Search NASA⌕ Search

SEARCH · Search NASA

Results for “GHz”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

A search for the rotational transitions of H2D+ at 1370 GHz and H3O+ at 985 GHz

A search was made for the 1370 GHz lowest rotational transition of the molecular ion H2D+ in NGC 2264, W3, and the IRc2 region of M42. No emission lines were seen, but an absorption feature was detected toward IRc2. The column density and fractional abundance were calculated using a tentative identification of the line as the transition of para H2D+. The LSR velocity and the measured line width are consistent with the dynamical parameters of the hot core source. Physical parameters deduced from the data differ from those derived from millimeter-wave observations of the hot core condensation. It is suggested that significant amounts of low-density gas are associated with this region and that the material is cold enough for enhanced deuterium fractionation to occur. A search was also made for the 985 GHz transition of ortho H3O+ in W3 and IRc2 with negative results.

Boreiko, R. T.↗
NASA NTRS1992

Water vapor profiling over ocean surface with 90 GHz and 183 GHz measurements under clear and cloudy conditions

Radiometric measurements at 90 GHz and three sideband frequencies near the peak water vapor absorption line of 183.3 GHz were made with the Advanced Microwave Moisture Sounder (AMMS) aboard the NASA DC-8 aircraft over some regions of the Pacific Ocean. These measurements were used to retrieve atmospheric water vapor profiles over ocean surface using the algorithm developed by Schaerer and Wilheit (1979). The algorithm incorporates a mechanism to estimate cloud liquid water when the estimated relative humidity is greater than 95 percent. The results are compared with estimated values from measurements taken by the Special Sensor Microwave/Imager (SSMI) and TIROS Operational Vertical Sounder (TOVS). The water vapor profiles estimated from AMMS are generally higher at low altitudes and lower at high altitudes than those from the TOVS measurements. Cloud liquid water is retrieved from both AMMS and SSM/I measurements over the same general regions. The retrieved water vapor profiles show more fluctuations in these regions. It is concluded that the AMMS with only four channels of measurements may not be able to retrieve both water vapor and cloud information with authority.

Wang, J. R.↗
NASA NTRS1996

Natural Radio Source and Spacecraft Signal Measurements at Ka-Band (32.0 GHz) and X-Band (8.4 GHz) Using a 34-Meter Beam-Waveguide Antenna

From Intro.: NASA'a Deep Space Network (DSN) Technology Program at the Jet Propulsion Laboratory (JPL) is evaluating the use of the Ka-Band frequency allocation band (31.8 GHz to 32.3 GHz) for deep space to Earth telecommunications...This paper addresses the three current Ka-Band and X-Band activities, 1)KaAp, 2)SURSAT-1, and 3)KaBLE-II's upcoming Ka-Band experiments aboard Mars Global Surveyor.

Deep Space Network DSN Ka-Band Ka frequency↗
NASA NTRS2004

Use of the 37-38 GHz and 40-40.5 GHz Ka-bands for Deep Space Communications

This paper covers a wide variety of issues associated with the implementation and use of these frequency bands for deep space communications. Performance issues, such as ground station pointing stability, ground antenna gain, antenna pattern, and propagation effects such as due to atmospheric, charged-particle and space loss at 37 GHz, will be addressed in comparison to the 32 GHz Ka-band deep space allocation. Issues with the use of and competition for this spectrum also will be covered. The state of the hardware developed (or proposed) for operating in this frequency band will be covered from the standpoint of the prospects for achieving higher data rates that could be accommodated in the available bandwidth. Hardware areas to be explored include modulators, digital-to-analog converters, filters, power amplifiers, receivers, and antennas. The potential users of the frequency band will be explored as well as their anticipated methods to achieve the potential high data rates and the implications of the competition for bandwidth.

telecommunications↗
NASA NTRS1992

Modeling, design, fabrication, and testing of InP Gunn devices in the D-band (110 GHz - 170 GHz)

The development of fundamental Gunn sources for D-band frequencies requires improvements of doping profiles, processing technology, and circuit design. We have developed a technology for fabricating InP Gunn diodes using an InGaAs etch-stop layer between the InP substrate and the device layers. The epitaxial layers were grown by CBE. During device processing, the substrate is completely removed. Substrateless devices with an n(+) InGaAs cap layer are expected to have reduced contact and series resistances, and skin effect losses. This technology gives better uniformity and control of the device geometry across the processed chip. InP Gunn devices with a 1.7 micron long active region (doping : 9 x 10(exp 15) cm(exp -3)) have been mounted on copper heat sinks. Two tapered leads were then bonded to the diode and to four quartz standoffs. As a preliminary result, an output power of 13 mW at 82 GHz was obtained. Based on these RF measurements, we determine appropriate material parameters to be used in the Ensemble Monte Carlo model. Subsequently, we use this model to design and evaluate the performance of InP Gunn Devices for D-band frequencies. Using the same technology, we are currently processing Gunn devices with a 1 micron long active region for operation at higher frequencies.

Kamoua, R.↗
NASA NTRS2014

670 GHz Schottky Diode Based Subharmonic Mixer with CPW Circuits and 70 GHz IF

A coplanar waveguide (CPW) based subharmonic mixer working at 670 GHz using GaAs Schottky diodes. One example of the mixer has a LO input, an RF input and an IF output. Another possible mixer has a LO input, and IF input and an RF output. Each input or output is connected to a coplanar waveguide with a matching network. A pair of antiparallel diodes provides a signal at twice the LO frequency, which is then mixed with a second signal to provide signals having sum and difference frequencies. The output signal of interest is received after passing through a bandpass filter tuned to the frequency range of interest.

Chattopadhyay, Goutam↗
NASA NTRS1988

Polarization of microwave noise source radiation in the 30 GHz to 300 GHz range

Radiation spectra have been obtained in order to calculate the frequency bandwidth and polarization of three microwave noise sources. Results were obtained in the 1-10-mm wavelength region using a lamellar grating Fourier transform spectrometer and a helium-cooled bolometer detector. A secondary transmission region was found to have an input current as well as a polarization dependence, despite the directional output of the waveguide antenna.

Poutous, M. K.↗
NASA NTRS1994

An SIS Waveguide heterodyne Reciever for 600 GHz - 635 GHz

A waveguide SIS heterodyne receiver using a Nb/A10xNb junction has been built for astronomical observations of molecular tranitions in the frequency range 600GHz - 635GHZ, and has been successfully used at the Caltech Submillimeter Observatory (CSO).

SIS heterodyne receiver molecular transitions↗