Full-duplex Reflective Beamsteering Metasurface Featuring Magnetless Nonreciprocal Amplification

Abstract

Nonreciprocal radiation refers to electromagnetic wave radiation in which a structure provides different response under the change of the direction of the incident field. Modern wireless telecommunication systems demand versatile apparatuses which are capable of full-duplex nonreciprocal wave processing and amplification, especially in the reflective state. Here, we propose full-duplex reflective beamsteering metasurfaces for magnetless nonreciprocal wave amplification. To realize such a unique, extraordinary and versatile functionality, we propose a completely new architecture in which a chain of series cascaded radiating patches are integrated with nonreciprocal phase shifters, providing an efficient mechanism for wave reception, signal amplification, nonmagnetic nonreciprocal phase shifting and steerable wave reflection. Having accomplished all these functionalities in the reflective state, the metasurface represents a conspicuous apparatus for efficient, controllable and programmable wave engineering for wireless telecommunications. Such an ultrathin reflective metasurface can provide directive and diverse radiation beams, and steerable beams by simply changing the bias of the gradient active nonmagnetic nonreciprocal phase shifters. The proposed structure provides large wave amplification and is immune to undesired time harmonics, yielding a highly efficient full-duplex reflective beamsteering apparatus.

Metasurfaces: physics and applications in wireless communications

“…Figure 1 illustrates a possible scenario of a metasurface-assisted wireless communication in urban areas using active multi-functional metasurfaces [ 22 ]. In this scenario, nonreciprocal, frequency-converting and frequency-beamsteering metasurfaces are employed to enhance the versatility and efficiency of the communication network.…”

Reconfigurable Intelligent Surfaces: Design, Implementation, and Practical Demonstration

“…Due to the "multiplicative fading" effect introduced by RISs, achieving noticeable capacity gains is almost impossible for RISs without amplification in some cases where the direct link between the emitter and receiver is not weak, but recent studies have shown that active RISs with energy amplification can possibly overcome this effect [194]. The nonreciprocal and power-sensitive properties of chip amplifiers may influence the modulation signals and information transmission, which should be seriously considered for practical applications [195]- [197].…”

Lightweight Low-Noise Linear Isolator Integrating Phase-Engineered Temporal Loops

“…Isolators can be realized by the simultaneous breaking of time-reversal symmetry and spatial inversion [1][2][3]. Conventional techniques and structures for the realization of isolators include magnetically biased two-dimensional electron gas systems [4], gyroelectric waveguides [5], transistor-loaded transmission lines [6][7][8][9][10][11][12], magnetic ferrites [1,[13][14][15][16][17][18][19], nonlinearity [20], and space-time-modulation [21][22][23][24]. Although these approaches have their own unique advantages and applications, they suffer from distinct limitations and disadvantages that restrict their applications.…”

“…For instance, magnetically biased isolators require bulky magnets and are incompatible with integrated circuit technology [25]. An alternative approach is transistor-based isolators [8,10,12] which eliminate the bulky magnet and are compatible with integrated-circuit technology but suffer from limited power handling and noise performance, and are of limited availability at high frequencies. Nonlinear isolators may be a good choice for some applications but they only provide isolation to high power signals, while they pass low-level signals quasi-reciprocally [26].…”