Special Coverage

Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines

Crossed, Small-Deflection Energy Analyzer for Wind/Temperature Spectrometer

This analyzer has application in improving the predictability of GPS operations.

Determination of neutral winds and ion drifts in low-Earth-orbit missions requires measurements of the angular and energy distributions of the flux of neutrals and ions entering the satellite from the ram direction. The magnitude and direction of the neutral-wind (or ion-drift) determine the location of the maximum in the angular distribution of the flux. Knowledge of the angle of maximum flux with respect to satellite coordinates (pointing) is essential to determine the wind (or ion-drift) vector.

Posted in: Briefs, Physical Sciences, Spectroscopy, Spectroscopy, Satellites

Three Methods of Detection of Hydrazines

Concentrations could be measured more accurately than in prior methods.

Three proposed methods for measuring trace quantities of hydrazines involve ionization and detection of hydrazine derivatives. These methods are intended to overcome the limitations of prior hydrazine-detection methods.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Hydrazines, Test equipment and instrumentation, Test procedures

Cryogenic Moisture Apparatus

Testing for moisture uptake in materials can be performed under standardized cryogenic conditions.

The Cryogenic Moisture Apparatus (CMA) is designed for quantifying the amount of moisture from the surrounding air that is taken up by cryogenic-tank-insulating material specimens while under typical conditions of use. More specifically, the CMA holds one face of the specimen at a desired low temperature (e.g., the typical liquid-nitrogen temperature of 77 K) while the opposite face remains exposed to humid air at ambient or near-ambient temperature. The specimen is weighed before and after exposure in the CMA. The difference between the “after” and “before” weights is determined to be the weight of moisture absorbed by the specimen.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Humidity, Containers, Insulation, Materials properties

A Transportable Gravity Gradiometer Based on Atom Interferometr y

Gravity field mapping technology enables more detailed study of dynamic Earth processes like climate change.

A transportable atom interferometer-based gravity gradiometer has been developed at JPL to carry out measurements of Earth’s gravity field at ever finer spatial resolutions, and to facilitate high-resolution monitoring of temporal variations in the gravity field from ground- and flight-based platforms. Existing satellite-based gravity missions such as CHAMP and GRACE measure the gravity field via precise monitoring of the motion of the satellites; i.e. the satellites themselves function as test masses. JPL’s quantum gravity gradiometer employs a quantum phase measurement technique, similar to that employed in atomic clocks, made possible by recent advances in laser cooling and manipulation of atoms. This measurement technique is based on atom-wave interferometry, and individual laser-cooled atoms are used as drag-free test masses.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Test equipment and instrumentation, Satellites

Instrument for Analysis of Greenland’s Glacier Mills

A new instrument is used to study the inner workings of Greenland’s glacier mills by riding the currents inside a glacier’s moulin. The West Greenland Moulin Explorer instrument was deployed into a tubular shaft to autonomously record temperature, pressure, 3D acceleration, and location. It is built with a slightly positive buoyancy in order to assist in recovery.

The unit is made up of several components. A 3-axis MEMS (microelectromechanical systems) accelerometer with 0.001-g resolution forms the base of the unit. A pressure transducer is added that is capable of withstanding 500 psi (≈3.4 MPa), and surviving down to –40 °C. An Iridium modem sends out data every 10 minutes. The location is traced by a GPS (Global Positioning System) unit. This GPS unit is also used for recovery after the mission. Power is provided by a high-capacity lithium thionyl chloride D-sized battery. The accelerometer is housed inside a cylindrical, foot-long (≈30 cm) polyvinyl chloride (PVC) shell sealed at each end with acrylic. The pressure transducer is attached to one of these lids and a MEMS accelerometer to the other, recording 100 samples per second per axis.

This work was done by Alberto E. Behar, Jaret B. Matthews, and Hung B. Tran of the Jet Propulsion Laboratory; Konrad Steffen, Dan McGrath, and Thomas Phillips of the University of Colorado Boulder; and summer students Andrew Elliot, Sean O’Hern, Colin Lutz, Sujita Martin, and Henry Wang for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category. NPO-46514

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Analysis methodologies, Microelectricmechanical device, Microelectromechanical devices, Microelectricmechanical device, Microelectromechanical devices, Water, Weather and climate, Test equipment and instrumentation

Wavefront Correction for Large, Flexible Antenna Reflector

A wavefront-correction system has been proposed as part of an outer-space radio communication system that would include a large, somewhat flexible main reflector antenna, a smaller subreflector antenna, and a small array feed at the focal plane of these two reflector antennas. Part of the wave-front-correction system would reside in the subreflector, which would be a planar patch-element reflectarray antenna in which the phase shifts of the patch antenna elements would be controlled via microelectromechanical systems (MEMS) radio-frequency (RF) switches. The system would include the following sensing-and-computing subsystems:

Posted in: Briefs, TSP, Electronics & Computers, Antennas, Architecture, Microelectricmechanical device, Microelectromechanical devices, Wireless communication systems, Antennas, Architecture, Microelectricmechanical device, Microelectromechanical devices, Wireless communication systems, Spacecraft

Novel Microstrip-to-Waveguide Feed Employing a Double-Y Junction

This feed is useful for low-cost measurements involving waveguides up to X-band.

Previous microstrip-to-waveguide transitions either required a hermetically sealed waveguide configuration, or a balun that needed to be tuned according to the frequency band of interest. In this design, the balun is realized using a double-Y junction to transition from microstrip to coplanar strip feeding a quasi-Yagi dipole array (see figure). The length of the feed (Lf) extending into the waveguide is 15.54 mm. The length of the ground plane below the ULTRALAM substrate is 7.75 mm. The lengths L1, L2, and L3 are 8.50 mm, 4.38 mm, and 2.14 mm, respectively. These lengths were computed via a preliminary optimization aimed at improving the return loss at the band edges.

Posted in: Briefs, TSP, Electronics & Computers, Optimization, Waveguides, Waveguides

Thin-Film Ferroelectric-Coupled Microstripline Phase Shifters With Reduced Device Hysteresis

These are useful for electronically steerable ferroelectric reflectarray antennas.

This work deals with the performance of coupled microstripline phase shifters (CMPS) fabricated using BaxSr1-xTiO3 (BST) ferroelectric thin films. The CMPS were fabricated using commercially available pulsed laser deposition BST films with Ba:Sr ratios of 30:70 and 20:80. Microwave characterization of these CMPS was performed at upper Ku-band frequencies, particularly at frequencies near 16 and 18 GHz. X-ray diffraction studies indicate that the 30:70 films exhibit almost a 1:1 ratio between the in-plane and out-of-plane lattice parameters, suggesting that their cubics create strain-free films suitable for producing CMPS devices with reduced hysteresis in the paraelectric state.

Posted in: Briefs, TSP, Electronics & Computers, Antennas, Lasers, Antennas, Lasers, Fabrication, Ferrous metals and alloys, Performance tests

Two-Stage, 90-GHz, Low-Noise Amplifier

A device has been developed for coherent detection of the polarization of the cosmic microwave background (CMB). A two-stage amplifier has been designed that covers 75–110 GHz. The device uses the emerging 35-nm InP HEMT technology recently developed at Northrop Grumman Corporation primarily for use at higher frequencies. The amplifier has more than 18 dB gain and less than 35 K noise figure across the band.

Posted in: Briefs, TSP, Electronics & Computers, Amplifiers, Integrated circuits, Amplifiers, Integrated circuits

A 311-GHz Fundamental Oscillator Using InP HBT Technology

This is the first fundamental HBT oscillator operating above 300 GHz.

This oscillator uses a single-emitter 0.3-μm InP heterojunction bipolar transistor (HBT) device with maximum frequency of oscillation (fmax) greater than 500 GHz. Due to high conductor and substrate losses at submillimeter-wave frequencies, a primary challenge is to efficiently use the intrinsic device gain. This was done by using a suitable transmission-line media and circuit topology. The passive components of the oscillator are realized in a two-metal process with benzocyclobutene (BCB) used as the primary transmission line dielectric. The circuit was designed using microstrip transmission lines.

Posted in: Briefs, TSP, Electronics & Computers, Architecture, Integrated circuits, Transistors, Architecture, Integrated circuits, Transistors

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