A Prototype Quasi-Optical SIS Array Receiver
We report measurements on a prototype SIS array receiver consisting of a ten-element dipole antenna array with half square micron niobium SIS junctions.
SIS array antenna array mixer array SIS receiver w↗
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NASA Tech Briefs, March 2008
Topics covered include: WRATS Integrated Data Acquisition System; Breadboard Signal Processor for Arraying DSN Antennas; Digital Receiver Phase Meter; Split-Block Waveguide Polarization Twist for 220 to 325 GHz; Nano-Multiplication-Region Avalanche Photodiodes and Arrays; Tailored Asymmetry for Enhanced Coupling to WGM Resonators; Disabling CNT Electronic Devices by Use of Electron Beams; Conical Bearingless Motor/Generators; Integrated Force Method for Indeterminate Structures; Carbon-Nanotube-Based Electrodes for Biomedical Applications; Compact Directional Microwave Antenna for Localized Heating; Using Hyperspectral Imagery to Identify Turfgrass Stresses; Shaping Diffraction-Grating Grooves to Optimize Efficiency; Low-Light-Shift Cesium Fountain without Mechanical Shutters; Magnetic Compensation for Second-Order Doppler Shift in LITS; Nanostructures Exploit Hybrid-Polariton Resonances; Microfluidics, Chromatography, and Atomic-Force Microscopy; Model of Image Artifacts from Dust Particles; Pattern-Recognition System for Approaching a Known Target; Orchestrator Telemetry Processing Pipeline; Scheme for Quantum Computing Immune to Decoherence; Spin-Stabilized Microsatellites with Solar Concentrators; Phase Calibration of Antenna Arrays Aimed at Spacecraft; Ring Bus Architecture for a Solid-State Recorder; and Image Compression Algorithm Altered to Improve Stereo Ranging.
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NASA Tech Briefs, June 2003
Topics covered include: Nulling Infrared Radiometer for Measuring Temperature; The Ames Power Monitoring System; Hot Films on Ceramic Substrates for Measuring Skin Friction; Probe Without Moving Parts Measures Flow Angle; Detecting Conductive Liquid Leaking from Nonconductive Pipe; Adaptive Suppression of Noise in Voice Communications; High-Performance Solid-State W-Band Power Amplifiers; Microbatteries for Combinatorial Studies of Conventional Lithium-Ion Batteries; Correcting for Beam Aberrations in a Beam-Waveguide Antenna; Advanced Rainbow Solar Photovoltaic Arrays; Metal Side Reflectors for Trapping Light in QWIPs; Software for Collaborative Engineering of Launch Rockets; Software Assists in Extensive Environmental Auditing; Software Supports Distributed Operations via the Internet; Software Estimates Costs of Testing Rocket Engines; yourSky: Custom Sky-Image Mosaics via the Internet; Software for Managing Inventory of Flight Hardware; Lower-Conductivity Thermal-Barrier Coatings; Process for Smoothing an Si Substrate after Etching of SiO2; Flexible Composite-Material Pressure Vessel; Treatment to Destroy Chlorohydrocarbon Liquids in the Ground; Noncircular Cross Sections Could Enhance Mixing in Sprays; Small, Untethered, Mobile Roots for Inspecting Gas Pipes; Paint-Overspray Catcher; Preparation of Regular Specimens for Atom Probes; Inverse Tomo-Lithography for Making Microscopic 3D Parts; Predicting and Preventing Incipient Flameout in Combustors; MEMS-Based Piezoelectric/Electrostatic Inchworm Actuator; Metallized Capillaries as Probes for Raman Spectroscopy; Adaptation of Mesoscale Weather Models to Local Forecasting; Aerodynamic Design using Neural Networks; Combining Multiple Gyroscope Outputs for Increased Accuracy; and Improved Collision-Detection Method for Robotic Manipulator.
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Photonic Waveguide Choke Joint with Non-Absorptive Loading
A waveguide choke joint includes a first array of pillars positioned on a substrate, each pillar in the first array of pillars having a first size and configured to receive an input plane wave at a first end of the choke joint. The choke joint has a second end configured to transmit the input plane wave away from the choke joint. The choke joint further includes a second array of pillars positioned on the substrate between the first array of pillars and the second end of the choke joint. Each pillar in the second array of pillars has a second size. The choke joint also has a third array of pillars positioned on the substrate between the second array and the second end of the choke joint. Each pillar in the third array of pillars has a third size.
Wollack, Edward J.↗
Wavelength Control in Buried Heterostructure and Ridge Waveguide Lasers
High density wavelength division multiplexed (HD-WDM) systems place stringent requirements on the absolute wavelength and wavelength spacing of the elements in Distributed Feedback (DFB) laser arrays. An analysis of the fabrication tolerances for ridge waveguide and buried heterostructure DFB lasers is performed, showing the fabrication-induced wavelength variations present in these types of devices.
HD-WDM DFB distributed feedback laser arrays optic↗
Diffraction-Coupled, Phase-Locked Semiconductor Laser Array
Stable, narrow far field produced. Array of lasers fabricated on single chip. Individual laser waveguides isolated from each other except in end portions, where diffraction coupling takes place. Radiation pattern far from laser array has single, sharp central lobe when all lasers operate in phase with each other. Shape of lobe does not vary appreciably with array current. Applications include recording, printing, and range finding.
Katz, Joseph↗
Passive Element Shapes Antenna Radiation Pattern
Parasitic waveguide element suppresses ground-reflected multipath radiation. Small section of waveguide placed in front of phased-array antenna operating at 850 MHz modifies radiation field by reducing power density parallel to and below ground plane without significantly affecting primary radiation at angles greater than 20 degrees above horizontal. Acts as parasitic radiator that shifts phase of portion of wavefront by approximately 180 degrees, causing partial cancellation in ground plane, thereby reducing radiation intensity in that direction by about 10 dB. Produces corresponding reduction in multipath radiation scattered from ground. Waveguide technique also used to decouple two nearby antennas.
Bonebright, M. E.↗
Optical Backplane Interconnect Technology (OBIT)
We describe and analyze a novel approach to implementing an Optical Backplane Interconnect Technology (OBIT) that is capable of optically connecting any row of a 32x32 backplane array to any row of a second 32x32 array. Each backplane array is formed monolithically on a wafer. The technology is based on the use of Grating Surface Emitting (GSE) waveguides formed on a wafer containing quantum-well and separate confinement waveguide layers. These layers are used for transverse guiding, gain, modulation, detection, and for the formation of wavelength tunable distributed-Bragg reflector lasers. The required surface structures are formed photolithographically. The GSE waveguides act as efficient antennae that radiate light at angles selected by tuning the wavelength of the lasers. The same waveguides may be used as the receiving antennae when the array is used in the receiving mode. Thus, wavelength tuning is used to direct each row of the transmitting array to the desired row of the receiving array. In summary: The optical backplane array will have the following characteristics: Any row of a 32x32 GSE array may be optically connected to any row of a second 32x32 array. Only one switch decision is required to switch 32 parallel connections to any one of 32 positions. Each monolithic array can be used as both transmitter and receiver by switching the bias on the quantum-well switch-detectors. Separate transmitting and receiving structures could be provided for duplex operation. For a bit error rate of 10 sup 9 at 100-MHz data rate, a required laser power of 12 mW is calculated based on an estimated total optical loss of 40 dB.
Hammer, J. M.↗
Radial microstrip slotline feed network for circular mobile communications array
In mobile and satellite communications there is a need for low cost and low profile antennas which have a toroidal pattern. Antennas that have been developed for mobile communications include a L-Band electronically steered stripline phased array, a Ka-Band mechanically steered elliptical reflector antenna and a Ka-Band printed dipole. In addition, a L-Band mechanically steered microstrip array, a L-Band microstrip phased array tracking antenna for mounting on a car roof and an X-Band radial line slotted waveguide antenna have been demonstrated. In the above electronically scanned printed arrays, the individual element radiates normally to the plane of the array and hence require a phase shifter to scan the beam towards the horizon. Scanning in the azimuth is by mechanical or electronic steering. An alternate approach is to mount microstrip patch radiators on the surface of a cone to achieve the required elevation angle. The array then scans in the azimuth by beam switching.
Simons, Rainee N.↗
Recommendations Emerging from an Analysis of NASA's Deep Space Communications Capacity
During 2016-2017, NASA’s Space Communications and Navigation (SCaN) Office chartered a study of Deep Space Network (DSN) communications capacity relative to projected future-mission demand over the next 30 years. In this paper, we briefly describe the methodology used to analyze capacity vs. demand over such a broad timeframe, summarize key findings emerging from the analysis, and discuss the associated recommendations. Performing the analysis entailed: identifying key factors shaping the anticipated future mission set, identifying several alternative future mission set scenarios consistent with these factors, and then analyzing each mission set scenario in terms of required antenna capacity, downlink and uplink capabilities, and spectrum as a function of time. On the basis of these aggregate requirements, DSN loading simulations were then conducted that examined how well each of the postulated mission sets could load up onto the the DSN’s “in-plan” architecture. To the extent that capacity shortfalls emerged during these baseline simulations, architectural solutions to the shortfalls were then postulated and tested via additional simulations. In general, the trend analyses and baseline loading simulations indicated a significant progression in challenges over the next three decades. In the current decade, the DSN appeared to be operating very close to capacity. The first human exploration mission and its secondary payload launch opportunities for cubesats traveling beyond GEO contributed to this loading. As a consequence, the main challenge appeared to be managing peak assetcontention periods. In the next decade, the DSN continued to operate close to capacity but also began transitioning to more frequent human mission support. Upgrading for, and operating, a human-rated system while continuing to meet robotic mission customer requirements emerged as the key challenge. In the 2030’s and beyond, simulations suggested a need for fundamentally new capability and capacity. The high data rates and long link distances characteristic of human Mars exploration drove requirements far beyond what is currently “in plan.” The key challenge then became determining the most cost-effective combination of RF and optical assets for communicating with the postulated human Mars assets while still providing for the needs of all the other missions across the solar system. Various link budget, visibility, and loading analyses ultimately suggested that the human Mars exploration demands of the 2030’s could best be addressed with two cross-linked RF-optical areostationary relays (or an areostationary relay and deep space habitat) providing a dual “trunk link” to an array of 2-to-3 additional 34m beam waveguide antennas and an ~8.5m optical antenna at each DSN Complex. The dual “trunk link” would enable the same amount of total data return to Earth as a single trunk link at twice the data rate, but with only half the required array size on the ground, assuming use of Multiple Spacecraft Per Antenna (MSPA) techniques. MSPA techniques, including a Multiple Uplink Per Antenna (MUPA) technique currently under investigation, also showed promise for reducing asset contention in the decades prior to human Mars exploration.
Lee, Carlyn-Ann↗
Shaped Beam KU-Band Antenna Design
Antenna systems for a Ku-band synchronous orbit communications satellite were considered. A multiple beam offset feed cluster used in conjunction with an offset parabolic reflector was chosen for the antenna realization. For radiating elements in the feed array, polyrod or dielectric rod radiators fed by waveguide are investigated. Polyrod antennas shrink the cross section of the waveguide required, are fairly directive, and can be tapered to reduce sidelobes. As a consequence, it is thought that mutual coupling effects between adjacent elements will be minimal and the resultant physically small elements will allow greater packing densities for the drive elements in the feed array than would otherwise be possible.
Dudgeon, J. E.↗
Fundamental mode excitation via Joule–Thomson light expansion in nonlinear optical lattices
Under linear conditions, power injected from a single waveguide into a multi-core fiber array results in multimode propagation, progressively diminishing the spatial coherence of light. In this work, we introduce a comprehensive approach to mitigate this coherence loss by means of a nonlinear thermodynamic Joule–Thomson expansion. By leveraging the tools of optical thermodynamics, we demonstrate that as light undergoes a sudden transition from a small to a larger nonlinear optical array, it can abruptly drop its optical temperature to near-zero values. During this cooling process, light irreversibly flows into the system's fundamental mode with very high efficiency, synchronizing all elements of the lattice with the input port. We show that this nonlinear effect is highly predictable even in systems of arbitrary geometry and shape and can be controlled precisely by the initial conditions at the input of the array. In particular, for a single injection point, the reduction in optical temperature can be directly determined by the total power, irrespective of the input location.
Pyrialakos, Georgios G. (ORCID:0000000286129694)↗
A quasi-omnidirectional slot array antenna for spacecraft use at microwave frequencies
Quasi-omnidirectional resonant array of circumferential shunt slots in ring waveguides for narrow bandwidth space vehicle applications at microwave frequencies
Croswell, W. F.↗
Phase multiplying electronic scanning array
Scanning array was designed with properties of low RF loss and phase control. The array consists of a series of special waveguides, hybrids made up of two variable reactance branch arms for input signals, an edge slot for the difference port, and a sum arm for the unradiated signal.
Seaton, A. F.↗
NASA Tech Briefs, April 2003
Topics include: Tool for Bending a Metal Tube Precisely in a Confined Space; Multiple-Use Mechanisms for Attachment to Seat Tracks; Force-Measuring Clamps; Cellular Pressure-Actuated Joint; Block QCA Fault-Tolerant Logic Gates; Hybrid VLSI/QCA Architecture for Computing FFTs; Arrays of Carbon Nanotubes as RF Filters in Waveguides; Carbon Nanotubes as Resonators for RF Spectrum Analyzers; Software for Viewing Landsat Mosaic Images; Updated Integrated Mission Program; Software for Sharing and Management of Information; Optical-Quality Thin Polymer Membranes; Rollable Thin Shell Composite-Material Paraboloidal Mirrors; Folded Resonant Horns for Power Ultrasonic Applications; Touchdown Ball-Bearing System for Magnetic Bearings; Flux-Based Deadbeat Control of Induction-Motor Torque; Block Copolymers as Templates for Arrays of Carbon Nanotubes; Throttling Cryogen Boiloff To Control Cryostat Temperature; Collaborative Software Development Approach Used to Deliver the New Shuttle Telemetry Ground Station; Turbulence in Supercritical O2/H2 and C7H16/N2 Mixing Layers; and Time-Resolved Measurements in Optoelectronic Microbioanal.
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NASA Tech Briefs, March 2003
Topics covered include: Tool for Bending a Metal Tube Precisely in a Confined Space; Multiple-Use Mechanisms for Attachment to Seat Tracks; Force-Measuring Clamps; Cellular Pressure-Actuated Joint; Block QCA Fault-Tolerant Logic Gates; Hybrid VLSI/QCA Architecture for Computing FFTs; Arrays of Carbon Nanotubes as RF Filters in Waveguides; Carbon Nanotubes as Resonators for RF Spectrum Analyzers; Software for Viewing Landsat Mosaic Images; Updated Integrated Mission Program; Software for Sharing and Management of Information; Update on Integrated Optical Design Analyzer; Optical-Quality Thin Polymer Membranes; Rollable Thin Shell Composite-Material Paraboloidal Mirrors; Folded Resonant Horns for Power Ultrasonic Applications; Touchdown Ball-Bearing System for Magnetic Bearings; Flux-Based Deadbeat Control of Induction-Motor Torque; Block Copolymers as Templates for Arrays of Carbon Nanotubes; Throttling Cryogen Boiloff To Control Cryostat Temperature; Collaborative Software Development Approach Used to Deliver the New Shuttle Telemetry Ground Station; Turbulence in Supercritical O2/H2 and C7H16/N2 Mixing Layers; and Time-Resolved Measurements in Optoelectronic Microbioanal.
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Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging
Most optical systems require antennas with directive patterns. This means that the physical area of the antenna will be large in terms of the wavelength. When non-cooled systems are used, the losses of microstrip or coplanar waveguide lines impede the use of standard patch or slot antennas for a large number of elements in a phased array format. Traditionally, this problem has been solved by using silicon lenses. However, if an array of such highly directive antennas is to be used for imaging applications, the fabrication of many closely spaced lenses becomes a problem. Moreover, planar antennas are usually fed by microstrip or coplanar waveguides while the mixer or the detector elements (usually Schottky diodes) are coupled in a waveguide environment. The coupling between the antenna and the detector/ mixer can be a fabrication challenge in an imaging array at submillimeter wavelengths. Antennas excited by a waveguide (TE10) mode makes use of dielectric superlayers to increase the directivity. These antennas create a kind of Fabry- Perot cavity between the ground plane and the first layer of dielectric. In reality, the antenna operates as a leaky wave mode where a leaky wave pole propagates along the cavity while it radiates. Thanks to this pole, the directivity of a small antenna is considerably enhanced. The antenna consists of a waveguide feed, which can be coupled to a mixer or detector such as a Schottky diode via a standard probe design. The waveguide is loaded with a double-slot iris to perform an impedance match and to suppress undesired modes that can propagate on the cavity. On top of the slot there is an air cavity and on top, a small portion of a hemispherical lens. The fractional bandwidth of such antennas is around 10 percent, which is good enough for heterodyne imaging applications.The new geometry makes use of a silicon lens instead of dielectric quarter wavelength substrates. This design presents several advantages when used in the submillimeter-wave and terahertz bands: a) Antenna fabrication compatible with lithographic techniques. b) Much simpler fabrication of the lens. c) A simple quarter-wavelength matching layer of the lens will be more efficient if a smaller portion of the lens is used. d) The directivity is given by the lens diameter instead of the leaky pole (the bandwidth will not depend anymore on the directivity but just on the initial cavity). The feed is a standard waveguide, which is compatible with proven Schottky diode mixer/detector technologies. The development of such technology will benefit applications where submillimeter- wave heterodyne array designs are required. The main fields are national security, planetary exploration, and biomedicine. For national security, wideband submillimeter radars could be an effective tool for the standoff detection of hidden weapons or bombs concealed by clothing or packaging. In the field of planetary exploration, wideband submillimeter radars can be used as a spectrometer to detect trace concentrations of chemicals in atmospheres that are too cold to rely on thermal imaging techniques. In biomedicine, an imaging heterodyne system could be helpful in detecting skin diseases.
Chattopadhyay, Goutam↗
Aperture impedance of flared horns
The method of moments is often used when solving for the mutual coupling in arrays of aperture antennas. For elements that are waveguides or gradually flared horns the aperture fields can be approximated by a finite sum of waveguide modal functions. To solve for the flared horn case an approximation for the aperture impedances of the modes in the horn is needed. The WKB approach can be used to find these impedances, but this technique has an important limitation. It is known to fail in the vicinity of its turning points. The turning point is the cutoff point of the mode being considered. To overcome this limitation a different technique, the spherical mode approach, is discussed. This approach has no cutoff problems and works well for conical and pyramidal horns. Comparisons between the impedances and the resulting dominant mode reflection coefficient found using the two techniques are presented to illustrate this point.
Silvestro, J. W.↗