Table 2:

Notes. ^(a) The characteristics listed in this table correspond to those of monochromatic beams at band centre; the typical effect of including band-averaging is indicated for FWHM and ellipticity. Mean, minimum, and maximum are drawn from the set of all detectors at a given frequency; polarised and unpolarised detectors are separately indicated.
^(b) The mean of the minor and major axis at half-power found by fitting a bivariate Gaussian to the beam.
^(c) Mean FWHM (in arcmins) for beams averaged across the detector bandwidth, based on straight averaging of 5 frequencies equally spaced within the bandpass. This is indicative only, as it does not account for the bandpass shape of the detector, nor for the spectrum of the source. A more optimal way to account for broadband optical effects in the near sidelobes is described in Yurchenko et al. (2005); their analysis indicates that the effect of increasing the number of frequencies averaged from 3 to 9 is well below 1% in total power.
^(d) The ratio of major and minor axis.
^(e) Mean ellipticity of beams averaged across the detector bandwidth. This is indicative only, as for the FWHM.
^(f) The percentage of power reaching the detector without having reflected on either SR or PR.
^(g) The percentage of power reaching the detector having reflected only on the SR.
^(h) Since the shape of the multi-moded beam patterns is not Gaussian, the FWHM only partially represents it. A different parameter to use is the half-power angle in the azimuthally integrated power, whose mean is 4.08 and 3.3 arcmins for 545 and 857 GHz, respectively.