Works in progress
Cryogenic 7-beam receiver for 19-26 GHz
A cooled receiver with limited mapping capabilities. It will be used to perform mapping in the molecular lines of water vapor (blind searches, surveys in molecular complexes) ans ammonia (mapping of star forming regions).
From top to bottom you can see the corrugated feed-horns, the noise injection couplers (scheme below), the polarizer and orhtomode transducers (gold plated), and the 14 InSb receivers (blue boxes). All these components are cooled to 15K to reduce thermal noise.
Measured total equivalent noise (including Dewar window) is 25 K. The receiver will be installed at the Medicina radiotelescope in January 2008, and will be one of the first receivers available on SRT.
16 channel spectropolarimeter
This is a spectropolarimeter based on the ALMA Tunable filterboard,
to be used together with the 7 beam dual poalrization receiver
described above.
As the ALMA TFB board is based on programmable logic, it can be reconfigured for completely different purposes. Here we have implemented on a single board 8 independent digital baseband converers (dBBC), and 4 dual channel FFT spectrometers, with a resolution of 4096 points.
The instrument is composed of 2 TFB boards, and 2 ADC boards, developed locally, with 8 250 MS/s ADCs.
Final tests are in progress. First astronomical tests on a single channel have been performed on W3OH water maser in May 2007.
References
- Banham R., Valsecchi G., Lucci L., Pelosi G., Selleri S., Natale V., Nesti R., Tofani G. 2005, Microwave Journal 48, 112 Electroformed front-end at 100 GHz for Radioastronomical applications
- Comoretto, G., D'Ambrosi, A., Nesti, R., Russo, A., Palagi, P. 2006, Arcetri Technical Report n. 4 A modular multichannel spectrometer - design study
- Comoretto, G., Russo, A. 2007, Arcetri Technical Report n. 2 Software di comunicazione con il correlatore Altera
- Cresci, L., Lucci, L., Orfei A., Natale, V., Nesti, R., Panella, D., Pelosi, G., Rossi, L. 2006, Mem. SAit 10, 50 Front-end design at 22 GHz for the Gregorian focus of the new Sardinia Radio Telescope
- Lucci, L., Nesti, R., Pelosi, G., Selleri, P. 2005, in "The Wiley Enciclopedia of RF and Microwave Engineering", Kai Chang Ed. John Wiley & Sons, (New York, NY, USA), 1, 883 Corrugated Horns Antennas
- Lucci, L., Nesti, R., Pelosi, G., Selleri, P., Tofani G. 2006, IEEE AP-S International Symposium, 3443. Design of a circular waveguide directional coupler at 22GHz
- Natale, V., Nesti, R. 2006, IRA Internal Report n. 383 Optical performances of thin and composite vacuum windows
- Orfei, A., Bolli, P., Carbonaro, L., Cremonini, A., Cresci, L., Idda, T., Mariotti, S., Monari, J., Natale, V., Nesti, R., Nicotra, G., Olmi, L., Panella, D., et al. 2006, Mem. SAIt, Suppl., 10, 34 The SRT receiving system and the receivers for the commissioning phase
- Simons, J., Bij de Vaate, J.G., Ivashina, M.V., Zuliani, M., Natale, V., Roddis, N. 2006, in "The European Conference on Antennas and Propagation: EuCAP 2006", ESA SP-626 Design of a focal plane array system at cryogenic temperatures
- Orfei, A., Bolli, P., Cremonini, A., Mariotti, S., Monari, J., Natale, V., Nesti, R., Poloni, M., Scalambra, A., 2007, IRA Internal Report n. 400 Feasibility study for a multifeed in the 43 GHz band
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