Table 5: Maximum offset fluctuation $\Delta (Q+jU)$ in one orbit (90 min) induced by the horn temperature instabilities for the SPOrt experiment. The cases of the 22 and 90 GHz channels are reported, representing the best and worst cases among the SPOrt receivers. Details about horn temperature fluctuations ( $\Delta T_{\rm ph}^{\rm h}$) and antenna characteristics are also listed: horn attenuation ($A_{\rm h}$), OMT isolation ( |SB1|2), polarizer differential attenuation ( $A_{\perp }-A_{\parallel }$), $S\!P_{\rm omt}$ and $S\!P_{\rm pol}$ coefficients, and the $H_{\rm h}$ transfer function. $S\!P_{\rm omt}$ has been estimated with the approximation $S\!P_{\rm omt} \sim 2\; A_{\rm omt}\vert S_{A1}S_{B1}^*\vert$ as described in Carretti et al. (2001). The case of a 3 K variation is also shown, that is the natural horn temperature fluctuation without active control.
Configuration $\nu$ $\Delta T_{\rm ph}^{\rm h}$ $A_{\rm h}$ |SB1|2 $A_{\perp }-A_{\parallel }$ $S\!P_{\rm omt}$ $S\!P_{\rm pol}$ $H_{\rm h}$ $\Delta (Q+jU)$
  [GHz] [K] [dB] [dB] [dB]       [$\mu$K]
22 GHz 22 $\pm$0.2 0.05 -65 -33 $1.15\times 10^{-3}$ $2.45\times 10^{-4}$ $2.40\times 10^{-5}$ 4.8
90 GHz 90 $\pm$0.2 0.1 -60 -30 $2.05\times 10^{-3}$ $4.89\times 10^{-4}$ $8.75\times 10^{-5}$ 17.5
22 GHz (3 K) 22 $\pm$3 0.05 -65 -33 $1.15\times 10^{-3}$ $2.45\times 10^{-4}$ $2.40\times 10^{-5}$ 72.0
90 GHz (3 K) 90 $\pm$3 0.1 -60 -30 $2.05\times 10^{-3}$ $4.89\times 10^{-4}$ $8.75\times 10^{-5}$ 262.0


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