RECEIVER TECHNIQUES AND DETECTORS FOR USE AT MILLIMETER AND SUBMILLIMETER WAVE LENGTHS.
Receivers and detectors for submillimeter wavelengths
SUBMILLIMETER WAVE↗
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Integrated Submillimeter-Wave Mixer
Indium arsenide Schottky-Barrier diodes in gallium antimonide substrate mix submillimeter waves, producing much lower frequency output. Integrated diode array has relatively-high signal-to-noise ratio and wide frequency band. Operates at moderate cryogenic temperatures (100 K).
Maserjian, J.↗
Additional measurements and a refined analysis of the millimeter- and submillimeter-wave spectrum of methanol
A total of 414 previously unobserved millimeter- and submillimeter-wave transitions of (C-12)H3OH through J = 10 and v(t) = 2 are assigned. These data and previous measured spectral transitions are combined and fitted by a modified internal axis method (IAM) treatment in which the A and E substates are treated separately and a wide variety of new rotational-torsional interaction terms are employed. The modified IAM treatment reduces the overall rms deviation of the fits to the level of experimental accuracy. The resultant spectroscopic constants allow for the accurate prediction of 569 additional transitions through J = 12 or less.
Anderson, Todd↗
Generating Submillimeter-Wave Frequencies From Laser Pulses
Semiconductor photoconductive switches generate electrical pulses containing submillimeter-wavelength carrier signals (frequency between 300 and 3,000 GHz) and harmonics thereof when illuminated with short-rise-time pulses from lasers. Device of this type used as local oscilator in heterodyne submillimeter-wave receiver. Electrical output of device coupled via transmission line, waveguide, or antenna to mixer circuitry of receiver. Phase delays between optically activated semiconductor switches determine output carrier frequencies. N electrical pulses generated by each laser pulse. Thus, fundamental output frequency is N times laser-pulse-repetition rate.
Spencer, Michael G.↗
Concepts and techniques in the utilization of millimeter and submillimeter waves
A millimeter-submillimeter transmitter and receiver system for propagation studies with an optically pumped laser as a source and a quasi-optical superheterodyne receiver is described. Topics are discussed in the areas of extended microwave techniques, quasi-optical devices and methods, radiometry, and measurements of importance to spectroscopy and propagation. Measurements obtained with operational systems are highlighted and their significance to physical questions and future system applications discussed.
Rainwater, J. H.↗
Propagation of millimeter and submillimeter waves
Coherent radiation methods of measuring absorption spectra in planetary atmosphere, and millimeter and submillimeter wave propagation
Derr, V. E.↗
Bulk semiconductor materials for millimeter and submillimeter wave detection
Investigating electrical properties of bulk semiconductor materials for application as millimeter and submillimeter wave detectors
Eldumiati, I. I.↗
The pressure broadening of NO2 in the millimeter and submillimeter wave spectral region
Pressure-broadening parameters for 19 transitions of the millimeter and submillimeter wave spectrum of NO2 have been obtained experimentally. Results for broadening by N2, O2, and He are presented and compared with earlier theoretical calculations of the N2 and O2 parameters. A discussion of the relation between theoretical calculations and experimental measurements is presented.
Goyette, Thomas M.↗
Millimeter and submillimeter wave antenna structure
An integrated circuit antenna structure for transmitting or receiving millimeter and/or submillimeter wave radiation having an antenna relatively unimpaired by the antenna mounting arrangment is disclosed herein. The antenna structure of the present invention includes a horn disposed on a substrate for focusing electromagnetic energy with respect to an antenna. The antenna is suspended relative to the horn to receive or transmit the electromagnetic energy focused thereby.
Rebiez, Gabriel M.↗
Optically-switched submillimeter-wave oscillator and radiator having a switch-to-switch propagation delay
A submillimeter wave-generating integrated circuit includes an array of N photoconductive switches biased across a common voltage source and an optical path difference from a common optical pulse of repetition rate f sub 0 providing a different optical delay to each of the switches. In one embodiment, each incoming pulse is applied to successive ones of the N switches with successive delays. The N switches are spaced apart with a suitable switch-to-switch spacing so as to generate at the output load or antenna radiation of a submillimeter wave frequency f on the order of N f sub 0. Preferably, the optical pulse has a repetition rate of at least 10 GHz and N is of the order of 100, so that the circuit generates radiation of frequency of the order of or greater than 1 Terahertz.
Spencer, Michael G.↗
Properties of material in the submillimeter wave region (instrumentation and measurement of index of refraction)
The Properties of Materials in the Submillimeter Wave Region study was initiated to instrument a system and to make measurements of the complex index of refraction in the wavelength region between 0.1 to 1.0 millimeters. While refractive index data is available for a number of solids and liquids there still exists a need for an additional systematic study of dielectric properties to add to the existing data, to consider the accuracy of the existing data, and to extend measurements in this wavelength region for other selected mateials. The materials chosen for consideration would be those with useful thermal, mechanical, and electrical characteristics. The data is necessary for development of optical components which, for example, include beamsplitters, attenuators, lenses, grids, all useful for development of instrumentation in this relatively unexploited portion of the spectrum.
Lally, J.↗
Diode multipliers for submillimeter-wave InAlAs/InGaAs heterostructure monolithic integrated circuits
InAlAs/InGaAs heterostructures are studied as multiplier elements for submillimeter-wave monolithic integrated circuits. The designs considered for this purpose are based on the principle of conventional HEMT, HEMT with n+ bottom layer, and a new proposed scheme of quantum-confined modulated charge (QCMC). The QCMC diode is analyzed theoretically and experimentally showing its potential operation capability at 1.5 THz.
Kwon, Y.↗
The millimeter- and submillimeter-wave spectrum of (C-13)H3OH revisited
A total of 245 previously unobserved millimeter- and submillimeter-wave transitions of (C-13)H3OH for J not above 10 were assigned on the basis of measurements with a spectrometer which uses 40-60 GHz klystrons as fundamental radiation sources. These transitions were combined with the previously assigned 596 transitions and were analyzed using a modified internal-axis-method model which treats the symmetric (A) and degenerate (E) substates separately. As a result of the expansion of the (C-13)H3OH data set to cover the same range as the data set of a previous (C-12)H3OH analysis by Anderson et al. (1990), rigid criteria of self-consistency could be applied for the selection and the value of the constants between the isotopic species. The spectral constants obtained were used to make accurate predictions of 562 additional transitions of (C-13)H3OH for v(t) = 0, 1, 2 and rotational quantum number J equal to or less than 12.
Anderson, Todd↗
An extension of the high-resolution millimeter- and submillimeter-wave spectrum of methanol to high angular momentum quantum numbers
The high-resolution laboratory millimeter- and submillimeter-wave spectra of C-12H(3)OH and C-13H(3)OH have been extended to include transitions involving significantly higher angular momentum quantum numbers than studied previously. For C-12H(3)OH, the data set now includes 549 A torsional substate transitions and 524 E torsional substate transitions through J is not greater than 24, exclusive of blends. For C-13H(3)OH the data set now includes 453 A torsional substate transitions and 440 E torsional substate transitions through J is not greater than 24, exclusive of blends. The extended internal axis method Hamiltonian has been used to analyze the transitions to experimental accuracy. The molecular constants determined by this approach have been used to predict accurately the frequencies of many transitions through J = 25 not measured in the laboratory.
Anderson, Todd↗
Projected noise in submillimeter-wave mixers with InSb Schottky diodes
The reduction of the equivalent noise temperature in liquid-nitrogen-cooled submillimeter-wave mixers by the use of Schottky barriers on InSb instead of GaAs is evaluated by an analytical model that assumes limited local oscillator power and matched impedances. The calculations, executed at 1.0 and 1.8 THz, take plasma resonance and skin effect into account. For single and multiple contacts on homogeneous semiconductor materials of optimum doping, the noise of InSb diodes is smaller than that of GaAs diodes by a factor of 3 to 14. A simplified model is used to predict the performance of epitaxial structures as well as alternative materials.
Lieneweg, U.↗
Submillimeter-wave properties of thermospheric rocket plumes
The problem of detecting rocket plumes at thermospheric altitudes with satellite-borne submillimeter-wave radiometers is examined theoretically. To estimate the sizes of plume signatures contrasted against a 250-K earth background or in self-emission against the cold sky, a computer program has been developed to predict plume brightness temperatures and optical depths of rotational lines of plume molecular constituents (e.g., H2O) as a function of distance from the nozzle. The methods employed in the computations are described in general terms, and examples are presented to indicate that detectable H2O signatures extending to several thousand nozzle diameters should exist at plume altitudes above 250 km.
Litvak, M. M.↗
Small Explorer project: Submillimeter Wave Astronomy Satellite (SWAS). Mission operations and data analysis plan
The Mission Operations and Data Analysis Plan is presented for the Submillimeter Wave Astronomy Satellite (SWAS) Project. It defines organizational responsibilities, discusses target selection and navigation, specifies instrument command and data requirements, defines data reduction and analysis hardware and software requirements, and discusses mission operations center staffing requirements.
Melnick, Gary J.↗
The Submillimeter-wave Rotational Spectra of Interstellar Molecules
We discuss past and recent progress in our long-term laboratory program concerning the submillimeter-wave rotational spectroscopy of known and likely interstellar molecules, especially those associated with regions of high-mass star formation. Our program on the use of spectroscopy to study rotationally inelastic collisions of interstellar interest is also briefly mentioned.
Herbst, Eric↗