A roller shade structure controlled by radio-frequency (RF) wireless communication from a control device comprises a roller tube and a conductive enclosure. The conductive enclosure is mounted inside the roller tube for enclosing a motor drive system having a motor operable to controllably rotate the roller tube in a direction at a speed when a voltage is applied to the motor. A capacitive coupling is provided between the enclosure and the roller tube, the capacitive coupling providing an increased signal strength of RF signals received by the RF receiver.