Spatiotemporally Modulated Metasurface Antennas for Direct Signal Modulation

This paper introduces a novel simplified transmitter based on the space-time-coding (STC) metasurface antenna. The STC metasurface antenna can periodically ON-OFF switch its unit cell to form an equivalent sinusoidal amplitude distribution along the length of the wave-guiding structure to realize high-gain leaky radiation. Moreover, the phase of the radiated wave in the main-beam direction can be changed by shifting the equivalent sinusoidal amplitude distribution formed by the spatiotemporal modulation. The digital information can be encoded into the phase property of the radiated electromagnetic waves. Therefore, the STC metasurface antenna can realize direct signal modulation without requiring digital-to-analog converters, mixers, and filters. Experiment results demonstrate that the STC metasurface antenna can directly generate the modulated waveforms with the Quadrature Phase Shift Keying (QPSK) modulation scheme.