Figure 4 show the beam patterns in the K band. The side-lobe level is less than about -15 dB, except for the relatively high side-lobe level of about -10 dB for the separation angle of 2.0 deg at Ogasawara station. The side-lobe of the beam patterns has an asymmetric shape, but the main beam has a symmetric Gaussian shape without dependence on separation angle. The measured beam sizes (HPBW) in the K band and the Q band based on the data of the pointing calibration are also summarized in Table 4. The main beam sizes show no dependence on the dual-beam separation angle.
The optics of KVN antenna is a shaped Cassegrain type of which the main reflector and subreflector are shaped to have a uniform illumination pattern on an aperture plane. Because of the uniform illumination, KVN antennas can get higher aperture efficiency than value of typical Cassegrain type antenna. However, higher side-lobe level is inevitable. OTF images of Jupiter at K and Q bands are shown in Figure 4. The map size is 12' X 10' and the first side-lobe pattern is clearly visible. Typical side-lobe levels of KVN antennas are 13-14dB.