An Active "Cold" Noise Source

Frater, R. H.; Williams, D. R.

doi:10.1109/tmtt.1981.1130355

Cited by 76 publications

(26 citation statements)

References 5 publications

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“…For MIAWARA-C a commercial available active cold load, a so-called Colfet similar to the one described in Frater and Williams (1981), is used. Laboratory tests showed its noise temperature to be around 140 K.…”

Section: Correlation Receivermentioning

confidence: 99%

MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

2010

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Abstract. In this paper a new 22 GHz water vapor spectroradiometer which has been specifically designed for profile measurement campaigns of the middle atmosphere is presented. The instrument is of a compact design and has a simple set up procedure. It can be operated as a standalone instrument as it maintains its own weather station and a calibration scheme that does not rely on other instruments or the use of liquid nitrogen. The optical system of MIAWARA-C combines a choked gaussian horn antenna with a parabolic mirror which reduces the size of the instrument in comparison with currently existing radiometers. For the data acquisition a correlation receiver is used together with a digital cross correlating spectrometer. The complete backend section, including the computer, is located in the same housing as the instrument. The receiver section is temperature stabilized to minimize gain fluctuations. Calibration of the instrument is achieved through a balancing scheme with the sky used as the cold load and the tropospheric properties are determined by performing regular tipping curves. Since MIAWARA-C is used in measurement campaigns it is important to be able to determine the elevation pointing in a simple manner as this is a crucial parameter in the calibration process. Here we present two different methods; scanning the sky and the Sun. Finally, we report on the first spectra and retrieved water vapor profiles acquired during the Lapbiat campaign at the Finnish Meteorological Institute Arctic Research Centre in Sodankylä, Finland. The performance of MIAWARA-C is validated here by comparison of the presented profiles against the equivalent profiles from the Microwave Limb Sounder on the EOS/Aura satellite.

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Section: Correlation Receivermentioning

confidence: 99%

MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

2010

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“…The additional advantage of an electronic reference is that it does not generate undesired interference with the environment and the science signal. The basic principles behind this design was first developed in (Frater & Williams 1981), but so far there are only few existing implementations shown in Fabry & Meunier (2009) ;Straub, Murk & Kämpfer (2010) ;Scheeler & Popovic (2013).…”

Section: The Pseudo Correlation Receiver and The Cold Reference Sourcementioning

confidence: 99%

An integrated system at the Bleien Observatory for mapping the Galaxy

Chang

Monstein

Akeret

et al. 2016

Mon. Not. R. Astron. Soc.

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We describe the design and performance of the hardware system at the Bleien Observatory. The system is designed to deliver a map of the Galaxy for studying the foreground contamination of low-redshift (z=0.13-0.43) H I intensity mapping experiments as well as other astronomical Galactic studies. This hardware system is composed of a 7m parabolic dish, a dual-polarization corrugated horn feed, a pseudo correlation receiver, a Fast Fourier Transform spectrometer, and an integrated control system that controls and monitors the progress of the data collection. The main innovative designs in the hardware are (1) the pseudo correlation receiver and the cold reference source within (2) the high dynamic range, high frequency resolution spectrometer and (3) the phase-switch implementation of the system. This is the first time these technologies are used together for a L-band radio telescope to achieve an electronically stable system, which is an essential first step for wide-field cosmological measurements. This work demonstrates the prospects and challenges for future H I intensity mapping experiments.

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“…The theoretical foundations of cold transistor circuits were laid in 1981 [1], when it was shown that noise temperatures below ambient temperature could be achieved for FET based circuit by proper matching network design. Noise wave based analysis and generalised design flow have been presented in [11].…”

Section: Theorymentioning

confidence: 99%

“…Typical target temperature for the earth observation radiometers is 100-300 K and ACLs can provide low temperature calibration point. Previously published ACL realisations include hybrid designs [1][2][3][4][5] and monolithic microwave integrated circuit (MMIC) designs [6][7][8] for RF and microwave regions. The first millimetre wave MMIC designs have been reported in [9].…”

Section: Introductionmentioning

confidence: 99%

Active cold load MMICs for Ka‐, V‐, and W‐bands

Kantanen

Weißbrodt

Varis

et al. 2015

IET Microwaves, Antennas & Propagation

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Three active cold load circuits operating at millimetre-wave frequencies are presented. The circuits have been manufactured using 100 nm metamorphic high electron mobility transistor technology. On-wafer measurements of noise temperature and match are presented. Measured noise temperatures are 75 K, 141 K, and 170 K at 31.4 GHz, 52 GHz, and 89 GHz, respectively. Measured reflection coefficients are better than -19 dB for all designs

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An Active "Cold" Noise Source

Cited by 76 publications

References 5 publications

MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

An integrated system at the Bleien Observatory for mapping the Galaxy

Active cold load MMICs for Ka‐, V‐, and W‐bands

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