A transmission line structure for transmitting radio signals includes a first transmission line, a first ground region, and a second transmission line. The first transmission line is arranged on a first layer of a circuit board. The first transmission line includes a first signal line and a second signal line. The first ground region is arranged between the first and second signal lines. The first and second signal lines do not contact the first ground region. The second transmission line is arranged on a second layer of the circuit board, and the second layer is different from the first layer. The second transmission line does not contact the first transmission line, and the second transmission line interleaves with the first signal line, the second signal line and the first ground area.