Red Stocking under the RAF. They would airdrop an OSS agent into Germany with Deutschmarks a hand gun, some food a map and a JE radio. According to the book A Century of Spies by Jeffery Richelson Of the 34 teams dropped into Germany only 4 were considered a success. More here.
The JE radio operated in the VHF range. At the OSS Joan Eleanor was developed by DeWitt R. Goddard and Lt. Cmdr. Stephen H. Simpson, with some assistance from Alfred J. Gross. Reportedly it was named for Goddard's wife's Eleanor, and a WAC of Simpson's acquaintance named Joan, but that's apocryphal. In the field Joan was the transmitter and Eleanor was the receiver. The system operated on 260 MHz in FM and had a range of about 20 miles. The hand-held SSTC-502 transceiver used a dual triode tube to both send and receive via a small dipole antenna. It was about 6.5 inches long and only weighed 4 pounds.
On board the plane the radioman was crammed in a rear compartment normally intended for an aerial camera. The agent would have a specific time scheduled to transmit and his
signal would be received and recorded by a radioman on a
DeHavilland Mosquito flying above 30,000 feet. I note with some irony that these transmissions were recorded on wire recorders, a German invention. More here.
Some of the initial design work was performed at the RCA laboratories in Riverhead, NY. Goddard is reputed to have built several of the first units personally. Production units were manufactured by several different companies including Dictagraph, Citizens Radio, Freed Radio and Signal-U Mfg. The first units were deployed in 1944. DeWitt was still patenting parts of the unit as late as 1952. The technology was only declassified in 1976.