Item from three-body-problem by
The high-power microwave transmitter at Red Coast Base — the device with which Wenjie, in 1971, used the sun as an amplifier to broadcast humanity's first interstellar message.
Officially the transmitter is a cold-war anti-satellite microwave weapon. Functionally it is the most powerful directed radio source China possesses. Aimed at the sun at a precisely chosen frequency, its beam can be amplified by the sun's own microwave-cavity layers to roughly a hundred million times its base power, broadcasting an Earth-originating signal across light-years. In 1971, against orders, Wenjie keys this transmitter, points it at the sun, and sends a self-translating language primer with a short greeting. Eight years later the same dish receives the reply. The transmitter is the physical instrument of first contact, and almost no one alive in the present-day plot knows it ever happened.
A massive parabolic dish antenna twenty-some meters across, mounted on a steerable mount above the Red Coast control room. Below it, racks of vacuum-tube transmitter electronics, copper waveguides as thick as a man's arm, and a control console of toggle switches and analog dials labeled in handwritten Chinese. The whole installation hums when keyed; the air inside the equipment room smells of ozone.
Also known as: the Red Coast antenna, the dish