Radiation patterns of multi-moded corrugated horns for far-IR space applications

摘要: Multi-moded horn antennas are now being proposed for far-IR space imaging systems in which diffraction limited resolution is not required (e.g. the High-Frequency Instrument (HFI) on ESA PLANCK Surveyor). In such individual modes waveguide filter section feeding can couple independently to an overmoded detector (such as a bolometer integrating cavity). The number of chosen optimize coupling efficiency source without compromising any spillover losses. We consider detail case cylindrically symmetric corrugated configuration, presenting two alternative techniques modelling few-moded systems. first approach based mode-matching description propagation non-uniform structure, while second makes use hybrid mode solutions with walls assuming uniform but non-isotropic impedance. present practical examples comparing radiation patterns predicted by both models.