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 .