Complex beam patterns at 205 GHz as measured with the HPA technique after the warm focal plane, with the hexapod in home configuration, (a) Amplitude pattern, (b) Phase pattern. The coordinates are with respect to the warm focus. Because they were measured in the laboratory using the setup in Fig. 5b, we used the scanning plane axes as shown in Fig. 5a, with the warm focus in the xz-plane. We denote the amplitude and phase centres with black crosses. They are different, which indicates that the beam is tilted with respect to the scanning plane normal.