A spacecraft is disclosed having at least three flat side walls, at least one main communication antenna, including a radiating element having a central axis of radiation (AC-AC), a movable arm configured to move between a deployed position and a folded position, a reflector suitable for reflecting or receiving radiofrequency waves in a direction of emission (DE). The radiating element is fixed to a side wall so that the central axis of radiation (AC-AC) is arranged perpendicularly to the side wall, and the movable arm is shaped so that an offset angle (β) of between 25° and 65° is formed between the side wall and the direction of emission (DE), when the movable arm is in a deployed position.