Frequency‐Multiplexed Holographic‐Reflective Coding Metasurface for Independent Controls of Surface Wave and Spatially Propagating Wave

Abstract

metasurfaces have been widely employed in anomalous reflection and refraction, [11][12][13] beam manipulations, [14][15][16] and microwave imaging. [17][18][19] Generally, the EM property of metaatoms is firstly characterized by reflection or transmission coefficients to determine if the metasurface works in the reflection state or transmission state, and then the amplitude and phase distributions of the meta-atoms can be designed delicately to modulate spatially propagating waves (SPW) in multiple degrees of freedom. In 2014, the concept of coding metasurface was proposed and the distribution of meta-atoms is described by coding sequences. [20] The EM waves are manipulated by different coding sequences and can be controlled by digital devices further, which builds a bridge between the physical field and the information field, indicating potential applications in wireless communications [21][22][23] and smart devices. [24,25] In addition, surface impedance is another property to characterize the holographic metasurface, which is widely used in the design of holographic antenna. [26][27][28][29] The surface impedance of holographic metasurface is modulated periodically to radiate surface waves (SW) to leaky waves with different polarizations and directions. Similar to the reflective (or transmissive) metasurfaces with discrete phase distributions, the value of surface impedance can also be discretized and the radiative properties of the holographic antenna will be maintained, [30] which simplifies the design and fabrication process and provides a possible way for the development of reconfigurable holographic antennas.Recently, with the increasing demands for device integration and communication capacity, more and more multiplexed metasurfaces have been proposed, including the frequencymultiplexed metasurfaces, [31][32][33][34][35] polarization-multiplexed metasurfaces, [36][37][38][39] and space-multiplexed metasurfaces. [40][41][42] In addition, the multiplexed metasurface for mathematical operations and imaging processing is also widely explored, which can be a promising candidate for highly efficient analog processors to implement parallel computing tasks. [43,44] However, these multiplexed metasurfaces are either only based on phase and amplitude modulations to control SPW [31][32][33][38][39][40][41][42][43][44] or based on surface impedance modulation to control SW, [34][35][36][37] and the research on multiplexed metasurface that can control both SPW and SW simultaneously is still very limited. In 2019, we proposed aIn recent years, frequency-multiplexed metasurfaces have received extensive attention due to the increasing demands for device integration and communication capacity. However, most of previously reported works can only manipulate either surface waves (SW) or spatially propagating waves (SPW). In this paper, a frequency-multiplexed holographic-reflective-integration (HRI) coding metasurface is proposed, which can independently manipulate SW and SPW at different frequencies with a shared aperture....

A scalar–tensor impedance metasurface for frequency‐multiplexed multifunctional orbital angular momentum beams generation

“…Table 1 shows the performance comparison with the published multifunction HIMS. 14,19,20 The proposed scalar-tensor HIMS has the following unique advantages: (i) more flexible multifunction design due to decoupling scalar and tensor parts design. (ii) High AE (14.93% at f L = 11.2 GHz, much higher than conventional scalar HIMS, 23.3% at f H = 18.2 GHz).…”

“…13 A dual-frequency OAM metasurface with a hybrid of scalar impedance coding at low frequency and reflection phase operates at high frequency. 14 The above HIMSs are solely formed by scalar or tensor units, and the composite unit cell is tensor HIMS-phase or scalar HIMSphase. To the knowledge of the authors, there is no result on scalar-tensor HIMS.…”

“…A dual‐circular polarized multi‐beam transmit‐array antenna is proposed by combining the tensor HIMS and hybrid phase compensation 13 . A dual‐frequency OAM metasurface with a hybrid of scalar impedance coding at low frequency and reflection phase operates at high frequency 14 . The above HIMSs are solely formed by scalar or tensor units, and the composite unit cell is tensor HIMS‐phase or scalar HIMS‐phase.…”

Wideband directional-fed holographic metasurface with integrated monopole and parabolic reflector for far-/near-field beams manipulations

“…Holographic metasurface features single-layer planar topology, simple feeding network, and flexible beam manipulation compared to classical high-gain antennas such as transmitarray and reflectarray [14][15][16][17]. Therefore, it is with great potential to be integrated with active circuits, and can implement practical functions such as frequency scanning [18,19], holographic imaging [20][21][22][23], vortex beam generators [24][25][26][27][28][29], and so on.…”

Design of 2.5 Bit Programmable Metasurface Unit Cell for Electromagnetic Manipulation

“…Moreover, programmable electromagnetic metasurfaces are generally produced using printed circuit board (PCB) technology, making them cost-effective compared to large-scale reflector or phased array antennas with complex devices. Electromagnetic metasurfaces can also enable applications like vortex wave generation [7,8], electromagnetic focusing [9,10], and holographic imaging [11,12], offering vast prospects in communication and beyond. Recently, reconfigurable metasurfaces have emerged as a highly active area of research.…”