A Multibeam SIS Mixer Module for a Focal Plane Array Receiver

The integration of many receiver units into a receiver array is a common method of improvement of imaging systems. This approach, well known in the mm band for Schottky mixer arrays, has not so far been developed for Superconductor - Insulator - Superconductor (SIS) junction mixers, which give the best sensitivity in the short mm wave range and in the submm range.We demonstrate for the first time a practical low noise multibeam receiver module using SIS mixer technology. The basis for the integration of several SIS mixers with a common local oscillator source is given by the saturation of the SIS receiver noise dependence upon local oscillator power. The module comprises three identical SIS mixers integrated with a common local oscillator, coupled through a three branch waveguide directional coupler. The multibeam module has been developed for a focal plane array receiver of the 30 meter radio telescope of the Institut de Radioastronomie Millimétrique (IRAM).     

A 345 GHZ heterodyne receiver for the James Clerk Maxwell Telescope

In this paper we describe the design and performance of a low-noise 345 GHz heterodyne receiver. The mixer uses a lead alloy SIS tunnel junction mounted in reduced height rectangular waveguide and is tuned with a single backshort. Local oscillator power is provided by a broad-band Gunn oscillator which drives a frequency quadrupler. The heterodyne performance has been verified in the laboratory using a gas absorption cell. In November 1991 this receiver was successfully commissioned and by direct comparison with a Schottky diode receiver we confirm a best receiver noise temperature of 150K (DSB) at 355 GHz and a tuning range of 300 to 380 GHz. The receiver is now available as a JCMT facility instrument.     

Development of the physical principles of the design and implementation of a 500–700 GHz spectrometer with a superconducting integrated receiver

A spectrometer based on the effect of freely decaying polarization in the frequency range 500–700 GHz has been designed. Radiation sources are harmonics from a quantum semiconductor superlattice frequency multiplier. The receiving system of this spectrometer is constructed using a superconducting integrated receiver based on a superconductor-insulator-superconductor mixer and a flux-flow oscillator operating as a heterodyne oscillator. The spectrometer has been used to measure absorption lines of NH₃ in a sample of expired air (572 GHz).     

A 492 GHz Submillimeter-Wave Receiver

A 492 GHz submillimeter receiver was designed for application to the POrtable Submillimeter Telescope (POST). The receiver includes a Schottky diode mixer, a phase-locked Gunn oscillator at 82.3 GHz coupled with multipliers (×2×3), and low-noise amplifiers. In this paper, the system configuration and performance will be introduced.     

Integrated Superconducting Submillimeter-Wave Receivers

We overview recent achievements in the field of cryogenic submillimeter-wave receivers based on superconductor–insulator–superconductor (SIS) tunnel junctions. The main attention is paid to the novel superconducting integrated receivers (SIRs) with an on-chip superconducting local oscillator. The single-chip microcircuit of the receiver, which integrates a quantum mixer based on the nonlinearity of a quasi-particle current in the SIS junction, a planar superconducting receiving antenna, and a cryogenic local oscillator, is described. Being dc-powered only by batteries, such a microcircuit operates as a submillimeter-wave superheterodyne receiver without any additional microwave equipment. Such receivers are very attractive for radioastronomical research, space communication systems, and monitoring of the environment from satellites, balloons, and special aircraft. A breadboard of a superconducting spectrometer with a phase-locked flux-flow oscillator (FFO) has been developed and tested. A frequency resolution better than 10 kHz was reached at a frequency of 365 GHz. We describe a balloon-borne 500-650 GHz integrated spectrometer for oblique atmospheric sounding, developed for the international Terahertz Limb Sounder (TELIS) project. The first flight is scheduled for 2005.     

Integrated superconducting spectrometer for atmosphere monitoring

The results of the development of sub-mm Superconducting Integrated Receiver (SIR) for monitoring of the Earth’s atmosphere from high-altitude balloons are presented. The microchip of the superconducting integrated receiver comprising local oscillator based on the long Josephson junction (flux flow oscillator, FFO) is developed and successfully tested. The receiver noise temperature as low as 200 K is measured at a frequency of 650 GHz. The possibility to phase-lock FFO to the reference oscillator, which is vitally important for spectrometer operation, is demonstrated. To ensure the possibility of remote tuning of a phase-locked (PL) SIR onboard a balloon, a number of approaches for the PL SIR automatic computer control are developed and tested. New modifications of the superconducting local oscillator (FFO) are developed, fabricated and tested. The FFO design is optimized for the integrated spectrometer. The FFO linewidth is studied at frequencies of up to 700 GHz using a specially developed technique. A free-running linewidth between 9 and 2 MHz is measured in the frequency range from 500 to 700 GHz. As a result, the spectral ratio of the phased-locked FFO ranges from 35 to 90%. The effect of FFO linewidth imperfections on the retrieval procedure of the atmosphere gas spectra is studied.     

A W-band microwave receiver for Te diagnosis in the tokamak TJ-1

This paper describes a 95 GHz receiver system based on a solid state oscillator which makes it possible to measure the electron temperature of the plasma in the tokamak TJ-1. We discuss the construction of the receiver system and its calibration, which is carried out by using a noise source in this band. The characteristics obtained for a 0,5 eV signal are presented. The results show that the receiver has a very low noise level, even for powers on the order of several picowatts.     

L波段合成孔径辐射计接收链路分析与设计

提出了合成孔径辐射计对接收链路的技术要求,并在此基础上设计了工作于L波段的合成孔径辐射计的接收链路.通过ADS(Advanced Design System)软件对该接收链路进行了系统级仿真,仿真结果表明,系统增益为129 dB,噪声系数约为1.8 dB,满足了设计目标对系统增益和噪声系数的要求.     

一类混沌系统的同步方法

针对一类混沌系统的特点,任意构造满足一定条件的响应系统,根据滑模控制策略得到实现两者同步的反馈控制器.在可测同步误差基础上,利用扩张状态观测器来估计驱动系统与“构造”的响应系统之间的差异,把上述反馈控制策略转变为物理可实现的控制器并实现两者的同步.以Duffing和Chua’s电路为例的仿真表明效果良好 关键词： 混沌同步 滑模控制 扩张状态观测器     

A microprocessor stabilized submillimeter laser system

A mechanically and thermally stable submillimeter laser has been constructed and has an amplitude and frequency stability suitable for use as a local oscillator in a heterodyne receiver for astronomical investigations. The microprocessor stabilization reduces the receiver noise for different kinds of Schottky barrier diodes used. A short-time amplitude stability (10 minutes) of about ±0.5% and a long time amplitude stability (1 hour) of about ±1.2% have been recorded. Integration times up to one hour with a spectral resolution better than 200 KHz are possible with such a stabilized system.     

Investigation of a heterodyne receiver with open structure mixer at 324 GHz and 693 GHz

The performance of a submillimeter heterodyne receiver using an HCOOH laser local oscillator and an open structure mixer with a Schottky barrier diode has been optimized for 693 GHz. Working at room temperature a single sideband (SSB) system noise temperature of 7,300 K, a mixer noise temperature of 6,100 K and a conversion loss of 12 dB has been achieved. The same receiver system has been investigated at 324 GHz using an HCOOD laser local oscillator yielding a noise temperature of 3,100 K (SSB), a mixer noise temperature of 2,400 K (SSB) and a conversion loss of 10 dB (SSB). An acousto-optical spectrometer has also been constructed, with 1024 channels and a channel-bandwidth of 250 kHz. The system NEP per channel was 2.5×10^–17 W/Hz^1/2 at 324 GHz and 5.0×10^–17 W/Hz^1/2 at 693 GHz.     

Gunn oscillator injection locking circuit at millimeter wave frequencies

Millimeter wave frequencies are proposed as carriers of microcell future mobile systems. High frequencies in the region of 60–62 Ghz are suggested. A serious difficulty in this context is the lack of sufficient gain in active devices. Both on receiver and transmitter units this difficulty is faced. Mixing, amplification, carrier recovery and modulation / demodulation subsytems are required to be operational at these higher frequencies. Presently the MMIC 's show also limited performance. In this report an alternative approach active processing technique is examined based on an injection locking in Gunn oscillator. A non-linear analysis is applied to determine the fundamental properties of injection locking in Gunn oscillator performance under the influence of an external signal. Details of waveguide action is taken into account by solving the corresponding boundary condition problem. Finally experimental results are presented for a 30GHz oscillator.     

Quantum Homodyne Detection Based on Polarization Diversity Technique

A polarization diversity receiver scheme is presented for improving efficiency of balance homodyne detection. The proposed scheme may mitigate polarization fluctuation between signal and local oscillator field. With simple linear optical component and electronic processing circuit, the noise caused by differential phase and polarization mode between signed and local oscillators may be significantly decreased. To track the polarization fluctuation, a novel algorithm based on polarization diversity receiver which can achieve better performance in terms of linear quantum optics principle is proposed.     

Minimum noise temperature of a practical SIS quantum mixer

Noise temperature of a SIS quantum mixer has been calculated as function of local oscillator voltage and signal source conductance on the basis of a measured I–V characteristic. Applying Tucker's quantum theory of mixing /1/, it is shown that the SIS mixer is quantum noise limited. Using cryogenic intermediate frequency amplifier, receiver noise temperature of 20 K seems to be possible at mm wavelength.     

The UCB/MPE cassegrain submillimeter heterodyne spectrometer

The UCB/MPE Submillimeter Heterodyne Spectrometer is a system for ascronomical spectroscopy in the high-frequency atmospheric windows from 500 to 1000 GHz. It contains a molecular laser local oscillator, a cooled Schottky open structure mixer, a quasi-optical coupling system, and an acousto-optical spectrometer. The compact receiver mounts at the Cassegrain focus of large infrared astronomical telescopes. The receiver noise temperature on the telescope is approximately 3500 K (DSB) during observations of the CO J=76 line at 806.652 GHz. The spectrometer's frequency resolution and instantaneous bandwidth (<2 MHz resolution across 1.1 GHz) are well suited for observations of molecular emission lines from a variety of astronomical sources.     

8mm波段外差时序多色仪实验

诊断托卡马克及其他磁约束聚变装置等离子体电子温度分布的有效手段之一是测量其电子迴旋辐射谱。现在世界上各聚变实验室为此所使用的谱仪有两大类:一类是时序谱仪,其中有扫频外差接收机和各种扫描干涉仪(如法-玻干涉仪,迈克尔逊干涉仪等);另一类是多色仪(如光栅光谱仪)。谱仪的频率范围一般在毫米波和亚毫米波段。对时序谱仪的要求除具有一定的频带宽度和接收灵敏度外,最主要的是扫描速率(指完成一幅给定谱宽的测量所需的时间T_t)。目前以返波管为本振的扫频外差接收机扫描速率最高。如60—90GHz扫频仪,T_t=1—10ms。各种扫描干涉仪则由于采用机械扫描,速率较低。     

Optical phase locked-loop homodyne receiver using an eight-port 90° optical hybrid

The performance of a PSK optical phase locked-loop (PLL) homodyne system based on an eight-port 90° optical hybrid, which is used to suppress the local oscillator (LO) intensity noise in both data recovery arm (I arm) and carrier recovery arm (Q arm), is evaluated. Incomplete cancellation of LO intensity noise results from unmatched photodetectors, couplers pathlengths, and non-ideal couplers power splitting ratio. Optimum LO power can be found for the given receiver parameters.     

AN UNCOOLED VERY LOW NOISE SCHOTTKY DIODE RECEIVER FRONT-END FOR MIDDLE ATMOSPHERIC OZONE AND CARBON MONOXIDE MEASUREMENTS

The paper describes an uncooled front-end of the Schottky diode receiver system, which may be applied for observations of middle atmospheric ozone and carbon monoxide thermal emission lines at frequencies 110.8 GHz and 115.3 GHz, respectively. The mixer of the front-end has utilized high-quality Schottky diodes that allowed us to reduce the mixer conversion loss. The combination of the mixer and an ultra-low-noise IF amplifier in the one integrated unit has resulted in double-sideband (DSB) receiver noise temperature of 260 K at a local oscillator (LO) frequency of 113.05 GHz in the instantaneous IF band from 1.7 to 2.7 GHz. This is the lowest noise temperature ever reported for an uncooled ozone receiver system with Schottky diode mixers.     

Compact 1.9 THz BWO local-oscillator for the GREAT heterodyne receiver

The 1.9 THz local-oscillator (LO) of the GREAT heterodyne receiver is presented. The LO is based on a frequency tripled backward-wave oscillator source. The frequency stabilization system is described and an astigmatic imaging system, developed for improved beam coupling, is presented. Allan variances and temperature dependent power drifts are analyzed. The LO is designed as a stand-alone system and fits into GREAT’s local-oscillator compartments. It produces more than 1.5 μW of stable output power to pump the hot electron bolometer mixers of the GREAT instrument.