Development, design and realization of cryogenic radio receivers of the Sardinia radio telescope

Radio astronomy sources emit a very low signal of the order of 10. Therefore, in order to detect a celestial signal, very sensitive instruments are required, starting from the radio receivers installed on the radio telescopes. In this case, one of the main targets is to reduce the noise of the receivers (TRIC). The work of the thesis covers a wide field of knowledge, from the design of a single passive microwave device such as directional coupler, a 180° hybrid or waveguide to microstrip transition, to the general performances of each component in the front-end of the receiver. In this thesis, we have designed and measured the single devices at room and cryogenic temperature with different instruments, like vector network analyser or spectrum analyzer. In the first part we focus on the LP Band receiver of the Sardinia Radio Telescope. In this regard, we describe the design of the low losses devices before the low noise amplifier, and the cryogenic architecture of the whole cryogenic coaxial receiver. In the second part, we present the design of the S band multi beam cryogenic receiver of the Sardinia Radio Telescope. Measured performance of the radio telescope is provided in this case.