An electronic device may be provided with first, second, and third antennas and a dock flex. A first feed terminal for the first antenna may be coupled to a second feed terminal for the second antenna over a first path. The first path may be coupled to ground over a second path. Tuning components may be interposed on the first and second paths. The third antenna may be patterned on a first portion of the dock flex. Front end components for the first antenna may be mounted to a second portion of the dock flex. The first and second portions may extend from a tail of the dock flex. The tail may be wrapped around a plastic support block to hold the second portion over the first portion. The plastic support block may have a snap hook clip that holds the second portion in place.