Antenna array with metal tracks and PCB transmission line as the feed structure

Abstract

There is disclosed an antenna array comprising: a dielectric substrate having an upper surface and an opposed lower surface; a conductive transmission line formed on or in the dielectric substrate; a conductive metal track disposed under the lower surface of the dielectric substrate substantially parallel to the transmission line; a slotted metal track disposed over the upper surface of the dielectric substrate substantially parallel to the transmission line; and a plurality of antenna elements disposed above the slotted metal track and configured to couple with slots of the slotted metal track so as to radiate or receive electromagnetic signals.

Description

P395892GB1 / WO spec 19-3-261ANTENNA ARRAY WITH METAL TRACKS AND PCB TRANSMISSION LINE AS THE FEED STRUCTUREBackground of the Invention

[0001] Antennas are a fundamental component in wireless communication systems, enabling the transmission and reception of electromagnetic signals. Among the various types of antenna designs, those employing waveguide technology are widely recognized for their low loss and superior shielding performance. Traditional metal waveguides, such as the ones described in U.S. Patent No. 5,831,583 by Lagerstedt and Lagerlof, feature antenna arrays fed by air-filled waveguides of different sizes to achieve dual polarization. These waveguides provide excellent performance in terms of polarization purity and minimal loss, primarily through the implementation of slots cut into the waveguide structure. However, these air-filled waveguide systems are inherently bulky and heavy, posing significant challenges in applications where size and weight constraints are critical.

[0002] To address the issue of size reduction, innovations such as the introduction of ridged waveguides have been explored, as documented by Eva Rajo-lglesias and colleagues. By incorporating ridges into the waveguide, the overall dimensions can be slightly reduced without compromising the waveguide's electromagnetic performance. However, the addition of ridges introduces an increase in weight, offsetting some of the advantages gained through size reduction.

[0003] An alternative approach is the planar realization of waveguides, such as the substrate integrated waveguide (SIW), as detailed by Yang Fei et al. SIW technology leverages standard printed circuit board (PCB) processing methods, replacing the metal walls of traditional waveguides with periodic metallic vias. This approach significantly reduces the cost, weight, and thickness of the waveguide, making it an attractive option for compact and lightweight antenna designs. Despite these advantages, SIW-based antennas face a critical drawback: the use of dielectric-filled waveguides results in higher signal loss, especially at higher operating frequencies or larger antenna sizes. Even with the use of lower-loss dielectric materials, the inherent lossy nature of the dielectric medium limits the efficiency of SIW-based antennas.

[0004] Despite these advantages, SIW technology has notable limitations, particularly due to the lossy dielectric materials used to fill the waveguide. The dielectric's inherent losses become more pronounced at higher operating frequencies or larger antenna sizes, resulting in reduced efficiency. While the use of low-loss dielectric materials can mitigateP395892GB1 / WO spec 19-3-262this issue to some extent, it does not eliminate the performance challenges associated with SIW-based antennas.

[0005] Given the limitations of both traditional waveguides and SIW-based solutions, there is a clear need for innovative antenna designs that combine the strengths of these technologies while addressing their respective weaknesses. The invention of an antenna array with metal tracks and a PCB transmission line as the feed structure provides a novel approach to overcoming these challenges. This design leverages the superior performance of metal waveguides with the compactness and manufacturability of PCB technology, achieving a balance between efficiency, weight reduction, and costeffectiveness. By integrating metal tracks and PCB-based feeding structures, this invention represents a significant advancement in the development of high-performance, lightweight antenna arrays suitable for modern wireless communication systems.Objective of the Patent Application

[0006] The objective of this patent application is to provide an innovative antenna array that incorporates metal tracks and a PCB transmission line as the feed structure, offering a groundbreaking solution that combines the advantages of traditional air-filled metal waveguides and PCB transmission lines. This novel design achieves a compact size, lightweight construction, and significantly reduced signal loss, addressing critical limitations of existing waveguide and PCB-based antenna systems.

[0007] The invention seeks to leverage the flexibility and manufacturability of PCB transmission lines to enhance the performance and adaptability of the antenna array. Unlike conventional waveguides that require complex and precise fabrication techniques to achieve slow-wave effects, such as comb-shaped or nail-shaped structures, this invention inherently facilitates the slow-wave effect through the dielectric PCB's transmission line design. The introduction of additional structures along the transmission line further enhances the slow-wave effect, making the antenna highly effective for specific applications such as reconfigurable leaky wave antenna arrays.

[0008] By integrating metal tracks with PCB transmission lines, the proposed design achieves a very small size and low weight, offering significant advantages in applications where space and weight constraints are critical. Furthermore, the innovative combination of these technologies ensures very low transmission loss, a key requirement for high-performance antenna systems. The use of PCB transmission lines provides unparalleled design flexibility, enabling configurations that would be challenging with conventional waveguides.P395892GB1 / WO spec 19-3-263

[0009] The invention also simplifies the implementation of the slow-wave effect, which is critical for specific applications like reconfigurable leaky wave antenna arrays. Unlike traditional waveguides that require complex and precision-dependent comb- or nail-shaped structures to slow down waves, this design leverages the inherent properties of the dielectric PCB to achieve the same effect. Additional structures can be incorporated along the transmission line to further enhance the slow-wave effect, offering scalability and adaptability for high-frequency and precision-demanding applications. This streamlined approach avoids fabrication challenges often encountered in traditional waveguide designs, particularly at high operation frequencies where critical accuracy is essential.

[0010] From a commercial perspective, the proposed antenna array is highly cost-effective and easy to fabricate, leveraging the simplified design and manufacturing processes associated with PCB-based architectures. The adaptability of the design makes it suitable for a wide range of antenna applications, ensuring its versatility in meeting diverse market needs. Additionally, its unique combination of compactness, low loss, and flexibility offers a competitive edge in addressing specialized application demands. This invention represents a transformative solution in antenna design, balancing superior performance, manufacturability, and cost-efficiency for modern communication technologies.Summary of the Invention

[0011] According to the present invention, there is provided an antenna array comprising:a dielectric substrate having an upper surface and an opposed lower surface; a conductive transmission line formed on or in the dielectric substrate;a conductive metal track disposed under the lower surface of the dielectric substrate substantially parallel to the transmission line;a slotted metal track disposed over the upper surface of the dielectric substrate substantially parallel to the transmission line; anda plurality of antenna elements disposed above the slotted metal track and configured to couple with slots of the slotted metal track so as to radiate or receive electromagnetic signals.

[0012] The antenna array may be generally one-dimensional, comprising a single transmission line, a single conductive metal track and a single slotted metal track, generally coextensive with each other, and a one-dimensional array of antenna elements arranged over the slotted metal track.

[0013] In more complex implementations, the antenna array may comprise:a plurality of substantially parallel transmission lines formed on or in the dielectric substrate;P395892GB1 / WO spec 19-3-264a corresponding plurality of conductive metal tracks disposed under the lower surface of the dielectric substrate each substantially parallel to one of the transmission lines; anda corresponding plurality of slotted metal tracks disposed over the upper surface of the dielectric substrate each substantially parallel to one of the transmission lines;wherein the antenna elements are disposed above each of the plurality of slotted metal tracks.

[0014] In this way, a two-dimensional antenna array may be formed, which may have useful beamforming and beam steering functionalities.

[0015] The antenna elements may overlap the slots of the slotted metal track or tracks. The slots in the slotted metal track serve to guide radio frequency, RF, energy from the transmission line on or in the dielectric substrate to the antenna elements. In other words, the antenna elements are arranged to enable RF coupling between the slots and the antenna elements.

[0016] The antenna elements may further comprise reconfigurable components configured for dynamic adjustment of at least one of a radiation pattern, frequency or polarization. The reconfigurable components may comprise tuneable elements such as varactors or microelectromechanical, MEMS, switches.

[0017] The slots of the slotted metal track or tracks may be tuneable slots or may be configured as a metasurface. In some embodiments, the slots of the slotted metal track or tracks are configured as a programmable metasurface.

[0018] In some embodiments, the conductive transmission line is not in direct conductive contact with the metal track. In some embodiments, the conductive transmission line is not in direct contact with the slotted metal track.

[0019] The antenna array may further comprise power combining and / or beamforming circuitry to feed a radio frequency signal to the metal track or metal tracks disposed under the lower surface of the dielectric substrate.

[0020] The transmission line or lines may be configured to support slow-wave transmission of radio frequency, RF, signals. Slow-wave transmission means that a phase velocity of the RF signal is less than the speed of light.

[0021] Reconfigurable components, such as tuneable elements including varactors or MEMS switches, may be integrated along the transmission line or lines. These reconfigurable components may help to promote slow-wave transmission of RF signals along the transmission line or lines.P395892GB1 / WO spec 19-3-265Detailed Description of the Invention

[0022] The present invention relates to an antenna array that integrates metal tracks and a PCB transmission line as a feed structure to create a compact, lightweight, and low-loss antenna system. The invention utilizes a unique structural configuration comprising a metal track, a PCB transmission line, slotted metal tracks, and the antenna elements, as illustrated in the provided figure 1.

[0023] The metal track at the base serves as the initial transmission medium for feeding electromagnetic signals into the system. The metal track is fabricated using a conductive material with low resistive losses to ensure efficient signal propagation. Its role is to interface with external systems or sources and transfer the input signal to the PCB layer without significant attenuation. This foundational component combines the robustness of traditional metal waveguides with a simplified planar geometry, allowing for reduced size and weight. Directly above the metal track is the PCB transmission line, which acts as a bridge between the metal track and the slotted metal track layer. This transmission line is designed on a dielectric substrate, enabling precise control of signal propagation while maintaining low losses. One of the critical features of the PCB transmission line is its inherent ability to facilitate the slow-wave effect, which slows down the electromagnetic waves for enhanced control and efficiency. This slow-wave capability is further amplified by introducing additional structures along the PCB, enabling fine-tuning for specific applications such as reconfigurable leaky wave antenna arrays. The use of PCB technology also provides flexibility in manufacturing and integration, making it cost-effective and easy to scale for various designs.

[0024] Above the PCB layer is the slotted metal track, which forms the immediate feeding structure for the antenna array. This component features carefully designed slots that guide the electromagnetic waves into the antenna elements while ensuring efficiency and low loss. The slot geometry and placement are optimized to achieve efficient coupling between the transmission line and the antenna array, enabling high performance across a wide range of frequencies. The slotted metal track also contributes to minimizing weight while preserving the shielding and low-loss characteristics of traditional waveguide designs. The topmost component in the structure is the antenna itself, which radiates the electromagnetic signals into free space or receives signals from the environment. The antenna elements are directly fed by the slotted metal track, ensuring high efficiency and low loss in signal transfer. Depending on the specific application, the antenna array can be designed to support various configurations, such as linear or planar arrays, to achieve desired beamforming or polarization characteristics. The antenna design takes fullP395892GB1 / WO spec 19-3-266advantage of the slow-wave effects generated by the underlying PCB transmission line, enabling precise control over beam shaping and reconfigurability.

[0025] The integration of these components creates a seamless feed structure that combines the advantages of traditional metal waveguides and PCB-based systems. The metal track provides a robust and low-loss signal path, while the PCB transmission line introduces flexibility and slow-wave effects critical for high-frequency operations. The slotted metal track ensures efficient coupling and polarization purity, and the antenna radiates the signal with high efficiency and minimal distortion.

[0026] The invention's unique design allows for a compact and lightweight structure with very low transmission losses, making it suitable for a wide range of applications, including reconfigurable phased arrays and leaky wave antennas. Furthermore, the simplified fabrication process associated with PCB technology reduces manufacturing complexity and cost, while the integration of metal tracks ensures superior performance at high frequencies. This combination of features makes the invention a highly versatile and commercially viable solution for modern wireless communication systems.

[0027] The invention relates to an antenna array architecture that integrates metal tracks, PCB transmission lines, slotted metal tracks, and an antenna array, working in conjunction with beamformers and power combiners to create a compact, efficient, and flexible wireless communication system. This innovative structure optimises performance in terms of size, weight, and signal loss, making it ideal for advanced communication applications.

[0028] The Figure 2 illustrates the architecture of the antenna array, which consists of multiple modular units. Each unit includes a metal track, a PCB transmission line (PCB1), a slotted metal track, and antenna elements. These modular units are connected to a central beamformer(s) and power combiner(s), which manage the input and output of RF signals to and from the system. At the base of the architecture, the beamformer(s) and power combiner(s) are depicted as the manipulation of signal magnitude and phase. This component is responsible for handling the RF signal input / output and distributing the signals to the individual modular units. Each modular unit includes a metal track at the lowest level, which serves as the initial transmission medium. The metal track connects directly to the PCB transmission line (PCB1), which acts as the next layer in the feed structure. PCB1 enables signal propagation while introducing slow-wave effects to enhance signal control and efficiency. Above the PCB transmission line is the slotted metal track, which contains strategically designed slots to guide the RF energy from PCB1 into the antenna array. These slots optimise the coupling of signals and ensure efficient energy transfer to the antenna. The antenna array is shown at the top of the structure, consisting of multiple antenna elements, each fed by the slotted metal tracks of the modular units.P395892GB1 / WO spec 19-3-267These antenna elements radiate or receive electromagnetic signals based on the operation of the system.

[0029] The modular units are depicted as repeating elements, connected to the beamformer(s) and power combiner(s), which integrate all units into a cohesive system. This drawing provides a clear depiction of the layered structure and the functional relationships between the components of the antenna array.

[0030] The modular design ensures that each unit operates seamlessly within the overall architecture. The metal track, PCB transmission line, and slotted metal track work in tandem to deliver low-loss, high-efficiency signal feeding to the antenna array. The use of PCB1 introduces enhanced manufacturing flexibility and reduced complexity, while the slow-wave effect enables precise control at high frequencies. The integration of beamformers and power combiners further extends the system's versatility, making it suitable for a wide range of applications in wireless communication, including phased arrays, reconfigurable antennas, and high-frequency systems.

[0031] The Fig 3 depicts the antenna array architecture, which is designed to accommodate flexible configurations depending on the specific application requirements. The modular architecture consists of metal tracks, PCB transmission lines (PCB1), slotted metal tracks, and the antenna array elements. These components form the core structure, while additional functionalities such as reconfigurable components such as PIN diodes, liquid crystal displays (LCDs), varactors, etc, beamformers, and power combiners are shown as optional elements that can be included or omitted based on system needs.

[0032] The core structure of the antenna array is composed of modular units, each with Metal Track as the initial signal pathway, providing low-loss transmission and interfacing with external systems or sources. PCB Transmission Line (PCB1) as the intermediate layer, introducing slow-wave effects for enhanced signal control and precision. This PCB layer provides high flexibility and adaptability in the system design. Slotted Metal Track features slots that efficiently couple electromagnetic signals from the PCB to the antenna elements. Positioned at the top, the antenna elements radiate or receive electromagnetic waves and can be tailored for specific beamforming or radiation requirements.

[0033] The architecture can include reconfigurable elements such as tuneable slots or programmable metasurfaces along the PCB transmission line or antenna array. These components enable dynamic adjustment of radiation patterns, frequencies, or polarisation, making the system suitable for applications such as adaptive communication and leaky wave antennas. Alternatively, these reconfigurable components can be omitted in simpler, fixed-frequency or fixed-pattern designs.P395892GB1 / WO spec 19-3-268

[0034] The drawing depicts beamformers and power combiners as part of the architecture. When included, they allow for dynamic beam steering, signal amplification, and multi-channel operation. These components integrate and synchronise the RF signals from multiple modular units, making the system capable of advanced functionalities such as phased array operation or multi-user communication. In applications where beamforming or power combining is unnecessary, the architecture can operate without these components or in combination. This reduces the system's complexity and cost, making it more suitable for basic operations or static configurations.

[0035] The flexibility of the architecture allows it to be adapted to a wide range of applications. For high-performance systems requiring dynamic reconfiguration or beam steering, the architecture can incorporate both reconfigurable components and beamformers / power combiners. For simpler, cost-sensitive systems, it can function effectively with only the core elements, offering a static yet efficient antenna array design. The modular design ensures scalability, allowing the architecture to meet diverse requirements, from basic fixed-pattern systems to advanced, reconfigurable, and adaptive antenna arrays, all while maintaining its compact and lightweight nature.

[0036] Fig 4 presents a cross-sectional representation of the layered components that constitute the antenna. The uppermost layer of the structure is the antenna element, which is responsible for radiating or receiving electromagnetic waves. The arrows labelled u (horizontal direction) and w (vertical direction) represent the directions of electric and magnetic field components or signal propagation. This indicates the orientation of the radiation or wave propagation from the antenna. Beneath the antenna is the slotted metal track, which is a key part of the feed structure. This layer features precisely designed slots (visible as horizontal cuts in the diagram), which guide the electromagnetic energy from the transmission line to the antenna with minimal loss and high efficiency. Below the slotted metal track is the PCB transmission line. This layer consists of a dielectric substrate with conductive traces that form the transmission line. This layer is responsible for carrying the RF signal while providing a slow-wave effect that enhances the control and precision of the signal propagation. At the base of the structure is the metal track, which serves as the foundation for the signal feed. This track provides low-loss transmission and interfaces with external signal sources or other components. The supporting structure underneath the metal track provides mechanical stability and structural integrity to the entire antenna system. It ensures proper alignment of the layers and offers robustness for various applications. The diagram clearly shows the multi-layered structure of the antenna, which integrates the slotted metal track, PCB transmission line, and metal track to ensure efficient signal feed and radiation. The side view demonstrates the compactness of theP395892GB1 / WO spec 19-3-269antenna system, with thin layers stacked efficiently to achieve a lightweight and low-profile design.

[0037] This cross-sectional view provides insight into how the various layers interact to ensure efficient signal transmission, coupling, and radiation, while maintaining a compact and mechanically stable design.

[0038] According to an embodiment the waveguide structure featuring a conductive metal track with inner dimensions constrained within the range of 0.05A < a < 0.45A and 0.05A < b < 0.45A, where a and b represent the inner width and height of the track, respectively, and A denotes the wavelength of the centre frequency. A printed circuit board (PCB) is positioned within the waveguide structure, wherein its placement can be either centrally aligned or positioned asymmetrically near the inner upper or lower surfaces of the metal track, ensuring that no direct contact occurs with the conductive surfaces. This configuration facilitates efficient electromagnetic wave propagation while optimizing signal integrity, impedance matching, and minimizing unwanted reflections. The inventive structure provides a compact and scalable solution for high-frequency signal transmission in microwave and millimetre-wave applications.

[0039] Fig 5 depicts a detailed three-dimensional view of the antenna array architecture, showcasing its modular structure, which is adaptable to different configurations. This system consists of key components that include metal tracks, PCB transmission lines, slotted metal tracks, and antenna elements. The design is inherently flexible, allowing it to be implemented with or without reconfigurable components, depending on the application requirements. The array consists of multiple antenna elements aligned on the topmost layer. These elements are designed to radiate or receive electromagnetic signals. These elements can operate in a fixed configuration or, optionally, include reconfigurable components for dynamic adjustment of the radiation pattern, frequency, or polarisation. Each antenna element is connected to a slotted metal track, visible beneath the antenna elements. The slots efficiently couple the electromagnetic energy from the underlying transmission lines into the antenna elements while minimising losses. These tracks serve as a precise feeding structure, optimised for either static or reconfigurable operation. A key feature of this architecture is the PCB transmission line, which lies below the slotted metal tracks. The transmission line is implemented on a dielectric substrate, providing both signal propagation and slow-wave effects, which are critical for high-frequency and reconfigurable applications. This layer can include additional structures to enhance reconfigurability or operate in a static configuration for simpler designs. At the bottom of the structure, the metal track forms the foundational layer, providing low-loss signal propagation and robust mechanical support for the array. The metal track feeds the signalP395892GB1 / WO spec 19-3-2610into the PCB layer and can function independently or in conjunction with beamformers and power combiners.

[0040] When implemented with reconfigurable components, the antenna array can dynamically adapt to varying requirements, such as beam steering, frequency tuning, or polarisation adjustment. The reconfigurable components may include tuneable elements, such as varactors or MEMS switches, integrated along the transmission lines or at the antenna element level. This configuration is ideal for advanced applications like adaptive phased arrays, leaky wave antennas, or multi-band communication systems.

[0041] In simpler designs, the antenna array operates in a static configuration, with fixed radiation patterns and frequency responses. Omitting reconfigurable components reduces complexity, cost, and power consumption, making the system more suitable for basic applications or mass production. This setup is effective for fixed-beam arrays, standard communication systems, or single-frequency operation.

[0042] The modular design allows for straightforward scaling of the array, whether in static or dynamic configurations. The slow-wave effects inherent to the PCB transmission line ensure efficient signal propagation and precise control, regardless of whether reconfigurable features are included. The architecture can be tailored to budgetary constraints by excluding reconfigurable components when not required. This antenna array offers a versatile solution, seamlessly integrating fixed or reconfigurable features to meet the needs of a wide range of applications, from basic static systems to advanced adaptive arrays.

[0043] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0044] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments.P395892GB1 / WO spec 19-3-2611The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0045] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

P395892GB1 / WO spec 19-3-2612CLAIMS:

1. An antenna array comprising:a dielectric substrate having an upper surface and an opposed lower surface; a conductive transmission line formed on or in the dielectric substrate;a conductive metal track disposed under the lower surface of the dielectric substrate substantially parallel to the transmission line;a slotted metal track disposed over the upper surface of the dielectric substrate substantially parallel to the transmission line; anda plurality of antenna elements disposed above the slotted metal track and configured to couple with slots of the slotted metal track so as to radiate or receive electromagnetic signals.

2. The antenna array of claim 1, comprising:a plurality of substantially parallel transmission lines formed on or in the dielectric substrate;a corresponding plurality of conductive metal tracks disposed under the lower surface of the dielectric substrate each substantially parallel to one of the transmission lines; anda corresponding plurality of slotted metal tracks disposed over the upper surface of the dielectric substrate each substantially parallel to one of the transmission lines;wherein the antenna elements are disposed above each of the plurality of slotted metal tracks.

3. The antenna of any preceding claim, wherein the antenna elements overlap the slots of the slotted metal track or tracks.

4. The antenna array of any preceding claim, wherein the antenna elements further comprise reconfigurable components configured for dynamic adjustment of at least one of a radiation pattern, frequency or polarization.

5. The antenna array of any preceding claim, wherein the slots of the slotted metal track or tracks are tuneable slots or form a metasurface.

6. The antenna of any preceding claim, wherein the conductive transmission line is not in direct conductive contact with the metal track.P395892GB1 / WO spec 19-3-26137. The antenna of any preceding clam, wherein the conductive transmission line is not in direct contact with the slotted metal track.

8. The antenna array of any preceding claim, further comprising power combining and / or beamforming circuitry to feed a radio frequency signal to the metal track or metal tracks disposed under the lower surface of the dielectric substrate.

9. The antenna array of any preceding claim, wherein the transmission line or lines is or are configured to support slow-wave transmission of radio frequency signals.

10. The antenna array of any preceding claim, wherein reconfigurable components, such as tuneable elements including varactors or MEMS switches, are integrated along the transmission line or lines.

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