Frequency multipliers for millimeter and submillimeter wavelengths

Article Abstract:

All-solid-state local oscillators in the terahertz frequency range are required for space-borne radio astronomy and remote sensing of the atmosphere. Solid-state oscillators cannot yet produce the required local oscillator power at submillimeter wavelengths, however, so frequency multipliers are needed. Submillimeter-wave frequency multipliers are based primarily on a whisker-contacted Schottky diode as the nonlinear element. The multiplier theory and tools for analysis and design of millimeter- and submillimeter-wave multipliers are discussed. Also discussed are the Schottky diode model at submillimeter frequencies, use of Schottky multiplier chains versus direct higher-order multipliers, and the effect of cooling on Schottky diode multipliers. Among the alternative diodes presented are the high electron mobility varactor, barrier-intrinsic-n diode, barrier-n-n diode, quantum well diode, and single barrier varactor.

Integrated circuits, Circuit design, Diodes, Communications Circuits, Oscillators, Frequency Multipliers, Schottky TTL

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Submillimeter receivers for radio astronomy

Article Abstract:

The number of radio observatories dedicated to millimeter-wave observations of astronomical sources has increased rapidly since the beginning of millimeter-wave radio astronomy in the early 1970s. The submillimeter wave band is one of the last areas of the electromagnetic spectrum to be investigated. There are currently only two specially designed ground-based submillimeter telescopes in use: the James Clerk Maxwell Telescope and the Caltech Submillimeter Observatory, both on Mauna Kea, Hawaii. Submillimeter receiver instrumentation is comparable to the development of millimeter receivers in the 1980s. Among the receivers described are bolometers for continuum observation, hot-electron mixer receivers for narrow-band spectral line observation, and heterodyne receivers (Schottky diode and superconducting tunnel junction). The Schottky diode mixer is the element of choice at the shortest submillimeter wavelengths.

Bandwidth, Industry Analysis, Instruments, Bandwidth Technology, Frequency

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Millimeter and submillimeter wavelength radio astronomy

Article Abstract:

Improvements in the design and accurate construction of radio telescopes and related receiving equipment has resulted in successful observations in the millimeter and submillimeter wavelength ranges that have substantially changed our view of nature of the universe, particularly its chemistry. High-precision ground-based telescopes are approaching frequency resolutions of 1000GHz, while low-noise HEMT amplifiers and SIS mixers offer sensitivity within a factor of 4 of photon noise at 100GHz. The combination of these technologies has reduced the impacts of all noise sources, with the atmosphere being the sole major signal degradation source left. Details of the design and precision measurement of such telescopes, antennas, and receivers are described.

Systems analysis, Performance improvement (Computers), Trends, System Design, Telescopes, Performance Improvement, Radio Frequency, technical

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