Millimeter wave pumped parametric amplifier
A negative resistance parametric amplifier is reported that employs a discrete varactor diode for high frequency pump excitation in the millimeter wave range.
Dickens, L. E.↗
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Observation of the J = 2 to J = 1 transition of interstellar CO at 1.3 millimeters
The NRAO 36-foot antenna at Kitt Peak with a novel type of millimeter-wave superheterodyne receiver was used in observations of 1.3-mm line interstellar radiation due to J ? 2-1 transitions of C(12)0(16) and C(13)0(16). The liquid-helium-cooled hot-electron bolometer mixer of the superheterodyne receiver was used as the detecting element. The Orion Nebula CO system was found to be thermalized, showing a peak excitation temperature of about 76 K.
Phillips, T. G.↗
Sensitivity of Josephson-effect millimeter-wave radiometer
The noise temperature and the minimum detectable temperature of a Josephson junction in video detection of microwave and millimeter-wave radiation has been calculated. We use the well-known method based on a Fokker-Planck equation. The noise temperature can be very close to ambient temperature. Because its predetection bandwidth is very wide, a Josephson-effect radio telescope receiver can have a minimum detectable temperature better than that of a traveling-wave maser.
Ohta, H.↗
The influence of polarization on millimeter wave propagation through rain
The limitations which precipitation depolarization will place on future millimeter wave earth-satellite communications systems employing orthogonal-polarization frequency sharing was studied and the possibility of improving the fade resistance of such systems either through polarization diversity operation or by the choice of the polarization(s) least subject to attenuation was examined. Efforts were confined largely to ground-based communications systems investigated during a twenty-seven month period. Plans to extend the theoretical results to satellite systems are discussed.
Bostian, C. W.↗
ATS-6 millimeter wavelength propagation experiment
The fixed 20/30 GHz ground terminal is described in detail; it is being used for path diversity measurements in the ATS-6 millimeter wavelength propagation experiment. The current status and summary of operations are reviewed.
Hodge, D. B.↗
A millimeter-wave reflection-beam isolator
A new and simple type of millimeter-wave isolator using a solid-state magnetoplasma in a reflection-beam system is described. Some data are presented showing performance at 94 GHz. Practical considerations indicate that performance should be much closer to ideal at higher frequencies.
Kanda, M.↗
Detection of 2.6-millimeter radiation probably due to nitrogen sulfide
Results are reported for observations of millimeter-wavelength radiation in Sgr B2 at two frequencies corresponding to the transitions between the J = 5/2 and J = 3/2 Lambda-doublet sublevels in the 2 Pi(1/2) state of nitrogen sulfide. Difficulties in making a positive identification of the source of this radiation are discussed which result from the apparently anomalous ratio of the hyperfine components. However, it is noted that observations of the d-state by Gottlieb et al. (1975) showing the hyperfine components more exactly in their optically thin ratio confirm that the observed radiation is due to nitrogen sulfide.
Kuiper, T. B. H.↗
Experimental performance of 75-millimeter-bore arched outer-race ball bearings to 2.1 million DN
An experimental investigation was performed to determine the operating characteristics of arched outer-race bearings and to compare the data with those for a similar, but conventional, deep-groove ball bearing. The bearings were tested over a range of shaft speeds up to 28,000 rpm at a thrust load of 2200 newtons (500 lb). One bearing was operated at 26,000 rpm with a range of thrust loads. The amounts of arching were 0.13, 0.25, and 0.51 millimeter (0.005, 0.010, and 0.020 in.). All bearings operated satisfactorily; the arched bearing outer-race temperatures and torques were consistently higher than those for the conventional bearing.
Coe, H. H.↗
Review of data analysis procedures for the ATS-6 millimeter wave experiment
Predictions of satellite downlink attenuation through the use of ground based measurements form a substantial part of the ATS-6 millimeter wave experiment (MWE). At the downlink frequencies (20 and 30 GHz), the major causes of attenuation are the density and the size distribution of rain drops along the propagation path. Ground station data, which include radar and rain gauge records, measure quantities related to the meteorological parameters of interest and thereby provide a prediction of downlink attenuation with which the measured attenuation can be compared. The calibration and data analysis procedures used in the MWE are reviewed with the object of improving the accuracy of such ground based predictions.
Meneghini, R.↗
ATS-6 millimeter wavelength propagation experiment
The Ohio State University participation in the ATS-6 Millimeter Wavelength Propagation Experiment is summarized. Attenuation was measured simultaneously at 20 and 30 GHz on earth space propagation paths to two ground terminals located at Columbus, Ohio. In addition, 20 and 30 GHz radiometric temperatures were measured along the same propagation paths; and the 20 GHz radiometric temperature was also measured at a third ground terminal. The results of these measurements are presented, and diversity gains for the four pairs of propagation paths are discussed. The scintillation characteristics of the received signals are also presented.
Hodge, D. B.↗
Twenty and thirty GHz millimeter wave experiments with the ATS-6 satellite
Studies at 11 locations in the continental United States were directed at an evaluation of rain attenuation effects, scintillations, depolarization, site diversity, coherence bandwidth, and analog and digital communications techniques using the Applications Technology Satellite-6(ATS-6). In addition to direct measurements on the 20- and 30-GHz links, methods of attenuation prediction with radars, rain gages, and radiometers were developed and compared with the directly measured attenuation. Initial data results of the ATS-6 millimeter wave experiment were presented. The first section describes the experiment objectives, flight hardware, and modes of operation. The remaining six sections present papers prepared by the major participating organizations in the experiment. The papers present a comprehensive summary of the significant results of the initial 11 months of ATS-6 experiment measurements and related radiometric, radar, and radio-meteorology studies.
Ippolito, L. J.↗
Definition Study for Space Shuttle Experiments Involving Large, Steerable Millimeter-Wave Antenna Arrays
The potential uses and techniques for the shuttle spacelab Millimeter Wave Large Aperture Antenna Experiment (MWLAE) are documented. Potential uses are identified: applications to radio astronomy, the sensing of atmospheric turbulence by its effect on water vapor line emissions, and the monitoring of oil spills by multifrequency radiometry. IF combining is preferable to RF combining with respect to signal to noise ratio for communications receiving antennas of the size proposed for MWLAE. A design approach using arrays of subapertures is proposed to reduce the number of phase shifters and mixers for uses which require a filled aperture. Correlation radiometry and a scheme utilizing synchronous Dicke switches and IF combining are proposed as potential solutions.
Levis, C. A.↗
Permittivity of water at millimeter wave-lengths
Work performed on the permittivity of seawater and ice at 100 GHz was described. Measurements on water covered the temperature range from 0 to 50 C, while the measurements on ice were taken near - 10 C. In addition, a small number of measurements were made on the reflectivity of absorber materials used in a previous program on research in millimeter wave techniques. Normal incidence reflectivity was measured, and the result was used to obtain the index of refraction. For the case of normal incidence, reflectivity at a fixed temperature was reproducible to 1% for values near 40%. For reflectivity measurements on ice, the lack of attenuation leads to reflection from the back surface of the sample; this complication was circumvented by using a wedge shaped sample and freezing the water in a container lined with absorber material.
Blue, M. D.↗
On the structure of filaments from centimeter and millimeter observations
From filament observations at centimeter and millimeter wavelengths, it is shown that the transition layer between the dense cool filamentary material and the ambient hot rarified corona is rather thin, of the order of some hundred kilometers. Hence, the difference in the sizes of filaments in the radio and optical domains is of the order of 1000 km or 2 sec, thus not detectable by the instruments so far used for observations of filaments.
Butz, M.↗
The GSFC 20 and 30 GHz millimeter wave propagation experiment
The Goddard Space Flight Center Millimeter Wave Experiment (MWE) aboard ATS-6, designed to evaluate the propagation characteristics of earth-space communications links at 20 and 30 GHz, is outlined, and the major results to date are presented. The 20 and 30 GHz transmitters operate through spot beam or continental coverage antenna systems. The transmitted signals consist of 9 tones spaced out to 1440 MHz. A communications link 6 GHz up and 20 or 30 GHz down is provided. Attenuation ratio measurements between the 20 and 30 GHz links indicate values higher than those predicted. Clear sky scintillations have been observed with spectral components up to about 50 Hz. Observations of rain depolarization indicate that attenuation effects predominate over depolarization effects in frequency re-use communications systems in the 20 GHz region. Various methods of predicting path attenuation are under investigation.
Ippolito, L. J.↗
The GSFC 20 and 30 GHz millimeter wave propagation experiment
The preliminary results of the Goddard Space Flight Center Millimeter Wave Experiment, flown aboard ATS-6 to investigate the propagation characteristics of earth-space communications links at 20 and 30 GHz, are discussed. The spacecraft transmitters operate through spot beam (2 deg) or continental coverage (6 by 9 deg) antenna systems. The transmitted signals consist of a set of nine tones spaced out to 1440 MHz to allow measurement of wideband attenuation and coherence through precipitation. Initial data on precipitation depolarization and attenuation effects indicate that attenuation effects will exert the stronger influence on the design of frequency re-use communications systems in the 20 GHz region. The use of four ground terminals separated by 30 to 78 km to reduce the effects of rain attenuation has been successful, with improvement approaching the theoretical maximum demonstrated for five events. Preliminary results on the use of on-beam radar measurements for predicting rain attenuation are encouraging.
Ippolito, L. J.↗
Questions of the analysis of millimeter-wave frequency converters on diodes with a Schottky barrier
Millimeter-wave frequency converters on a diode with a Schottky barrier were analyzed. The analysis includes investigation of the effect of the variable capacitance of the diode's elements on the frequency converters. Specifically, the transmission, impedance, and noise characteristics of the frequency converters were examined.
Bordonskiy, G. S.↗
A compendium of millimeter wave propagation studies performed by NASA
Key millimeter wave propagation experiments and analytical results were summarized. The experiments were performed with the Ats-5, Ats-6 and Comstar satellites, radars, radiometers and rain gage networks. Analytic models were developed for extrapolation of experimental results to frequencies, locations, and communications systems.
Kaul, R.↗