Radio Squad debuted in July of 1936 starring the character Sandy Kean and his partner Larry trent. The series ran in More Fun Comics through 1943. Unlike many contemporary comics, about astronauts and cowboys radio Squad stories are set in a contemporary and realistic locale.
Radio Squad was predated by another radio-themed comic strip "Radio Patrol." It debuted three years prior to radio squad and was created bywriter Eddie Sullivan and artist Charlie Schmidt. It's hero is Sergeant Pat O'Hara, who worked with an assistant and somtimes co-star Molly Day. In some respect both comics many have influenced Dick Tracey.
There are actually collections of Radio patrol for sale here.
Radio Patrol also became a movie serial in 1937. I've found very littel information on it, but somone was kind enough to post a trailer on YouTube.