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NASA NTRS2019

Crazy Antennas

Everyone here is familiar with traditional antennas, time-honored favorites like dipoles and solid parabolic reflectors. But occasionally, circumstances call for something peculiar. This paper will describe a number of unusual antennas for particular communications scenarios that have been developed at the NASA Glenn Research over the past decade or so. The list includes: a K-band scanning ferroelectric reflectarray; a UHF "Vivaldi" for cellular connectivity to unmanned aerial vehicles; a Ku-band array that develops a top-hat pattern to feed a zone plate antenna; an active antenna that toggles between Iridium and GPS bands; a VHF hybrid spiral/dipole for orientation determination on Venus; and a Ku-band deployable reflector that strongly resembles a giant beach ball. Design strategy and performance results will be included, and trends towards cognitive antennas will be discussed.

Romanofsky, Robert↗

NASA NTRS1974

The community satellite 1

NASA's Applications Technology Satellite-6 is being used to test a variety of new space communications concepts requiring the use of a geosynchronous-orbit spacecraft. These include broadcast of health and education television programs to small, low-cost ground receiving units in remote regions. Other studies to be conducted are related to aeronautical and maritime communications, position-location, and traffic-control techniques. Questions concerning spacecraft tracking and data relay are also investigated. The 1,402 kg spacecraft consists essentially of an Earth Viewing Module connected to a deployable reflector antenna. Details regarding the planned experiments and the spacecraft design are discussed and a brief history of the ATS program is presented.

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NASA NTRS1977

AAFE large deployable antenna development program: Executive summary

The large deployable antenna development program sponsored by the Advanced Applications Flight Experiments of the Langley Research Center is summarized. Projected user requirements for large diameter deployable reflector antennas were reviewed. Trade-off studies for the selection of a design concept for 10-meter diameter reflectors were made. A hoop/column concept was selected as the baseline concept. Parametric data are presented for 15-meter, 30-meter, and 100-meter diameters. A 1.82-meter diameter engineering model which demonstrated the feasiblity of the concept is described.

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NASA NTRS1978

On space deployable antennas and electronics: Plans and programs

Technology plans are presented for developing deployable reflectors having diameters of 30 to 300 meters and surface accuracies of several millimeters for L and X band applications, as well as for the electronic subsystems required for such large structures. An electromagnetic analysis method for predicting the radio frequency performance of large reflectors involves projecting field points onto an aperture plane. The data points in the aperture plane are quantized to produce contours of constant phase and amplitude. Far field patterns are then calculated using reduced computer storage.

Campbell, T. G.↗

NASA NTRS1979

Deployable antenna technology development for the Large Space Systems Technology program

The critical technologies associated with the development of deployable reflector antenna technology for the LSST program will be derived from NASA mission models and the subsequent requirements will be related to the classes of missions involved. The approach formulated for the development of reflector technology is based on the development of specific reflector concepts that have been identified as leading candidates for future applications. The development approach will be augmented by supporting technology disciplines such as controls, materials, electromagnetic analysis, as well as the capability of analytically predicting the overall performance of the large space system.

Freeland, R. E.↗

NASA NTRS1979

Study of advanced sunflower precision deployable antenna

The maximum deployed diameter stowable in shuttle was determined for the original concept and for new more efficient concepts. Estimates of weight, surface accuracy and cost were made for the various configurations. Five critical technologies were identified which would be required to manufacture large solid deployable reflectors. These technologies are concerned with surface accuracy improvement and verification.

Giebler, M. M.↗

NASA NTRS1980

Large space systems technology program

Technical challenges of shuttle-era large space systems include the development of space-configured spacecraft concepts, compatibility with the space transportation system, and cost effectiveness. The objectives and organization of NASA's large space structures program are outlined and program elements are discussed. The technology for the offset wrap-rip and the maypole (hoop/column) antenna concepts are discussed as well as analysis techniques for predicting the electromagnetic performance of a broad class of large reflectors. Deployable systems, assembly methods, and modular control systems for space platforms are described. Assembly equipment and devices, surface sensors and shape control, control and stabilization, and integrated analysis and design are also considered.

James, R. L., Jr.↗

NASA NTRS1982

Space infrared astronomy - Overview of NASA planning

The present status and potential future direction of the NASA space infrared astronomy program is reviewed. Projects and project concepts discussed include the Infrared Astronomy Satellite, Small Infrared Telescope on Spacelab 2, Cosmic Background Explorer, Shuttle Infrared Telescope Facility, Space Telescope, large deployable reflector, molecular line survey, and infrared interferometer in space. Needs for continued engineering development in critical technology areas such as detectors, cryogenics, optics, and space structures are indicated.

Hauser, M. G.↗

NASA NTRS1982

Submillimetre astronomy from space platforms

The scientific need and the technical feasibility of a 10-m class far infrared telescope in space were studied and culminated in the recommendation of the large deployable reflector (LDR). The scientific considerations for such a project are described and the general characteristics of LDR are derived. A scientific program culminating in LDR is suggested.

Kuiper, T. B. H.↗

NASA NTRS1982

Astronomy and astrophysics for the 1980's, volume 1

The programs recommended address the most significant questions that confront contemporary astronomy and fall into three general categories: prerequisites for research initiatives, including instrumentation and detectors, theory and data analysis, computational facilities, laboratory astrophysics, and technical support at ground-based observatories; programs including an Advanced X-ray Astrophysics Facility, a Very-Long Baseline Array, a Technology Telescope and a Large Deployable Reflector; and programs for study and development, including X-ray observatories in space, instruments for the detection of gravitational waves from astronomical objects, and long duration spaceflights of infrared telescopes. Estimated costs of these programs are provided.

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NASA NTRS1983

Advances in structural concepts

A number of different structural concepts are currently under development as a means of placing large structures in orbit. Three commonly considered concepts are described. The radial rib structure and the hoop-column structure have undergone considerable early development because of their seeming potential for providing a reliably deployable reflector surface. In the present paper, attention is focused on truss structures which historically have been widely used in ground based structures because of their inherent simplicity, versatility, and high stiffness.

Mikulas, M. M., Jr.↗

NASA NTRS1983

Phased-array-fed antenna configuration study. Volume 1: Technology assessment

The status of the technologies for phased-array-fed dual reflector systems is reviewed. The different aspects of these technologies, including optical performances, phased array systems, problems encountered in phased array design, beamforming networks, MMIC design and its incorporation into waveguide systems, reflector antenna structures, and reflector deployment mechanisms are addressed.

Sorbello, R. M.↗

NASA NTRS1984

Technology Panel Reports

Results are presented from five technology panels which convened to identify relevant technologies within their discipline for the Large Deployable Reflector (LDR) and to assess the current and projected state of these technologies. The five panels considered the following topics: optics, materials and structure, sensing and control, science instruments, and systems and missions.

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NASA NTRS1984

Conceptual design of a hybrid Ge:Ga detector array

For potential applications in space infrared astronomy missions such as the Space Infrared Telescope Facility and the Large Deployable Reflector, integrated arrays of long-wavelength detectors are desired. The results of a feasibility study which developed a design for applying integrated array techniques to a long-wavelength (gallium-doped germanium) material to achieve spectral coverage between 30 and 200 microns are presented. An approach which builds up a two-dimensional array by stacking linear detector modules is presented. The spectral response of the Ge:Ga detectors is extended to 200 microns by application of uniaxial stress to the stack of modules. The detectors are assembled with 1 mm spacing between the elements. Multiplexed readout of each module is accomplished with integration sampling of a metal-oxide-semiconductor (MOS) switch chip. Aspects of the overall design, including the anticipated level of particle effects on the array in the space environment, a transparent electrode design for 200 microns response, estimates of optical crosstalk, and mechanical stress design calculations are included.

Parry, C. M.↗

NASA NTRS1985

LDR system concepts and technology

The Large Deployable Reflector is a 20 meter diameter infrared/submillimeter telescope planned for the late 1990's. The Astronomy Survey Committee of the National Academy of Sciences (Field Committee) recommended LDR as one of the two space based observatories that should start development in the 80's. LDR's large aperture will give it unequaled resolution in the wavelength range from 30 to 1000 microns. To meet LDR performance goals will call for advances in several technology disciplines including: optics, controls, thermal control, detectors, cryogenic cooling, and large space structures.

Pittman, B.↗

NASA NTRS1985

Large Antenna Control Methods: Current Status and Future Trends

Current methods for control of large antennas, as well as future trends required for improved performance are addressed. Some of the target missions in which these methods would be used are: the Land Mobile Satellite System (LMSS) for communications; the Satellite Surveillance (SSS) for aircraft traffic control; the orbiting Very Long Baseline Interferometer (VLBI), or QUASAT, for radio astronomy; and the Large Deployable Reflector (LDR) for IR and submillimeter astronomy.

Rodriguez, G.↗

NASA NTRS1985

Submillimeter local oscillators for spaceborne heterodyne applications

Existing and prospective submillimeter local oscillator technologies are surveyed and compared with respect to criteria of suitability for application in spaceborne submillimeter heterodyne receivers as those proposed for the Large Deployable Reflector (LDR). Solid-state and plasma devices are considered in terms of fundamental limitations.

Petuchowski, S. J.↗

NASA NTRS1983

Alignment and phasing of deployable telescopes

The experiences in coaligning and phasing the Multi-Mirror Telescope (MMT), together with studies in setting up radio telescopes, are presented. These experiences are discussed, and on the basis they furnish, schemes are suggested for coaligning and phasing four large future telescopes with complex primary mirror systems. These telescopes are MT2, a 15-m-equivalent MMT, the University of California Ten Meter Telescope, the 10 m sub-mm wave telescope of the University of Arizona and the Max Planck Institute for Radioastronomy, and the Large Deployable Reflector, a future space telescope for far-IR and sub-mm waves.

Woolf, N. J.↗