An electronically steerable passive array antenna and method for using the array antenna to steer the radiation beams and nulls of a radio signal are described herein. The array antenna includes a radiating antenna element capable of transmitting and receiving radio signals and one or more parasitic antenna elements that are incapable of transmitting or receiving radio signals. Each parasitic antenna element is located on a circumference of a predetermined circle around the radiating antenna element. A voltage-tunable capacitor is connected to each parasitic antenna element. A controller is used to apply a predetermined DC voltage to each one of the voltage-tunable capacitors in order to change the capacitance of each voltage-tunable capacitor and thus enable one to control the directions of the maximum radiation beams and the minimum radiation beams (nulls) of a radio signal emitted from the array antenna.