HERA is a multi-pixel receiver working at 1 mm of wavelength. Each pixel is
an heterodyne mixer using a SIS junction. There are nine pixels per
polarization. The pixels of one polarization follow a square
pattern, the distance between two pixels being
. Both
polarizations are aligned. Hence, HERA has 18 pixels in total looking at 9
different sky position simultaneously. The polarizations of HERA can
simultaneously be tuned at two different frequencies.
The number of used polarization,
can thus be set to 1 or 2 and the
number of pixels per polarization is
.