Design of the low C-band passive front end for the beam waveguide focus of the Sardinia radio telescope

This paper presents the electromagnetic design of part of a receiver passive front-end at C band (4.2-5.6 GHz) to be used for radio astronomy applications. The front-end devices here shown are a circular corrugated horn, a differential phase shifter and an orthomode transducer, which are required to study the circular polarization content of the sky signal. All of these components are developed in waveguide technology, best suited for high sensitivity receivers. Design and fabrication aspects are presented and test results discussed.