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Appendix A: On the so-called "baffle'' options

The use of a properly designed reflective ring-baffle around the primary mirror, proposed to meet the edge taper requirement, and a minor modification in the design of the feeds (which will depend on their precise location in the focal plane) allow to obtain the illumination required to recover the PLANCK angular resolution.

Table 1: Parameters of telescope designs analyzed
Design $D_{\rm p}$ (mm) $F_{\rm p}$ (mm) 2a (mm) 2c (mm) $d_{{\rm m}-{\rm s}}$ (mm) $f_{{\rm eff}}/D$
BAFFLE.1550 1550.0 720 1200 514.29 1065.69 1.08
BAFFLE.1750 1750.0 720 1200 514.29 1065.69 1.08

We have carried out a second set of simulated beam patterns, for non-standard telescopes, assuming telescope configurations as listed in Table 5 and keeping the 30 dB edge taper requirement for all the channels.

A decisive comparison can be made in terms of equivalent angular resolution.

The results achieved with a system which includes the ring-baffle can be understood using the Method 1 and by comparing the plots of Figs. 13 and 14 with those of Fig. 6: only up to $\sim 1.5^\circ$ of scan angle a reduction of the magnitude of angular degradation can be reached. The second and third - left and right - panels from the top in Fig. 15 show the results of Method 3 for these two configurations and compare them with those holding for the three configurations of Table 1.

The comparison with the PHASE A telescope shows an improvement in the angular resolution restricted to regions very close to the optical axis and therefore not relevant for all (LFI and HFI) receivers, which are located at the same relevant distance from the centre as in the case of the PHASE A telescope. These options do not allow to reach then the crucial goal of 10' resolution at 100 GHz.

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