This proposal is responsive to NASA SBIR Subtopic S1.03: Technologies for Passive Microwave Remote Sensing; specifically, the item titled “Correlating radiometer front‐ends and low 1/f‐noise detectors for 100 – 700 GHz.” The focus is on low DC power radiometers for SmallSats and CubeSats and the use of the correlating receiver architecture to achieve useful system stability without the requirement for Dicke switching or noise-injection. These will be LNA based radiometers and the correlating technology will be used to attenuate the impact of gain instabilities in the amplifiers. Compact size and power efficiency are critical for the SmallSat form factor and VDI’s innovative receiver integration technology is critical for the success of this effort. As is the use of VDI’s technology for achieving optimal packaging of amplifiers, using microfabricated waveguide probes, in the frequency band of interest. The Phase I research includes the demonstration of two prototype correlating receivers: one using direct detection (LNA – RF Detector) and the other using a heterodyne receiver (LNA – Mixer – IF Detector). Also included is an investigation of 1/f noise in direct detectors in the 100 – 700 GHz range. The deliverables include the two correlating receiver systems.
The NASA applications include atmospheric temperature profiling, ice cloud sensing and detection of molecular species in planetary atmospheres. LNAs can improve the sensitivity and reduce the DC power requirements of atmospheric remote sensing instruments. But to realize these gains, a compact correlating radiometer technology is required. Present missions that could benefit from this technology include MIT’s NASA funded TROPICS program, GSFC’s ONR-670 GHz polarimeter project and TWICE.
There is an emerging market for SmallSat and CubeSat remote sensing technology. For example, the follow-on to TROPICs would require an annual launch of 6 – 8 complete CubeSats. Compact receivers with advanced functionality can also benefit imaging systems for portal security and aviation safety (inexpensive detection of icing conditions).