Cloud observations are of significant importance in the study of long-term climatic trends. These observations require high-resolution radars at 94GHz. We have developed a compact multichip module ...(MCM) 94GHz radar receiver and the state of the art InP MMICs to construct it. The LNA MMIC determined the noise figure of the receiver, 3dB, and conversion gain of 17dB. This LNA MMIC was complemented by a second harmonic mixer MMIC that had very low conversion loss of 9.5dB despite the operation at second harmonic frequency. The MCM receiver provided the system requirement of 2dB noise figure when cooled to 170K.
GeoSTAR Lambrigtsen, B; Gaier, T; Tanner, A ...
Eos (Washington, D.C.),
12/2006, Letnik:
87, Številka:
52
Magazine Article
The Geostationary Synthetic Thinned Aperture Radiometer, GeoSTAR, is a new concept for a microwave atmospheric sounder intended for geostationary satellites such as the GOES weather satellites ...operated by NOAA. A small but fully functional prototype has recently been developed at the Jet Propulsion Laboratory to demonstrate the feasibility of using aperture synthesis in lieu of the large solid parabolic dish antenna that is required with the conventional approach. Spatial resolution requirements dictate such a large aperture in GEO that the conventional approach has not been feasible, and it is only now i? with the GeoSTAR approach i? that a GEO microwave sounder can be contemplated. Others have proposed GEO microwave radiometers that would operate at sub-millimeter wavelengths to circumvent the large-aperture problem, but GeoSTAR is the only viable approach that can provide full sounding capabilities equal to or exceeding those of the AMSU systems now operating on LEO weather satellites and which have had tremendous impact on numerical weather forecasting. GeoSTAR will satisfy a number of important measurement objectives, many of them identified by NOAA as unmet needs in their GOES-R pre-planned product improvements (P3I) lists and others by NASA in their research roadmaps and as discussed in a white paper submitted to the NRC Decadal Survey. The performance of the prototype has been outstanding, and this proof of concept represents a major breakthrough in remote sensing capabilities. The GeoSTAR concept is now at a stage of development where an infusion into space systems can be initiated i? either on a NASA sponsored research mission or on a NOAA sponsored operational mission. GeoSTAR is an ideal candidate for a joint i?research to operationsi? mission, and that may be the most likely scenario. Additional GeoSTAR related technology development and other risk reduction activities are under way, and a GeoSTAR mission is feasible in the GOES-R/S time frame, 2014-2016. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.
Proc 3rd ESA Workshop on millimetre wave technology and
applications (ESPOO, 21-23 May 2003), Page 69 The LFI (Low Frequency Instrument) on board the ESA Planck satellite is
constituted by an array ...of radiometric detectors actively cooled at 20 K in the
30-70 GHz frequency range in the focal plane of the Planck telescope. In this
paper we present an overview of the LFI instrument, with a particular focus on
the radiometer design. The adopted pseudo-correlation scheme uses a software
balancing technique (with a tunable parameter called gain modulation factor)
which is effective in reducing the radiometer susceptibility to amplifier
instabilities also in presence of small non-idealities in the radiometric chain
components, provided that the gain modulation factor is estimated with an
accuracy of the order of 0.2%. These results have been recently confirmed by
experimental laboratory measurements conducted on the LFI prototype radiometers
at 30, 70 and 100 GHz.
The LFI (Low Frequency Instrument) on board the ESA Planck satellite is constituted by an array of radiometric detectors actively cooled at 20 K in the 30-70 GHz frequency range in the focal plane of ...the Planck telescope. In this paper we present an overview of the LFI instrument, with a particular focus on the radiometer design. The adopted pseudo-correlation scheme uses a software balancing technique (with a tunable parameter called gain modulation factor) which is effective in reducing the radiometer susceptibility to amplifier instabilities also in presence of small non-idealities in the radiometric chain components, provided that the gain modulation factor is estimated with an accuracy of the order of 0.2%. These results have been recently confirmed by experimental laboratory measurements conducted on the LFI prototype radiometers at 30, 70 and 100 GHz.
Low-Noise Amplifier for 100 to 180 GHz Kangaslahti, P; Pukala, D; Fung, K M ...
NASA Tech Briefs,
08/2009, Letnik:
33, Številka:
8
Magazine Article, Trade Publication Article
A three-stage monolithic millimeter-wave integrated-circuit (MMIC) amplifier designed to exhibit low noise in operation at frequencies from about 100 to somewhat above 180 GHz has been built and ...tested. This is a prototype of broadband amplifiers that have potential utility indiverse applications, including measurement of atmospheric temperature and humidity and millimeter-wave imaging for inspecting contents of opaque containers.
Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and ...the highest efficiency for class-A operation in W-band (75-110 GHz).
New circuits have been designed and fabricated with operating frequencies over 325 GHz. In order to measure S-parameters of these circuits, an extensive process of wafer dicing and packaging, and ...waveguide transition design, fabrication, and packaging would be required. This is a costly and time-consuming process before the circuit can be tested in waveguide. The new probes and calibration procedures will simplify the testing process.
Future remote sensing instruments will require focal plane spectrometer arrays with higher resolution at high frequencies. One of the major components of spectrometers are the local oscillator (LO) ...signal sources that are used to drive mixers to down-convert received radio-frequency (RF) signals to intermediate frequencies (IFs) for analysis. By advancing LO technology through increasing output power and efficiency, and reducing component size, these advances will improve performance and simplify architecture of spectrometer array systems. W-band power amplifiers (PAs) are an essential element of current frequency-multiplied submillimeter-wave LO signal sources. Substantial W-band (75-110 GHz) power is required due to the lossy passive frequency multipliers used to generate higher frequency signals in nonlinear Schottky diode based LO sources. By advancing PA technology, the LO system performance can be increased with possible cost reductions compared to current gallium arsenide (GaAs) PA technology.
For humidity and temperature sounding of Earth's atmosphere, a single-antenna/LNA (low-noise amplifier) is needed in place of two separate antennas for the two frequency bands. This results in ...significant mass and power savings for GeoSTAR that is comprised of hundreds of antennas per frequency channel. Furthermore, spatial anti-aliasing would reduce the number of horns. An anti-aliasing horn antenna will enable focusing the instrument field of view to the "hurricane corridor" by reducing spatial aliasing, and thus reduce the number of required horns by up to 50 percent.
A single-pixel prototype of a W-band detector module with a digital back-end was developed to serve as a building block for large focal-plane arrays of monolithic millimeter-wave integrated circuit ...(MMIC) detectors. The module uses low-noise amplifiers, diode-based mixers, and a WR10 waveguide input with a coaxial local oscillator. State-of-the-art InP HEMT (high electron mobility transistor) MMIC amplifiers at the front end provide approximately 40 dB of gain. The measured noise temperature of the module, at an ambient temperature of 300 K, was found to be as low as 450 K at 95 GHz.
