Improved sensitivity of a low noise aperture array tile for the SKA

Aperture array technology is one of the candidate technologies for the 500 MHz to 1500 MHz frequency range of the SKA. The feasibility and low noise potential of aperture arrays have been demonstrated with small test systems before, e.g. with a 50 K system noise temperature, measured on a 1 m² prototype tile in 2010. However, further reduction of the array noise temperature is essential to optimize the ratio of effective collecting area and system noise temperature. This is made possible by applying new, lower noise, technology to the LNA design. Thus the sensitivity requirement for the Mid Frequency Aperture Array of the SKA could be satisfied at lower cost. Results of a step by step approach to reduce the system noise temperature to below 40 K, giving at least 20% improvement, are presented.