Active Metamaterial Antenna with Beam Scanning Manipulation Based on a Digitally Modulated Array Factor Method

In this communication, we report the scanning manipulation on radiation beams with an active metamaterial (MTM) antenna using p-i-n diode switches. Thanks to the MTM antenna possessing periodical configuration with isolated units, p-i-n diodes in each unit are capable of being actuated individually with OFF/ON-states (coding sequences 0/1), equivalently tuning the phase constant \beta of each cell either in state \beta _{0} or state \beta _{1}. Therefore, for MTM array with a certain number of units, we can obtain plenty of tunable states presented via digitally coding sequence combinations, thereby manipulating beam scanning in a fixed frequency band. Especially, for the first time, we propose the digitally modulated array factor (DMAF) method for the MTM array: introducing unit-cell dispersion curves of both 0/1 states to the array factor, thus, map the digitally coding sequences linearly to the scanning beams at a fixed frequency, resulting in scanning functionalities. Experiments are implemented with applying micro-control-unit (MCU) to the active MTM antenna for driving p-i-n diodes, and measurements demonstrate beam scanning continuously from -30° to +30° at fixed frequencies around 5 GHz, validating the proposed method.