Frequency Scanning Dual-Mode Asymmetric Dual-OAM-Wave Generation Base on Broadband PB Metasurface

Abstract

Increasing information capacity is significant for high-speed communication systems in a congested radio frequency sequence. Vortex waves carrying mode orthogonal orbital angular momentum (OAM) have gained considerable attention in recent years, owing to their multiplexing quality. In this study, a broadband Pancharatnam–Berry (PB) metasurface element with a simple structure is proposed, which exhibits an efficient reflection of the co-polarized component and a full 2π phase variation in 10.5–21.5 GHz under circularly polarized wave incidence. By convolution and addition operations, the elaborate phase distribution is arranged and the corresponding metasurface-reflecting dual-mode asymmetric dual-OAM waves is constructed. Under continuous control of the working frequency, the OAM vortex beams with the topological charges 1 and −1 are steered to scan within the angle range of 11.9°–24.9° and 17.9°–39.1° at φ = 315° and 135° planes, respectively. The simulation and measurement results verified the feasibility of generating frequency-controlled asymmetric dual beams and the validity of dual-mode OAM characteristics, both in the near and far fields. This design approach has considerable potential in OAM wave multiplexing and wireless communication system transmission.

High-Efficiency Multi-Channel Orbital Angular Momentum Multiplexing Enabled by the Angle-Dispersive Metasurface

“…Since the topological charge l can be any integer, the number of OAM modes is theoretically unlimited, and different OAM modes are initially orthogonal to each other. Due to these fantastic characteristics, multiple EM waves with different frequencies, polarizations, or spatial directions can be converted to OAM beams with orthogonal modes for coaxial transmission [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. This OAM multiplexing method offers a new degree of freedom in addition to the frequency, polarization, phase, and amplitude to manipulate the wireless signals, which can significantly increase the transmission capacity of wireless communication and remote sensing [ 19 , 20 ].…”

Polarization-Dependent Coding Metasurface with Switchable Transmission and RCS Reduction Bands

“…Metasurfaces attain a considerable attention in military stealth due to low profile and strong electromagnetic (EM) wave manipulation abilities [ 9 , 10 , 11 ]. They can easily control the amplitude, polarization, and phase of EM waves [ 12 , 13 , 14 ]. Recently, it has been observed that metasurfaces have extensively been used to perform absorption and scattering.…”