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 fullduplex 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.

Intelligent-Metasurface-Assisted Full-Duplex Wireless Communications

“…Figure 2 shows a reflective intelligent metasurface (RIM) for full-duplex nonreciprocal beamsteering and amplification [11]. This RIM is composed of an array of phase-gradient cascaded radiator-amplifier-phaser unit cells.…”

“…Hence, the TIM makes an efficient connection between the cellular and satellite networks. To improve the functionality of the temporal TIM in this application, appropriate beamsteering mechanisms [7], [11], [15] can be added to the frequency conversion functionality of the TIM.…”

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].…”

Magnet-Free Circulator Formed By A Time-Varying Nonreciprocal Phase Shifter

“…Nonmagnetic nonreciprocity is conventionally achieved through nonreciprocal properties of transistors at microwave frequencies, [7][8][9][10][11][12][13] and electro-optical modulators at optical frequencies. 14 However, these techniques substitute the absence of cumbersome magnetic bias for other tangible drawbacks, such as poor noise performance and strong nonlinearities of transistors, or the complexity and large size of the electro-optical modulators.…”