usually, if he's a legit broadcasting station, he would need not just a license, but a construction permit as well, and wouldn't be asking how to build one, as commercial broadcast equipment is something a station usually buys, not builds from scratch. one of the reasons for that is that it has to pass regulatory compliance testing, and the equipment manufacturers that supply broadcast equipment have already jumped through those hoops so the broadcaster only needs to verify the equipment is operating properly rather than navigate through the expensive and time consuming compliance testing jungle required for newly designed transmitters.