An improved antenna system (10) provides significant cost reduction and improves the modularity of the antenna system by combining the power supply lines and the control lines on a single line (12). Control circuitry (22) is responsive to a power supply signal which acts as the power supply for the antenna system to control the operation of the antenna system. In certain embodiments, the improved antenna system is connected to a single line (12) which carries communication signals and the power supply signal. As such, the antenna system combines the communication lines, the power supply lines and control lines to provide a modular antenna system at a reduced cost.; In controlling the antenna system, the control circuitry (22) can control the operation of signal circuitry, (17) which handles the communication signals, in response to the control information provided by the power supply signal. The control circuitry can control other features of the antenna system, such as antenna diversity circuitry (20), in response to the power supply signal. The control information can be provided by the power supply signal in a variety of forms, such as power supply bias voltage levels and/or interruptions in the power supply signal. The control circuitry responds to the control information to control the operation of the antenna system in a desired manner.