Medicina Radio Astronomical Station

IRA - Institute of Radio Astronomy

INAF - National Institute for Astrophysics

Receiver Design and Development

Three receivers are currently under development in the Microwaves Labs of the station,: a Ku-Band (13.5-17.5 GHz) double-feed receiver for the Medicina 32-m dish, a C-Band (4.2-5.6 GHz) single-feed receiver and a Q-Band (33-50 GHz) 19-feed receiver for the Sardinia Radio Telescope.

Many elements are taken into account when selecting the frequency range of a receiver. As concerns the new receiver for the Medicina 32-m dish, the Ku Band was chosen following the scientific goals expressed by the researchers working for IRA (Institute of Radio Astronomy), in this case mainly involving single-dish observations. Moreover, both the RFI local distribution and the 32-m antenna technical features led to this choice. The double-feed solution was selected as it allows “real-time" corrections for atmospheric variations.

The same Microwaves Labs hosted the development all the receivers already installed in the 32-m dish: two C-Band (4.3-5.8 GHz and 5.9-7.1 GHz) single-feed receivers and a SXKL-Bands receiver (S: 2.2-2.36GHz, X: 8.18-8.98GHz, K: 21.86-24.14GHz, L: 1.35-1.45GHz e 1.595-1.715GHz). Recently, this old K-Band receiver has been dismounted, and a new dual-feed K-Band receiver was installed in the Cassegrain focus.

It is worth to mention the past production of a X/Ka-Band (8.2-8.6 GHz and 31.85-32.25 GHz) coaxial receiver, built for the primary focus of both the Medicina and Noto 32-m antennas. This receiver was used for the "doppler tracking" of the Cassini satellite.

All the three receivers now installed in the Sardinia Radio Telescope were developed and tested in Medicina. Two of them, the C-Band (5.7-7.7 GHz) and the 7-feed K-Band (18-26.5 GHz), with the proper adapting interfaces, were extensively tested on the 32-m dish.

A few years ago, in the framework of the SKA (Square Kilometre Array) international project, the Medicina technical group designed and built the blocks of the BEST (Basic Element for SKA Training) demonstrators. 8 reflectors of the North-South section of the Northern Cross were reviewed and upgraded, in order to provide them with new receiving systems, to produce advanced technology and to verify the basic SKA concepts: reliability, replicability and low cost. This new system is still installed and operational.

The new receiving system has an input bandwidth of 16 MHz, centered on 408 MHz (the working frequency of the Northern Cross). Inside each receiver box an analogue fibre optic link is implemented, in order to send RF data with minimal attenuation.