Jan 02, 2026 21:00:00

Open.space: An open-source phased array antenna that can communicate with the world using the moon

One of the joys of

amateur radio is communicating with strangers somewhere in the world, and long-distance radio communication (DX), which transmits radio waves as far as possible, is a major goal for amateur radio operators. Various methods are used to achieve DX, including transmitting higher-power radio waves, using higher antennas, utilizing the ionosphere, which reflects shortwave radio waves, and using artificial satellites. One such method is lunar reflection communication (Earth-Moon-Earth, or EME) . Because the reflection coefficient of radio waves on the moon's surface is extremely low, EME was previously thought to be impractical. However, an open-source phased array antenna called 'open.space' has emerged specifically for EME.

Open Source meets Outer Space
https://open.space/

To put it simply, a phased array antenna is a device that improves communication efficiency by arranging many small antenna elements on a flat surface and controlling them as a single antenna, such as by strengthening the directionality of radio waves. Radio waves reflected from the lunar surface are very weak, but by utilizing a phased array antenna, signals can be sent and received efficiently.

The Quad is the smallest model of open.space's phased array antenna, and while it can be used alone, it also functions as a building block for larger arrays. Quad is a

software-defined radio (SDR) tile consisting of four antenna elements, and is compatible with the Raspberry Pi pipeline ( GNU Radio , Python/C++, and SoapySDR ). Pricing is yet to be determined, but is expected to range from $49 to $99 (approximately ¥7,650 to ¥15,450).

The Mini is a starter phased array antenna. It features 72 antenna elements, providing powerful directivity on its own, but it can also be expanded. At the time of writing, the price ranges from $899 to $1,499 (approximately $140,000 to $230,000).

The Moon is a serious EME model. It boasts 240 antenna elements, providing

the beamforming gain and effective radiated power (EIRP) required for lunar reflection. Prices range from $2,499 to $4,999 (approximately ¥390,000 to ¥780,000).

EME is purely a hobby, and considering its practicality, it's hard to get your hands on one, but if you have the heart of a boy and the financial means of an adult, you might want to pursue your romantic side and consider buying one.