Abstract

In this work, we describe the design, development and status of implementation of a Water Vapor Radiometer (WVR) at 183 GHz. The architecture of the instrument is based on a pseudo-correlation radiometer with analog sideband separation and includes 1/f mitigation through phase-switching. The advantage of such type of receiver is that the result of the pseudo-correlation is directly proportional to the difference between the sky input and a known temperature load, avoiding the need for mechanical chopping or steering for calibration purposes. The improved sensitivity of the development comes from the use of non-commercial Monolithic Microwave Integrated Circuits (MMIC) chips instead of the typical Schottky diode mixers at the input. The heart of the development involves the use of G-band MMIC LNAs and mixers fabricated with 35nm gate InP-based High Electron Mobility Transistor (HEMT). Hence, the receiver noise temperature of the development will outperforms existing alternatives in the market. The instrument includes 12 independent frequency samples, or sub-bands, for PWV spectrum fitting, and we forecast sensitivity per sub-band of 170 mK, at an output instrument rate of 1 Hz.