BEST (Basic Element for Ska Training)

The scientific whole world community is designing a new radiotelescope generation: the SKA (Square Kilometer Array). It will have 1 million square meters of collecting area and an operating bandwidth for sky observation, spanning from 0.1 up to 25 GHz. SKA will be a technological giant and it is going to answer the unsolved problems of the modern astrophysics. To reach definitive design of SKA, all the research institutes of the world are designing new technologies and developing new algorithms to be tested on "test bed antennas". The Italian demonstrator called BEST (Basic Element for Ska Training) exploits the large collective area of the Northern Cross Antenna located in Medicina (BO). Due to the high sensibility, the Northern Cross Antenna offers the possibility to realize also science.
BEST project is structured in 3 main steps described below:

1. BEST-1: 4 receivers were installed on a cylindrical reflector of the North-South arm (Ag = 176 m2).
2. BEST-2: 32 receivers were installed on 8 cylindrical reflectors of the North-South arm (Ag = 1410 m2).
3. BEST-3lo: 18 receiver were installed on a part of the East-West arm (Ag = 800 m2).

For the future more receivers could be installed on the whole Northern Cross Antenna (BEST-ione project: BEST-Italian Observatory for New Experiments), but this expansion is not foreseen for the actual projects.

SKA project is coordinated by ISSC (International SKA Steering Committee).
In 2012 a final SKA prototype will be realized and the construction of the final version will be prepared. All the research institutes of the world (Europe, South Africa, Australia, Canada, China, India, United States of America) are involved to study and to realize the following tasks:

· Antennas
· Front-end
· Optical Links (analogue and digital)
· Digital receivers
· Beam-forming algorithms
· Post-processing algorithms
· Calibration

BEST project took part of the European program SKADS (SKA Design Studies). It started since the middle of 2005 and finished at the end of 2009. It shared all the scientific and technological concepts in which are involved a large number of countries (Italy, Holland, France, England, Germany, Russia, Spain, Poland and Sweden).