LiteBIRD MHFT W-band RF breadboard modeling and characterisation

Abstract

As for any CMB instrument, the accurate knowledge of the beam shape is crucial in order to limit the signal contamination and to have a precise CMB power spectrum reconstruction from the data. The MHFT on the future JAXA-led LiteBIRD space mission, based on a refractive design, will have a wide frequency coverage ranging from 89 to 448 GHz. In order to validate the modeling tools and the level of accuracy achievable on the experimental RF characterisation prior to any complete prototype, a simpler breadboard has been developed for W-Band (75-110 GHz). We present here both the modeling and the RF characterisation results of this breadboard which consists of a dielectric lens that is fed by a corrugated horn. The measurements were performed in the Near-Field, the Far-Field being then obtained through a transformation.