Studies on an amplitude hologram as a submillimeter-wave collimator at circular polarisation

A hologram can be used as a collimator in the submillimeter-wave compact antenna test range (CATR). Previously, when a horn has been used as the feed, operation of the hologram has been limited to the vertical electric field polarisation. Use of a dual reflector feed system as the feed allows us to design holograms that operate also at the horizontal polarisation. Here, we show by simulation at 310 GHz that the operation of such holograms can be almost identical at both linear polarisations, thus, letting us to assume that these holograms can be used also at the circular polarisation.