Optimisation of the LFI Edge Taper values. I. FH #3 and #9 Main Beam and Full Pattern Simulations w/o Shields

Abstract

This technical note describes preliminary electromagnetic simulations performed on the LFI feed horns (FH) #3 and #9 coupled to the Planck telescope, with the aim of optimising the LFI Edge Taper (ET). The ET optimisation is mandatory to reach the LFI angular resolution requirement, and possibly the goal, preserving at the same time the needed straylight rejection. The analysis is carried out at 100 GHz, where the scientific benefit of gaining angular resolution is most important. Five different FH designs have been considered: the FH #3 and #9 Qualification Model (QM) designs, and FH designs denoted with #3A, #9A, and #9B, which have been specifically designed with an edge taper that leads to an angular resolution of 12’, 10’, and 9.5’, respectively, when Gaussian feed models are considered. For FH horn design the main beam and the full pattern have been computed. The effect of shields has not been considered here, and will be the subject of a forthcoming note.