A Versatile Shaped-Beam Space-Time-Coding Metasurface Antenna Based on 1-Bit Phase Control

To mitigate the Doppler fading that arises in high-mobility communication systems and improve channel capacity, it is essential to develop innovative methods for flexibly manipulating the radiated electromagnetic (EM) wave’s frequency. This paper proposes a new space-time-coding metasurface antenna (STCMA) that enables unidirectional frequency conversion, beam steering, and shaped-beam generation. The proposed STCMA contains a microstrip line and forty perturbation unit cells. Each unit cell is inserted with two positive-intrinsic-negative (PIN) diodes to achieve 1-bit phase control. The radiated field from each unit cell can be switched between two states with equal amplitude and 180° phase differences by changing the bias voltages of the two diodes. A generalized STC principle for 1-bit control scheme is developed to control the radiated field above the antenna aperture flexibly. To be specific, the radiation amplitude and phase of each unit cell can be tailored by the duty cycle and time delay of the coding sequence, respectively. An STCMA with beam steering and sidelobe suppression capability is developed and experimentally verified. Additionally, the proposed STCMA also enables generating shaped-beams, such as flat-top radiation patterns.