American Personnel in the Mid East, Which AAF?

My grandfather served in the Middle East (Egypt, Palestine, and Iraq) from late 1944 though early 1946 as a member of the USAAF. He worked with radios and was trained in something called the Contol Net System. My question is, which AAF unit would he have served under, i.e. the 8th in England, 5th in Australia, etc.?