PURPOSE: To operate the pulling-in, capturing, and following-up operation of the other satellite, and to make an antenna compact by switching the switch of a power feeding part for communication between satellites, and changing the antenna aperture area of a radio wave radiated from a primary radiator.

CONSTITUTION: A beam radiated from a main primary radiator 1 widely reaches a sub-reflecting mirror 19 as shown by AA', and it is reflected on a main reflecting mirror 18, and finally the radio wave is radiated from a wide antenna aperture face BB'. On the other hand, the beams radiated from a main primary radiator 1 and a sub-primary radiator 2 are made thin, and the radio wave narrowly reaches the sub-reflecting mirror 19 as shown by CC'. Therefore, the radio waves reaches the main reflecting mirror 18 in narrow wide, and an antenna aperture face DD' is made narrow. At the time of pulling-in the radio wave from the other satellite by the capturing operation, a distributor 13 of the power feeding part for communication between the satellites is turned on, and the beam is made thick by using the plural primary radiators in a satellite (a) at a radiation side. Thus, an other satellite (b) can easily pull-in the beam of the satellite (a). At the time of starting communication, the distributor 13 of the power feeding part for communication between the satellites is turned off, the beam is made thin, a gain is increased, and the communication is operated.