To eliminate a heat loss caused by a spacecraft by supplying an amplified RF signal to a multiplexer means, transmitting the RF signal by a passive transmission subarray antenna connected to the multiplexer, and radiating a heat loss from a reconstructable passive array antenna panel.

Payload panels 12, 14 constructed of a plurality of passive array transmission antennas control an antenna radiation pattern form electronically, use an array-antenna structure body, hold a traveling-wave-tube amplifier(TWTA) and a multiplexer, and execute a heat radiation function and an RF radiation function. In a standardizing panel, an active array receiving antenna 15 is used, and multiple reconstructable antenna patterns to the up-link are generated. In addition, a developed payload radiates all the heat generated inside. Therefore, payload electric power is increased without depending on the dimension of a bus. In this way, power conversion efficiency to the payload can be increased.