Trevor Wadley

Trevor Lloyd Wadley, (1920 – May 21, 1981) was a South African electrical engineer of the 20th century. He was best known for his development of the Wadley Loop circuit for greater stability in communications receivers.

Born in Durban in 1920, Wadley trained at Howard College (now of the University of Natal) in his hometown, where he studied under Hugh Clark and Eric Phillips. He was known as a student for his habit of rarely, if ever, taking notes in lectures due to his near-eidetic memory. During World War II, he was recruited into the Special Signal Services and trained on the British RADAR project.

After the war, Wadley joined South Africa's National Institute for Telecommunication Research as a designer of radio equipment and instrumentation. He developed an ionosonde for measuring Earth's ionosphere, and a ranging tellurometer. It was also here that he invented the Wadley Loop receiver, which allowed precision tuning over wide bands, a task that had previously required switching out multiple crystals. The Wadley Loop was first used in the Racal RA-17 a 1950s top of the range British military short wave receiver still considered one of the finest radio receivers ever made and later in the South African made commercially available "Barlow-Wadley XCR-30" radio. He also invented the tellurometer, which could measure up to a distance of 80 km; it was used in land surveying. Today, it is used in a wide range of equipment but modified with current technology.