Performance Evaluation of Irbene RT-16 Radio Telescope Receiving System

Abstract In the present paper, recent measurement results of refurbished Irbene RT-16 radio telescope receiving system performance are presented. The aim of the research is to evaluate characteristics of RT-16, which will allow carrying out necessary amplitude calibration in both single dish and VLBI observations, to improve the performance of existing system as well as to monitor, control and compare performance if possible changes in the receiving system will occur in future. The evaluated receiving system is 16 m Cassegrain antenna equipped with a cryogenic receiver with frequency range from 4.5 to 8.8 GHz, which is divided into four sub-bands. Multiple calibration sessions have been carried out by observing stable astronomical sources with known flux density by using in-house made total power registration backend. First, pointing offset calibration has been carried out and pointing model coefficients calculated and applied. Then, amplitude calibration, namely antenna sensitivity, calibration diode equivalent flux density and gain curve measurements have been carried out by observing calibration sources at different antenna elevations at each of the receiver sub-bands. Beam patterns have also been evaluated at different frequency bands. As a whole, acquired data will serve as a reference point for comparison in future performance evaluation of RT-16.

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The New Wuqing 70 m Radio Telescope and Measurements of Main Electronic Properties in X-band

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/ac47ab ◽

2022 ◽

Author(s):

De-Qing Kong ◽

Chunlai Li ◽

Hongbo Zhang ◽

Yan Su ◽

Jian-Jun Liu ◽

...

Keyword(s):

Flux Density ◽

Radio Telescope ◽

Noise Temperature ◽

Calibration Model ◽

Space Communications ◽

Condi Tions ◽

X Band ◽

Measurement Results ◽

Pointing Accuracy ◽

Exploration Mission

Abstract The new Wuqing 70 m radio telescope is firstly used for the downlink data reception in the first Mars exploration mission of China, and will be used for the other deep space communications and radio astronomical observations in the future. The main specifications and measurement results of some properties in X-band are introduced in this paper, such as pointing calibration, gain and efficiency, system noise temperature, system equivalent flux density, and variations with elevation. The 23 parameters pointing calibration model considering the atmospheric refraction correction in real time is presented in the telescope, and the pointing accuracy is reached 5.70″ in azimuth direction and 6.07″ in elevation direction respectively for different weather condi-tions. More than 62% efficiencies are achieved at full elevation range, and more than 70% in the mid-elevation. The system equivalent flux density of X-band in the mid-elevation is reached 26 Jy.

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HYGIENIC ASSESSMENT OF ELECTROMAGNETIC RADIATION LEVELS OF BASE STATIONS,INSTALLED ON THE ROOFS OF BUILDINGS AND THE TERRITORY OF LAND PLOTS IN TASHKENT

UZBEK MEDICAL JOURNAL ◽

10.26739/2181-0664-2021-5-1 ◽

2021 ◽

Vol 2 (5) ◽

pp. 5-11

Author(s):

G. A. Tashpulatova ◽

◽

A. N. Krasavin

Keyword(s):

Public Health ◽

Electromagnetic Radiation ◽

Flux Density ◽

Energy Flux ◽

Mobile Communications ◽

Base Station ◽

Base Stations ◽

Cellular Communications ◽

Measurement Results ◽

Energy Flux Density

This article is about instrumental measurements of the FR EMR energy flux density. The measurement results were analyzed with the division of the data obtained by the purpose of buildings and the height of the antenna equipment placement, a hygienic assessment of the RF EMR levels created by the equipment of base stations of cellular communications, installed on the roofs of residential and public buildings and adjacent territories of Tashkent is given. A proposal is made on the rational placement of radio engineering facilities.Keywords:electromagnetic field; electromagnetic safety; base station for mobile communications; protection of public health; sanitary supervision

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The Distribution of Radio Polarisation in Three Southern Galaxies

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000024073 ◽

1991 ◽

Vol 9 (2) ◽

pp. 266-268

Author(s):

J. I. Harnett ◽

U. Klein ◽

R. Wielebinski ◽

R. F. Haynes

Keyword(s):

Cosmic Rays ◽

Magnetic Fields ◽

Radio Telescope ◽

Spiral Galaxies ◽

Total Power ◽

Transport Mechanisms ◽

Contour Plots ◽

Preliminary Study ◽

Poloidal Magnetic Fields

AbstractWe are studying the distribution and morphology of magnetic fields in southern face-on and edge-on galaxies with the intention of clarifying the distribution, lifetimes and transport mechanisms of cosmic rays, and investigating the intensity and orientation of the disc, halo and poloidal magnetic fields. As a preliminary study, before the Australia Telescope was available, we observed a sample of well-known southern spiral galaxies with the Parkes radio telescope.Here, we present the resulting polarisation images for three galaxies, NGC 253, M 83 and NGC 4945, which were observed at 4.75 GHz and 8.55 GHz. The corresponding total power contour plots have been already published by Harnett et al. (1989a, 1990).

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Performance Evaluation of Two Port and Four Port Measurement for Twisted Pair Cable

International Journal of Electrical and Computer Engineering (IJECE) ◽

10.11591/ijece.v8i4.pp2624-2632 ◽

2018 ◽

Vol 8 (4) ◽

pp. 2624

Author(s):

Azhari Bin Asrokin ◽

Mohamad Kamal Bin A. Rahim

Keyword(s):

Performance Evaluation ◽

Frequency Band ◽

Measurement Technique ◽

Network Analyzer ◽

Differential Mode ◽

Twisted Pair ◽

The Core ◽

S Parameter ◽

Measurement Results ◽

S Parameters

A balance-unbalance (balun) transformer is commonly used to connect the balance 100 Ohm twisted pair cable to the unbalance 50 Ohm network analyzer ports, but due to the limitations of the core (i.e. ferrite) inside the balun, the balun can only effectively operates at a certain band of frequencies. This limitation can be eliminated by using a 4-port vector network analyzer (VNA) which is done by connecting the VNA’s ports to each conductor end. The extracted S-parameters will then be transformed to a 2-port S-parameters in differential mode at both ports. To validate the measurement technique, S-parameter measurement by using the 4-Port Network Analyzer without any balun will be compared to the measurement which used the 2-Port Network Analyzer with the balun transformers. Two twisted pair cable distances are selected as reference which are 500, and 1000 meters with nominal copper diameter of 0.5mm. Based on the measurement results, the 4-ports measurement shows good correlation with the 2-ports measurement especially at 500m distance. This shows that the 4-ports measurement setup is suitable to be used to measure twisted pair copper cable and possible to measure at a higher frequency band such as up to 500 MHz but at a shorter twisted pair cable distance.

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5 Years of VLBI and X-Ray Observations of NRAO 140

Symposium - International Astronomical Union ◽

10.1017/s0074180900133881 ◽

1988 ◽

Vol 129 ◽

pp. 35-36

Author(s):

Alan P. Marscher

Keyword(s):

Flux Density ◽

Low Frequency ◽

Total Flux ◽

X Ray ◽

The Core ◽

Vlbi Observations ◽

Superluminal Motion ◽

Low Frequency Variability ◽

Jet Structure

The author and his collaborators have observed NRAO 140 twice at X-ray energies and numerous times with multifrequency VLBI. The VLBI observations reveal a knotty jet structure with superluminal motion of the innermost two knots relative to the core. The VLBI core decreased by about a factor of 2 in flux density between 1980 and late 1984. The X-ray flux also declined by about the same factor during this period. Monitoring at 18 cm during periods of low-frequency variability has revealed pronounced changes in the relative brightnesses of the components of the source while the total flux density has varied by ≲ 10%.

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e-VLBI observations of GRB 080409 afterglow with an Australasian radio telescope network

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/16/11/164 ◽

2016 ◽

Vol 16 (11) ◽

pp. 164

Author(s):

Aquib Moin ◽

Philip G. Edwards ◽

Steven J. Tingay ◽

Chris J. Phillips ◽

Anastasios K. Tzioumis ◽

...

Keyword(s):

Radio Telescope ◽

Vlbi Observations

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Space-VLBI observations of OH masers

Symposium - International Astronomical Union ◽

10.1017/s0074180900222171 ◽

2002 ◽

Vol 206 ◽

pp. 105-111 ◽

Cited By ~ 2

Author(s):

Vyacheslav I. Slysh ◽

Maxim A. Voronkov ◽

Irina E. Val'tts ◽

Victor Migenes ◽

K.M. Shibata ◽

...

Keyword(s):

Brightness Temperature ◽

Lower Limit ◽

Radio Telescope ◽

Angular Resolution ◽

Main Line ◽

Radio Telescopes ◽

Space Radio Telescope ◽

Vlbi Observations ◽

Interstellar Scattering

We report on the first space-VLBI observations of the OH masers in two main-line OH transitions at 1665 and 1667 MHz. The observations involved the space radio telescope on board the Japanese satellite HALCA and an array of ground radio telescopes. The maps of the maser region and images of individual maser spots were produced with an angular resolution of 1 mas, which is several times higher than the angular resolution available on the ground. The maser spots were only partly resolved and a lower limit to the brightness temperature 6 × 1012 K was obtained. The masers seem to be located in the direction of low interstellar scattering.

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Radio light-curve for WR 146 (HM19-3, WC6+O8.5), a colliding wind binary

Symposium - International Astronomical Union ◽

10.1017/s0074180900205883 ◽

1999 ◽

Vol 193 ◽

pp. 390-391

Author(s):

Diah Y.A. Setia Gunawan ◽

A. Ger de Bruyn ◽

Karel A. van der Hucht ◽

Peredur M. Williams

Keyword(s):

Light Curve ◽

Flux Density ◽

Radio Telescope ◽

Time Scale ◽

Preliminary Results ◽

Average Flux

We report preliminary results of monitoring the flux from the Wolf-Rayet object WR 146 with the Westerbork Synthesis Radio Telescope at 21 cm since 1989. We find the average flux density slowly rising in the period 1989–1997, with evidence of shorter time-scale variability.

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