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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 127 records · Page 7

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NASA NTRS1990

Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

Kunath, Richard R.↗

NASA NTRS1990

Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

Kunath, Richard R.↗

NASA NTRS1994

Measuring Frequency Instability Of A Large Antenna

Frequency instability of antenna under test determined from measurement of phase deviation between outputs of two antennas. Fiber-optic system used to minimize spurious component of frequency instability contributed by propagation of signal from reference antenna to Allan-variance-measuring instrument. Intended primarily to reveal contributions of wind and air-temperature effects on antenna and beam-waveguide structures to overall frequency instabilities of received signals. Technique simpler, less expensive, potentially capable of providing instability data in shorter measuring times, and more precise.

Otoshi, Tom Y.↗

NASA NTRS1982

Concepted design of a surface measurement system for large deployable space antennas

The sensor system is in essence a point design, specifically interfacing with the Harris, Inc., 1000 meter deployable mesh communication antenna. The design can, without large modification, be adapted to other large deployable antennas such as the Lockheed Wrap-rib, the General Dynamics Precision Erectable Truss and the TRW Advanced Sunflower antennas. Measurements are optical displacements. The elements of the system are a central cluster of receivers near the apex of the antenna and active bright targets at the antenna. The cluster defines a single coordinate frame from which all surface positions are referenced. The receivers continuously observe an extended array of sample points located throughout the reflecting surface and its supporting structure. For the Harris antenna, the surface samples are at the mesh gore lines and at the supporting hoop. Output data is in real-time, compatible with on-board processing and active control of antenna figure. Lifetime of the system is at least 10 years continuous operation in space.

Neiswander, R. S.↗

NASA NTRS1992

Optimizing the G/T ratio of the DSS-13 34-meter beam-waveguide antenna

Calculations using Physical Optics computer software were done to optimize the gain-to-noise-temperature (G/T) ratio of Deep Space Station (DSS)-13, the Deep Space Network's (DSN's) 34-m beam-waveguide antenna, at X-band for operation with the ultra-low-noise amplifier maser system. A better G/T value was obtained by using a 24.2-dB far-field-gain smooth-wall dual-mode horn than by using the standard X-band 22.5-dB-gain corrugated horn.

Esquivel, M. S.↗

NASA NTRS1996

Switched-Polarization Birefringent Optical Delay Lines

Controllable birefringent optical delay lines proposed for use in photonically controlling phases of signals in radiating elements of phased-array antennas. Features low optical insertion losses and made very compact, enabling high packing densities where multiple delay channels needed. Polarization switched in segments to adjust overall delay. Furthermore, two or more delay lines cascaded increases delay-adjustment range.

Yao, Xiaotian Steve↗

NASA NTRS2000

Recent Trends in the Analysis of Quasioptical Systems

The recent trend in microwave instruments is the use of multiple millimeter and submillimeter wavelength bands. These systems are typically analyzed by using physical optics, Gaussian beams or ray tracing techniques. Physical optics offers high accuracy at the expense of computation time. This trade-off becomes particularly apparent in the analysis of multiple reflector antennas, such as beam waveguide antennas, where physical optics is used to compute the current on each reflector from the current on the previous reflector. At the other end of the spectrum is ray tracing approaches that ignore diffraction effects entirely. These methods are fast but sacrifice the ability to predict some effects accurately. An intermediate approach is to use an appropriate set of expansion functions to model the field between the reflectors. If the set is chosen wisely only a few coefficients need to be determined from each reflector current. The field is then computed at the next reflector through the use of the expansion functions and their coefficients rather than by using the previous reflector current. For a beam waveguide system with no enclosing tubes an excellent set of expansion functions is the Gaussian beam mode set. In many cases a preliminary design which includes the effects on diffraction may be obtained by considering only the fundamental mode and a thin lens model for the reflectors. Higher-order modes are included to model the effects of the curved reflector, which include asymmetric distortion of the beam, cross polarization, and beam truncation. This paper describes a computer code implementing higher-order Gaussian beam scattering by multiple reflector systems. There are four essential steps in the algorithm. (1) Compute the current on the first reflector using physical optics using either a feed model or by an incident set of Gaussian beam modes. (2) Find the direction of propagation for the reflected Gaussian beam-set using ray tracing. (3) Determine the waist size and location for the output beam set by examining the amplitude and phase distribution of the current on the reflector. (4) Compute the amplitudes of the individual modes in the output mode set. These steps are then repeated for each addition reflector in the chain. In each of these cases the previous Gaussian beam set provides the input field for the current calculation. Details of the four steps discussed above will be discussed. Examples will compare results from the Gaussian beam approach to pure physical optics, illustrating both its merits and limitations. Hybrid approaches capable of eliminating some of the limitations will also be discussed.

Hoppe, D. J.↗

NASA NTRS1987

Structural design options for the new 34 meter beam waveguide antenna

In addition to the successful network of 34 m High Efficiency antennas recently built by JPL, the Deep Space Network (DSN) is embarking on the construction of a 34 m high performance, research and development antenna with beam waveguide optics at the Venus site. The construction of this antenna presents many engineering challenges in the area of structural, mechanical, RF, and pointing system design. A set of functional and structural design requirements is outlined to guide analysts in the final configuration selection. Five design concepts are presented covering both the conventional center-fed beam optics as well as the nonconventional, by-pass beam configuration. The merits of each concept are discussed with an emphasis on obtaining a homologous design. The preliminary results of structural optimization efforts, currently in progress, are promising, indicating the feasibility of meeting, as a minimum, all X-band (8.4 GHz) requirements, with a goal towards meeting Ka-band (32 GHz) quality performance, at the present budget constraints.

Katow, S.↗

NASA NTRS1990

Dual-shaped offset reflector antenna designs from solutions of the geometrical optics first-order partial differential equations

In obtaining solutions to the first-order nonlinear partial differential equations (PDEs) for synthesizing offset dual-shaped reflectors, it is found that previously observed computational problems can be avoided if the integration of the PDEs is started from an inner projected perimeter and integrated outward rather than starting from an outer projected perimeter and integrating inward. This procedure, however, introduces a new parameter, the main reflector inner perimeter radius p(o), when given a subreflector inner angle 0(o). Furthermore, a desired outer projected perimeter (e.g., a circle) is no longer guaranteed. Stability of the integration is maintained if some of the initial parameters are determined first from an approximate solution to the PDEs. A one-, two-, or three-parameter optimization algorithm can then be used to obtain a best set of parameters yielding a close fit to the desired projected outer rim. Good low cross-polarization mapping functions are also obtained. These methods are illustrated by synthesis of a high-gain offset-shaped Cassegrainian antenna and a low-noise offset-shaped Gregorian antenna.

Galindo-Israel, V.↗

NASA NTRS1994

Monolithic Optical-To-Electronic Receiver

Monolithic optoelectronic integrated circuit converts multiplexed digital optical signals into electrical signals, separates, and distributes them to intended destinations. Developed to deliver phase and amplitude commands to monolithic microwave integrated circuits (MMIC's) at elements of millimeter-wave phased-array antenna from single optical fiber driven by external array controller. Also used in distribution of high-data-rate optical communications in local-area networks (LAN's). Notable features include options for optical or electrical clock inputs; outputs for raw data, addresses, and instructions for diagnosis; and optical-signal-detection circuit used to reduce power consumption by 80 percent between data-transmission times. Chip fabricated by processes available at many major semiconductor foundries. Distribution of digital signals in aircraft, automobiles, and ships potential application.

Kunath, Richard↗

NASA NTRS2012

Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

photon counting detection↗

NASA NTRS2006

Overview of Small and Large-Scale Space Solar Power Concepts

An overview of space solar power studies performed at the Boeing Company under contract with NASA will be presented. The major concepts to be presented are: 1. Power Plug in Orbit: this is a spacecraft that collects solar energy and distributes it to users in space using directed radio frequency or optical energy. Our concept uses solar arrays having the same dimensions as ISS arrays, but are assumed to be more efficient. If radiofrequency wavelengths are used, it will necessitate that the receiving satellite be equipped with a rectifying antenna (rectenna). For optical wavelengths, the solar arrays on the receiving satellite will collect the power. 2. Mars Clipper I Power Explorer: this is a solar electric Mars transfer vehicle to support human missions. A near-term precursor could be a high-power radar mapping spacecraft with self-transport capability. Advanced solar electric power systems and electric propulsion technology constitute viable elements for conducting human Mars missions that are roughly comparable in performance to similar missions utilizing alternative high thrust systems, with the one exception being their inability to achieve short Earth-Mars trip times. 3. Alternative Architectures: this task involves investigating alternatives to the traditional solar power satellite (SPS) to supply commercial power from space for use on Earth. Four concepts were studied: two using photovoltaic power generation, and two using solar dynamic power generation, with microwave and laser power transmission alternatives considered for each. All four architectures use geostationary orbit. 4. Cryogenic Propellant Depot in Earth Orbit: this concept uses large solar arrays (producing perhaps 600 kW) to electrolyze water launched from Earth, liquefy the resulting hydrogen and oxygen gases, and store them until needed by spacecraft. 5. Beam-Powered Lunar Polar Rover: a lunar rover powered by a microwave or laser beam can explore permanently shadowed craters near the lunar poles to search for water ice and other frozen volatiles. Near such craters are mountain peaks and highlands that are in near permanent sunlight. Power can be beamed from a collector on a sunlit mountain or crater rim to a rover inside a crater. Near-term applications of space solar power technology can therefore pave the way toward large-scale commercial power from space.

Potter, Seth↗

NASA NTRS1993

An Improved Solution for Integrated Array Optics in Quasi-Optical mm and Submm Receivers: the Hybrid Antenna

The hybrid antenna discussed here is defined as a dielectric lens-antenna as a special case of an extended hemi-spherical dielectric lens that is operated in the diffraction limited regime. It is a modified version of the planar antenna on a lens scheme developed by Rutledge. The dielectric lens-antenna is fed by a planar-structure antenna, which is mounted on the flat side of the dielectric lens-antenna using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of extension of the hemi- spherical lens and different lens sizes. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. At 115 GHz the aperture efficiency was measured to be (76 4 +/- 6) % for a diffraction limited beam with sidelobes below -17 dB. Results of a single hybrid antenna with an integrated Superconductor-Insulator-Superconductor (SIS) detector and a broad-band matching structure at submillimeter wavelengths are presented. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays.

Buttgenbach, Thomas H.↗

NASA NTRS2017

MCRadar: A Monte Carlo Solver for Cloud and Precipitation Radar

Multiple scattering produces anomalous echoes in observed radar profiles that cannot be explained by other phenomena. These effects are most obvious for spaceborne platforms, at shorter wavelengths, and in convection, as multiple scattering is governed by antenna beam width, optical depth, and albe do; however, multiple scattering has been observed in a range of precipitating conditions. To account for the effects of multiple scattering, Monte Carlo integration is employed in a flexible framework to enable arbitrary radar configurations with finite Gaussian beams for three-dimensional atmospheric scenarios. The three-dimensional nature of the model, coupled with the finite antenna response, also allows for consideration of nonuniform beam filling effects that often coincide with multiple scattering. Examples of airborne and spaceborne radars at various wavelengths are used to illustrate the effects of multiple scattering and nonuniform beam filling. The MCRadar code is currently available in the development version of ARTS.

Adams, Ian Stuart↗

NASA NTRS2011

Experimental Evaluation of Optically Polished Aluminum Panels on the Deep Space Network's 34 Meter Antenna

The potential development of large aperture ground?based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation is to polish the aluminum reflector panels of 34?meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by state of?the?art polished aluminum panels. Theoretical analyses of receiving antenna pointing, temporal synchronization and data detection have been addressed in previous papers. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. Two polished aluminum panels (a standard DSN panel polished to high reflectance, and a custom designed aluminum panel with much better surface quality) have been mounted on the 34 meter research antenna at Deep?Space Station 13 (DSS?13), and a remotely controlled CCD camera with a large CCD sensor in a weather?proof container has been installed next to the subreflector, pointed directly at the custom polished panel. The point?spread function (PSF) generated by the Vertex polished panel has been determined to be smaller than the sensor of the CCD camera, hence a detailed picture of the PSF can be obtained every few seconds, and the sensor array data processed to determine the center of the intensity distribution. In addition to estimating the center coordinates, expected communications performance can also been evaluated with the recorded data. The results of preliminary pointing experiments with the Vertex polished panel receiver using the planet Jupiter to simulate the PSF generated by a deep?space optical transmitter are presented and discussed in this paper.

optical receiver↗

NASA NTRS1991

Advanced optical sensing and processing technologies for the distributed control of large flexible spacecraft

The objective was to examine state-of-the-art optical sensing and processing technology applied to control the motion of flexible spacecraft. Proposed large flexible space systems, such an optical telescopes and antennas, will require control over vast surfaces. Most likely distributed control will be necessary involving many sensors to accurately measure the surface. A similarly large number of actuators must act upon the system. The used technical approach included reviewing proposed NASA missions to assess system needs and requirements. A candidate mission was chosen as a baseline study spacecraft for comparison of conventional and optical control components. Control system requirements of the baseline system were used for designing both a control system containing current off-the-shelf components and a system utilizing electro-optical devices for sensing and processing. State-of-the-art surveys of conventional sensor, actuator, and processor technologies were performed. A technology development plan is presented that presents a logical, effective way to develop and integrate advancing technologies.

Williams, G. M.↗

NASA NTRS1976

Multiple dielectric layer effects on the space shuttle orbiter S-band quad antennas

A mathematical tool is developed for evaluation of antenna radiation pattern effects on the shuttle orbiter S band quad antennas. A ray optics approach is used which includes multiple internal reflections with special consideration to reflection from the metallic orbiter skin. Significant depolarization may occur as the angle from the normal increases. The effect of changing tile thickness on the beamwidth of the upper quads versus the lower quads results in a small increase in the lower quad beamwidth compared with the beamwidth in the upper quads. The optimization and evaluation of the S band quads and the computer tool developed may be used to evaluate other shuttle orbiter antennas.

Lindsey, J. F.↗

NASA NTRS1982

Development of computer models for the prediction of large distorted antenna characteristics

A program for calculating the radiation patterns of analytic reflector antennas, using geometric optics and aperture plane integration techniques, was modified and extended to include nonanalytic surfaces. The original program, while capable of predicting patterns for a variety of reflectors, both smooth and multipanelled, was subject to the restriction that the surface had to be expressed analytically, i.e., described by a set of mathematical equations. This restriction was removed by adapting a technique which allows the reflector configuration to be interpolated from a finite set of points measured on the surface. Criteria for choosing both the number and distribution of these measured surface points were developed by comparing the predicted antenna radiation patterns with measured laboratory results. Test cases involved relatively smooth as well as grossly distorted arbitrary surfaces. Finally, surface point accuracies were established by applying random error analysis to the measurement process.

Moskowitz, S. M.↗