Spy Tech: A Quiet Radio for Spies
During World War II, British engineers developed the S-Phone, a low-power radio transceiver designed for covert communication by spies. The S-Phone operated at a high frequency to avoid detection and allowed agents to communicate with aircraft without revealing their positions. The United States also created a similar device called Joan-Eleanor, which had a longer range and used ordinary batteries for convenience.
- ▪The S-Phone operated around 380 MHz and had an output power below 200 mW.
- ▪The Joan-Eleanor radio was designed by OSS engineers and had a range of about 20 miles.
- ▪Both radios used uncommon frequencies to minimize the risk of enemy detection.
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Spy Tech: A Quiet Radio For Spies No comments by: Al Williams May 20, 2026 Title: Copy Short Link: Copy Normally, when you think of a radio transmitter, you want the strongest signal and range. But if your radio operator is secretly operating as a spy, broadcasting their position isn’t a feature; it is a liability. This fact didn’t escape World War II radio designers. In late 1942, the British realized they needed a way for Special Operation Executive agents, resistance members, and other friendly forces to communicate with an aircraft without attracting undue attention. Two engineers from the Royal Corps of Signals developed a pair of transceivers — the S-Phone — operating around 380 MHz just for this purpose.
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