KVN has the unique capability to observe four frequency bands simultaneously. KVN quasi-optics are designed to enable this multi-frequency observation. Following figures shows the layout of quasi-optics and receivers viewing from sub-reflector side. The quasi-optics system splits one signal from sub-reflector into four using three dichroic low-pass filters marked as LPF1, LPF2 and LPF3 in the figure. The splitted signals into four different frequency bands are guided to corresponding receivers.