The QUIJOTE (Q-U-I JOint TEnerife) experiment combines the operation of two radio-telescopes and three instruments working in the microwave bands from 10 to 47 GHz at the Teide Observatory, Tenerife, which has already been presented in previous SPIE meetings. The new Multi Frequency Instrument (MFI2) led by the Instituto de Astrofísica de Canarias (IAC) aims to characterize the polarized emission of the Cosmic Microwave Background (CMB), as well as Galactic and extra-Galactic sources, at medium and large angular scales. This instrument has five polarimeters, three working in the microwave band of 10-15 GHz, and two working in the microwave band of 15-20 GHz. The instrument is composed of a cylindrical aluminum 6061-T6 cryostat cooled by a closed Gifford-McMahon helium cycle cryocooler with two stage shields (first stage at 30 K, and second stage at 10 K). The opto-mechanical system consists of five horns aligned with the focal plane of the telescope where the signal enters the instrument, each horn is followed by an OMT, a 90º Hybrid and two LNAs cooled down below 20 K, all of which represents the Front-End Module (FEM). This signal leaves the instrument by a feedthrough where the Back End Module (BEM) waits at room temperature to process the signals.
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