Description:TECHNICAL FIELD
The present disclosure relates to the field of wireless communication systems, specifically to reconfigurable intelligent surfaces for electromagnetic wave manipulation. More particularly, the present disclosure relates to a reconfigurable intelligent surface designed to enhance the performance of wireless networks by dynamically controlling the reflection, direction, and propagation of electromagnetic waves, particularly in non-line-of-sight environments.
BACKGROUND
Reconfigurable Intelligent Surfaces (RIS) enable power-efficient wavefront engineering in modern wireless communication systems, offering real-time manipulation of electromagnetic waves to optimize signal integrity, network coverage, and spectrum utilization in next-generation wireless communication systems. By employing passive beamforming, RIS structures manipulate incident signals, thereby enhancing signal quality, coverage, and spectral efficiency without requiring active transmission.
Phased-array antennas and relay-based communication are both widely used in modern wireless systems, but each faces significant challenges that impact their efficiency and practicality. Phased-array antennas suffer from high power consumption due to the need for multiple active RF chains, phase shifters, and power-intensive amplifiers, as well as complex hardware and high costs. These factors also result in thermal management issues and limited scalability, making them impractical for large-scale deployment. Similarly, relay-based communication, while enhancing wireless coverage, introduces increased latency, energy consumption, and noise amplification, which degrades signal quality. Furthermore, relay systems require additional infrastructure and frequency bands, increasing costs, reducing spectrum efficiency, and limiting network capacity. These challenges hinder the full potential of both technologies in extensive network applications.
Conventional Reconfigurable Intelligent Surface designs often rely on slow, inflexible tuning mechanisms, such as mechanical adjustments or fixed configurations, which limit adaptability and responsiveness in dynamic wireless environments. With the rapid advancements in wireless communication technologies, particularly in the transition towards 5G and 6G networks, the demand for reliable and high-performance systems has escalated. One of the major challenges in modern wireless communication is maintaining robust connectivity in environments where line-of-sight (LoS) paths between transmitters and receivers are obstructed by physical barriers such as walls, buildings, or other obstacles. In these non-line-of-sight (NLoS) conditions, traditional communication methods often experience signal degradation, poor coverage, and increased latency. As a result, enhancing communication in such challenging environments has become a critical area of focus for next-generation wireless systems.
RIS can be deployed on building facades, walls, and street infrastructure to overcome signal blockages and interference in densely populated cities, enhancing network coverage and reducing dead zones. In subways, tunnels, and underground facilities, where signal penetration is limited, RIS can be strategically positioned along walls or ceilings to extend coverage and improve connectivity. Factories and warehouses often experience severe signal reflections and attenuation due to metallic structures and machinery. RIS dynamically redirects signals around obstacles, effectively creating virtual pathways to maintain connectivity. This redirection significantly enhances signal coverage and reduces dead zones in complex environments. Thus, RIS can enhance real-time IoT communication, automation reliability, and wireless network efficiency in such settings. This ensures higher data rates, lower latency, and more reliable communication, which are critical for applications like smart cities, autonomous vehicles, and indoor wireless networks. Another notable benefit is scalability and flexibility, as RIS can be seamlessly deployed on various surfaces, allowing easy integration into existing infrastructure while optimizing wireless coverage and efficiency.
The desired features of RIS include enhanced signal coverage, reduced dead zones, and improved overall performance of wireless communication systems in complex environments. Unlike conventional methods that depend on additional infrastructure, such as relay stations or repeaters, there is a growing need for an RIS that offers a more cost-effective and scalable solution.
Existing RIS designs depend on complex multi-element systems for wave manipulation, resulting in complex array structures and higher power consumption. These prior art designs encounter scalability and performance challenges, particularly when applied to large surfaces or high-frequency bands. Notably, certain prior RIS configurations incorporate 5×5 sub-elements per unit, which leads to complex control systems and scalability issues. Some solutions struggle with high power consumption, performance degradation at extreme angles, and difficulties in expanding the RIS array for larger setups. Additionally, other RIS designs face significant fabrication complexities, such as the need for precise liquid crystal alignment, complicating mass production and real-world deployment. Furthermore, many existing RIS technologies rely on mechanical tuning or fixed configurations, which hinder adaptability and limit operational efficiency.
Accordingly, an RIS architecture integrating electronic and programmable tuning mechanisms to optimize wave reflection, minimize interference, and extend network reach is highly desirable for 5G, beyond 5G, and future wireless networks. Such an architecture must address key challenges related to scalability, efficiency, and real-time signal reconfiguration, ensuring adaptability to evolving communication demands. An RIS featuring a simplified hardware, consisting of a metasurface with tunable reflective elements, eliminating the need for complex amplifiers and RF chains is needed, particularly for 6G networks, IoT, and smart environments. The RIS needs to swiftly adapt to evolving network conditions, dynamically optimizing performance in response to shifts in traffic loads, frequency variations, and propagation environments, ensuring consistent and efficient communication. Moreover, a key attribute of RIS is its ability to enhance spectral efficiency through intelligent wavefront manipulation, without the need for additional frequency bands, thereby significantly improving overall network performance.
Therefore, there is a need for a scalable alternative to traditional RIS architecture, that allows precise control of the reflection angle by dynamically controlling the phase and amplitude of reflected electromagnetic waves in real-time for adaptive wavefront manipulation in advanced communication systems.
SUMMARY
In one aspect of the present disclosure, a reconfigurable intelligent surface for electromagnetic wave manipulation is provided.
The reconfigurable intelligent surface for electromagnetic wave manipulation includes a plurality of unit cells arranged in a two-dimensional array. Each unit cell includes a first substrate layer, a top layer, positioned on the upper surface of the first substrate layer and, a second substrate layer attached to the lower surface of the first substrate layer, a third substrate layer attached to the lower surface of the second substrate layer and a ground layer integrated to the lower surface of the third substrate layer, that includes a capacitive patch with an RF circuitry, configured to supply and manage electrical signals required to operate the reconfigurable intelligent surface. The top layer is made of conducting material and includes an outer conductive patch and an inner conductive patch. The outer conductive patch and the inner conductive patch are structurally distinct and electrically isolated from each other. The first substrate layer, the second substrate layer, and the third substrate layer are made of dielectric materials. A 1-bit PIN diode is mounted on the ground layer and is configured to connect the outer conductive patch and the inner conductive patch. A plurality of vias is provided that are configured to electrically connect the top layer to the ground layer. The outer conductive patch is configured with a U-shaped geometry and the inner conductive patch is configured with a slotted square structure. The RF circuitry selectively controls the 1-bit PIN diode to dynamically alter the phase and amplitude of the reflected electromagnetic waves, thereby enabling the reconfigurable intelligent surface to control the reflection angles of the impinging electromagnetic waves.
In some aspects of the present disclosure, the outer conductive patch is positioned proximate to the outer periphery of the first substrate layer, and the inner conductive patch is positioned inward relative to the outer conductive patch. The conductive patches are arranged symmetrically with respect to an axis on the surface of the top layer, the axis passing through the midpoint of a connected side of the U-shaped outer conductive patch in a direction perpendicular to the connected side.
In some aspects of the present disclosure, the reconfigurable intelligent surface operates at a center frequency of 3.5 GHz within a frequency range of 3.3 GHz to 3.8 GHz.
In some aspects of the present disclosure, the outer conductive patch and the inner conductive patch are printed on the top surface of the first substrate layer and are interconnected by means of the 1-bit PIN diode.
In some aspects of the present disclosure, the 1-bit PIN diode implemented in each unit cell is configured to shift the phase of the incident wave by 180 degrees.
In some aspects of the present disclosure, width of each slot of the inner conductive patch is less than 1mm.
In some aspects of the present disclosure, the gap between the outer conductive patch and the inner conductive patch is 0.1 mm.
In some aspects of the present disclosure, the 1-bit PIN diode is connected to the backside of the unit cell through vias, thereby preventing interference with the manipulation of electromagnetic waves on the top layer.
In some aspects of the present disclosure, the second substrate layer is thicker than the first substrate layer and the third substrate layer.
In some aspects of the present disclosure, the first substrate layer, the second substrate layer, and the third substrate layer comprise glass epoxy (FR4) substrates having a dielectric constant of 4.4 and a loss tangent of 0.002.
In some aspects of the present disclosure, the design of the RIS (100) utilizes a glass epoxy (FR4) substrate with a microstrip technique, offering a cost-effective design.
In some aspects of the present disclosure, the first substrate layer and the third substrate layer are designed to be of the same thickness.
In some aspects of the present disclosure, the ground layer comprises a square conducting layer with a sidelength of 15 mm placed at the centre of the third substrate layer.
In some aspects of the present disclosure, the unit cells are fabricated in a four-layer printed circuit board structure.
In some aspects of the present disclosure, each unit cell has a dimension of 26 mm × 26 mm.
In some aspects of the present disclosure, the two-dimensional array comprises 256 unit cells arranged in a 16 × 16 grid and has overall dimensions of 420 mm × 420 mm.
In some aspects of the present disclosure, the unit cells are configured to reflect the normally impinging electromagnetic waves at an angle of 5° with a gain of 12 dB, at an angle of 10° with a gain of 11 dB, and at an angle of 40° with a gain of 10 dB.
In some aspects of the present disclosure, a method of operating a reconfigurable intelligent surface for electromagnetic wave manipulation in a wireless communication system is provided. The method includes the steps of providing a reconfigurable intelligent surface comprising an array of programmable unit cells, each unit cell configured with a 1-bit PIN diode to manipulate electromagnetic waves, receiving an electromagnetic signal from a transmitter antenna, wherein the signal is directed toward the reconfigurable intelligent surface at a specified angle of incidence, dynamically adjusting the reflection pattern of the reconfigurable intelligent surface based on pre-configured control signals transmitted from a RF circuitry, wherein the RF circuitry modifies the behavior of the unit cells through the 1-bit PIN diodes to achieve desired reflection characteristics, reflecting the received signal from the reconfigurable intelligent surface, wherein the signal is reflected toward a receiver antenna with manipulated phase and amplitude determined by the programmed reflection patterns of the reconfigurable intelligent surface, measuring the reflected signal at the receiver antenna, wherein the reflected signal is analyzed to obtain performance metrics including signal strength and reflection efficiency, and adjusting the reflection patterns of the reconfigurable intelligent surface in real-time to optimize signal propagation and coverage, based on feedback from the receiver antenna and the performance metrics obtained by measuring the reflected signal at the receiver antenna.
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations. In the drawing,
Figure 1A illustrates a reconfigurable intelligent surface (RIS) system, in accordance with an aspect of the present disclosure;
Figure 1B illustrates a unit cell of the reconfigurable intelligent surface (RIS) system, in accordance with an aspect of the present disclosure;
Figure 2A illustrates the unit cell, showing both the top layer and the side view, in accordance with an aspect of the present disclosure;
Figure 2B illustrates the unit cell, showing both the ground layer and the side view, in accordance with an aspect of the present disclosure;
Figure 3A illustrates the top layer, in accordance with an aspect of the present disclosure;
Figure 3B illustrates the ground layer, in accordance with an aspect of the present disclosure;
Figure 4 illustrates a graph of reflection amplitude vs frequency, representing S11 phase when the PIN diode is in its ON and OFF states, in accordance with an aspect of the present disclosure;
Figure 5 illustrates a graph of reflection phase vs frequency, representing S11 phase when the PIN diode is in its ON and OFF states, in accordance with an aspect of the present disclosure;
Figure 6A illustrates a top view of the reconfigurable intelligent surface, in accordance with an aspect of the present disclosure;
Figure 6B illustrates a bottom view of the reconfigurable intelligent surface, in accordance with an aspect of the present disclosure;
Figure 7A illustrates a detailed view of the ground layers of the unit cells, in accordance with an aspect of the present disclosure;
Figure 7B illustrates a detailed view of the ground layers of the unit cells, showing the RF circuitry in each unit cell, in accordance with an aspect of the present disclosure;
Figure 8A illustrates a pattern arranged in the RIS to achieve a 5-degree reflection of the incident wave, in accordance with an aspect of the present disclosure;
Figure 8B illustrates the reflected electromagnetic wave, that has been simulated in HFSS corresponding to Pattern 1 of figure 8A, under normal incidence of the electromagnetic wave on the RIS surface, in accordance with an aspect of the present disclosure;
Figure 9A illustrates a pattern arranged to achieve a 10-degree reflection of the incident wave, in accordance with an aspect of the present disclosure;
Figure 9B illustrates the reflected electromagnetic wave, that has been simulated in HFSS corresponding to Pattern 2 in Figure 9A, under normal incidence of the electromagnetic wave on the RIS surface, in accordance with an aspect of the present disclosure;
Figure 10A illustrates a pattern arranged to achieve a 40-degree reflection of the incident wave, in accordance with an aspect of the present disclosure;
Figure 10B illustrates the reflected electromagnetic wave, that has been simulated in HFSS corresponding to Pattern 3 in Figure 10A, under normal incidence of the electromagnetic wave on the RIS surface, in accordance with an aspect of the present disclosure;
Figure 11 illustrates a detailed schematic of a unit cell with its structural design and functional components, in accordance with an aspect of the present disclosure;
Figure 12 illustrates measured reflected electromagnetic wave for pattern 1 under normal incidence to the RIS surface of Figure 8A, in accordance with an aspect of the present disclosure;
Figure 13 illustrates measured reflected electromagnetic wave for pattern 2 under normal incidence to the RIS surface of Figure 9A, in accordance with an aspect of the present disclosure;
Figure 14 illustrates measured reflected electromagnetic wave for pattern 3 under normal incidence to the RIS surface of Figure 10A, in accordance with an aspect of the present disclosure;
Figure 15 illustrates a measurement setup used for characterizing the RIS prototype in accordance with an aspect of the present disclosure;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. Thus, the following description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, known details are not described in order to avoid obscuring the description.
References to one or an embodiment in the present disclosure can be references to the same embodiment or any embodiment; and, such references mean at least one of the embodiments.
Reference to "one embodiment", "an embodiment", “one aspect”, “some aspects”, “an aspect” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others.
The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be placed upon whether or not a term is elaborated or discussed herein. In some cases, synonyms for certain terms are provided.
A recital of one or more synonyms does not exclude the use of other synonyms.
The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and is not intended to further limit the scope and meaning of the disclosure or of any example term. Likewise, the disclosure is not limited to various embodiments given in this specification. Without intent to limit the scope of the disclosure, examples of instruments, apparatus, methods and their related results according to the embodiments of the present disclosure are given below. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the disclosure. Unless otherwise defined, technical and scientific terms used herein have the meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions will control.
Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the disclosure will become more fully apparent from the following description and appended claims, or can be learned by the practice of the principles set forth herein.
As mentioned before, there is a need for a scalable alternative to traditional RIS architecture, that allows precise control of the reflection angle by dynamically controlling the phase and amplitude of reflected electromagnetic waves in real-time for adaptive wavefront manipulation in advanced communication systems, specifically designed to enhance 5G and 6G communications. The present disclosure demonstrates improved reconfigurability and adaptability of the RIS through the use of PIN diodes.
In one aspect of the present disclosure, a reconfigurable intelligent surface (100) for electromagnetic wave manipulation is provided.
Figure 1A illustrates a system of reconfigurable intelligent surface (100), in accordance with an aspect of the present disclosure.
In some aspects of the present disclosure, thickness of reconfigurable intelligent surface (100) may be of the order of a subwavelength of the operating frequency.
The reconfigurable intelligent surface (100) includes a plurality of unit cells (102) arranged in a two-dimensional array.
In some aspects of the present disclosure, the reconfigurable intelligent surface (100) operates at a centre frequency of 3.5 GHz within a frequency range of 3.3 GHz to 3.8 GHz.
In some aspects of the present disclosure, the reflected wave may be steered in a desired direction or optimized to meet specific communication or signal-processing requirements by coordinating the adjustments across all unit cells (102) in the RIS (100).
Mathematically, the scattering field generated by the RIS for an incident EM wave with x- or y-polarization can be modeled based on the collective contributions of all M x N unit cells. Each unit cell acts as a discrete scattering element, introducing controlled phase shifts and amplitude changes to the incident wave. The total scattering field can thus be expressed as the superposition of the fields scattered by each unit cell, typically represented in terms of array factor formulations or other mathematical models that account for the geometry, arrangement, and individual responses of the unit cells. This model forms the basis for analyzing and designing RIS systems to achieve desired wavefront transformations effectively.
Mathematically can be modeled as follows:

• Amn: Amplitude of the element
• ejαmn : Phase term of coefficient of (m,n)
• |Гmn| : reflection coefficient magnitude.
• ejФmn : Phase shift due to reflection,
• fmn(θ,Ф) : Element pattern function,
• K0: wavenumber,
• dx and dy: spacing between element in x and y direction
Assuming identical reflection magnitudes, the reflection phase matrix of the RIS can be represented as

The optimal phase compensation of unit cell (m,n) can be obtained as:

where,
• p: Location of Electromagnetic source,
• q: Focusing point location,
• rmn: Position of unit cell (m, n)
In the 1-bit unit cell RIS, the available states are "0" and "1" only, which correspond to the 0° and 180° phase shifts, respectively. Thus, the phase quantization can be calculated as:

subsequently, the reflection coefficient of unit cell (m, n) is derived as

The received signal at the receiver of the RIS-aided wireless communications system is expressed as:

where, hTx-RIS-Rxm,n is the cascade channel gain from the transmitter to the unit cell (m, n) and the receiver, hTx-Rx is the direct channel between the transmitter and receiver, xTx is the transmitted signal, դ is the additive white Gaussian noise.
Figure 1B illustrates a unit cell (102) of the reconfigurable intelligent surface (100) system, in accordance with an aspect of the present disclosure.
Each unit cell (102) includes a first substrate layer (104), a top layer (106), positioned on the upper surface of the first substrate layer (104) and, a second substrate layer (108) attached to the lower surface of the first substrate layer (104), a third substrate layer (110) attached to the lower surface of the second substrate layer (108) and a ground layer (112) integrated to the lower surface of the third substrate layer (110). The first substrate layer (104), the second substrate layer (108), and the third substrate layer (110) are made of dielectric materials.
In some aspects of the present disclosure, the second substrate layer (108) is thicker than the first substrate layer (104) and the third substrate layer (110).
In some aspects of the present disclosure, the first substrate layer (104) and the third substrate layer (110) are designed to be of the same thickness.
In some aspects of the present disclosure, the height of the first substrate layer (104), the second substrate layer (108), and the third substrate layer (110) are 0.35 mm, 2.4 mm, and 0.35mm respectively.
In some aspects of the present disclosure, the first substrate layer (104), the second substrate layer (108), and the third substrate layer (110) comprise glass epoxy (FR4) substrates having a dielectric constant of 4.4 and a loss tangent of 0.002.
In some aspects of the present disclosure, the unit cells (102) are fabricated in a four-layer printed circuit board structure.
In some aspects of the present disclosure, each unit cell (102) has a dimension of 26 mm × 26 mm.
In some aspects of the present disclosure, the two-dimensional array comprises 256-unit cells (102) arranged in a 16 × 16 grid and has overall dimensions of 420 mm × 420 mm.
In some aspects of the present disclosure, the unit cells (102) are configured to reflect the normally impinging electromagnetic waves at an angle of 5° with a gain of 12 dB, at an angle of 10° with a gain of 11 dB, and at an angle of 40° with a gain of 10 dB.
Figure 2A illustrates the unit cell (102), showing both the top layer (106) and the side view, in accordance with an aspect of the present disclosure.
The top layer (106) is made of conducting material and includes an outer conductive patch (114) and an inner conductive patch (116). The outer conductive patch (114) and the inner conductive patch (116) are structurally distinct and electrically isolated from each other. A plurality of vias (122) are provided that are configured to electrically connect the top layer (106) to the ground layer (112).
The top layer (106) may include an array of patch elements that are used to manipulate the incident electromagnetic waves according to the desired reflection patterns.
Figure 2B illustrates the unit cell (102), showing both the ground layer (112) and the side view, in accordance with an aspect of the present disclosure.
The ground layer (112) may include a capacitive patch with an RF circuitry (120), configured to supply and manage electrical signals required to operate the reconfigurable intelligent surface (100). A 1-bit PIN diode (118) is mounted on the ground layer (112) and is configured to connect the outer conductive patch (114) and the inner conductive patch (116).
In some aspects of the present disclosure, PIN diodes (118) may be employed to manipulate the incident electromagnetic waves, directing them toward the desired direction to optimize communication efficiency.
In some aspects of the present disclosure, the strategic placement of the PIN diodes (118) on the backside of the unit cell (102) helps prevent any electromagnetic interference with the top layer (106), ensuring optimal performance and signal integrity.
In some aspects of the present disclosure, the 1-bit PIN diode may be implemented in each unit cell (102) and may be configured to shift the phase of the incident wave by 180 degrees.
In some aspects of the present disclosure, the ground layer (110) comprises a square conducting layer with a sidelength of 15 mm placed at the centre of the third substrate layer (108).
Figure 3A illustrates the top layer (106), in accordance with an aspect of the present disclosure.
The outer conductive patch (114) is configured with a U-shaped geometry and the inner conductive patch (116) is configured with a slotted square structure.
In some aspects of the present disclosure, the outer conductive patch (114) and the inner conductive patch (116) are printed on the top surface of the first substrate layer (104) and are interconnected by means of the 1-bit PIN diode (118).
In some aspects of the present disclosure, the symmetrical design of these patches ensures distinct impedance characteristics for the ON and OFF states of the 1-bit PIN diode (118).
In some aspects of the present disclosure, the outer conductive patch (114) is positioned proximate to the outer periphery of the first substrate layer (104), and the inner conductive patch (116) is positioned inward relative to the outer conductive patch (114), wherein the conductive patches are arranged symmetrically with respect to an axis on the surface of the top layer (106), the axis passing through the midpoint of a connected side (132) of the U-shaped outer conductive patch (114) in a direction perpendicular to the connected side (132).
In some aspects of the present disclosure, the gap (134) between the outer conductive patch (114) and the inner conductive patch (116) is 0.1 mm.
In some aspects of the present disclosure, the dimensions of the parallel sides (128) of the U-shaped outer conductive patch (114) is 23.5 mm, the connected side (132) of the U-shaped outer conductive patch (114) is 25 mm , the outer side length (124) of the square inner conductive patch (116) is 17 mm, inner side length (126) of the square inner conductive patch (116) inside the slots is 15.6 mm, and the gap (134) between the outer conductive patch (114) and the inner conductive patch (116) is 0.1mm.
In some aspects of the present disclosure, width of each slot (130) of the inner conductive patch (116) is less than 1mm.
Figure 3B illustrates the ground layer (112), in accordance with an aspect of the present disclosure.
The outer dimensions of the third substrate layer (110) are given by a first side (140) and a second side (142).
The outer dimensions of the ground layer (112) are given by a side1 (144) and side2(146).
The RF circuitry (120) selectively controls the 1-bit PIN diode (118) to dynamically alter the phase and amplitude of the reflected electromagnetic waves. This enables the reconfigurable intelligent surface (100) to control the reflection angles of the impinging electromagnetic waves.
In some aspects of the present disclosure, the 1-bit PIN diode (118) may be connected to the backside of the unit cell (102) through vias (122), thereby preventing interference with the manipulation of electromagnetic waves on the top layer (106).
In some aspects of the present disclosure, the first side (140) and the second side(142) are of equal length.
In some aspects of the present disclosure, the first side (140) and the second side (142) are equal and it may have a value of 26 mm.
In some aspects of the present disclosure, the side1 (144) and the side2(146) are equal and it may have a value of 15 mm.
In some aspects of the present disclosure, the width (148) of the third substrate layer that is visible outside the ground layer is 5.5 mm.
In some aspects of the present invention, simulation using High-Frequency Structure Simulator (HFSS) may closely mirror the real-world performance of the PIN diode (118), providing a more reliable prediction of the behavior of the RIS system (100) in practical applications.
In an exemplary scenario, the RIS system (100) may be designed and simulated using High-Frequency Structure Simulator (HFSS), employing periodic boundary conditions and Floquet port excitation to ensure accurate modeling of its behavior. In the simulation, the PIN diode (118) can be represented as a series RLC circuit, implemented as a lumped RLC boundary condition within HFSS. This approach enables precise representation of the diode's electrical characteristics.
The parameters of the RLC circuit—Resistance (R), Inductance (L), and Capacitance (C)—obtained from the PIN diode's datasheet, with values of R=5.2 Ω, L=30 pH, and C=0.20 pF, respectively are used. These parameters are crucial for accurately capturing the diode's electrical response in both its ON and OFF states. To further enhance simulation fidelity, the physical dimensions of the RLC boundary condition were carefully matched to the actual size of the PIN diode (118).
In some aspects of the present disclosure, the unit cell (102) achieves a 180° phase difference between the ON and OFF states of the PIN diode (118) at the center frequency of 3.5 GHz.
In some aspects of the present disclosure, the PIN diode (118) creates a reflective response pattern for electromagnetic waves.
Figure 4 illustrates a graph of reflection amplitude vs frequency, representing S11 phase when the PIN diode (118) is in its ON and OFF states, in accordance with an aspect of the present disclosure.
Figure 5 illustrates a graph of reflection phase vs frequency, representing S11 phase when the PIN diode (118) is in its ON and OFF states, in accordance with an aspect of the present disclosure.
Figures 4 and 5 illustrate the simulated results for the unit cell (102). Figure 4 illustrates the S11 phase when the PIN diode is in its ON and OFF states, and Figure 5 illustrates the reflection amplitude for these states.
In an exemplary scenario, extensive simulations were conducted using Ansys HFSS 2022. In the simulation model, the RIS and a standard horn antenna were placed in two separate enclosures, utilizing the finite element boundary integral (FE-BI) method to reduce the computational cost associated with the space between the horn and the RIS.
Figure 6A illustrates a top view of the reconfigurable intelligent surface (100), in accordance with an aspect of the present disclosure.

Figure 6B illustrates a bottom view of the reconfigurable intelligent surface (100), in accordance with an aspect of the present disclosure.
Figure 6A illustrates a top view of the designed RIS array, comprising 256 unit cells (102) arranged in a 16×16 grid.
Figure 6B illustrates a bottom view of the RIS (100). The pattern of the RIS is achieved by toggling the PIN diodes (118) between their ON and OFF states.
Figure 7A illustrates the design of the RF circuitry (120) integrated into the ground layers (112) of the unit cells (102), in accordance with an aspect of the present disclosure.
Figure 7B illustrates a bottom view of the fabricated RIS unit cell (102) showcasing the RF circuitry (120), in accordance with an aspect of the present disclosure.
In some aspects of the present disclosure, the RIS (100) may be carefully designed to have ON/OFF pattern of the PIN diodes (118) to achieve optimal performance at a specific incident frequency, assuming constant environmental and design factors.
In an exemplary scenario, three distinct patterns are simulated, as shown in Figures 8A, 9A, and 10A. The RIS used in the simulations consists of 256 elements arranged in a 16 × 16 grid. The simulations were performed at a center frequency of 3.5 GHz, within a frequency range of 3.3 to 3.8 GHz.
Figure 8A illustrates a pattern arranged to achieve a 5-degree reflection of the incident wave, in accordance with an aspect of the present disclosure.
Pattern 1, as illustrated in Figure 8A, demonstrates the simulated reflection pattern, with the corresponding reflected electromagnetic wave angle presented in Figure 8B. The electromagnetic (EM) wave is normally incident (θi = 0°) on the RIS (100) and is reflected at an angle of θr = 5° with a gain of 12 dB.
This pattern is applied to the RIS (100) to study its influence on wave reflection and transmission. The S21 parameter, which represents the transmission coefficient, is measured for Pattern 1, and the results are presented Figure 12 at the centre frequency 3.5GHz.
Figure 8B illustrates the reflected electromagnetic wave, that has been simulated in HFSS corresponding to Pattern 1 of figure 8A, under normal incidence of the electromagnetic wave on the RIS surface, in accordance with an aspect of the present disclosure.
Figure 9A illustrates a pattern arranged to achieve a 10-degree reflection of the incident wave, in accordance with an aspect of the present disclosure.
Figure 9B illustrates the reflected electromagnetic wave, that has been simulated in HFSS corresponding to Pattern 2 in Figure 9A, under normal incidence of the electromagnetic wave on the RIS surface, in accordance with an aspect of the present disclosure.
For Pattern 2, the reflected angle θr is 10° with a gain of 11 dB, as shown in Figure 9B.
Figure 10A illustrates a pattern arranged to achieve a 40-degree reflection of the incident wave, in accordance with an aspect of the present disclosure.
Figure 10B illustrates the reflected electromagnetic wave, that has been simulated in HFSS corresponding to Pattern 3 in Figure 10A, under normal incidence of the electromagnetic wave on the RIS surface, in accordance with an aspect of the present disclosure.
For Pattern 3, the reflected angle θr is 40° with a gain of 10 dB, as shown in Figure 10B.
Pattern 1, illustrated in Figure 8A, demonstrates the simulated reflection pattern, with the corresponding reflected EM wave angle presented in Figure 8B. The electromagnetic wave is normally incident (θi = 0°) on the RIS (100) and is reflected at an angle of θr = 5° with a gain of 12 dB. Similarly, Patterns 2 and 3 are depicted in Figures 9A and 10A, respectively. For Pattern 2, the reflected angle θr is 10° with a gain of 11 dB, as shown in Figure 9B. For Pattern 3, the reflected angle θr is 40° with a gain of 10 dB, as shown in Figure 10B.
In an exemplary scenario, the simulations confirm the capability of the RIS (100) to control the reflection angles of electromagnetic waves through different ON/OFF patterns.
In some aspects of the present disclosure, the RF circuitry (120) may be used to dynamically adjust these patterns using PIN diodes (118) to toggle the ON/OFF states.
In some aspects of the present disclosure, the dimensions of the RIS (100) are 420 mm × 420 mm.
Figure 11 illustrates a detailed schematic of a single RIS unit cell (102) that shows its structural design and functional components, in accordance with an aspect of the present disclosure. The schematic provides details of the internal design and connectivity within the stack-up layers.
In an exemplary scenario, the schematic details the internal design of a unit cell (102) in a reconfigurable intelligent surface (100), where two conductive patches in the top layer (106) are connected by a 1-bit PIN diode (118). The RF circuitry (120) controls the state of the PIN diode (118), switching it between ON and OFF to alter the connection between the patches. This design allows the RIS to dynamically manipulate the reflection characteristics of electromagnetic waves, enabling real-time adjustments to optimize wireless communication in response to changing network conditions or interference.
Figure 12 illustrates measured reflected electromagnetic wave for pattern 1 under normal incidence to the RIS surface of Figure 8A, in accordance with an aspect of the present disclosure. The S21 parameter, which represents the transmission coefficient, is measured for Pattern 1, and the results are presented at the 3.5GHz.
Figure 13 illustrates measured reflected electromagnetic wave for pattern 2 under normal incidence to the RIS surface of Figure 9A, in accordance with an aspect of the present disclosure.
Figure 14 illustrates measured reflected electromagnetic wave for pattern 3 under normal incidence to the RIS surface of Figure 10A, in accordance with an aspect of the present disclosure.
When Patterns 2 and 3 are applied to the RIS (100), different reflection behaviors are observed at 3.5 GHz. In Pattern 2, the maximum power of the reflected electromagnetic wave is observed at an angle of 10 degrees relative to the normal to the RIS surface, as shown in Figure 13.
In the case of Pattern 3, the reflected wave deviates at an angle of 40 degrees from the normal to the RIS surface. The measured radiation pattern (S-parameters) is presented in Figure 14.
These results demonstrate that applying different patterns to the RIS (100) allows precise control of the reflection angle and corresponding transmission gain, highlighting the RIS's potential for adaptive wavefront manipulation in advanced communication systems.
In some aspects of the present disclosure, the fabrication of the RIS (100) provides a compact, efficient, and interference-free RIS design, suitable for advanced electromagnetic applications.
Figure 15 illustrates a measurement setup used for characterizing the RIS prototype in accordance with an aspect of the present disclosure.
Figure 15 illustrates the measurement setup for characterizing a passive reconfigurable intelligent surface (100) prototype within an anechoic chamber. The setup includes a transmitter horn antenna (140) to emit electromagnetic waves toward the RIS (100) and a receiver horn antenna (142) to capture the reflected or manipulated signals. The anechoic chamber ensures a controlled, interference-free environment, allowing precise evaluation of the RIS's ability to manipulate waves, including its impact on signal strength, phase shifts, and overall performance in wireless communication systems.
In an exemplary scenario, a measurement setup involving reconfigurable intelligent surface (100) and Universal Software Radio Peripheral (USRP), the RIS (100) is used to manipulate electromagnetic waves for improved signal coverage, especially in non-line-of-sight (NLoS) conditions. The USRP generates and processes signals via transmitter (140) and receiver (142) antennas, while the RIS (100) dynamically adjusts the phase and amplitude of reflected signals to redirect them around obstacles, enhancing communication in complex environments. By using software to control the RIS in real-time, the system enables precise wave manipulation, optimizing signal quality, minimizing interference, and ensuring reliable connectivity. This integration provides a flexible and scalable solution for wireless communication, particularly in challenging environments.
In an exemplary scenario, two horn antennas are used for characterizing the RIS prototype within the anechoic chamber. One of these antennas is configured to operate as a transmitter (140), while the other functions as a receiver (142). The transmitter antenna (140) is connected to a Vector Network Analyzer (VNA) to transmit signals, and the receiver antenna (142) is also connected to the VNA to measure the received signals. The transmitter (140) antenna is positioned perpendicular (normal) to the RIS surface (100) to ensure optimal signal transmission towards the surface (100). When the transmitter (140) emits a signal, it interacts with the reconfigurable intelligent surface (100), which reflects the signal based on the programmed reflection patterns. The reflected signal is then captured by the receiver (142) antenna. The VNA is used to measure the scattering parameter S21, which provides insights into the transmitted signal's reflection and reception characteristics through the RIS (100).
The RIS (100) is integrated with a RF circuitry (120) that dynamically adjusts the reflection patterns according to pre-defined configurations. These patterns are generated and controlled using MATLAB programming, enabling precise manipulation of the RIS surface's behaviour to achieve specific signal reflection and propagation characteristics. This arrangement allows for detailed analysis of the RIS's performance under varying conditions and configurations.
In another exemplary scenario, three distinct patterns are designed to investigate the behavior of the Reconfigurable Intelligent Surface (100) under varying conditions. One of these patterns, referred to as Pattern 1, is illustrated in Figure 8A. This pattern is applied to the RIS (100) to study its influence on wave reflection and transmission. The S21 parameter, which represents the transmission coefficient, is measured for Pattern 1, and the results are presented Figure 12 at the 3.5GHz.
For Pattern 1, the incident wave approaches the RIS (100) at a normal angle to its surface. The reflected wave deviates at an angle of 5 degrees from the RIS surface's normal direction.
When Patterns 2 and 3 are applied to the RIS, different reflection behaviours are observed at 3.5GHz. In Pattern 2, the maximum gain of the reflected electromagnetic wave is observed at an angle of 10 degrees relative to the normal to the RIS surface, as shown in Figure 13. Additionally, in the case of Pattern 3, the reflected wave deviates at an angle of 40 degrees from the normal to the RIS surface. The measured radiation pattern (S-parameters) is presented in Figure 14.
These results clearly demonstrate that applying different patterns to the RIS allows precise control of the reflection angle and corresponding transmission gain, highlighting the RIS's potential for adaptive wavefront manipulation in advanced communication systems.
In some aspects of the present disclosure, a method of operating (200) a reconfigurable intelligent surface (100) for electromagnetic wave manipulation in a wireless communication system is provided. The method includes the steps of providing (202) a reconfigurable intelligent surface (100) comprising an array of programmable unit cells (102), each unit cell (102) configured with a 1-bit PIN diode (118) to manipulate electromagnetic waves, receiving (204) an electromagnetic signal from a transmitter antenna (140), wherein the signal is directed toward the reconfigurable intelligent surface (100) at a specified angle of incidence, dynamically adjusting (206) the reflection pattern of the reconfigurable intelligent surface (100) based on pre-configured control signals transmitted from a RF circuitry (120), wherein the RF circuitry (120) modifies the behavior of the unit cells (102) through the 1-bit PIN diodes (118) to achieve desired reflection characteristics, reflecting (208) the received signal from the reconfigurable intelligent surface (100), wherein the signal is reflected toward a receiver antenna (142) with manipulated phase and amplitude determined by the programmed reflection patterns of the reconfigurable intelligent surface (100), measuring (210) the reflected signal at the receiver antenna (142), wherein the reflected signal is analyzed to obtain performance metrics including signal strength and reflection efficiency, and adjusting (212) the reflection patterns of the reconfigurable intelligent surface (100) in real-time to optimize signal propagation and coverage, based on feedback from the receiver antenna (142) and the performance metrics obtained in step (210).
In some aspects of the present disclosure, the RIS (100) is specifically designed to operate effectively in scenarios where a direct line-of-sight (LoS) path between the transmitter and receiver is unavailable. By leveraging its ability to manipulate electromagnetic waves, the RIS dynamically redirects signals around obstacles, effectively creating virtual pathways to maintain connectivity. This redirection significantly enhances signal coverage and reduces dead zones in complex environments. This adaptability ensures consistent communication even in environments with physical obstructions like walls, buildings, or other obstacles. The RIS (100) improves overall communication performance by maintaining robust connections in challenging NLoS conditions. This ensures higher data rates, lower latency, and more reliable communication, which are critical for applications like smart cities, autonomous vehicles, and indoor wireless networks. Also, this RIS (100) minimizes the need for extra hardware while delivering superior performance in NLoS scenarios. The RIS's ability to operate efficiently in NLoS conditions makes it suitable for diverse applications, including urban areas with dense building layouts, underground communication systems, and industrial environments. This versatility ensures seamless connectivity across various real-world challenges.
In some aspects of the present disclosure, each unit cell (102) of the RIS (100) is equipped with PIN diodes (118), enabling precise and efficient switching between ON and OFF states. This allows the RIS (100) to dynamically control the phase and amplitude of reflected electromagnetic waves, offering superior versatility in tailoring signal paths in real time. Also, the RIS (100) utilizes passive, low-power components, making it a more sustainable solution.
In some aspects of the present disclosure, the RIS (100) can reconfigure its reflection patterns instantly to adapt to varying network requirements. This capability ensures that the RIS (100) can optimize signal transmission for different scenarios, such as shifting user locations, changing interference levels, or varying environmental conditions.
In some aspects of the present disclosure, the RIS (100) can respond quickly to dynamic changes in network conditions by using the rapid switching ability of PIN diodes (118). This includes adjusting to alterations in traffic loads, frequency bands, or propagation environments, ensuring consistent and efficient communication.
In some aspects of the present disclosure, the RIS’s ability to focus and direct signals makes it suitable for supporting IoT networks and enhancing surveillance systems, providing advantages in areas that require precise control over connectivity and monitoring.
In some aspects of the present disclosure, the integration of PIN diodes (118) provides a distinct advantage, compared to conventional RIS designs that rely on slower or less flexible mechanisms like mechanical tuning or fixed configurations. This design enhances the system's responsiveness, improving overall network performance and user experience.
In some aspects of the present disclosure, the real-time adaptability and reconfigurability of the RIS (100) make it highly suitable for modern and future communication systems, such as 5G and 6G networks. This feature ensures that the RIS (100) meets the stringent demands of high-speed, low-latency, and high-capacity wireless communication in diverse environments.
In some aspects of the present disclosure, a single PIN diode (118) is employed within each unit cell (102) to shift the phase of the incident wave by 180 degrees, thereby reducing the overall complexity of the RIS array. Consequently, the DC power requirement for the entire RIS is significantly lower.
In some aspects of the present disclosure, an equivalent electrical impedance model for the RIS (100), both in the presence and absence of normally incident electromagnetic waves on the surface is provided.
In some aspects of the present disclosure, the design's adaptability makes it suitable for a wide range of applications across different frequency bands, catering to the evolving needs of communication technologies.
In some aspects of the present disclosure, the design of the RIS (100) is highly versatile and can be adapted to operate at any frequency, depending on industrial requirements. This flexibility is achieved using the 4-layer structure fabrication of the unit cells (102) of the RIS (100), which simplifies the manufacturing process while maintaining scalability.
In some aspects of the present disclosure, the RIS design is suitable for advanced wireless communication applications, and is highly efficient, scalable, and adaptable, as the compact size supports integration into existing infrastructures
The implementation set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detain above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementation described can be directed to various combinations and sub combinations of the disclosed features and/or combinations and sub combinations of the several further features disclosed above. In addition, the logic flows depicted in the accompany figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.  , Claims:We claim:
1. A reconfigurable intelligent surface (100) for electromagnetic wave manipulation comprises:
a plurality of unit cells (102) arranged in a two-dimensional array, each unit cell (102) comprises:
a first substrate layer (104) made of a dielectric material;
a top layer (106) made of a conducting material, positioned on the upper surface of the first substrate layer (104) and comprises an outer conductive patch (114) and an inner conductive patch (116), wherein the outer conductive patch (114) and the inner conductive patch (116) are structurally distinct and electrically isolated from each other;
a second substrate layer (108) made of a dielectric material and attached to the lower surface of the first substrate layer (104);
a third substrate layer (110) made of a dielectric material and attached to the lower surface of the second substrate layer (108);
a ground layer (112) integrated to the lower surface of the third substrate layer (110), comprises a capacitive patch with an RF circuitry (120), configured to supply and manage electrical signals required to operate the reconfigurable intelligent surface (100);
a 1-bit PIN diode (118) mounted on the ground layer and is configured to connect the outer conductive patch (114) and the inner conductive patch (116); and
a plurality of vias (122) that are configured to electrically connect the top layer (106) to the ground layer (112);
characterized in that, the outer conductive patch (114) is configured with a U-shaped geometry and the inner conductive patch (116) is configured with a slotted square structure;
wherein, the RF circuitry (120) selectively controls the 1-bit PIN diode (118) to dynamically alter the phase and amplitude of the reflected electromagnetic waves, thereby enabling the reconfigurable intelligent surface (100) to control the reflection angles of the impinging electromagnetic waves.

2. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the outer conductive patch (114) is positioned proximate to the outer periphery of the first substrate layer (104), and the inner conductive patch (116) is positioned inward relative to the outer conductive patch (114), wherein the conductive patches are arranged symmetrically with respect to an axis on the surface of the top layer (106), the axis passing through the midpoint of a connected side (132) of the U-shaped outer conductive patch (114) in a direction perpendicular to the connected side (132).

3. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the reconfigurable intelligent surface (100) operates at a center frequency of 3.5 GHz within a frequency range of 3.3 GHz to 3.8 GHz.

4. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the outer conductive patch (114) and the inner conductive patch (116) are printed on the top surface of the first substrate layer (104).

5. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the 1-bit PIN diode (118) implemented in each unit cell (102) is configured to shift the phase of the incident wave by 180 degrees.

6. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein width of each slot (130) of the inner conductive patch (116) is less than 1mm.

7. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the gap (134) between the outer conductive patch (114) and the inner conductive patch (116) is 0.1 mm.

8. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the 1-bit PIN diode (118) is connected to the backside of the unit cell (102) through vias (122), thereby preventing interference with the manipulation of electromagnetic waves on the top layer (106).

9. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the second substrate layer (108) is thicker than the first substrate layer (104) and the third substrate layer (110).

10. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the first substrate layer (104), the second substrate layer (108), and the third substrate layer (110) comprise glass epoxy (FR4) substrates having a dielectric constant of 4.4 and a loss tangent of 0.002.

11. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the first substrate layer (104) and the third substrate layer (110) are designed to be of the same thickness.

12. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the ground layer (110) comprises a square conducting layer with a sidelength of 15 mm placed at the centre of the third substrate layer (108).

13. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the unit cells (102) are fabricated in a four-layer printed circuit board structure.

14. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein each unit cell (102) has a dimension of 26 mm × 26 mm.

15. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the two-dimensional array comprises 256 unit cells (102) arranged in a 16 × 16 grid and has overall dimensions of 420 mm × 420 mm.

16. The reconfigurable intelligent surface (100) as claimed in claim 1, wherein the unit cells (102) are configured to reflect the normally impinging electromagnetic waves at an angle of 5° with a gain of 12 dB, at an angle of 10° with a gain of 11 dB, and at an angle of 40° with a gain of 10 dB.

17. A method of operating (200) a reconfigurable intelligent surface (100) for electromagnetic wave manipulation in a wireless communication system, comprising the steps of:

providing (202) a reconfigurable intelligent surface (100) comprising an array of programmable unit cells (102), each unit cell (102) configured with a 1-bit PIN diode (118) to manipulate electromagnetic waves;

receiving (204) an electromagnetic signal from a transmitter antenna (140), wherein the signal is directed toward the reconfigurable intelligent surface (100) at a specified angle of incidence;

dynamically adjusting (206) the reflection pattern of the reconfigurable intelligent surface (100) based on pre-configured control signals transmitted from a RF circuitry (120), wherein the RF circuitry (120) modifies the behavior of the unit cells (102) through the 1-bit PIN diodes (118) to achieve desired reflection characteristics;

reflecting (208) the received signal from the reconfigurable intelligent surface (100), wherein the signal is reflected toward a receiver antenna (142) with manipulated phase and amplitude determined by the programmed reflection patterns of the reconfigurable intelligent surface (100);

measuring (210) the reflected signal at the receiver antenna (142), wherein the reflected signal is analyzed to obtain performance metrics including signal strength and reflection efficiency; and

adjusting (212) the reflection patterns of the reconfigurable intelligent surface (100) in real-time to optimize signal propagation and coverage, based on feedback from the receiver antenna (142) and the performance metrics obtained in step (210).