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This paper describes two small aperture array demonstrators called Medicina and Sardinia Array Demonstrators (MAD and SAD, respectively). The objectives of these instruments are to acquire experience and test new technologies for a possible application to the low‐frequency aperture array of the low‐frequency telescope of the Square Kilometer Array phase 1 (SKA1‐LOW). The MAD experience was concluded in 2014, and it turned out to be an important test bench for implementing calibration techniques based on an artificial source mounted in an aerial vehicle. SAD is based on 128 dual‐polarized Vivaldi antennas and is 1 order of magnitude larger than MAD. The architecture and the station size of SAD, which is along the construction phase, are more similar to those under evaluation for SKA1‐LOW, and therefore, SAD is expected to provide useful hints for SKA1‐LOW. Italian demonstrators of low‐frequency aperture array for radio astronomyAerial unmanned vehicle for the instrumental calibration of an aperture arrayTechnological solutions implemented in the receiving chain of a low‐frequency aperture array

The BaR-SPOrt (Balloon-Borne Radiometers for Sky Polarization Observations) experiment, a program of the Agenzia Spaziale Italiana (ASI) co-funded by PNRA (Progetto Nazionale di Ricerca in Antartide) was originally designed as a payload for long duration balloons flights. The changing scenario, both scientific and strategic, has led us to propose it for the starting winter campaign of at the Concordia Base. Here the instrument and the features making it suitable to operate at Dome-C are described. After the initial setup, BaR-SPOrt should not require any kind of routine intervention by a dedicated base staff. The experiment will just need electrical power (less than 2 kW) and a suitable accommodation on the field. It can be fully monitored and controlled, including the data acquisition, through its own telemetry/telecommand link using IRIDIUM modems. Both the receiver and the critical electronics are housed inside a temperature-controlled vacuum chamber, providing the properly stabilized environment. The cold part of the radiometer employs a closed loop mechanical cryo-cooler that provides temperatures <70 ± 0.1 K with low power consumption (<200 W).

The BaR-SPOrt experiment is designed to measure the E-mode power spectrum of the Cosmic Microwave Background Polarization (CMBP) in the multipole range 50 < l< 1000. In the current configuration at 32 GHz it can explore up to l= 400. Recent low frequency observations of the target region show that the synchrotron emission should not contamine the CMBP already at 32 GHz. A 6-month observation of a 6° × 6° sky area during the polar night, in ideal environmental conditions, will allow the Italian-French collaboration to both measure the E–mode power spectrum with appropriate sensitivity and perform important tests of the anomalous dust emission. The BaR-SPOrt 32 GHz instrument, now under test and ready for operations by Spring 2005, is proposed for 1–2 years Winter operations at Dome C.