Complex-amplitude radiation-type metasurface enabling beamform-controlled energy allocation

Fifth-generation (5G) communication requires spatial multiplexing multiple-input multiple-output systems with integrated hardware. With the increase in the number of users and emergence of the Internet of Things devices, complex beamforming devices have become particularly important in future wireless systems to meet different communication requirements, where independent amplitude and phase modulations are urgently required for integrated beamforming devices. Herein, by utilizing the constructive interference between multiple geometric-phase responses, the mathematical relation for decoupling amplitude and phase modulations in the radiation-type operational mode is derived. Based on this strategy, complex-amplitude radiation-type metasurfaces (RA-Ms) are implemented, with an integrated feeding network. Such metasurfaces exploit full 2 π phase modulation and tailorable radiation amplitude in the circular polarization state. Meanwhile, a complex-amplitude retrieval method is developed to design the RA-Ms, enabling precise beamforming performances. On this basis, several functional devices based on the complex-amplitude RA-Ms, including energy-allocable multi-router, shape-editable beam generator, and complex beamformer, are demonstrated in the microwave region. The amplitude-phase decoupling mechanism with the retrieval method merges amplitude and phase modulations, and energy distribution into one compact and integrated electromagnetic component and may find applications in multi-target detection, 5G mobile communication, and short-range ground-to-sea radar.