Backfire antennas for telemetry and tracking applications.
Backfire antenna radiation characteristics and physical dimensions for tracking and telemetry applications, including five element array model
Dod, L. R.↗
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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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Evaluation of a low sidelobe phased array antenna
Low sidelobe phased array antenna radiation characteristics by performance testing
Profera, C. E., Jr.↗
Automatic reference level control for an antenna pattern recording system
Automatic gain control system keeps recorder reference levels within 0.2 decibels during operation. System reduces recorder drift during antenna radiation distribution determinations over an eight hour period.
Lipin, R., Jr.↗
Effects of reentry plasma on RAM C-1 VHF telemetry antennas
Reentry plasma effects on RAM C-1 VHF telemetry antenna radiation patterns
Croswell, W. F.↗
Antenna performance in the presence of a turbulent plasma
Antenna radiation patterns and electron density profiles in turbulent plasma flow
Chown, J. B.↗
Numerical evaluation of electromagnetic fields due to dipole antennas in the presence of stratified media
Two numerical methods are used to evaluate the integrals that express the em fields due to dipole antennas radiating in the presence of a stratified medium. The first method is a direct integration by means of Simpson's rule. The second method is indirect and approximates the kernel of the integral by means of the fast Fourier transform. In contrast to previous analytical methods that applied only to two-layer cases the numerical methods can be used for any arbitrary number of layers with general properties.
Tsang, L.↗
Refinement of the basic radar equation for clouds and precipitation
A derivation of the basic radar equation for clouds and precipitation is given that takes into account the antenna radiation pattern. The reasons for the differences in the equations used by various authors are demonstrated. More rigorous forms for writing down the basic equation are given.
Salman, Y. M.↗
An RF link analysis of MSBLS during ALT
An analysis of the microwave scanning beam landing system (MSBLS) ground station to orbiter radio frequency (RF) link was made to determine if the expected signal levels will be compatible with orbiter receiver capabilities. Of primary interest was whether or not loss of data will occur due to interference caused by the orbiter 101 nose boom which provides additional air data during the approach and landing test. The results of the analysis indicate that a small amount of data loss may occur due to the proximity of the MSBLS antennas and the nose boom. Tabulated data of antenna radiation patterns are given.
Speir, R. E.↗
More efficient microwave-power transmission
Small improvements in magnetron, receiving diodes, radiating antennas, and circulator sections of components add sizable improvement in microwave system efficiency. Further improvements in future are possible by adding new materials and designs to RF-to-dc converter-or removal of circulator, power supply and redesigning of magnetron to tolerate low or high power levels.
Dickinson, R. M.↗
Measurement of solar gravitational oblateness with gravity gradiometers
A very high sensitivity rotating gravity gradiometer onboard the spacecraft is described for measuring the gravitational oblateness of the Sun during a solar probe mission. The proposed instrument would be a self-contained structure in a thermal-vacuum-magnetic shield in the shape of a cross, with a mass of 20 kg and arm length of 1.0 m and thickness of 0.1 m. The sensor inside would have a resonant frequency of 1/30 Hz, a mechanical Q of one million and would use gravitational radiation antenna technology to achieve a sensitivity of 6 x 10 to the minus 8th power Eotvos, which would provide a measurement of the solar oblateness to an accuracy of 1.5 to 6 x 10 to the minus 8th power. The gravity gradiometer will require a spinning spacecraft, so that it will not sense the spacecraft gravity fields, but the gradiometer does not need to be at the spacecraft center of mass, or even on the spacecraft spin axis. Major problem areas to be addressed are demonstration of the instrument sensitivity prior to flight and the measurement and compensation for any residual spacecraft angular rates.
Forward, R. L.↗
Recent developments in the measurement of space time curvature
Development of a highly sensitive resonant capacitor displacement sensor and a multistage suspension system for a low-temperature gravitational radiation antenna is discussed; the antenna is suitable for studying gravitational collapses. The sensitivity limit of the device is assessed as a function of preamplifier noise. Experiments indicate that an electric field of about 160,000 v/cm may be applied to the resonator surface without a significant increase in Brownian noise. Use of the resonant capacitor sensor with very high Q antennae is also considered.
Richard, J.-P.↗
A survey of airborne radar systems for deployment on a High Altitude Powered Platform (HAPP)
A survey was conducted to find out the system characteristics of commercially available and unclassified military radars suitable for deployment on a stationary platform. A total of ten domestic and eight foreign manufacturers of the radar systems were identified. Questionnaires were sent to manufacturers requesting information concerning the system characteristics: frequency, power used, weight, volume, power radiated, antenna pattern, resolution, display capabilities, pulse repetition frequency, and sensitivity. A literature search was also made to gather the system characteristics information. Results of the survey are documented and comparisons are made among available radar systems.
Choudhury, B. J.↗
Development of electromagnetic analysis methods for large aperture antennas
Both deterministic and statistical analysis methods for investigating large aperture antenna radiation patterns are examined. The effects of surface errors on radiation patterns are discussed.
Cockrell, C. R.↗
Satellite Power Systems /SPS/ - Overview of system studies and critical technology
Systems studies and critical technology issues for the development and evaluation of Satellite Power Systems (SPS) for the photovoltaic generation of electrical energy and its transmission to earth are reviewed. Initial concept studies completed in 1976 and system definition studies initiated in the same year have indicated the technical feasibility of SPS and identified challenging issues to be addressed as part of the SPS Concept Development and Evaluation Program. Systems considered in the study include photovoltaic and solar thermal power conversion configurations employing klystron or solid state microwave generators or lasers for power transmission, and power transmission options, system constructability and in-orbit and ground operations. Technology investigations are being performed in the areas of microwave power transmission, structure/controls interactions and the behavior of key materials in the space/SPS environment. Favorable results have been obtained in the areas of microwave phase distribution and phase control, dc-RF conversion, antenna radiating element, and no insurmountable problems have been discovered in any of the investigations to date.
Manson, S. V.↗
Effects of antenna blockage on radio frequency performance of the microwave radiometer spacecraft
Radio frequency scaled models of the microwave radiometer spacecraft suspended feed concept were tested to determine the effects of aperture blockage on the antenna radiation pattern. Contributors to the uncertainty of the test measurements were evaluated, and an estimate of the blockage effects was made for comparison with the test measurements. The gain loss budget associated with reflector performance characteristics (aperture blockage, surface reflectivity, reflector roughness, and defocus) was determined.
Sikes, L. D.↗
IAC level "O" program development
The current status of the IAC development activity is summarized. The listed prototype software and documentation was delivered, and details were planned for development of the level 1 operational system. The planned end product IAC is required to support LSST design analysis and performance evaluation, with emphasis on the coupling of required technical disciplines. The long term IAC effectively provides two distinct features: a specific set of analysis modules (thermal, structural, controls, antenna radiation performance and instrument optical performance) that will function together with the IAC supporting software in an integrated and user friendly manner; and a general framework whereby new analysis modules can readily be incorporated into IAC or be allowed to communicate with it.
Vos, R. G.↗
Role of IAC in large space systems thermal analysis
Computer analysis programs to evaluate critical coupling effects that can significantly influence spacecraft system performance are described. These coupling effects arise from the varied parameters of the spacecraft systems, environments, and forcing functions associated with disciplines such as thermal, structures, and controls. Adverse effects can be expected to significantly impact system design aspects such as structural integrity, controllability, and mission performance. One such needed design analysis capability is a software system that can integrate individual discipline computer codes into a highly user-oriented/interactive-graphics-based analysis capability. The integrated analysis capability (IAC) system can be viewed as: a core framework system which serves as an integrating base whereby users can readily add desired analysis modules and as a self-contained interdisciplinary system analysis capability having a specific set of fully integrated multidisciplinary analysis programs that deal with the coupling of thermal, structures, controls, antenna radiation performance, and instrument optical performance disciplines.
Jones, G. K.↗