Apparatus and methods for efficient external control of the transmit power of a remote fixed gain antenna unit in RF communications. Apparatus embodiments include a separate feeding unit coupled to a remote fixed gain antenna unit through a single coaxial line. The feeding unit is operative to provide transmit control signals to the remote antenna unit based on power feedback created in the remote antenna unit and sent to the feeding unit over the single coaxial line. Feedback and transmit/receive control inputs are transmitted through the single coax line together with RF signals. The coax line may be long. The apparatus and methods may be used in a vehicular environment.