An antenna system is provided. In one example, the system includes a modal antenna having a driven element and a parasitic element. The system includes a radio frequency circuit. The system includes a transmission line coupling the radio frequency circuit to the modal antenna. The radio frequency circuit is configured to modulate a control signal onto an RF signal to generate a transmit signal for communication over the transmission line to the tuning circuit. The control signal can include a frame having a plurality of bits associated with the selected mode of the antenna. The radio frequency circuit is configured to encode the plurality of bits associated with the selected mode in accordance with a coding scheme. The coding scheme specifies a unique code for each mode of the plurality of modes. The unique code for each mode of the plurality of modes differs by at least two bits relative to the unique code for each other mode of the plurality of modes.