Beamsteering in Pattern Reconfigurable Arrays Using Directional Modulation

An array with pattern-reconfigurable elements is used to generate a digital modulation by switching the elements for every symbol. This technique is known as directional modulation. Because the modulation is generated at the antenna level, it gives control over the directions in which data is sent, unlike baseband modulation which transmits the same data in all directions at different power levels. A procedure for determining how to switch the elements to transmit only in a specified direction is outlined. Results indicate that compared to a traditional reconfigurable array, the directional modulation array allows information to be sent over a narrower beamwidth. Additionally, the method provides more selectivity in the possible transmit angles. Measured and calculated results from a four-element reconfigurable array are presented.