power savings are achieved from the reduced number of LO driver amplifiers needed. Currently we are in the process of assembling and testing hundreds of these receivers to demonstrate scalability of the receiver system. The receivers developed so far were demonstrated as an interferometer in laboratory tests and outdoor measurements of sun overpasses. Furthermore, we integrated the receivers into an airborne radiometer system, HAMMR.