Low-noise heterodyne receivers for near-millimeter-wave radio astronomy

Increased interest in the near-millimeter wavelength region, covering the range 3 mm to 300 µm, during the past decade has stimulated the development of sensitive heterodyne receivers for a wide range of applications. This review paper considers current low-noise receiver technology with emphasis on applications in radio astronomy. A brief discussion of the astrophysical importance of radio astronomy at millimeter wavelengths is presented. The concepts of receiver design and the particular problems associated with this region of the spectrum are discussed. The optimization of material parameters and device topology for both Schottky-barrier diodes and superconducting mixer elements is considered. The extension of waveguide mixer technology into the submillimeter region and the development of quasi-optical receivers is reviewed. Consideration is given to the recent development of efficient harmonic generators for local oscillator (LO) applications at near-millimeter wavelengths.     

Submillimeter receivers for radio astronomy

The state of development of receivers for submillimeter-wave radio astronomy is reviewed. Bolometers for continuum observation, hot-electron mixer receivers for narrowband spectral line observation, and heterodyne receivers, both Schottky diode and superconducting tunnel junction, are presented. At the lower frequency end of the submillimeter band, standard waveguide techniques, scaled from millimeter wavelengths, prevail. At wavelengths shorter than about 0.5 mm, quasioptical designs are preferred. In the case of Schottky diode receivers, corner cube designs are used almost exclusively, whereas integrated mixer designs are the focal point of research for superconductor-insulator-superconductor (SIS) receivers at these wavelengths. Although such designs are extensively reviewed, it is nevertheless the Schottky diode mixer remains the element of choice at the shortest submillimeter wavelengths     

Submillimeter astronomy [heterodyne spectroscopy]

Some of the aspects of submillimeter-wave astronomy which are relevant to the field of heterodyne spectroscopy are reviewed. Most of the discussion concerns the dense interstellar medium where stars are forming, with some work presented on nearby galaxies. Extremely sensitive receivers, large accurate telescopes, and high-mountain, airborne, or space platforms are gradually being developed, so that information is steadily improving in quality and scope. Examples are given of line surveys of heavy molecule spectra, extending from millimeter wavelengths well into the submillimeter, of light molecule spectroscopy, and of atomic fine-structure spectroscopy. The importance of the spatial information on atomic and ionized carbon is discussed. The gas cooling process which allows clouds to collapse to form stars by means of the submillimeter line emission is discussed. Also covered are regions suffering shocks, photodissociation regions, and stellar outflow regions. Work on the submillimeter spectrum of nearby galaxies is briefly described     

短毫米波和亚毫米波接收机的发展现状

本文概述了短毫米和亚毫米波接收机的发展现状，介绍了接收机的重要组成部件：混频器、振荡器和放大器的发展水平以及毫米波单片集成电路的现状，给出了接收机的最新性能指标。     

Radar astronomy at millimeter and submillimeter wavelengths

The scant two-decade existence of radar astronomy has seen important contributions by this new technique to positional astronomy, to the metrics of the solar system, and to the study of lunar and planetary surfaces. The role of millimeter wavelengths in this new astronomy is discussed and the problems unique to these short wavelengths defined. Brief mention is made of the importance of correlation of active and passive measurements and important new millimeter wave component requirements are listed. The implementation of an eight-millimeter radar capable of detecting the moon is described. At the eight-millimeter wavelength, the moon is found to be generally rough and has a radar cross section of about seven percent of its projected geometrical area. Methods of improving these measurements and their feasibility are outlined. Future equipment configurations capable of extending millimeter wave measurements can be implemented, given critical component development success.     

Spurious Signal Response of Broadband Solid–State Frequency Multipliers at Millimeter and Submillimeter Wavelengths

Heterodyne instruments at millimeter and submillimeter wavelengths often use wideband fixed-tuned frequency multipliers, in conjunction with broadband power amplifiers driven by frequency synthesizers, as the local oscillator (LO) source. At these frequencies the multipliers use Gallium Arsenide (GaAs) based Schottky varactor diodes as the nonlinear element, and like most other harmonic generators are susceptible to spurious signal interference. The state-of-the-art LO sources at these wavelengths use high power MMIC amplifiers at the initial stages, and are used to drive the subsequent multiplier stages to have enough LO power to pump the mixers. Because of the high input power environment and the presence of noise in the system, the multipliers become vulnerable to spurious signal interference. As the spurious signals propagate through the receiver system, they generate inter-modulation products which might fall in the passband of the heterodyne instrument and seriously degrade its performance. In this paper spurious signal response of solid-state frequency multipliers at millimeter and submillimeter wavelengths is investigated. Results of numerical harmonic balance simulations and laboratory experiments, which were found to show good agreement, are presented here.     

Noise Reduction in GaAs Schottky Barrier Mixer Diodes (Short Paper)

The sensitivity of heterodyne receivers operating at millimeter and submillimeter wavelengths is limited by the noise produced in the mixer element. In this paper we investigate the presence of excess noise in GaAs Schottky barrier mixer diodes. Comparison of the measured noise data with that predicted from noise models indicates that these devices typically exhibit excess noise. An additional fabrication step, which removes several hundred angstroms from the GaAs surface before the anode contact is formed, greatly reduces this excess noise. This additional step is outlined, and experimental evidence is presented.     

A bulk semiconductor imaging device for millimeter and submillimeter radiation

A device is described whereby millimeter or submillimeter wave images obtained from reflecting targets can be converted to visible displays providing a cathode ray tube presentation. The principle of the technique is based on the fact that transmitted power at these wavelengths can be modulated by a semiconductor panel in which the bulk conductivity is changed by electronic means. Experimental data is reported.     

毫米波准光功率合成技术的研究进展

总结了毫米波、亚毫米波频段的准光功率合成技术的研究进展,介绍了准光功率合成技术早期的研究成果。重点讨论了近期提出的引入全息技术的准光功率合成技术。全息技术有效地解决了器件小型化和散热间的矛盾,能满足未来更高频率的输出功率和效率的要求。     

Fabrication of wire-grid polarizers and dependence of submillimeter-wave optical performance on pitch uniformity

We describe a device for fabricating high-precision free-standing grids of fine wire, suitable for use as polarizing elements for radiation at millimeter and submillimeter wavelengths. Computer control of the winding process makes changing grid parameters particularly convenient and flexible. We present measurements of the mechanical uniformity and of the optical performance of wire grid polarizers made with 25 μm and 10 μm diameter wire. The flexibility of computer control is exploited to introduce a known degree of randomness in the grid pitch (center-to-center wire spacing), allowing the dependence of polarizer quality on uniformity to be quantified. This information allows prediction of the fabrication tolerances required for polarizers to be used at very high frequencies.     

Schottky-Diode Realization for Low-Noise Mixing at Millimeter Wavelengths

A short review of the current theory and technology of low-noise Schottky-barrier diodes for use at millimeter wavelengths is presented. Recent advances in fabrication technology are discussed which have yielded photolithographically produced GaAs diodes with a cutoff frequency in excess of 3000 GHz together with improved noise performance due to reduced contamination of the contact. Noise producing mechanisms in diodes are outlined and the limitations of noise reduction by cooling are considered. Finally, methods for overcoming the high-frequency limitations of conventional GaAs Schottky diodes are assessed.     

Measurement of complex permittivity and permeability of materials by quasi-optical method

A quasi-optical method for measuring the complex permittivity and permeability of materials at millimeter and submillimeter wavelengths is proposed. In principle, this method is applicable not only to solid samples but also to liquid and composite samples. The theory and experiment are described in this paper.

     

Present State of the Millimeter Wave Generation and Technique Art--1958

Two of the few fruitful approaches to the low millimeter and submillimeter wave generation problem appear to be frequency multiplication by means of nonlinear phenomena and frequency conversion by parametric systems. Current work on frequency multiplication using relativistic megavolt beams, crystal diodes, field emitters, ferrites, etc., is reviewed. A brief account of present efforts to extend conventional tubes below wavelengths of 3 mm is presented. Waveguide components used at 1 to 2 mm are described.     

1C6--Cyclotron resonance in semiconductors with far infrared laser

The quantum effects in the degenerate valence bands of germanium have been observed as multiple cyclotron resonance absorption lines at a temperature of 165°K. Additional lines were resolved at 40°K. The combination of high intensity magnetic fields up to 180 000 gauss and the output power of a cyanide submillimeter laser (0.337 millimeters) was used. The construction and operation of a simple resonance spectrometer is described. Cryogenic techniques and the choice of detectors are discussed. The possible use of molecular gas laser spectrometers for EPR, ferrimagnetic resonance, and antiferromagnetic resonance at submillimeter wavelengths is considered.     

电子迴旋脉塞研究的现状和展望

电子迴旋脉塞作为开拓毫米波、亚毫米波波谱的高功率相干辐射源,近年来研究工作十分活跃,取得了不少鼓舞人心的新进展。本文综述了迴旋单腔振荡器、迴旋管放大器、高次谐波迴旋管和强流相对论迴旋管等电子迴旋脉塞各类器件的研究现状,指出了一些技术关键问题及其解决措施,并展望了它的发展前景。     

Resonance phenomena in the magnetized semiconductor plasma and their application for the design of the millimeter and submillimeter wave components

A review of physical principles of design as well as some ways of technical realization of controlled resonance semiconductor devices at millimeter and submillimeter wavelengths is presented. The operation of such devices is based on cyclotron and magnetoplasma resonances as well as on Fabry-Perot resonance. Such choice has been made due to the fact that these resonance phenomena are the most typical ones for the magnetized semiconductor plasma.     

Planar Log-Periodic Antennas on Extended Hemishperical Silicon Lenses for Millimeter/Submillimeter Wave Detection Applications

In this paper, the radiation properties of log-periodic (LP) antennas on extended hemispherical dielectric lenses are investigated. The starting point is the far field pattern for the log-periodic antenna on a semi-infinite silicon substrate obtained from numerical simulation. Then the effects of extended hemispherical silicon dielectric lenses on this far field pattern are evaluated using ray tracing and field integration techniques. The far fields patterns out of the lenses are derived as a function of the extension length (L), from which the optimum L can be determined. The coupling efficiencies of the pattern to Gaussian beams are also calculated. The computation results show that the log-periodic antennas have good performance in terms of impedance and pattern and can be used in many submillimeter/THz systems. The simulation methods are verified by comparing the simulation results with experimental data from literature. The utilized approach represents an effective method for log periodic antenna-lens system design at millimeter/submillimeter wavelengths.     

Evaluation of a simplified Doppler frequency shifter

Mechanical Doppler frequency shifting of a millimeter or submillimeter wave signal provides a means to implement a sensitive and highly coherent heterodyne receiver in a laboratory system. The rotary shifter, which we have previously described, is a precision-machined device suitable for use down to submillimeter wavelengths. We found at 140GHz, however, that the coherence of such a system is not affected by mechanical imprecision of the frequency shifter, and that the system dynamic range is only moderately affected by mechanical imprecision and by certain design simplifications. We have therefore built several versions of simpler and less precise Doppler frequency shifters and report here on their performance at 140GHz.