Directional underwater communication with plasmonic antenna array

Abstract

Communication systems for underwater radar and related methods are described. In some examples, the system may include a plurality of plasmonic antennas arranged in a linear array, each configured to induce surface electronic waves propagating along a water surface, with the surface electromagnetic waves carrying an input signal. A frame may support the antennas, maintaining their alignment, while a control unit may provide control signals to individually adjust emission frequencies and phases, enabling the formation of a directional beam with an adjustable angle. The input signal may be detectable by an underwater receiver positioned at the beam angle, facilitating underwater communication and object detection.

Description

DIRECTIONAL UNDERWATER COMMUNICATION WITH PLASMONIC ANTENNA ARRAY FIELD OF TECHNOLOGY

[0001] The present disclosure relates generally to communication systems, and more specifically to directional underwater communication with plasmonic antenna array.BACKGROUND

[0002] Underwater communication and detection systems are utilized for various applications, including maritime security, environmental monitoring, and underwater exploration. These systems may employ different methods, such as acoustic technologies, to transmit and receive signals underwater. Such systems may be deployed in various aquatic settings, including ports, to facilitate underwater operations.SUMMARY

[0003] The described implementations relate to improved communication systems and associated methods for directional underwater communication with plasmonic antenna arrays. Some implementations address the limitations of existing underwater communication and detection systems by introducing a linear array of individually controlled antennas designed to operate at specific frequencies. This system may achieve directional electromagnetic wave emission underwater by coupling to surface electromagnetic waves propagating along the water surface. By leveraging resonance-based enhancements, some implementations may optimize the efficiency and range of electromagnetic wave propagation, even in challenging aquatic environments such as muddy freshwater or saltwater. The system’s design may incorporate scalable power distribution, allowing for adjustments in power and frequency to meet specific operational requirements. This ensures that the system may achieve practical communication ranges and detection capabilities while maintaining a compact and deployable form factor.

[0004] Some implementations may be particularly suited for applications requiring high-resolution detection and reliable communication in underwater environments, such as port security, diver communication, and underwater navigation. By enabling directional emission and resonance-based performance improvements, the system may provide a significant advancement over traditional acoustic and electromagnetic systems. Its adaptability to various aquatic conditions and its potential for integration into real-world applications may make it a valuable tool for enhancing underwater operations.

[0005] A plasmonic antenna system configured for underwater radar is described. The system may include a plurality of plasmonic antennas arranged in a linear array, a givenplasmonic antenna being configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal. The system may include a frame supporting the plurality of plasmonic antennas in the linear array, the frame configured to maintain alignment of the linear array. The system may include a control unit configured to provide control signals to the plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, the beaming angle being adjustable in response to control signals provided to the antennas, the input signal being detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle.

[0006] A method of forming a plasmonic antenna system configured for underwater radar is described. The method may include arranging a plurality of plasmonic antennas in a linear array, wherein a given plasmonic antenna may be configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal. The method may include providing a frame to support the plurality of plasmonic antennas in the linear array, the frame being configured to maintain alignment of the linear array. The method may include configuring a control unit to provide control signals to the plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, the beaming angle being adjustable in response to control signals provided to the antennas, wherein the input signal may be detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle.

[0007] In some examples of the technologies and related methods described herein, the plurality of plasmonic antennas may be configured for underwater operation.

[0008] In some examples of the technologies and related methods described herein, the plurality of plasmonic antennas may be disposed underwater during operation.

[0009] Some examples of the technologies and related methods described herein may further include a receiver housing configured to enclose the underwater receiver and protect it from environmental conditions.

[0010] In some examples of the technologies and related methods described herein, the receiver housing may be configured to shield the underwater receiver from physical impacts and maintain functionality.

[0011] In some examples of the technologies and related methods described herein, the frame may be constructed from a material resistant to corrosion in freshwater and saltwaterenvironments.

[0012] Some examples of the technologies and related methods described herein may further include transmitter housings configured to enclose the plurality of plasmonic antennas and protect them from physical damage.

[0013] In some examples of the technologies and related methods described herein, a given transmitter housing may be configured to prevent water ingress and maintain operational integrity.

[0014] In some examples of the technologies and related methods described herein, the control unit may be configured to adjust the beaming angle in response to changes in the input signal phase at different plasmonic antennas in the linear array.

[0015] In some examples of the technologies and related methods described herein, the plurality of plasmonic antennas may be configured to detect SEWs propagating along the surface of the body of water.

[0016] In some examples of the technologies and related methods described herein, the control unit may be configured to adjust the beaming angle in response to environmental conditions affecting the propagation of SEWs.

[0017] In some examples of the technologies and related methods described herein, the control unit may be configured to adjust the beaming angle in response to variations in the surface properties of the body of water.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 illustrates a system that demonstrates the concept of surface electromagnetic waves (SEWs), in accordance with one or more implementations.

[0019] FIG. 2 shows transmitter-receiver system which supports techniques for directional underwater communication with plasmonic antenna array in accordance with various aspects of the present disclosure.

[0020] FIG. 3 shows a graph illustrating theoretical performance of a linear array of individually controlled antennas operating at specific frequencies to achieve directional electromagnetic wave emission underwater by coupling to surface electromagnetic waves (SEWs) propagating along the water surface in accordance with various aspects of the present disclosure.

[0021] FIG. 4 shows a graph illustrating the SI 1 return loss (dB) in accordance with various aspects of the present disclosure.

[0022] FIG. 5 shows a flowchart illustrating a method involving directional underwater communication with plasmonic antenna array in accordance with various aspects of the present disclosure.DETAILED DESCRIPTION

[0023] The described implementations relate to improved communication systems and associated methods for directional underwater communication with plasmonic antenna arrays. In some examples, current underwater communication and detection systems may face significant challenges in achieving long-range, high-resolution performance. Acoustic systems, while widely used, may be constrained by low data rates and high susceptibility to environmental interference. Electromagnetic wave-based systems may be hindered by severe attenuation in water, particularly in saltwater, and difficulties in achieving directional emission. Existing antenna arrays designed for free-space applications may not be optimized for underwater use, where propagation losses and beam spreading may reduce their effectiveness. Furthermore, these systems may lack the ability to leverage resonance-based enhancements or scalable power distribution, limiting their operational range and efficiency. There may be a need for an underwater communication and detection system that overcomes these limitations by providing directional emission, enhanced range, and adaptability to various aquatic environments, including muddy freshwater and saltwater.

[0024] According to some implementations, communication systems may include a linear arrangement of plasmonic antennas that are individually controlled. This arrangement may allow for precise manipulation of electromagnetic surface waves (SEWs) induced by the system. The antennas may operate at specific frequencies in the VHF band, such as 30 megahertz or 50 megahertz, and these frequencies may be adjusted to optimize the system’s performance. Higher frequencies may result in a smaller overall system size.

[0025] The system may emit electromagnetic waves in a specific direction. This directional emission may be achieved by controlling the phase and amplitude of the signals sent to each antenna, enabling the formation of a focused beam. The system may be designed to function underwater, where it may emit surface electromagnetic waves that propagate along the water’s surface.

[0026] Some implementations may incorporate resonance-based enhancements, which may improve the system’s performance by leveraging resonant behaviors. These resonances may contribute to better directionality and efficiency in the emission of electromagnetic waves. The system may feature scalable power distribution, where the power supplied to each antenna maybe adjusted. For example, in one configuration, four antennas may each operate at 1 watt, resulting in a total power of 4 watts. Increasing the power may extend the communication range.

[0027] The system may achieve significant communication distances underwater. In some experiments, communication distances of hundreds of meters may have been achieved in freshwater, with the potential to reach several kilometers when power and frequency settings are optimized. The system may detect changes in the received signal when objects are placed in front of the beam, which may allow for monitoring and detection in aquatic environments.

[0028] The system may have been experimentally validated through underwater testing. In these tests, divers may have measured the received signal while swimming around the system, and data may have been collected to create an angular diagram of communication distances in various directions. The data may demonstrate the system’s ability to emit waves directionally.

[0029] The size of the system may be practical for real-world applications, allowing it to be installed in freshwater environments for purposes such as monitoring specific areas. The system’s performance may be measured as a function of power and frequency, with data collection helping to determine optimal settings for achieving desired operating distances and sensitivity.

[0030] The system may form a directional beam by controlling the output of each antenna. This beam may be scanned in different directions. Using multiple antennas may enhance the directionality of the emitted beam, reducing the spread of energy to undesired angles and focusing it in the intended direction.

[0031] Some implementations may exhibit resonant behaviors, which may be significant for achieving optimal performance. These resonances may enhance the directionality and efficiency of the emitted waves. The system may be particularly suitable for use in muddy freshwater environments, where other means of communication may be ineffective. It may provide reliable communication and detection capabilities in such conditions.

[0032] The system may have potential applications for aiding divers navigating underwater structures in low-visibility conditions. It may provide communication and detection support in such scenarios.

[0033] Aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. The described techniques may be implemented to support enhanced underwater communication and detection systems that may operate effectively in challenging environments, such as turbid or low-visibility aquatic conditions. The system may be scalable to accommodate varying operational requirements,including adjustments to antenna configurations and power levels, which may allow for tailored performance based on specific use cases. The ability to form directional beams may reduce interference and energy loss, potentially improving the efficiency and reliability of signal transmission. Resonant behaviors observed in the system may enable optimized performance by leveraging frequencies that enhance signal propagation and directionality. The system may be adaptable for integration into diverse aquatic applications, such as environmental monitoring, security, and navigation, where traditional communication methods may be impractical or ineffective.

[0034] Aspects of the disclosure are initially described in the context of communication systems. Aspects of the disclosure are additionally illustrated by and described with reference to example implementations. Aspects of the disclosure are further illustrated by and described with reference to a flowchart that relates to methods involving directional underwater communication with plasmonic antenna array.

[0035] FIG. 1 illustrates a system 100 that demonstrates the concept of surface electromagnetic waves (SEWs), in accordance with one or more implementations. The system 100 may include a conductive medium 102, such as a body of water, organic tissue, a metallic plane, and / or other conductive media. Adjacent to the conductive medium 102, there may be a dielectric medium 104, such as air and / or other dielectric media, which may interface with the conductive medium 102. The interface 106 between the conductive medium 102 and the dielectric medium 104 may be where SEWs are generated and may propagate.

[0036] The system 100 may also include a transmitter 108, which may be positioned near the interface 106. The transmitter 108 may be positioned within the conductive medium 102 or within the dielectric medium 104. The transmitter 108 may be responsible for generating an electromagnetic field that may induce SEWs at the interface 106 of the conductive medium 102 and the dielectric medium 104. The excited SEWs may then travel along the interface 106, as indicated by the arrow of SEW 110, which may represent the direction of wave propagation.

[0037] To help visualize the phenomenon of SEWs, one may consider an analogy to ripples on a pond. When a stone is dropped into a still pond, ripples may form and spread out across the surface of the water. Similarly, the transmitter 108 may be thought of as the stone, and the SEWs may be akin to the ripples that spread along the conductive medium 102. Just as the ripples may move outward from the point of impact, SEWs may propagate along the interface 106, carrying energy with them.

[0038] The system 100 may further include a receiver 112, which may be positioned at a distance from the transmitter 108 along the interface 106. The receiver 112 may be positioned within the conductive medium 102 or within the dielectric medium 104. The receiver 112 may be configured to receive the SEWs after they have propagated along the interface 106. This may be analogous to placing one’s hand in the water at a distance from where the stone was dropped, feeling the ripples as they pass by.

[0039] Additionally, the system 100 may include an object 114 positioned within the conductive medium 102 or within the dielectric medium 104, which may be representative of an obstacle that SEWs may encounter during propagation. The interaction of SEWs with the object 114 may lead to scattering of waves, similar to how water ripples may change direction or form patterns when they encounter a leaf or a rock in the pond.

[0040] The system 100 may include an energy source 116, such as a radio frequency generator, which may be connected to the transmitter 108. The energy source 116 may provide the necessary power for the transmitter 108 to generate the electromagnetic fields that excite the SEWs. This may be thought of as the force with which the stone is thrown into the pond, affecting the size and strength of the resulting ripples.

[0041] In some implementations, the system 100 may include a control unit 118, which may be operatively coupled to the transmitter 108 and / or the receiver 112. The control unit 118 may be responsible for coordinating the generation and detection of SEWs, much like a person orchestrating the timing of stones being dropped into the pond to create a specific pattern of ripples.

[0042] From a more technical perspective, SEWs may be understood as a type of wave that propagates along the interface between two media with different dielectric properties. In FIG. 1, the conductive medium 102 and the dielectric medium 104 may form such an interface (e.g., interface 106) where SEWs may be excited and propagate. The transmitter 108 may serve as a transducer that converts electrical signals from the energy source 116 into electromagnetic fields, which may then couple to the interface 106 and give rise to SEWs.

[0043] The propagation of SEWs along the interface 106 may be characterized by a wave vector that is parallel to the interface 106. This wave vector may be larger than the wave vector of free photons in the dielectric medium 104, which may result in a confinement of the electromagnetic field to the vicinity of the interface 106. The SEW’s field strength may decay exponentially in the direction perpendicular to the interface 106, as illustrated by a field strength 120 extending into the dielectric medium 104 and the conductive medium 102. These fieldstrengths may also decay as the SEW propagates along the interface 106, as illustrated by an attenuated field strength 122. The receiver 112 may be designed to couple to these confined, attenuated fields and receive the SEWs after they have propagated along the interface 106.

[0044] The excitation of SEWs by the transmitter 108 may involve the conversion of the electromagnetic energy into a surface-bound mode, which may be facilitated by the specific design of the transmitter 108. The transmitter 108 may be optimized to match the impedance of the SEWs to maximize energy transfer into the surface wave mode. The object 114 submerged within the conductive medium 102 may introduce perturbations in the SEWs, which may be detected by the receiver 112 and analyzed by the control unit 118 to infer properties of the object 114. Examples of such properties may include one or more of size, shape, location, material properties, and / or other properties.

[0045] The mathematical description of SEWs may be derived from Maxwell’s equations, which govern the properties of electromagnetic fields. The wave equation for TM-polarized SEWs may be reduced to a one-dimensional Schrodinger equation:^7 + (fc2- 7(z)) i / ; = 0 (EQN. 1)where / > is the effective wave function introduced as Ez= i / i / Ve , and V(z) is the effective potential energy that guides the propagation of SEWs along the interface. The term k2may represent the total energy of the SEWs and the term e may represent the dielectric permittivity of the medium.

[0046] For TE-polarized SEWs, the wave equation may not depend on the gradient term 7(z) and may be expressed as:±^ + fc2Ez= 0 (EQN. 2)

[0047] In the case of a sharp interface between two media with dielectric permittivities exand e2> the SEW wave vector for TM-polarized waves may be given by:ksEw = (EQN- 3)where m is the angular frequency of the SEWs, and c is the speed of light in vacuum.

[0048] The presence of dielectric permittivity gradients across the interface 106 may lead to additional terms in the effective potential Vz, which may result in the formation of a potential well that supports bound states of SEWs. These bound states may correspond to surface modeswith long propagation lengths and may be excited by the transmitter 108 with appropriate impedance matching.

[0049] The system 100 may thus utilize SEWs for various applications, including communication and sensing, by exploiting the unique properties of SEWs at the interface 106 between the conductive medium 102 and the dielectric medium 104. The control unit 118 may process the received signals to extract information about the propagation and interaction of SEWs with the environment and objects within it.

[0050] In some implementations, the transmitter 108 and / or the receiver 112 may include one or more plasmonic antennas. A given plasmonic antenna may be the same as or similar to, or include one or more aspects of, the antennas disclosed in U.S. Patent Application Serial No. 17 / 570,968 entitled “Apparatus, Methods and Systems for Electromagnetic Signal Transmission Through a Conductive Medium” filed on January 7, 2022; International Application No.PCT / US2024 / 061379 entitled “Surface Electromagnetic Wave Antenna” filed on December 20, 2024; and International Patent Application No. PCT / US2025 / 015358 entitled “Hybrid Antenna With Dynamic Signal Routing For Free-Space And Near-Metal Environments” filed on February 11, 2025, of which the entirety is incorporated by reference for all purposes.

[0051] FIG. 2 shows transmitter-receiver system 200 which supports techniques for directional underwater communication with plasmonic antenna array in accordance with various aspects of the present disclosure. As depicted in FIG. 2, the transmitter-receiver system 200 may include one or more of a frame 202, a transmitter housing 204, a beaming angle 206, a receiver housing 208, and / or other components.

[0052] The frame 202 may include a structure to support the arrangement of the transmitterreceiver system. The frame 202 may be designed to maintain the alignment of the linear array of plasmonic antennas. The frame 202 may be constructed from materials that are resistant to corrosion and suitable for underwater use. In some implementations, the frame 202 may be adjustable to accommodate different configurations of the antenna array. The frame 202 may also include mounting points for securing the transmitter housing 204 and the receiver housing 208.

[0053] The transmitter housing 204 may include an enclosure for components associated with signal transmission. The transmitter housing 204 may be designed to protect the internal components from water ingress and physical damage. Such internal components may include one or more plasmonic antennas (e.g., the transmitter 108 and / or the receiver 112, as described herein). The transmitter housing 204 may be made from durable materials that can withstand underwater conditions. In some implementations, the transmitter housing 204 may includeconnectors for power and control signals. The transmitter housing 204 may be positioned on the frame 202 to ensure optimal signal transmission.

[0054] The beaming angle 206 may represent the directional emission pattern of the transmitted signal. The beaming angle 206 may be adjustable based on the control signals provided to the plasmonic antennas. The beaming angle 206 may be determined by the phase and amplitude of the signals emitted by each antenna in the array. In some implementations, the beaming angle 206 may be optimized for specific underwater environments. The beaming angle 206 may facilitate achieving the desired communication range and scanning capabilities.

[0055] The receiver housing 208 may include an enclosure for components associated with signal reception. The receiver housing 208 may be designed to protect the internal components from water ingress and physical damage. Such internal components may include one or more plasmonic antennas (e.g., the transmitter 108 and / or the receiver 112, as described herein). The receiver housing 208 may be made from materials that are suitable for underwater use. In some implementations, the receiver housing 208 may include connectors for power and control signals. The receiver housing 208 may be positioned on the frame 202 to ensure optimal signal reception.

[0056] In some implementations, the frame 202 may serve as a structural support for the transmitter housings 204, which may be arranged linearly along the length of the frame 202. The transmitter housings 204 may house individual plasmonic antennas that are configured to emit electromagnetic waves at specific frequencies to induce SEWs. The beaming angle 206 may represent the directional emission of the electromagnetic waves, which may be influenced by the arrangement and operation of the antennas within the transmitter housings 204. The receiver housing 208 may be positioned at a distance from the frame 202 to detect the emitted signals, which may propagate through the medium via the SEWs induced by the plasmonic antennas in the transmitter housings 204.

[0057] FIG. 3 shows a graph 300 illustrating theoretical performance of a linear array of individually controlled antennas operating at specific frequencies to achieve directional electromagnetic wave emission underwater by coupling to surface electromagnetic waves (SEWs) propagating along the water surface in accordance with various aspects of the present disclosure. The graph 300 may represent the directional emission patterns under different scenarios, which may be relevant to optimizing communication range and detection capabilities in aquatic environments.

[0058] The graph 300 comprises three sub-graphs. The top-left sub-graph may depict the measured emission pattern of the antenna array. The bottom-left sub-graph may illustrate thetheoretical emission pattern without losses, and the bottom-right sub-graph may represent the theoretical emission pattern with losses.

[0059] Each sub-graph may have a circular polar plot with angular coordinates ranging from 0 to 360 degrees, marked at intervals of 30 degrees. The radial coordinates may represent the magnitude of the emission pattern, with the scale varying depending on the sub-graph. The top sub-graphs may use a linear scale with units of measurement in W / meters2, while the bottom subgraphs may use a normalized scale ranging from 0 to 1.

[0060] The data points in each sub-graph may be represented by continuous lines. In the topleft sub-graph, the line may exhibit a polygonal shape, indicating the measured emission pattern of the antenna array. The bottom-left sub-graph may display a more symmetrical pattern, indicating the theoretical emission without losses, while the bottom-right sub-graph may show a distorted pattern, representing the theoretical emission with losses.

[0061] The lines in the sub-graphs may be differentiated by their styles. The top-left subgraph may use a solid line, while the top-right sub-graph may use a dashed line. The bottom-left sub-graph may use a dotted line, and the bottom-right sub-graph may use a dash-dotted line. These line styles may help distinguish between the different scenarios depicted in the graph 300.

[0062] The graph 300 may highlight notable features such as peaks and valleys in the emission patterns. For instance, the top-left sub-graph may show peaks at specific angles, indicating stronger emissions in those directions. The bottom-left sub-graph may show a central peak, representing the ideal emission without losses, while the bottom-right sub-graph may display multiple peaks and valleys, indicating the impact of losses on the emission pattern.

[0063] In summary, the graph 300 may provide a comprehensive visual representation of how losses may affect the performance of the linear array of antennas. The detailed description of the axes, data points, and line styles may enable a person skilled in the art to understand and interpret the emission patterns depicted in the graph 300.

[0064] FIG. 4 shows a graph 400 illustrating the SI 1 return loss (dB) in accordance with various aspects of the present disclosure. The graph 400 may represent the return loss characteristics of a linear array of individually controlled antennas operating at specific frequencies to achieve directional electromagnetic wave emission underwater. This graph 400 may be relevant to the system’s performance in optimizing communication range and detection capabilities in aquatic environments.

[0065] The horizontal axis of the graph 400 may be labeled with frequency values, ranging from 0.00 MHz to 100.00 MHz. The scale on the horizontal axis may be linear, with specificfrequency markers at 33.33 MHz, 66.66 MHz, and 100.00 MHz. The vertical axis may be labeled with return loss values in decibels (dB), ranging from 0 dB to -20 dB, also on a linear scale.

[0066] The data points in the graph 400 may be represented by a continuous line, indicating the return loss at various frequencies. The line may exhibit several peaks and valleys, which may correspond to the resonance frequencies and the efficiency of the antenna array at those frequencies. Notable features of the graph 400 may include a significant dip in return loss around the 33.33 MHz mark, indicating a frequency where the antenna array may achieve optimal performance with minimal signal reflection. Other peaks and valleys may suggest varying levels of performance across the frequency spectrum.

[0067] The line style used in the graph 400 may be a solid line, which may help differentiate it from other potential data sets or measurements. The trends observed in the graph 400 may provide insights into the frequency-dependent behavior of the antenna array, which may be critical for understanding its operational efficiency in different aquatic environments.

[0068] By examining the graph 400, one may interpret the data to understand how the antenna array’s return loss varies with frequency, thereby supporting the system’s design and optimization for underwater communication and detection applications.

[0069] FIG. 5 shows a flowchart illustrating a method 500 involving directional underwater communication with plasmonic antenna array in accordance with various aspects of the present disclosure.

[0070] At 502, the method 500 may include arranging a plurality of plasmonic antennas in a linear array, wherein a given plasmonic antenna is configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal. The operations of 502 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 502 may involve a frame 202 as described with reference to FIG. 2

[0071] At 504, the method 500 may include providing a frame to support the plurality of plasmonic antennas in the linear array, the frame being configured to maintain alignment of the linear array. The operations of 504 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 504 may involve a frame 202 and a transmitter housing 204 as described with reference to FIG. 2.

[0072] At 506, the method 500 may include configuring a control unit to provide control signals to the plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, thebeaming angle being adjustable in response to control signals provided to the antennas, wherein the input signal is detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle. The operations of 506 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 506 may involve a beaming angle 206 and a receiver housing 208 as described with reference to FIG. 2.

[0073] It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Furthermore, aspects from two or more of the methods may be combined.

[0074] Aspect 1 : A plasmonic antenna system configured for underwater radar, comprising: a plurality of plasmonic antennas arranged in a linear array, a given plasmonic antenna being configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal; a frame supporting the plurality of plasmonic antennas in the linear array, the frame configured to maintain alignment of the linear array; and a control unit configured to provide control signals to the plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, the beaming angle being adjustable in response to control signals provided to the antennas, the input signal being detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle.

[0075] Aspect 2: The system of aspect 1, wherein the plurality of plasmonic antennas is configured for underwater operation.

[0076] Aspect 3: The system of any of aspects 1 through 2, wherein the plurality of plasmonic antennas is disposed underwater during operation.

[0077] Aspect 4: The system of any of aspects 1 through 3, further comprising a receiver housing configured to enclose the underwater receiver and protect it from environmental conditions.

[0078] Aspect 5: The system of any of aspects 1 through 4, wherein the receiver housing is configured to shield the underwater receiver from physical impacts and maintain functionality.

[0079] Aspect 6: The system of any of aspects 1 through 5, wherein the frame is constructed from a material resistant to corrosion in freshwater and saltwater environments.

[0080] Aspect 7: The system of any of aspects 1 through 6, further comprising transmitter housings configured to enclose the plurality of plasmonic antennas and protect them from physical damage.

[0081] Aspect 8: The system of any of aspects 1 through 7, wherein the transmitter housing is configured to prevent water ingress and maintain operational integrity.

[0082] Aspect 9: The system of any of aspects 1 through 8, wherein the control unit is configured to adjust the beaming angle in response to changes in the input signal phase at different plasmonic antennas in the linear array.

[0083] Aspect 10: The system of any of aspects 1 through 9, wherein the plurality of plasmonic antennas is configured to detect SEWs propagating along the surface of the body of water.

[0084] Aspect 11 : The system of any of aspects 1 through 10, wherein the control unit is configured to adjust the beaming angle in response to environmental conditions affecting the propagation of SEWs.

[0085] Aspect 12: The system of any of aspects 1 through 11, wherein the control unit is configured to adjust the beaming angle in response to variations in the surface properties of the body of water.

[0086] Aspect 13: A method of forming a plasmonic antenna system configured for underwater radar, the method comprising: arranging a plurality of plasmonic antennas in a linear array, wherein a given plasmonic antenna is configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal; providing a frame to support the plurality of plasmonic antennas in the linear array, the frame being configured to maintain alignment of the linear array; and configuring a control unit to provide control signals to the plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, the beaming angle being adjustable in response to control signals provided to the antennas, wherein the input signal is detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle.

[0087] Aspect 14: The method of aspect 13, further comprising configuring the plurality of plasmonic antennas for underwater operation.

[0088] Aspect 15: The method of any of aspects 13 through 14, further comprising disposing the plurality of plasmonic antennas underwater during operation.

[0089] Aspect 16: The method of any of aspects 13 through 15, further comprising forming a receiver housing configured to enclose the underwater receiver and protect it from environmental conditions.

[0090] Aspect 17: The method of any of aspects 13 through 16, further comprising constructing the frame from a material resistant to corrosion in freshwater and saltwater environments.

[0091] Aspect 18: The method of any of aspects 13 through 17, further comprising forming transmitter housings configured to enclose the plurality of plasmonic antennas and protect them from physical damage.

[0092] Aspect 19: The method of any of aspects 13 through 18, further comprising adjusting the beaming angle in response to environmental conditions affecting the propagation of SEWs

[0093] Aspect 20: The method of any of aspects 13 through 19, further comprising adjusting the beaming angle in response to variations in the surface properties of the body of water

[0094] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0095] In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0096] Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0097] The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0098] The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

AMENDED CLAIMSreceived by the International Bureau on 15 June 2026 (15.06.2026)What is claimed is:

1. A plasmonic antenna system configured for underwater radar, comprising:a plurality of plasmonic antennas arranged in a linear array, a given plasmonic antenna being configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal;a frame supporting the plurality of plasmonic antennas in the linear array, the frame configured to maintain alignment of the linear array; anda control unit configured to provide control signals to plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, the beaming angle being adjustable in response to control signals provided to the antennas, the input signal being detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle.

2. The system of claim 1 , wherein the plurality of plasmonic antennas is configured for underwater operation.

3. The system of claim 1 , wherein the plurality of plasmonic antennas is disposed underwater during operation.

4. The system of claim 1 , further comprising a receiver housing configured to enclose the underwater receiver and protect it from environmental conditions.

5. The system of claim 4, wherein the receiver housing is configured to shield the underwater receiver from physical impacts and maintain functionality.

6. The system of claim 1 , wherein the frame is constructed from a material resistant to corrosion in freshwater and saltwater environments.

7. The system of claim 1 , further comprising transmitter housings configured to enclose the plurality of plasmonic antennas and protect them from physical damage.

8. The system of claim 6, wherein the transmitter housing is configured to prevent water ingress and maintain operational integrity.

9. The system of claim 1 , wherein the control unit is configured to adjust the beaming angle in response to changes in the input signal phase at different plasmonic antennas in the linear array.

10. The system of claim 1 , wherein the plurality of plasmonic antennas is configured to detect SEWs propagating along the surface of the body of water.

11. The system of claim 1 , wherein the control unit is configured to adjust the beaming angle in response to environmental conditions affecting the propagation of SEWs.

12. The system of claim 1 , wherein the control unit is configured to adjust the beaming angle in response to variations in the surface properties of the body of water.

13. A method of forming a plasmonic antenna system configured for underwater radar, the method comprising:arranging a plurality of plasmonic antennas in a linear array, wherein a given plasmonic antenna is configured to induce surface electronic waves (SEWs) propagating along a surface of a body of water, the SEWs carrying an input signal;providing a frame to support the plurality of plasmonic antennas in the linear array, the frame being configured to maintain alignment of the linear array; andconfiguring a control unit to provide control signals to the plurality of plasmonic antennas to individually control emission at specific frequencies and phases to yield a beam with a beaming angle relative to the linear array, the beaming angle being adjustable in response to control signals provided to theantennas, wherein the input signal is detectable by an underwater receiver configured to detect SEWs and positioned at the beaming angle.

14. The method of claim 13, further comprising configuring the plurality of plasmonic antennas for underwater operation.

15. The method of claim 13, further comprising disposing the plurality of plasmonic antennas underwater during operation.

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