SBIR-STTR Award

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. Potential NASA Applications (Limit 1500 characters, approximately 150 words) 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. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) 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).

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 100–700GHz.” The focus is on low DC power radiometers for Small/CubeSats and the use of correlating receivers to improve system stability without the requirement for Dicke switching or noise-injection. Both direct detection (DD) and heterodyne (Het) correlating radiometers are of interest to NASA. The Het systems are technically preferred because of the excellent frequency resolution. However, the DD systems, with appropriate filters, can often achieve the necessary resolution with even lower size, weight and power requirements. Thus, the choice between Het and DD systems is mission specific. Through the Phase II effort, VDI will develop and demonstrate both types of correlating radiometers at frequencies of highest interest to NASA for atmospheric research and weather monitoring, specifically 118 and 183 GHz. At the end of Phase II, VDI will have demonstrated a total of four radiometer systems. At 118GHz, VDI will demonstrate a single channel DD correlating radiometer and a deliverable Het correlating radiometer with broad available IF bandwidth. At 183GHz, VDI will demonstrate two DD radiometer systems, a single channel prototype and a four-channel deliverable system. All systems are expected to achieve excellent performance and the four-channel DD and heterodyne systems will be sufficiently compact for use on Small/CubeSat platforms. Throughout the effort, VDI will focus on the development of basic building blocks for radiometers, including 90-degree hybrids, 180-degree phase shifters, narrow band filters and low 1/f noise detector diodes. Each of the components will be demonstrated at 118 and 183 GHz, and the prospects for scaling to higher frequency will be evaluated, with an emphasis on determining how to extend operation throughout the 100–700GHz range. Potential NASA Applications (Limit 1500 characters, approximately 150 words): NASA applications include weather monitoring, atmospheric studies and investigations of planetary atmospheres. Correlating radiometers are known to improve performance over the more standard radiometers used in the present generation of Small/CubeSats such as TROPICS, TEMPEST-D, MiRaTa. However, they have not yet been implemented primarily due to the added complexity, which increases size, weight and power requirements. However, with increased system integration and advanced component design, these challenges can be alleviated. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): TEMPEST-D and TROPICS are technology demonstrators for future systems of many CubeSats offering global observations. The goal is to replace the billion-dollar satellites with a more versatile and affordable technology that can be cost-effectively updated on a routine basis. These CubeSats must be produced by industry, and the proposed research will foster that goal. Duration: 24