Journal of Information and Intelligence xxx (xxxx) xxx

Contents lists available at ScienceDirect

Journal of Information and Intelligence

journal homepage: www.journals.elsevier.com/journal-of-information-and-
intelligence

An electromechanically reconfigurable intelligent surface for

enhancing Sub-6G wireless communication signal
Kai Qu, Ke Chen *, Jianmin Zhao, Na Zhang, Qi Hu, Junming Zhao, Tian Jiang,
Yijun Feng *
School of Electronic Science and Engineering, Nanjing University, Nanjing 210023, China

A R T I C L E I N F O A B S T R A C T

Keywords: Reconfigurable intelligent surface (RIS) is emerged as a promising technique to solve the chal-
Reconfigurable intelligent surface lenges faced by future wireless communication networks. Although the most commonly used
Electromechanical electrically-controlled RISs can achieve millisecond-scale speed of dynamic switch, they have a
Sub-6G
large number of microwave circuit elements (such as PIN diodes or varactors) which will bring
Signal enhancement
non-negligible insertion loss, and the complicity of the bias network to electrically addressing each
element will increase with the expansion of the RIS aperture. Aiming at further reducing the
fabrication cost and power consumption, herein an electromechanical RIS used for sub-6G wireless
communication is proposed. The electromechanical RIS is designed with a passive metasurface
and step-motor driver modules, providing simultaneous high-efficiency reflection (over 80%) and
continuous reflection phase coverage of 360
. Through electromechanical control, the RIS system
can realize different reflective wavefront shaping, and has been employed in the indoor sub-6G
wireless environment demonstrating a maximum signal improvement of 8.3 dB. The proposed
electromechanical RIS is particularly useful for wireless signal enhancement in static blind area,
and has the obvious advantage of not requiring continuous power supply after the RIS being
regulated. Therefore, it greatly reduces the overall cost and power consumption which may have
potentials in indoor application scenarios for improving wireless communication performance.

1. Introduction

With the fast development of mobile communication technology, the fifth-generation communication (5G) technology has
been gradually deployed worldwide [1–3]. Although compared with the previous generations, 5G has achieved significant improve-
ments in reducing communication delay, realizing ultra-connectivity characteristics, increasing communication security and trans-
mission speed [2–4], it has also exposed some challenges that cannot be ignored. Firstly, as the 5G shifting to high frequencies the
propagation environment become worse due to the higher transmission loss of high-frequency electromagnetic (EM) waves, which is
more vulnerable to the impact of obstacles. For some non-line-of-sight (NLOS) areas, it is almost equivalent to being in the signal blind
zone [5,6]; secondly, the technology limitation of large-scale multiple antennas, has put forward more stringent requirements for an-
tenna manufacture and system integration [1,3]; thirdly, large number of 5G base stations need to be deployed in various actual sce-
narios, which will greatly increase the energy consumption and maintenance costs; the final challenge is the adaptability to wireless
propagation environment [7–10]. Conventional mobile communication systems have suffered from the only passive adaptation to

* Corresponding author.
E-mail addresses: ke.chen@nju.edu.cn (K. Chen), yjfeng@nju.edu.cn (Y. Feng).

https://doi.org/10.1016/j.jiixd.2023.06.009
Received 26 February 2023; Received in revised form 25 June 2023; Accepted 26 June 2023
Available online xxxx
2949-7159/© 2023 The Author(s). Published by Elsevier B.V. on behalf of Xidian University. This is an open access article under the CC BY-NC-ND
license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Please cite this article as: K. Qu et al., An electromechanically reconfigurable intelligent surface for enhancing Sub-6G wireless
communication signal, Journal of Information and Intelligence, https://doi.org/10.1016/j.jiixd.2023.06.009
K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

various wireless propagation environments for a long time [2]. How to dynamically reconstruct the environment on demand is the core
issue to break through the current technical bottleneck.
Recently, Reconfigurable Intelligent Surfaces (RISs) have received significant attentions in both academia and industry because of
their potential to overcome the abovementioned challenges [10–14]. Originating from the concept of tunable metasurface, RISs have
been considered as an effective methodology to reconfigure the wireless propagation environment, and further improve the coverage of
wireless networks [15]. As a kind of two-dimensional structure, the sub-wavelength profile of RIS allows it to be seamlessly installed on
flat or even curved surfaces of buildings or walls. Besides, low fabrication costs, low latency, low power consumption are also the typical
advantages of RISs [16]. In the microwave frequencies, most of the RIS designs are based on the integration with PIN diodes, varactors,
or other voltage-driven circuit elements [17]. The PIN diodes acting as a switch are often integrated in RIS element which can present
different resonance modes under the ON and OFF states of PIN diode, thus providing 1-bit, 2-bit or even more phase states. In recent
years, PIN-diode-embedded RISs have been demonstrated to achieve beam forming [18–21], signal coverage enhancement [22,23], and
direct modulation in wireless communication [24–28]. Unlike PIN diodes, which can only provide discrete phase responses, varactors
have been employed to realize continuous phase modulation in RISs designs. The capacitance of varactors can continuously change with
the variation of reverse biasing voltage, thus realizing the continuous phase shift of the output EM waves for more complicated
wavefront tailoring [28–30]. These kinds of electrically-controlled RISs can achieve millisecond-scale switching speed, providing sig-
nificant advantages in beam scanning and other real-time applications [21,30–32]. However, PIN diodes or varactors usually bring
obvious insertion loss and further lead to the deterioration of the whole efficiency. Selecting diodes with low insertion loss can alleviate
this problem, but the fabrication cost will correspondingly increase. Most importantly, electrically-controlled RISs can only realize
preset EM functions under the condition of continuous power supply. Undoubtedly, such working mechanism is energy-consuming for
application scenarios that do not need to reconfigure EM functions from time to time.
In order to further improve operating efficiency and reduce costs on the basis of maintaining the reconfigurable ability of EM func-
tions, electromechanical RIS is proposed for some particular application scenarios that do not require frequent EM beam regulation, such
as indoor signal enhancement for static blind area. Different electromechanically reconfigurable metasurfaces based on piezoelectric
actuator [33], spring device [34], and micromotors [16,35,36] are proposed recently. Composed of passive metasurface and mechanical
driver module, these reconfigurable metasurfaces have both the typical advantages of high efficiency and reconfigurability, and possess
functionalities for retroreflector [35], beam forming [36], wireless communication [16], and reconfigurable focusing [37,38], etc.
However, the passive metasurfaces and mechanical drivers in most of these designs are complicated to install and only support limited and
discrete phase states. Therefore, designing a practical electromechanical RIS that is easy to fabricate and assemble, low-cost, while still has
significant flexibility in wavefront tailoring, is urgently needed in wireless communication application.
Here in this work, we propose a practical electromechanical RIS based on the integration of passive metasurface and step-motor
driver modules and controlled by Field Programmable Gate Array (FPGA) for working at sub-6G wireless communication band. The
proposed RIS generates EM waves with diverse wavefront via varying thickness of air layer in each cell between the high-efficiency
passive metasurface and movable metallic ground. 360
full phase range at 2.55 GHz can be provided for the reflected wave by
moving metal ground driven by the step-motor module. All the step motors are independently controlled by direct-current (DC) pulse
signal sent by the FPGA and the displacement of movable ground can be arbitrarily controlled. The proposed RIS can support two
working modes: beam scanning and static beam forming (Fig. 1a and b). When the whole RIS system is powered on, by considering the

Fig. 1. Schematic diagram and application scenario of the proposed electromechanical RIS. (a) Beam scanning mode during power supply. (b) Static
beam forming mode without power supply. (c) Actual indoor 5G communication scenario without the proposed RIS. (d) Signal enhancement for
indoor 5G communication with the assistance of the proposed RIS.

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K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

actual application scenario, users can control the RIS to generate the required reflection beam scanning via FPGA. Then the whole
system can work statically generating the required directive beam in the power-off beam forming mode all the time until the EM
function needs to be reconfigured again. Thus, the proposed RIS can be deployed in particular indoor signal-weak areas (Fig. 1c) and
obtain signal enhancement to effectively improve the communication quality in the weak areas (Fig. 1d). Such electromechanical RIS
possesses significant energy-saving advantage compared with the typical diode-embedded electrically-controlled RISs.

2. Numerical analysis and simulation

2.1. Design of the metasurface and driver module

For an electromechanical RIS, passive metasurface and driver module are the two indispensable components in the whole system.
Under the illumination of incident EM waves, passive metasurface maintains the operating efficiency of the whole system at a high level;
driver module offers degree of freedom for the manipulation of output EM response and makes the passive metasurface “reconfigurable”
and “intelligent”. Since the working mechanism of the passive metasurface determines the specific type of driver module (lifting,
rotating, etc.), we start with the design of the passive metasurface.
Considering that dual-polarization operation mode has better polarization adaptability, we choose a mirror symmetric structure in
both x and y directions in the design of the high-efficiency passive metasurface, and a typical square metallic patch is chosen as the basic
resonant structure. The material of the metallic patch is copper with thickness of 0.018 mm. It is printed on the F4B substrate with
thickness of 2 mm and relative permittivity of 2.65. For a single meta-atom (containing one metallic patch) operating at 2.55 GHz, its
period is set as 32 mm. In order to strengthen the manipulation effect of the reflected waves, we combine 44 meta-atoms into a
supercell. Unlike the supercell forming a phase gradient [39,40], the supercell proposed here is to comply with the periodic boundary
hypothesis in simulation, and weaken the effect brought by the coupling between the adjacent different meta-atoms on phase
modulation [41]. As shown in Fig. 2a, there is an air layer between the F4B substrate and movable metallic ground with thickness hair
varying from 0 mm to 14 mm. Other dimensions are set as the size of each metallic patch a ¼ 22.5 mm and the period of a supercell
p ¼ 128 mm. The configuration of the driver module is depicted in Fig. 2b. Three identical step motors (28BYJ-48, rated at 5 V) are fixed
on another substrate and connected with the movable metallic ground through screws. The three step motors are controlled to rotate
synchronously by pulse signals sent by the FPGA to make the movable metallic ground move smoothly in the z direction via transmission
structure of gear and screw (Fig. 2c).
To verify the EM performance of high efficiency and flexible wavefront tailoring, the proposed RIS supercell is simulated with the
commercial software CST Microwave Studio. The boundary conditions in x and y directions are set as unit cell, that in z direction is set as
open (add space). Under the illumination of linearly polarized waves, the simulated co-polarization phase and amplitude responses with
different hair values are plotted in Fig. 2d and Fig. 2e, respectively. The thickness of air layer directly affects the phase dispersion, which
is embodied in the effective phase shift at 2.55 GHz with the variation of hair. The dispersive phase shift coverage when hair varies is due
to the resonance-based phase modulation mechanism, which limits the bandwidth of the electromechanical RIS. Such drawback may be
mitigated by optimizing the thickness of dielectric layer or configuring multi-resonance operating mode. Besides, the reflection
amplitude of the supercell also slightly decreases with the increase of hair due to the EM resonance. Fig. 2f shows the detailed simulated

Fig. 2. Design and EM performance of the RIS supercell. (a) Schematic diagram and (b) driver module of the RIS supercell. (c) Photograph of the
driver module. Reflection (d) phase, and (e) amplitude spectra with different values of hair. (f) Reflection amplitude and phase responses versus hair at
2.55 GHz.

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phase/amplitude responses at 2.55 GHz versus hair. A full coverage of 360
and high reflection amplitude maintained over 0.9 can be
obtained when hair varies from 2 mm to 14 mm, which is executed by the driver module within seconds. Particularly, we also compare
the EM performances of the supercell with and without the driver module (three motors and three screws), which show ignorable
difference between them indicating that the driver module has almost no interference to the performance of the designed passive
metasurface. The simulated results demonstrate that the proposed RIS supercell could provide stable and reliable phase modulation, and
may have excellent potential in efficiently manipulating EM field in different application scenarios.

2.2. Numerical analysis of the RIS prototype

To verify the performance of the proposed design, we consider a RIS protype with 1616 supercells (6464 meta-atoms). Benefiting
from the capability of independent control for each supercell, the proposed RIS can be imposed one-dimensional and two-dimensional
phase profiles, and is capable of manipulating EM waves in the near and far fields. In Fig. 3a–d, we show different typical EM functions
that can be provided by the RIS prototype. Under the illumination of linearly polarized plane waves, the RIS prototype can operate as a
flat lens (Fig. 3a) and can focus the EM energy in free space to a point. This function of energy convergence can be applied to indoor or
outdoor wireless energy transfer. If the focal position is set as (x0, y0, z0) ¼ (0 mm, 0 mm, 2000 mm), the required phase distribution Ф(x,
y) can be calculated as
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2π
Φðx; yÞ ¼  ðx  x0 Þ2 þ ðy  y0 Þ2 þ z20 ; (1)
λ

where λ is the wavelength at 2.55 GHz, (x, y) is the position of each supercell. Based on this phase distribution, we retrieve the cor-
responding hair according to Fig. 2f, and the distribution of hair shown in Fig. 3e can be obtained.
In addition to the near-field focusing, the proposed RIS prototype can also be used for various beam forming. When loaded with a
periodic phase gradient of “0
, 90
, 180
, 270
” in the x direction, the RIS protype can generate a single beam deflected in the xoz plane.
Accordingly, the hair distribution also has a periodic shift of “12.5 mm, 10.5 mm, 8 mm, 2 mm” in the x direction, which can be
intuitively seen from Fig. 3f. The deflection angle θ for this single beam can be calculated as 13
according to the generalized Snell's law
[42]:

λ dφ
sin θ ¼  ; (2)
2π dx

where φ is the reflection phase. The proposed RIS can also be used to provide multi-beam with different deflection angles in different
planes. As examples, two beams shown in Fig. 3c are generated by the RIS prototype loaded with a two-dimensional periodic phase
gradient, which is calculated by performing convolution operation [43] on the periodic phase gradient of “0
, 90
, 180
, 270
” in the x
direction and that of “0
, 72
, 144
, 216
, 288
” in the y direction. The deflection angles of these two beams are 13
in the xoz plane and
11
in the yoz plane, respectively. The hair distribution to meet this beam-forming requirement is displayed in Fig. 3g, which has
obvious two-dimensional periodic characteristic when compared with Fig. 3f. With regard to the typical checkerboard phase distri-
bution, we also applied this RIS prototype to verify the generated quad-beam (Fig. 3d) by setting the supercells at staggered intervals of
hair ¼ 8 mm and hair ¼ 12.5 mm (Fig. 3h). In actual application, it is only necessary to control the motors of each supercell to drive its
movable metallic ground so that the thickness of air layers meet different hair distributions in turn, and then the corresponding EM
functions can be reconstructed from the previous one to the next.

Fig. 3. Different EM functions and required distributions of hair. (a) Simulation result of RIS-based lens with focal length of 2000 mm. (b) Calculated
scattering pattern of a single beam with deflection angle of 13
in the xoz plane. (c) Calculated scattering pattern of two beams deflected by 13
in the
xoz plane and 11
in the yoz plane, respectively. (d) Calculated scattering pattern of the quad beams with a typical phase distribution of check-
erboard pattern. (e)–(h) The required distributions of hair corresponding to (a)–(d), respectively.

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K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

3. Experimental verifications

3.1. Beam forming demonstration of the RIS

In order to verify the actual EM performance and the reconfigurable capability of the proposed electromechanical RIS, a prototype
with a size of 512512 mm2 is fabricated and then measured in the microwave anechoic chamber (Fig. 4a). The manufactured prototype
is composed of 44 supercells (or 1616 meta-atoms), and its front side (Fig. 4b) is a passive metasurface fabricated by the printed
circuit board (PCB) technology. As clearly seen in Fig. 4c, each supercell is integrated with three motors and a motor driver board. When
operating in power-on mode, the sixteen motor driver boards on the back of the prototype are powered in parallel by a voltage source
with output voltage of 12 V. A series of aluminum cavities are arranged between these supercells, preventing EM waves from leaking
through the gap between the movable metallic grounds. It should be noted that designed RIS has a flat surface without any movable part
which will be beneficial to the deployment in real world scenarios.
In the far-field measurement as shown in Fig. 4a, both the transmitting and receiving antenna are set as y polarization. A metal plate
with the same size as the fabricated prototype is used for the calibration. We first impose a one-dimensional phase profile of “0
, 0
,
180
, 180
” in the y direction on the RIS. As intuitively seen in Fig. 4d, a twin-beam with deflection angle of 13
is experimentally
observed in the yoz plane, which is in good agreement with the full-wave simulation results and the theoretically calculated deflection
angles. Particularly, the measured intensity of both beams in their deflection direction are over 0.63, proving an overall efficiency above
80% at the twin-beam-forming mode. To verify working mode of other dual-beam deflection angle, we reconstruct the phase profile of
the prototype to “0
, 180
, 0
, 180
” via FPGA. The measured and simulated one-dimensional results are provided in Fig. 4e, which
indicates the function of the RIS prototype has been reconfigured to another twin-beam with deflection angles of 27
and similar high
working efficiency. The fabricated RIS prototype shows high efficiency and capability of reconfigurable wavefront tailoring, which lays
a foundation to provide efficient beam forming and may be applied to wireless communication scenarios.

Fig. 4. Experimental demonstration of the actual EM performance and reconfigurable capability of the RIS prototype. (a) Experimental environment.
(b) Front and (c) rear views of the RIS prototype with 44 supercells. Simulated and measured results of the generated twin beams in the yoz plane
with one-dimensional phase gradients of (d) “0
, 0
, 180
, 180
”, and (e) “0
, 180
, 0
, 180
” along y direction.

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K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

3.2. Indoor signal enhancement demonstration of the RIS

In actual indoor application scenarios, communication quality is often seriously degraded due to the presence of walls, corners and
other fixed obstacles, which leads to NLOS areas of signal transmission [16]. The scattering and multipath effect in the EM waves
propagation are obvious, particularly in indoor long and narrow areas [44]. Herein, we prove that the fabricated RIS prototype can
effectively improve the signal quality of communication through indoor experiment.
We test the proposed RIS in a common scenario composed of a corner as shown in Fig. 5a. Although such a NLOS area is not typical
enough due to the indoor diffraction effect of the low operating frequency, the signal intensity inside the corner is still weak relative to
other locations, and we try to demonstrate that the signal in this area can be effectively enhanced by our electromechanical RIS. We use a
signal generator connected with the transmitting horn antenna to generate directive wireless signal propagation, and use an omnidi-
rectional antenna connected to the spectrometer to receive the signal. Particularly, eight positions (points 1–8) in this area are selected
to test the receiving signal in turn, and the distance between two adjacent positions is set as 500 mm. When RIS is not deployed in this
application scenario, the measured results of signal intensity at the eight positions are shown in Fig. 5b. Since points 7 and 8 are close to
the path of direct radiation of the transmitting antenna and are closest to the opposite wall which effectively reflect EM waves, the
received signals at these two points are the strongest. However, the signal intensity at point 1, 2, 5 inside the corner is very weak, which
indicates that the communication quality may be significantly deteriorated at these positions. In order to compare and verify the effect of
signal enhancement, we do not change other experimental setups, but add the RIS prototype on the wall where the antenna is directly
exposed. The RIS prototype is placed 5000 mm away from the transmitting antenna. It is controlled by FPGA to generate the same beam
forming as that in Fig. 3b, and then the power supply is cut off. As clearly seen in Fig. 5c, all the signals at these eight positions are
significantly enhanced. To the aim of characterizing the enhancement effect of the RIS prototype more intuitively, Fig. 5d only displays
the enhancement value at each position. In the eight sampled positions, the average signal enhancement reaches 5.2 dB. Especially,
points 1 and 2 achieve the most significant enhancement, reaching 8.2 dB and 8.3 dB, respectively. It should be noted that the value of
signal enhancement is closely related to the aperture of RIS. If we expand the RIS prototype (4.35λ4.35λ) used in this experiment to a

Fig. 5. Experimental demonstration of the RIS-assisted wireless signal enhancement. (a) Experimental environment of the typical signal-weak area in
a corner. Measured signal intensity distribution at the NLOS area (b) without RIS, and (c) with RIS. (d) Measured signal enhancement at the
NLOS area.

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K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

larger array, the maximum enhancement value can be obviously increased [45–47]. For instance in our previous work, the signal
enhancement up to 22 dB can be obtained by using a large RIS prototype composed of 24  24 meta-atoms [22]. Thus, the test results
clearly indicate that the electromechanical RIS can obviously improve in-door wireless signal intensity in the signal-weak area in a
zero-power consumption operation mode. There is no longer any energy consumption in the whole working process once the adjustment
of RIS's phase distribution is finished, which greatly reduces the operation cost compared with the conventional diode-based elec-
trically-controllable RISs.

4. Conclusion

In this paper, we have investigated an electromechanical RIS that can flexibly manipulate EM waves and be applied to improve the
indoor wireless communication signal. The proposed RIS composed of a passive metasurface and step-motor driver module has been
demonstrated capable of flexible controlling the reflected wavefront by mechanically changing the air layer thickness between the
passive metasurface and metallic ground. By encoding one- or two-dimensional phase profiles in the RIS, reflected EM waves can be
modulated in near and far field to enact functionalities such as EM wave focusing or various beam forming. A RIS prototype composed of
1616 meta-atoms has been realized and successfully applied to solve the problem of weak signal coverage of indoor wireless
communication due to the influence of complex indoor environment, exhibiting obvious signal enhancement at sub-6G frequency band.
The proposed electromechanical RIS is particular applicable to certain scenarios of static weak signal coverage where the whole system
can work statically in the power-off mode all the time after the RIS being regulated. Therefore, the advantages of such an electrome-
chanical RIS in energy saving are particularly prominent compared with the diode-based RIS, which may provide more potentials in
practical applications in future wireless communication.

Acknowledgments

This work was supported by National Natural Science Foundation of China (62071215, 62271243, 91963128), National Key
Research and Development Program of China (2017YFA0700201), the Joint Fund of Ministry of Education for Equipment Pre-research
(8091B032112), Priority Academic Program Development of Jiangsu Higher Education Institutions, Fundamental Research Funds for
the Central Universities and Jiangsu Provincial Key Laboratory of Advanced Manipulating Technique of Electromagnetic Wave.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to
influence the work reported in this paper.

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K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

Kai Qu received his BE degree in optical engineering from the Harbin Institute of Technology, Harbin, China, in 2019. He is currently pursuing
a PhD in electronic science and engineering at Nanjing University, Nanjing, China. His current research focuses on the multifunctional
metasurfaces.

Ke Chen received his BS and PhD degrees in electronic science and engineering from Nanjing University, Nanjing, China, in 2012 and 2017,
respectively. He is currently an associate professor at the Department of Electronic Engineering, School of Electronic Science and Engineering,
Nanjing University. His research interests include electromagnetic metamaterials and metasurfaces and their applications to wireless
communication and photonic devices. He received the Best Excellent Doctoral Dissertation Award of China Education Society of Electronics in
2018, Young Scientist Award of URSI General Assembly and Scientific Symposium (GASS) in 2021, and Young Scientist Award of International
Applied Computational Electromagnetics Society (ACES) in2021.He has hosted more than 10 research projects, such as the National Science
Foundation of China and the Joint Fund of Ministry of Education for Equipment Pre-research. He has authored or co-authored over 70 peer-
reviewed journal articles and over 60 refereed international conference papers.

Jianmin Zhao received the B.E. degree in communication engineering from Nanjing University, Nanjing, China, in 2020, where he is currently
pursuing the M.E. degree in electronic science and engineering. His current research focuses on multiple control systems of active
metasurfaces.

Na Zhang received the B.E. degree in electronic information engineering from Xidian University, Xi'an, China, in 2015, the M.E. degree in
electromagnetic field and microwave technology from the State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, China, in
2018, and the Ph.D. degree in electronic science and engineering from Nanjing University, Nanjing, China, in 2021. She is currently a Research
Fellow at Nanjing University. Her current research interests include metasurfaces and antenna arrays.

Qi Hu received the B.E. degree in communication engineering from the Communication University of China, Beijing, China, in 2019. She is
currently pursuing the Ph.D. degree in electronic science and engineering with Nanjing University, Nanjing, China. Her current research
focuses on metasurfaces.

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K. Qu et al. Journal of Information and Intelligence xxx (xxxx) xxx

Junming Zhao received his BS and PhD degrees in electronic science and engineering from Nanjing University, Nanjing, China, in 2003 and
2009, respectively. Since 2009, he has been a faculty member at the Department of Electronic Engineering, School of Electronic Science and
Engineering, Nanjing University, where he is currently a professor. From January 2014 to January 2015, he was a visiting scholar with the
Group of Antennas and Electromagnetics, School of Electronic Engineering and Computer Science, Queen Mary College, University of London.
His research interests include electromagnetic metamaterials and metasurfaces and their applications to novel microwave functional devices.

Tian Jiang received his MSc and PhD degrees from the Department of Electronic Science and Engineering, Nanjing University, Nanjing, China,
in 2004 and 2007, respectively. Since 2007, he has been a faculty member and currently, a professor at the Department of Electronic Engi-
neering, School of Electronic Science and Engineering, Nanjing University. His research interests include electromagnetic metasurfaces and
their application to microwave and photonic devices.

Yijun Feng received his PhD from the Department of Electronic Science and Engineering, Nanjing University, in 1992. Since then, he has been
a faculty member and is currently a full professor and deputy dean of the School of Electronic Science and Engineering, Nanjing University.
From September 1995 to July 1996, he was a visiting scientist at the physics department of Technical University of Denmark. From August
2001 to August 2002, he was a visiting researcher at the University of California, Berkeley. His research interests include electromagnetic
metamaterials and their application to microwave and photonic devices, electromagnetic wave theory, and novel microwave functional
materials. He has conducted more than 20 scientific research projects, including National 973, 863 Projects, National Natural Science
Foundation projects, and the National Key Research and Development Program in China. He has served as the General Co-Chair of 2018 IEEE
International Workshop on Antenna Technology, and Technical Program Co-Chair of 2013 International Symposium on Antennas and
Propagation. He has received the 2010 Science and Technology Award (first grade) of Jiangsu Province, and the 2021 Science and Technology
Award (first grade) of Shanxi Province, China. He has authored or co-authored over 200 peer-reviewed journal papers and over 160 refereed
international conference papers.

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