Description:FIELD OF INVENTION
The present disclosure relates to the field of intelligent reflective surface wireless communication. More particularly, the present disclosure relates to a passive intelligent reflective surface (IRS) with assorted unit cells and operating method thereof, for fixed wireless network system.

BACKGROUND OF THE INVENTION
The intelligent reflective surface (IRS) is useful in scenarios where the channel conditions are relatively static or predictable, or where ultra-low power consumption and hardware simplicity are paramount, they are preferred because the dynamic RIS require real-time control signals which are achieved with the help of complex circuitry and tuning components. In prior arts, the intelligent reflective surface (IRS) structures achieve beam steering by incorporating external control systems to reconfigure unit-cell materials and employing multi-step layer fabrication to adjust the electromagnetic response. These measures inevitably introduce complex circuitry and elevate maintenance requirements owing to the additional control electronics. The external control system includes tuning components, and optimizing algorithms.
The passive Intelligent Reflective Surfaces (IRS) utilize a fundamentally different approach. The performance of each unit cell in a passive IRS is primarily governed by the shape, size, and material of the unit cell itself, which directly determines how each unit cell interacts with incoming electromagnetic waves. The geometry and material composition of the unit cell influence the reflection or transmission characteristics of the electromagnetic wave. Specifically, the arrangement and configuration of the unit cell’s surface (e.g., its patch size, orientation, and material properties) are designed to impart a specific phase shift to the reflected wave. The design of each unit cell requires precise control over its geometrical shape and material composition, which is typically achieved through advanced simulation and design processes. This added complexity makes the implementation of passive IRS systems more intricate compared to conventional IRS approaches that utilize external control systems.
There is a need for technology that eliminates the requirement of multiple materials or complex geometric structures, control circuitry, and a need for system that minimizes fabrication complexity, and operates with essentially zero power consumption, thereby making it especially well-suited for energy-constrained deployments such as remote sites and battery-powered IoT networks.

SUMMARY OF THE INVENTION
In one aspect of the present disclosure, a passive intelligent reflective surface (IRS) that operates with elements for steering the beam in the desired direction is provided.
The present disclosure describes a passive Intelligent Reflective Surface (IRS) comprising a grid of unit cells arranged on a two-layer printed circuit board (PCB). The IRS includes a hybrid set of unit cells, specifically first unit cells and second unit cells, each configured to operate in distinct first phase shift state and second phase shift state, respectively. The first unit cells and second unit cells are predefined based on the required reflection phase at the operating frequency of the IRS. The unit cells are passively configured, eliminating the need for external control circuitry or power supply.
In some aspects of the present disclosure, this configuration enables the passive IRS to effectively manipulate the phase of the reflected signals, thereby providing beam steering and signal enhancement for wireless communication systems without the need for complex or active components.
In another aspect of the present disclosure, the method for operating passive IRS involves configuring the patch elements and transmission lines are in two distinct unit cells based on the required tuning parameters for the desired frequency. The patch element is connected to a transmission line to reflect a predetermined phase shift in the first phase shift state of the first unit cell. The patch element is connected to the ground plane to reflect a different, predetermined phase shift in the second phase shift state of the second unit cell. The patch elements are arranged in a configuration that reflects the signal in alignment with the frequency requirements. The unit cells are also arranged in an MxN grid according to a state matrix generated by the codebook, ensuring proper signal reflection and phase manipulation.
In another aspect of the present disclosure, the passive IRS may operate with a straightforward first phase shift and second phase shift configuration for patches.
In another aspect of the present disclosure, the passive IRS may be ideal for energy-constrained environments like remote areas or IoT networks.
In another aspect of the present disclosure, the passive IRS may be easily deployed over large surfaces without added complexity.
In yet another aspect of the present disclosure, the method for operating passive IRS unit cells uses passive building blocks without requiring active components, that reduces the overall complexity of the intelligent surface and maintains performance without dynamic adjustments.

DETAILED DESCRIPTION OF THE 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 1 illustrates an architectural diagram of a passive IRS unit cells in two distinct configurations; and
Figure 2 illustrates a perspective view of the passive (IRS) unit cells in two configurations;
Figure 3A and 3B illustrate schematic diagrams of the IRS board: Figure 3A shows the IRS board containing all elements in first phase shift state, while Figure 3B shows the IRS board containing all elements in the second phase shift state for the two configurations;
Figure 4A shows the magnitude response obtained from CST Studio 2025 and Figure 4B shows the phase response obtained from CST Studio 2025;
Figure 5A shows photographs of VNA testing results for the IRS board with all first phase shift elements, while Figure 5B shows the results for the IRS board with all second phase shift elements;
Figure 6 shows a graphical diagram illustrating the comparison between analytical predictions and actual measurements using a passive intelligent reflective surface (IRS); and
Figure 7 shows a flowchart illustrating the method for operating passive IRS.

DETAILED DESCRIPTION OF THE PRESENT INVENTION
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.
The term “IRS” refers to Intelligent reflective surface or reflective surface, any type of device that can be configured to manipulate the incident EM waves to steer, focus or otherwise modify the signal without tuning components.
As mentioned before, there is a need for technology that eliminates the need for complex control systems and tuning components, and that reduces failure risks. Therefore, the present disclosure provides a passive intelligent reflective surface (IRS) that achieves the required phase profile entirely passively, thereby markedly reducing system complexity, power consumption, and cost while preserving effective beam-steering capability. The passive unit may comprise an array of unit cells that are configured to operate in fixed first phase shift and second phase shift state. Each unit cell is permanently fabricated in one of two complementary configurations with designated first phase shift and second phase shift. These configurations are geometrically distinct and respectively impart first and second predetermined reflection phases at the design frequency. The desired phase distribution across the surface is established at manufacture by selecting the appropriate first phase shift or second phase shift geometry for each unit cell, thereby eliminating any post-installation control circuitry or power supply.
The passive intelligent reflective surface (IRS) may be configured to operate with a straightforward first and second phase shift (ON and OFF) configuration for patches. The passive IRS cell may be operated without tuning components that reduces failure risks, where it benefits them with low maintenance due to the absence of real-time control mechanisms. The passive IRS may be easily deployed over large surfaces without added complexity.
Figure 1 illustrates an architectural diagram of a passive intelligent reflective surface (IRS) unit cells in two distinct configurations.

The passive IRS 100 comprises a plurality of unit cells arranged in a grid configuration on a two-layer printed circuit board (PCB). The passive IRS 100 comprises hybrid set of unit cells that are classified as one or more first unit cells 102 and one or more second unit cell 104, where first unit cell 102 is configured to operate in first phase shift state and second unit cell 104 is configured to operate in second phase shift state. Each first unit cell 102 comprises a substrate layer 1, a ground plane 2, a patch element 3 and a microstrip transmission line 4. The substrate layer 1 located on the top of the substrate is adapted to interact with electromagnetic waves, enabling reflection. The ground plane 2 located at the bottom layer is adapted to provide grounding mechanism. The patch element 3, situated on top of the substrate layer 1. The phase shift is determined based on the connection between the patch element 3 and the transmission line 4. The transmission line 4 is configured to provide the phase delay to the reflected signal, electrically connected to the patch element 3. The presence of the microstrip transmission line 4 introduces a layer of control, thereby enabling the unit cell to provide directivity to the reflected electromagnetic wave. The transmission line 4 functions to direct the reflected signal, thus guiding its direction without the need for active components. This passive directivity is achieved by manipulating the phase of the reflected wave through fixed components (i.e., the transmission line and patch element), as opposed to requiring active circuitry or control systems. The configuration of the transmission line (4) with the patch element (3) dictates the phase shift applied to the reflected signal. The length of the transmission line (4), along with its interaction with the patch element, controls the phase delay introduced to the incident signal, thereby enabling manipulation of the phase of the reflected waves. In some aspects of the present disclosure, each second unit cell 104 that is configured to operate in second phase shift state comprises a substrate layer 1 that located on the top of the substrate is adapted to interact with electromagnetic waves. The ground plane 2 is adapted to provide grounding mechanism, and the patch element 3 is directly grounded, bypassing the transmission line 4, which results in a different, predetermined phase shift. The patch element 3 modifies the phase of the reflected signal based on the designed resonant properties of the patch element 3, allowing for specific phase control in IRS applications. The first phase shift and second phase shift unit cells (102, 104) are predefined based on the required reflection phase at the specific working frequency of the IRS.
In some aspects of the present disclosure, each unit cell is fabricated on a two-layer printed circuit board (PCB) using an FR-4 substrate. The bottom layer consists of a ground plane 2, while the top layer 1 features a patch element 3. The bottom layer serves as the continuous ground plane, while the top layer contains both the patch and the transmission line. The transmission line is therefore inherently referenced to the ground plane beneath it, and thus, transmission line is acting as an open circuit. Two distinct unit cell designs are used to achieve different reflection phase responses. In one configuration (referred to as "first phase shift state"), the patch is connected to a transmission line, resulting in a specific phase shift. In the other configuration ("second phase shift state"), the patch is directly grounded without a transmission line, producing a different phase shift. These predefined phase profiles are used to statically configure the IRS, eliminating the need for any external controller or power supply.
In some aspects of the present disclosure, the passive IRS unit cells are configured for optimized operation in the mmWave and terahertz frequency ranges, employing an efficient design. Additionally, aspects of the present disclosure may include the operation of the passive IRS unit cells within a tuning frequency range of 3.5 GHz, further improving their functionality.
Figure 2 illustrates a perspective view of the passive IRS unit cells in two configurations.

In some aspects of the present disclosure, the passive IRS unit cells 100 may be configured to be employed in fixed wireless systems and environments where signal behavior is predictable. Each unit cell is configured separately to operate in two different based on the configuration, where in first configuration in first cell, referred to as the ‘first phase shift’ state, the passive IRS unit cell comprises a reflector layer 1 that is adapted to interact with electromagnetic waves enabling reflection, a ground plane 2 configured to provide a grounding mechanism for elements, a patch element 3 that is located on the substrate layer 1 is adapted to capture the signal, and a transmission line 4 is adapted to create a conductive path by connecting with the patch element 3. The patch element 3 is electrically connected to the transmission line 4 in the first configuration, resulting in a predetermined phase shift of the reflected signal to operate with the first phase shift. In the second configuration, the IRS unit cell is adapted to reflect the signal without any phase shift, as transmission line 4 is not connected to patch element 3. The patch element 3 is configured to capture the signal and modify it by altering the substrate design. In this state, the patch element (3) is directly grounded, bypassing the transmission line (4), resulting in a different, predetermined phase shift. These predefined phase profiles are statically configured in the IRS, such that no external controller or power supply is required for operation.
In some aspects of the present disclosure, the unit cells operating in the first phase shift state refer to the first unit cell 102, which comprises a transmission line 4 connected to the patch element 3 and the ground plane 2, forming a closed conductive path. The phase shift in the first phase shift state is achieved by introducing a phase delay, which is determined by the length of the transmission line 4 in the first unit cell 102. The incident signal is reflected with a phase shift, which is dictated by the length of the transmission line and the properties of the patch element. and is designed based on the frequency requirements during the fabrication process. The properties of the patch element may include size, shape, and material. In some aspects of the present disclosure, the transmission line on the top layer forms a closed conductive path with the continuous ground plane on the bottom layer, separated by the dielectric substrate, in a two-layer PCB configuration. The signal conductor (transmission line) and the ground plane together act as a parallel plate structure, ensuring that return current always flows through the ground plane.
In some aspects of the present disclosure, the microstrip transmission line on the top layer forms a closed conductive path with the continuous ground plane on the bottom layer, separated by the dielectric substrate. The signal conductor (transmission line) and the ground plane together act as a parallel plate structure, ensuring that return current always flows through the ground plane.
In some aspects of the present disclosure, the unit cells operating in the second phase shift state refer to the second unit cell 104, which is directly connected to the ground plane 2, bypassing the transmission line 4, and producing a different, predetermined phase shift. In this configuration, the incident signal is reflected with a phase shift based on dimension of transmission line 4, and presence of transmission line above or behind the patch phase shift will differ. The phase shift will vary depending on the properties of the patch element 3 and length of transmission line 4. Both the first phase shift and second phase shift states are pre-determined during the fabrication stage, with phase shifts tailored to meet specific frequency requirements based on the application. Aspects of the present disclosure include application but not limited to IoT networks and fixed coverage enhancement.
In some aspects of the present disclosure, each second unit cell 104 may be configured to modify the phase based on characteristics of the patch element.
Figure 3A and 3B illustrate layout diagram of the passive IRS unit cells in two configurations;

In some aspects of the present disclosure, the passive IRS can include an M x N array of unit cells 100, flexibly arranged in a linear or an alternating layout based on the required frequency. Examples of the substrates include but are not limited to FR4 substrates etc. Aspects of the present disclosure may also include various sizes of array unit according to the requirement.
In some aspects of the present disclosure, the transmission line 4 may be adapted to provide precise control over the phase shifts introduced by each first and second unit cells (102, 104). By tuning the length of these lines in first unit cell and based on the properties of the patch element in second unit cell, from equation, the phase difference can be adjusted by placing the combinations of two respective patch elements to achieve the desired beam steering angles (10°, 15°, 30°, 40°and 50°). The transmission line lengths 4 are adjusted accordingly to achieve the phase difference of 0 and 180 degrees.
In some aspects of the present disclosure, the passive IRS can include an M x N array of unit cells 100, the patch element 3 is directly grounded to the ground plane 2 in second configuration. The phase shift is determined based on the specific properties of the patch element, which induces a predetermined phase shift in the reflected signal. By strategically configuring the first and second phase shift states of the unit elements, different beam steering angles may be achieved. The advantage of designing distinct unit cells is that each one may be specifically tailored to react in a way that maximizes performance for a given frequency range, which helps optimize the overall electromagnetic response of the IRS.
In some aspects of the present disclosure, the different beam steering angles can be achieved by strategically configuring the first and second phase shift states of the unit elements. This approach demonstrates the advantage of designing distinct unit cells that are specifically tailored to provide the desired electromagnetic response at a given operating frequency. By tuning the length of the transmission line, the operating frequency of the design can be adjusted.
Figure 4A and 4B illustrate graphical diagrams the presents the simulated reflection coefficient responses of the designed passive IRS element obtained using CST Studio 2025; where, Figure 4A shows the magnitude response of the reflection coefficient;

The continuous curve corresponds to the second phase shift state, while the dotted curve corresponds to the first phase shift state. Both states demonstrate reflection coefficients below –10 dB around the operating frequency of 3.5 GHz, which confirms good impedance matching and efficient reflection with minimal losses.
Figure 4B shows the phase response of the reflection coefficient. Again, the continuous curve represents the second phase shift state, and the dotted curve represents the first phase shift state. The difference between the two curves confirms that the designed element achieves distinct and controllable phase shifts at the target frequency, which is essential for beam steering.
From the results, the phase-shifting reflecting surface (PSRS) element with second phase profile achieves a reflection loss of approximately −30 dB, while the element with first phase profile shows a reflection loss of about −19.36 dB. Importantly, At the center frequency of 3.5 GHz, the phase difference between the two states is 202°, which is very close to the target of 180°. This validates that the passive IRS element can effectively create two distinct phase states, meeting the required specifications.
Figure 5A and 5B shows the result obtained from VNA respectively for first phase shift state and second phase shift state of IRS containing 8*5 elements of respective types, where figure 5A presents the measured reflection response corresponding to the first phase shift state, and figure 5B presents the measured reflection response corresponding to the second phase shift state;

The simulated results were empirically validated by measurements obtained using a vector network analyzer (VNA). The VNA-derived magnitude and phase responses at approximately 3.5 GHz were substantially consistent with the CST-based simulations, thereby verifying that the fabricated IRS unit cell reproduces the intended electromagnetic characteristics. This agreement confirms the accuracy of the computational model and substantiates the practical applicability of the disclosed IRS.
In an aspect of the present disclosure, the passive IRS is constructed using an array of 8×5 elements, incorporating both phase profiles. Each unit cell is designed with a patch element backed by a ground plane, fabricated on an FR4 substrate with dielectric constant εr=4.3, loss tangent of 0.025, and thickness of 1.6mm. The metallic patch has dimensions of PL=20.03 mm (length) and PW=26.08mm (width), while the overall element size is SL=40.06mm by SW=52.16mm. For the first phase profile, the optimized transmission line dimensions are ML=10.015mm and MW=2.86mm.
In this design, the element is specifically tuned to operate at 3.5 GHz. The patch dimensions and substrate characteristics are optimized to resonate precisely at this frequency, ensuring that the IRS provides maximum reflection efficiency with minimal dielectric and conductor losses. This ensures accurate beam steering and wavefront shaping while maintaining a strong and stable reflection amplitude.
Figure 6 shows a comparison between analytical predictions (a) and actual measurements (b) using a passive intelligent reflective Surface (IRS);

The passive IRS used in the experiment consists of 8 rows and 5 columns of unit cells, where all elements can be configured to be either in the first phase shift or second phase shift state. These states correspond to two distinct phase shifts as provided by the elements, as explained previously. This figure presents a comparison between analytical predictions and actual measurements using a passive IRS. The passive IRS used in the experiment consists of 8 rows and 5 columns of unit cells, where all elements can be configured to be either in the first or second phase shift state. These states correspond to two distinct phase shifts as provided by the elements, as explained previously.
To conduct the experiment, we prepared six such IRS boards, each identical in size and design. These boards were arranged in a specific sequence: : all first phase shift state, all first phase shift state, all second phase shift state, all second phase shift state, all first phase shift state, all first phase shift state. This arrangement was chosen strategically to achieve a desired beam pattern through passive beam steering.
For the transmission, a pure cosine tone was used to modulate a carrier frequency. The transmitter was placed at the center of the setup. At various receiver positions located within a 45-degree angular sector (an arc), we measured the received signal strength. Received signal contains two component: the signal was received directly from the transmitter, and the other where the signal was received in combination with the reflection from the passive IRS boards.
The results shown in the figure demonstrate a strong agreement between the analytical model and the experimental measurements. Similar quantitative patterns are observed in both cases, validating the effectiveness of the passive IRS arrangement in achieving beam steering. And by comparing the data we found that with help of passive IRS on an average we can get improvement in the received signal as compared to the signal only received from the transmitter.
In an exemplary scenario, the comparison between analytical predictions and actual measurements using the passive IRS. The passive IRS used in the experiment consists of 8 rows and 5 columns of unit cells, where all elements can be configured to be either in the first phase shift state or second phase shift state. These first phase shift and second phase shift states correspond to two distinct phase shifts as provided by the elements, as explained previously. To conduct the experiment, we prepared six such IRS boards, each identical in size and design. These boards were arranged in a specific sequence with first phase shift state, and second phase shift state: all first phase shift state, all first phase shift state, all second phase shift state, all second phase shift state, all first phase shift state, all first phase shift state. This arrangement was chosen strategically to achieve a desired beam pattern through passive beam steering. For the transmission, a pure cosine tone was used to modulate a carrier frequency. The transmitter was placed at the center of the setup. At various receiver positions located within a 45-degree angular sector (an arc), we measured the received signal strength. The received signal contains two components the signal was received directly from the transmitter, and the other where the signal was received in combination with the reflection from the passive IRS boards. The results shown in the figure demonstrate a strong agreement between the analytical model and the experimental measurements. Similar quantitative patterns are observed in both cases, validating the effectiveness of the passive IRS arrangement in achieving beam steering. And by comparing the data we found that with help of passive IRS on an average we can get improvement in the received signal as compared to the signal only received from the transmitter.
Figure 7 shows a flowchart that depicts a method 700 for operating passive IRS 100;

The method 700 may include the following steps:
At step 702, configuring the patch elements and transmission line in two distinct unit cells according to the required tuning parameter with respect to the desired frequency.
At step 702a, connecting the patch element to a transmission line to reflect predetermined phase shift with a phase delay in first phase shift state of first unit cell.
At step 702b, connecting the patch element to the ground plane to reflect different predetermined phase shift in second phase shift state of second unit cell.
At step 704, arranging the patch elements in a desired configuration to reflect the signal in accordance with the frequency requirements and arranging unit cells in a MxN grid to achieve the desired beamforming pattern.
In an exemplary scenario, a passive IRS is deployed to improve signal strength and beam steering in a fixed wireless communication environment. The IRS is composed of unit cells arranged in a grid configuration, with each unit cell capable of being configured into two distinct states: the first phase shift configuration and the second phase shift configuration. These two configurations allow for the manipulation of the reflected signal phase and enable the system to control the direction of the reflected signal, thus achieving beam steering. The first phase shift configuration involves the patch element of each unit cell being electrically connected to a transmission line, which introduces a predetermined phase shift to the reflected signal. The phase shift is designed to steer the signal in a specific direction, enhancing signal coverage in areas where the signal may otherwise be weak. In the second phase shift configuration, the patch element is directly grounded, bypassing the transmission line. This configuration produces a different phase shift, directing the reflected signal in an alternative direction. The second configuration is used to optimize signal propagation across the surface and to control the beam direction based on the desired coverage area. By strategically configuring the first and second phase shift states across the array of unit cells, different beam steering angles can be achieved, allowing the passive IRS to guide the reflected signal in a controlled manner. This capability enables improved signal quality and coverage in areas with obstructions or limited line-of-sight, without requiring tuning components or real-time adjustments. The ability to configure the IRS unit cells in the first and second configurations allows for effective beam steering in a fixed wireless communication environment. By predefining the phase shifts in these configurations, the system can passively steer the reflected signal to enhance coverage and signal strength. This eliminates the need for complex control systems, reduces maintenance, and minimizes power consumption, making the passive IRS a low-cost, low-maintenance solution for improving wireless communication systems.
In another exemplary scenario, the passive IRS is deployed within a fixed wireless communication system to enhance the coverage and performance of a smart building's Internet of Things (IoT) network. The goal of the system is to provide reliable wireless connectivity for a range of IoT devices, such as sensors, cameras, and actuators, while minimizing interference and signal degradation. The IRS comprises a plurality of unit cells, each configured to operate in either a first phase shift state or a second phase shift state, and/or in combination of both phase shift unit cells. This configuration allows for flexible phase control and signal reflection, enabling the system to optimize coverage and direct the signal precisely where it is needed most. The passive IRS is installed within the building as an array of unit cells arranged on a two-layer printed circuit board PCB. These unit cells operate in two distinct states: the first phase shift state and the second phase shift state. In the first phase shift state, each unit cell includes a patch element 3 connected to a transmission line 4. The transmission line controls the phase delay applied to the incident electromagnetic wave. The length of the transmission line is chosen to introduce a specific phase shift, based on the frequency requirements of the system. In second phase shift state, the patch element 3 is directly grounded, bypassing the transmission line 4. This grounding configuration reflects the signal with a different, predetermined phase shift. The unit cells are designed to handle high-frequency signals, ensuring efficient signal reflection and phase manipulation even at these high frequencies. The passive IRS thus improves signal capacity and supports low-latency communication, which is especially important for applications in IoT networks and smart buildings. A key advantage of the passive IRS is its low-maintenance nature. The system in the present invention operates passively, eliminating the need for tuning components or a control system. This design reduces the risk of failure and negates the requirement for real-time adjustments. The passive IRS configuration integrated into the present invention significantly lowers operational complexity and power consumption, as each unit cell shifts the phase without the need for tuning components or batteries. This makes the passive IRS a cost-effective solution for large-scale deployments, such as smart buildings or IoT networks. The passive IRS not only enhances signal strength and coverage but also provides energy-efficient performance. As a result, the system ensures reliable and predictable connectivity for all IoT devices in the building, including smart lighting, climate control, and security systems. This passive IRS system is particularly beneficial for fixed wireless applications, where the behavior of the signal is predictable and real-time control is not required. By arranging the first phase shift state and second phase shift state unit cells based on frequency requirements, the passive IRS provides a scalable, low-maintenance, and cost-effective solution for seamless wireless connectivity across diverse environments.
The implementations described in the foregoing description are not exhaustive and do not represent all possible implementations consistent with the subject matter disclosed herein. While certain variations have been detailed, other modifications, adaptations, or enhancements are possible within the scope of the invention. For instance, the disclosed features may be combined or sub-combined in various ways to achieve the intended functionality. Additionally, the logic flows described or depicted in the figures are not restricted to the specific sequences presented and may be executed in alternative orders to achieve similar results. The scope of the invention is defined solely by the appended claims and encompasses all such variations and equivalents. , C , C , Claims:WE CLAIM
1. A passive intelligent reflective surface (IRS) (100) for wireless communication system, comprises:
a plurality of IRS unit cells, where plurality of first unit cells (102) comprises:
a substrate layer (1) that is fabricated on a two-layer printed circuit board (PCB);
a ground plane (2) that is adapted to provide a grounding mechanism;
a patch element (3) that is located on the substrate layer (1) is configured to interact with electromagnetic waves;
a transmission line (4) that is adapted to provide phase shift based on the required frequency. and
wherein, the patch element (3) is configured to operate in a first phase shift state when connected to a transmission line, the length of the transmission line changing the specific phase shift of the reflected signal;
a plurality of second unit cells (104) comprises:
a substrate layer (1) that is fabricated on a two-layer printed circuit board (PCB);
a ground plane (2) that is adapted to provide a grounding mechanism; and
a patch element (3) that is located on the substrate layer (1) is configured to interact with electromagnetic waves; and
wherein, the patch element (3) is configured to operate in second state when directly connected to the ground plane, reflecting a phase shift determined by the resonant properties of the patch element (3).
2. The passive IRS (100) as claimed in claim 1, wherein said unit cells (102, 104) that are configured to operate in two distinct states are employed to apply a phase shift to the incident wave.
3. The passive IRS (100) as claimed in claim 2, wherein said patch elements (3) are etched on a two-layer printed circuit board.
4. The passive IRS (100) as claimed in claim 1, wherein the phase shift applied to the reflected signal is determined by the configuration and length of the transmission line in first unit cell.
5. The passive IRS (100) as claimed in claim 1, wherein said patch element 3 is configured to modify the phase of the reflected signal based on geometric properties and the dielectric material between the patch element and the ground plane in second unit cell.
6. The passive IRS (100) as claimed in claim 1, wherein the system is optimized for no power consumption and is suitable for IoT networks, fixed wireless installations, or other applications requiring predictable signal coverage.
7. A method for operating passive IRS unit cell (100) comprising:
a. configuring 702 the patch elements and transmission line in two distinct unit cells according to the required tuning parameter with respect to the desired frequency to operate in following states by:
i. connecting 702a the patch element to a transmission line to reflect predetermined phase shift in first phase shift state;
ii. connecting 702b the patch element to the ground plane to reflect different predetermined phase shift in second phase shift state; and
b. arranging 704 said unit cells in a desired configuration to reflect the signal in accordance with the frequency requirements.