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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.

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At least 55 records · Page 3

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NASA NTRS2014

Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

This paper presents the design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37 to 43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

Simons, Rainee N.↗

NASA NTRS2014

Scalable Background-Limited Polarization-Sensitive Detectors for mm-wave Applications

We report on the status and development of polarization-sensitive detectors for millimeter-wave applications. The detectors are fabricated on single-crystal silicon, which functions as a low-loss dielectric substrate for the microwave circuitry as well as the supporting membrane for the Transition-Edge Sensor (TES) bolometers. The orthomode transducer (OMT) is realized as a symmetric structure and on-chip filters are employed to define the detection bandwidth. A hybridized integrated enclosure reduces the high-frequency THz mode set that can couple to the TES bolometers. An implementation of the detector architecture at Q-band achieves 90% efficiency in each polarization. The design is scalable in both frequency coverage, 30-300 GHz, and in number of detectors with uniform characteristics. Hence, the detectors are desirable for ground-based or space-borne instruments that require large arrays of efficient background-limited cryogenic detectors.

Millimeter-Wave Detectors↗

NASA NTRS2014

Design of a K/Q-Band Beacon Receiver for the Alphasat Technology Demonstration Payload (TDP) #5 Experiment

This paper describes the design and performance of a coherent KQ-band (2040 GHz) beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed at the Politecnico di Milano (POLIMI) for use in the Alphasat Technology Demonstration Payload 5 (TDP5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40 GHz to improve the performance of existing statistical rain attenuation models in the Q-band. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation. The receiver system has been characterized in the lab and demonstrates a system dynamic range performance of better than 58 dB at 1 Hz and better than 48 dB at 10 Hz rates.

rain fade↗

NASA NTRS2014

Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

The design and test results of a novel waveguide multimode directional coupler for a CW millimeter-wave satellite beacon source are presented. The coupler separates the second harmonic power from the fundamental output power of a traveling-wave tube amplifier. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37 to 42 GHz) and VW-band (71 to 76 GHz) satellite-to-ground signals.

Telecommunications↗

NASA NTRS2014

Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

Satellite Communications↗

NASA NTRS2014

Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

This paper presents the design and test results of a CW millimeter-wave satellite beacon source, based on the second harmonic from a traveling-wave tube amplifier and utilizes a novel waveguide multimode directional coupler. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37-42 GHz) and V/W-band (71- 76 GHz) satellite-to-ground signals.

Simons, Rainee N.↗

NASA NTRS2014

Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

This paper presents the design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37-43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

Simons, Rainee N.↗

NASA NTRS2014

Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

The design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator is presented. The intended applications of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37 to 43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

Satellite Communications↗

NASA NTRS2014

Design of a K/Q-Band Beacon Receiver for the Alphasat TDP#5 Experiment

beacon receiver↗

NASA NTRS2016

Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

Antenna↗

NASA NTRS2016

Statistical Analysis of Instantaneous Frequency Scaling Factor as Derived From Optical Disdrometer Measurements At KQ Bands

The rain rate data and statistics of a location are often used in conjunction with models to predict rain attenuation. However, the true attenuation is a function not only of rain rate, but also of the drop size distribution (DSD). Generally, models utilize an average drop size distribution (Laws and Parsons or Marshall and Palmer [1]). However, individual rain events may deviate from these models significantly if their DSD is not well approximated by the average. Therefore, characterizing the relationship between the DSD and attenuation is valuable in improving modeled predictions of rain attenuation statistics. The DSD may also be used to derive the instantaneous frequency scaling factor and thus validate frequency scaling models. Since June of 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have jointly conducted a propagation study in Milan, Italy utilizing the 20 and 40 GHz beacon signals of the Alphasat TDP#5 Aldo Paraboni payload. The Ka- and Q-band beacon receivers provide a direct measurement of the signal attenuation while concurrent weather instrumentation provides measurements of the atmospheric conditions at the receiver. Among these instruments is a Thies Clima Laser Precipitation Monitor (optical disdrometer) which yields droplet size distributions (DSD); this DSD information can be used to derive a scaling factor that scales the measured 20 GHz data to expected 40 GHz attenuation. Given the capability to both predict and directly observe 40 GHz attenuation, this site is uniquely situated to assess and characterize such predictions. Previous work using this data has examined the relationship between the measured drop-size distribution and the measured attenuation of the link [2]. The focus of this paper now turns to a deeper analysis of the scaling factor, including the prediction error as a function of attenuation level, correlation between the scaling factor and the rain rate, and the temporal variability of the drop size distribution both within a given rain event and across different varieties of rain events. Index Terms-drop size distribution, frequency scaling, propagation losses, radiowave propagation.

Radio Attenuation↗

NASA NTRS2016

Statistical Analysis of Instantaneous Frequency Scaling Factor as Derived From Optical Disdrometer Measurements At KQ Bands

The rain rate data and statistics of a location are often used in conjunction with models to predict rain attenuation. However, the true attenuation is a function not only of rain rate, but also of the drop size distribution (DSD). Generally, models utilize an average drop size distribution (Laws and Parsons or Marshall and Palmer. However, individual rain events may deviate from these models significantly if their DSD is not well approximated by the average. Therefore, characterizing the relationship between the DSD and attenuation is valuable in improving modeled predictions of rain attenuation statistics. The DSD may also be used to derive the instantaneous frequency scaling factor and thus validate frequency scaling models. Since June of 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have jointly conducted a propagation study in Milan, Italy utilizing the 20 and 40 GHz beacon signals of the Alphasat TDP#5 Aldo Paraboni payload. The Ka- and Q-band beacon receivers provide a direct measurement of the signal attenuation while concurrent weather instrumentation provides measurements of the atmospheric conditions at the receiver. Among these instruments is a Thies Clima Laser Precipitation Monitor (optical disdrometer) which yields droplet size distributions (DSD); this DSD information can be used to derive a scaling factor that scales the measured 20 GHz data to expected 40 GHz attenuation. Given the capability to both predict and directly observe 40 GHz attenuation, this site is uniquely situated to assess and characterize such predictions. Previous work using this data has examined the relationship between the measured drop-size distribution and the measured attenuation of the link]. The focus of this paper now turns to a deeper analysis of the scaling factor, including the prediction error as a function of attenuation level, correlation between the scaling factor and the rain rate, and the temporal variability of the drop size distribution both within a given rain event and across different varieties of rain events. Index Terms-drop size distribution, frequency scaling, propagation losses, radiowave propagation.

Statistics↗

NASA NTRS2016

Impact of Scattering Model on Disdrometer Derived Attenuation Scaling

NASA Glenn Research Center (GRC), the Air Force Research Laboratory (AFRL), and the Politecnico di Milano (POLIMI) are currently entering the third year of a joint propagation study in Milan, Italy utilizing the 20 and 40 GHz beacons of the Alphasat TDP#5 Aldo Paraboni scientific payload. The Ka- and Q-band beacon receivers were installed at the POLIMI campus in June of 2014 and provide direct measurements of signal attenuation at each frequency. Collocated weather instrumentation provides concurrent measurement of atmospheric conditions at the receiver; included among these weather instruments is a Thies Clima Laser Precipitation Monitor (optical disdrometer) which records droplet size distributions (DSD) and droplet velocity distributions (DVD) during precipitation events. This information can be used to derive the specific attenuation at frequencies of interest and thereby scale measured attenuation data from one frequency to another. Given the ability to both predict the 40 gigahertz attenuation from the disdrometer and the 20 gigahertz time-series as well as to directly measure the 40 gigahertz attenuation with the beacon receiver, the Milan terminal is uniquely able to assess these scaling techniques and refine the methods used to infer attenuation from disdrometer data. In order to derive specific attenuation from the DSD, the forward scattering coefficient must be computed. In previous work, this has been done using the Mie scattering model, however, this assumes a spherical droplet shape. The primary goal of this analysis is to assess the impact of the scattering model and droplet shape on disdrometer-derived attenuation predictions by comparing the use of the Mie scattering model to the use of the T-matrix method, which does not assume a spherical droplet. In particular, this paper will investigate the impact of these two scattering approaches on the error of the resulting predictions as well as on the relationship between prediction error and rain rate.

Radio Transmission↗

NASA NTRS2017

Statistical Analysis of Instantaneous Frequency Scaling Factor as Derived from Optical Disdrometer Measurements at V/W Bands

Since October 2015, NASA Glenn Research Center (GRC) and the Air Force Research Laboratory (AFRL) have collaboratively operated an RF terrestrial link in Albuquerque, New Mexico to characterize atmospheric propagation phenomena at 72 and 84 GHz. The W/V-band Terrestrial Link Experiment (WTLE) consists of coherent transmitters at each frequency on the crest of the Sandia Mountains and a corresponding pair of receivers in south Albuquerque. The beacon receivers provide a direct measurement of the link attenuation, while concurrent weather instrumentation provides a measurement of the atmospheric conditions. Among the available weather instruments is an optical disdrometer which yields an optical measurement of rain rate, as well as droplet size and velocity distributions (DSD, DVD). In particular, the DSD can be used to derive an instantaneous scaling factor (ISF) by which the measured data at one frequency can be scaled to another - for example, scaling the 72 GHz to an expected 84 GHz timeseries. Given the availability of both the DSD prediction and the directly observed 84 GHz attenuation, WTLE is thus uniquely able assess DSD-derived instantaneous frequency scaling at the V/W-bands. Previous work along these lines has investigated the DSD-derived ISF at Ka and Q-band (20 GHz to 40 GHz) using a satellite beacon receiver experiment in Milan, Italy. This work will expand the investigation to terrestrial links in the V/W-bands, where the frequency scaling factor is lower and where the link is also much more sensitive to attenuation by rain, clouds, and other atmospheric effects.

Radio Transmission↗

NASA NTRS2016

Dust Temperatures and Opacities in the Central Parsec of the Galactic Center Modeled from Analysis of Multi-Wavelength Mid-Infrared Images

We have analyzed multi-wavelength mid-infrared images of the central parsec of the Galactic Center using a two-temperature line-of-sight (LOS) radiative transfer model at each pixel of the images, giving maps of temperatures, luminosities and opacities of the hot, warm, cold (dark)dust components. The data consists of images at nine wavelengths in the mid-infrared (N-band and Q-band) from the Thermal Region Camera and Spectrograph (T-ReCS) instrument operating at the Gemini South Observatory. The results of the LOS modeling indicate that the extinction optical depth is quite large and varies substantially over the FOV. The high-resolution images of the central parsec of the Galactic center region were obtained with T-ReCS at Gemini South in January 2004. These images provide nearly diffraction-limited resolution (approx. 0.5) of the central parsec. The T-ReCS images were taken with nine filters (3.8, 4.7, 7.7, 8.7, 9.7, 10.3, 12.3, 18.3 and 24.5m), over a field-of-view (FOV) of 20 x 20 arcsec.

Varosi, F.↗

NASA NTRS2016

Impact of Scattering Model on Disdrometer Derived Attenuation Scaling

NASA Glenn Research Center (GRC), the Air Force Research Laboratory (AFRL), and the Politecnico di Milano (POLIMI) are currently entering the third year of a joint propagation study in Milan, Italy utilizing the 20 and 40 GHz beacons of the Alphasat TDP5 Aldo Paraboni scientific payload. The Ka- and Q-band beacon receivers were installed at the POLIMI campus in June of 2014 and provide direct measurements of signal attenuation at each frequency. Collocated weather instrumentation provides concurrent measurement of atmospheric conditions at the receiver; included among these weather instruments is a Thies Clima Laser Precipitation Monitor (optical disdrometer) which records droplet size distributions (DSD) and droplet velocity distributions (DVD) during precipitation events. This information can be used to derive the specific attenuation at frequencies of interest and thereby scale measured attenuation data from one frequency to another. Given the ability to both predict the 40 GHz attenuation from the disdrometer and the 20 GHz timeseries as well as to directly measure the 40 GHz attenuation with the beacon receiver, the Milan terminal is uniquely able to assess these scaling techniques and refine the methods used to infer attenuation from disdrometer data.In order to derive specific attenuation from the DSD, the forward scattering coefficient must be computed. In previous work, this has been done using the Mie scattering model, however, this assumes a spherical droplet shape. The primary goal of this analysis is to assess the impact of the scattering model and droplet shape on disdrometer derived attenuation predictions by comparing the use of the Mie scattering model to the use of the T-matrix method, which does not assume a spherical droplet. In particular, this paper will investigate the impact of these two scattering approaches on the error of the resulting predictions as well as on the relationship between prediction error and rain rate.

statistics↗

NASA NTRS2017

Statistical Analysis of Instantaneous Frequency Scaling Factor as Derived from Optical Disdrometer Measurements at VW Bands

Since October 2015, NASA Glenn Research Center (GRC) and the Air Force Research Laboratory (AFRL) have collaboratively operated an RF terrestrial link in Albuquerque, New Mexico to characterize atmospheric propagation phenomena at 72 and 84 GHz. The WV-band Terrestrial Link Experiment (WTLE) consists of coherent transmitters at each frequency on the crest of the Sandia Mountains and a corresponding pair of receivers in south Albuquerque. The beacon receivers provide a direct measurement of the link attenuation, while concurrent weather instrumentation provides a measurement of the atmospheric conditions.Among the available weather instruments is an optical disdrometer which yields an optical measurement of rain rate, as well as droplet size and velocity distributions (DSD, DVD). In particular, the DSD can be used to derive an instantaneous scaling factor (ISF) by which the measured data at one frequency can be scaled to another for example, scaling the 72 GHz to an expected 84 GHz timeseries. Given the availability of both the DSD prediction and the directly observed 84 GHz attenuation, WTLE is thus uniquely able assess DSD-derived instantaneous frequency scaling at the VW-bands. Previous work along these lines has investigated the DSD-derived ISF at Ka and Q-band (20 GHz to 40 GHz) using a satellite beacon receiver experiment in Milan, Italy [1-3]. This work will expand the investigation to terrestrial links in the VW-bands, where the frequency scaling factor is lower and where the link is also much more sensitive to attenuation by rain, clouds, and other atmospheric effects.

Radio Attenuation↗

NASA NTRS2018

Three Years of Atmospheric Characterization at Ka/Q-band with the NASA/POLIMI Alphasat Receiver in Milan, Italy

Since June of 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have jointly conducted a propagation campaign within the framework of the Alphasat propagation experiment through a propagation terminal at the POLIMI campus in Milan, Italy. The terminal utilizes the 20 GHz and 40 GHz beacons broadcast by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and consists of dual coherent Ka- and Q-band beacon receivers. These provide a direct measurement of the signal attenuation and scintillation and are complemented by concurrent weather instrumentation that provides measurements of the atmospheric conditions at the receiver. The primary goal of these measurements is to improve model predictions of communication system performance at 40 GHz. Over three years of concurrent measurements have now been collected from the terminal, and herein we present a statistical analysis of the results thus far, as well as a summary of recent hardware upgrades to the receivers that were made in September 2017.

Radio Transmission↗