Antenna system

Abstract

The disclosure relates to an antenna system (200) comprising: two antennas (210, 220) arranged next to each other; and a radio frequency inhibitor (100) arranged between the two antennas (210, 220) for inhibiting propagation of electromagnetic waves between the two antennas (210, 220), the radio frequency inhibitor (100) comprising: an elongated flat body (110) extending along a longitudinal axis (111) between the two antennas (210, 220), the elongated flat body (110) comprising a plurality of corrugated sections (112) with beveled edges (113), wherein the corrugated sections (112) are arranged to form a wavy structure along the longitudinal axis (111), wherein the corrugated sections (112) are configured to produce diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor (100) to achieve destructive interference and to thereby inhibit the propagation of the electromagnetic waves between the two antennas (210, 220).

Description

[0001] ANTENNA SYSTEM

[0002] TECHNICAL FIELD

[0003] The disclosure relates to the field of wireless communications and antenna design. The disclosure relates to an antenna system with a radio frequency inhibitor, for example a multiple antenna system.

[0004] BACKGROUND

[0005] In wireless communications, antenna design and optimization play a fundamental role in ensuring reliable and efficient system performance. The performance of a multiple-antenna system degrades when the elements are too close together, due to an increase in mutual coupling (MC). This phenomenon, which is frequently overlooked despite its critical nature, arises from the proximity of two or more antennas, thereby affecting their electrical properties and increasing the complexity of the system. Mutual coupling, which negatively impacts the efficiency of multiple antennas (MIMO), can be the electromagnetic interaction between antennas. Antennas that are closely spaced can produce significant coupling, which might negatively impact the antenna system's performance and can have consequences for various aspects such as the radiation pattern, input impedance, signal-to-noise ratio (SNR), feed impedance, reflection loss, and signal correlation. When two (or more) antennas operating in the same frequency range are installed in close vicinity there can be a risk of a high coupling between them. In these conditions the possibility to simultaneously transmit with one of the antennas and to receive with another one (namely Full-Duplex operation) can be challenging. In other words, the isolation between Tx and Rx sections is important as it can directly impact the performance of the Full-Duplex system.

[0006] SUMMARY

[0007] This disclosure provides a solution to increase the isolation between co-located antennas without degrading their radiating performance.

[0008] The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

[0009] Embodiments of the disclosure present electromagnetic structures that reduce the coupling between co-located antennas, e.g., antennas installed in close vicinity (e.g., distance lower than few tens of the operating wavelength). Further embodiments present electromagnetic structures reducing the coupling between antennas sharing the same mechanic (same ground plane) and potentially the same radome. This coupling is also called intra-module coupling because it relates to two or more antennas belonging to the same apparatus (or module).

[0010] Embodiments of the disclosure present an antenna system, where a transmitting antenna and a receiving antenna are placed next to each other, e.g., on the same mechanical chassis and / or covered by the same radome. Embodiments of the disclosure present radio frequency inhibitors, e.g., electromagnetic structures that are reducing the coupling between two antennas arranged next to each other. Such RF inhibitors can reduce several coupling mechanisms such as coupling by space wave outside the module; coupling by inner and surface waves bounded within the radome; coupling by space wave inside the module (guided between the ground and the radome); and coupling by surface wave along the ground plane. In order to describe the disclosure in detail, the following terms and notations will be used.

[0011] RF Radio Frequency

[0012] EBG Electromagnetic Band Gap

[0013] DGS Defected Ground Structure

[0014] MIMO Multiple Input Multiple Output

[0015] ISAC Integrated Sensing And Communication

[0016] GTD Geometric Theory of Diffraction

[0017] In this disclosure, radio frequency (RF) inhibitors are described. RF inhibitors are also referred to as radio frequency barriers or physical radio frequency barriers that increase decoupling between two (or more) antennas. These devices obstruct the propagation of electromagnetic waves and enhance isolation between two antennas. The disclosure also relates to a defected scattering fence to improve antenna to antenna isolation.

[0018] Such RF barriers exploit the principles of the Geometric Theory of Diffraction (GTD), to improve the isolation between two antennas and prevent the direct propagation of electromagnetic waves by diffraction and scattering, which occur when waves encounter an obstacle. Specifically, when a ray impinges on an edge, it produces a set of diffracted rays forming what is called a diffraction cone or Keller's cone obeying the law of diffraction. According to this theory, the presence of an obstacle in the path of electromagnetic waves creates a diffracted wavefront that spreads out in a cone-shaped pattern behind the obstacle, thereby reducing the direct propagation of waves. This is achieved by properly designing the barrier's shape and size to match the wavelength of the electromagnetic waves in use.

[0019] Embodiments of the disclosure present an innovative RF barrier named Defected Scattering Fence or RF inhibitor. It consists of a series of geometric features, such as slots or protrusions, designed to break up the smooth surface of the barrier. When an electromagnetic wave encounters a defected wall, the direct ray from the transmitting antenna can impact the barrier multiple times, producing a diffracted wave that is directed toward the receiving antenna each time. These diffracted waves have the same amplitudes but random phases, meaning that they are uniformly distributed in phase angle. Due to the random phase angles, as the number of diffracted waves increases, their contributions to the total field at the receiving antenna tend to cancel each other out. This effect, known as "destructive interference", causes the phasor sum of all diffracted waves to approach zero as the number of contributions increases. An example of a defected scattering fence or RF inhibitor implementation is depicted in Figure 1, where the diffraction edges can be properly designed by considering all the possible degrees of freedom.

[0020] The disclosed RF inhibitor is able to counteract the coupling mechanisms described above and consists in a lightweight, low- cost and simple to be manufactured isolating structure that can be placed between the two antennas resulting in an enhancement of the isolation among them (intra-module isolation).

[0021] This isolating structure or RF inhibitor is able to block the surface wave over the ground and the space wave inside the module, while relies on a smart exploitation of Keller’s cone diffraction to achieve destructive interference and reduce the coupling due by the space wave outside the module and the waves bounded within or around the radome.

[0022] The disclosed solution - named Defected Scattering Fence or RF inhibitor - is a novel technique because, instead of suppressing surface currents (e.g., by means of DGS, EBG or Soft Surfaces) or canceling the undesired signal received by the Rx antenna (e.g., decoupling networks), it produces multiple diffracted waves that have the same amplitudes but random phases. As the number of diffracted waves increases, their contributions to the total field at the receiving antenna tend to cancel each other out (destructive interference). There are several advantages that can be realized by the disclosed solution: 1 ) Space Efficiency: The Defected Scattering Fence or RF inhibitor requires a much smaller space compared to traditional solutions such as EBGs, DGS, and soft surfaces. 2) Versatility: The Defected Scattering Fence or RF inhibitor operates properly with different radiating modes and is therefore suitable for Phased Array Antennas. The Defected Scattering Fence stands out from alternatives such as decoupling networks and EBG structures by providing a broadband solution. Its broad operating frequency range enhances versatility and efficacy, making it suitable for diverse communication systems. 3) Compatibility with Dual-Polarized Antennas: The Defected Scattering Fence or RF inhibitor operates properly with dual-polarized antennas. 4) Simplified Manufacturing: The manufacturing process for the Defected Scattering Fence or RF inhibitor is straightforward, eliminating the need for additional complex structures like extra PCBs for EBGs or decoupling networks within the system. The Defected Scattering Fence or RF inhibitor serves as a versatile add-on component, offering easy installation between antennas without requiring modifications to the ground plane or antenna structure. This feature enables seamless removal and repositioning, providing a convenient solution that minimizes the risks associated with potential errors during design or fabrication. 5) Enhanced Isolation: The Defected Scattering Fence or RF inhibitor can be seamlessly combined with lossy or absorbing materials to achieve higher isolation.

[0023] According to a first aspect, the disclosure relates to an antenna system comprising: two antennas arranged next to each other; and a radio frequency inhibitor arranged between the two antennas for inhibiting propagation of electromagnetic waves between the two antennas, the radio frequency inhibitor comprising: an elongated flat body extending along a longitudinal axis between the two antennas, the elongated flat body comprising a plurality of corrugated sections with beveled edges, wherein the corrugated sections are arranged to form a wavy structure along the longitudinal axis, wherein the corrugated sections are configured to produce diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor to achieve destructive interference and to thereby inhibit the propagation of the electromagnetic waves between the two antennas.

[0024] The corrugated sections of the flat body can be realized as corrugated flat sections like a corrugated metal. The corrugated flat sections may thus extend along a curved or corrugated plane or plate.

[0025] The antenna system and RF inhibitor increase the isolation between co-located antennas without degrading their radiating performance. It has been demonstrated that a proper design of the RF inhibitor will not affect the main beam of the antenna array even when steering to off-broadside directions.

[0026] The antenna system provides a simpler and cheaper solution to increase the isolation between co-located antennas with respect to standard approach at reduced costs and manufacturing complexity. The antenna system does not suffer the negative effect of aging like RF absorbers, hence there is no need for maintenance. The antenna system needs only a reduced space to be effective in increasing the isolation with respect to standard approaches, hence it is very space efficient. The antenna system operates properly with different radiating modes and is therefore suitable for Phased Array Antennas and for Dual-Polarized antennas, it thus provides flexibility. The RF inhibitor of the antenna system can be produced with metallized plastics resulting in a lightweight solution. It serves as a versatile add-on component, enabling seamless removal and repositioning, thereby providing flexibility. The antenna system provides a remarkable improvement in terms of spectral efficiency because the communication system can potentially double the spectral efficiency thanks to the Full-Duplex operation, hence the antenna system provides improved performance. It enables new system services / capabilities like to integrate the sensing feature together with communication, thereby providing flexibility and new product (market) opportunities.

[0027] In an exemplary implementation of the antenna system, at least two corrugated sections of the elongated flat body have a different size and / or a different curvature with respect to each other. Varying the size and curvature of the corrugated sections increases the diversity of the design resulting in more variations of the diffractions on the propagation of the electromagnetic waves, thereby achieve a better destructive interference and inhibition of the propagation of the electromagnetic waves.

[0028] In an exemplary implementation of the antenna system, each corrugated section comprises two arms that are arranged next to each other; wherein one arm of a corrugated section merges into a corresponding arm of an adjacent corrugated section. The RF inhibitor with two arms arranged next to each other shows a better isolation than a straight barrier with the same width and height.

[0029] In an exemplary implementation of the antenna system, each corrugated section is defined by a curvature angle between the two arms of the corrugated section, and a length, a height and a depth of a respective arm of the two arms. Curvature angle, length, height and depth bring a noticeable improvement of the isolation with respect to a straight barrier design.

[0030] In an exemplary implementation of the antenna system, at least two of the following parameters are different for at least two corrugated sections of the plurality of corrugated sections: the curvature angle between the two arms, the length of the two arms, the height of the two arms, and the depth of the two arms. Such variation of the above parameters further improves isolation. The parameters can also be referred to as properties of the antenna system.

[0031] In an exemplary implementation of the antenna system, the arms of the elongated flat body are asymmetrically arranged such that a first arm and a last arm of the elongated flat body point to different half-spaces; or the arms of the elongated flat body are symmetrically arranged such that a first arm and a last arm of the elongated flat body point to a same half-space. Both of the above designs disrupt the direct propagation of the electromagnetic waves between the two antennas and minimize mutual coupling.

[0032] In an exemplary implementation of the antenna system, the elongated flat body comprises a first main surface facing one antenna of the two antennas and a second main surface opposite to the first main surface, wherein the two main surfaces are delimited by two lateral surfaces that form edges with the two main surfaces. The two main surfaces and two lateral surfaces delimited by edges improve the isolation between the two antennas and prevents the direct propagation of the electromagnetic waves by diffraction and scattering.

[0033] In an exemplary implementation of the antenna system, the elongated flat body comprises one or more slots and / or protrusions at the first main surface and / or the second main surface of the elongated flat body. The slots and protrusions provide irregularities in the pattern of the RF inhibitor, thereby improving diffraction of the electromagnetic waves.

[0034] In an exemplary implementation of the antenna system, the slots and / or protrusions are breaking up a surface structure of the first main surface and / or the second main surface and are configured to produce further diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor to increase the destructive interference. The further diffractions increase the variety of diffractions resulting in improved destructive interference and inhibition of the propagation of the electromagnetic waves.

[0035] In an exemplary implementation of the antenna system, the two antennas comprise phased array antennas capable to steer a radiated beam inside a certain field of view and / or dual polarized antennas. Such antenna types are often used. The RF inhibitor can effectively protect such an antenna system against coupling of the antennas. In an exemplary implementation of the antenna system, the elongated flat body is built with one or a combination of the following materials: a metal, a metal alloy, metallized plastic and a lossy material. This allows flexibility in production and manufacture. In particular metallized plastic allows a lightweight solution.

[0036] In an exemplary implementation of the antenna system, the elongated flat body is formed as one or a combination of the following: a single piece, a stack of multiple slices; an alignment of multiple pieces aligned along the longitudinal axis. In that way, long and thick RF inhibitors can be easily produced and transported. It allows design flexibility.

[0037] In an exemplary implementation of the antenna system, the antenna system comprises at least one second radio frequency inhibitor arranged next to the radio frequency inhibitor between the two antennas. By using such combination of RF inhibitors, improved isolation can be achieved.

[0038] In an exemplary implementation of the antenna system, the elongated flat body is formed according to a sine wave shape or a zig-zag shape or another modified analytical shape along the longitudinal axis. It has shown in simulations that such designs are optimal with respect to isolation efficiency.

[0039] In an exemplary implementation of the antenna system, the two antennas are arranged with the radio frequency inhibitor on a same ground plane; and / or wherein the two antennas share a same radome. In such a way multiple antenna structures such as MIMO antennas can be provided with improved isolation characteristics.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further embodiments of the disclosure will be described with respect to the following figures, in which:

[0042] Figure 1 shows a 3-dimensional representation of an antenna system with a radio frequency inhibitor and an enlarged view of the radio frequency inhibitor;

[0043] Figure 2 shows a 3-dimensional representation of a radio frequency inhibitor and a top view of the radio frequency inhibitor;

[0044] Figure 3 shows a 3-dimensional representation of a radio frequency inhibitor and a top view of the radio frequency inhibitor;

[0045] Figure 4 shows a 3-dimensional representation of two radio frequency inhibitors placed next to each other and a top view of the two radio frequency inhibitors;

[0046] Figure 5 shows two different 3-dimensional representations of a radio frequency inhibitor, and atop view of the radio frequency inhibitor;

[0047] Figure 6 shows two different 3-dimensional representations of a radio frequency inhibitors;

[0048] Figure 7 shows two different 3-dimensional representation of a radio frequency inhibitors;

[0049] Figure 8 shows another 3-dimensional representation of a radio frequency inhibitor;

[0050] Figure 9 shows another 3-dimensional representation of a radio frequency inhibitor; and Figure 10 shows a performance diagram of an antenna system.

[0051] DETAILED DESCRIPTION OF EMBODIMENTS

[0052] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the disclosure is defined by the appended claims.

[0053] It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

[0054] Figure 1 shows a 3-dimensional representation of an antenna system 200 with a radio frequency inhibitor 100 according to an embodiment and an enlarged view of the radio frequency inhibitor 100.

[0055] The antenna system 200 comprises two antennas 210, 220 arranged next to each other; and a radio frequency inhibitor 100 arranged between the two antennas 210, 220 for inhibiting propagation of electromagnetic waves between the two antennas 210, 220.

[0056] The radio frequency inhibitor 100 comprises an elongated flat body 110 extending along a longitudinal axis 111 between the two antennas 210, 220. The elongated flat body 110 comprises a plurality of corrugated sections 112 with beveled edges 113. The corrugated sections 112 are arranged to form a wavy structure along the longitudinal axis 111.

[0057] The corrugated sections 112 are configured to produce diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor 100 to achieve destructive interference and to thereby inhibit the propagation of the electromagnetic waves between the two antennas 210, 220.

[0058] Although Figure 1 shows the RF inhibitor 100 arranged in the middle of the two antennas 210, 220, the RF inhibitor 100 can also be placed closer to the first antenna 210 or closer to the second antenna.

[0059] Fig. 1 shows that the longitudinal axis 111 of the RF inhibitor 100 is parallel to the edges of both antennas 210, 220. In other embodiments the longitudinal axis 111 can be at an angle to the edges of the antennas 210, 220.

[0060] The RF inhibitor 100 can separate more than the two antennas 210, 220 (not shown in Figure 1), for example 2 (or any other number of) antennas can be placed on one side of the RF inhibitor 100 and another 2 (or any other number of) antennas can be placed on the other side of the RF inhibitor 100.

[0061] Another RF inhibitor 100 or more than one RF inhibitors 100 can be placed next to the RF inhibitor 100 to improve the isolation effect. Thereby, a stack of RF inhibitors 100 can be created to increase electromagnetic isolation. More than one RF inhibitors 100 can be applied for separating more than two antennas (not shown in Figure 1). For example, each two antennas can be separated by a respective RF inhibitor 100. These multiple RF inhibitors 100 may cross each other where necessary. In Figure 1, the RF inhibitor 100 is represented as a 2-dimensional form extending along the longitudinal axis 111. In other embodiments, the RF inhibitor 100 may at least partially surround one or both antennas 210, 220, e.g., by forming a square (or half-square) or a circle (or half-circle) around the respective antenna.

[0062] At least two corrugated sections 112 of the elongated flat body 110 may have a different size and / or a different curvature with respect to each other, e.g., as shown in Figure 5.

[0063] Each corrugated section 112 may comprise two arms 113a, 113b that are arranged next to each other. One arm 113a of a corrugated section 112 may merge into a corresponding arm 113a of an adjacent corrugated section 112 as shown in Figure 1.

[0064] Each corrugated section 112 can be defined by a curvature angle (a) 114 between the two arms 113a, 113b of the corrugated section, and a length (L) 115, a height (H) 116 and a depth (T) 117 of a respective arm of the two arms 113a, 113b as shown in Figure 1.

[0065] At least two of the following parameters can be different for at least two corrugated sections 112 of the plurality of corrugated sections 112: the curvature angle 114 between the two arms 113a, 113b, the length 115 of the two arms 113a, 113b, the height 116 of the two arms 113a, 113b, and the depth 117 of the two arms 113a, 113b. The arms 113a, 113b of the elongated flat body 110 may be asymmetrically arranged such that a first arm 113a and a last arm 113b of the elongated flat body 110 point to halfspaces as shown in Figure 2, for example. Alternatively, the arms 113a, 113b of the elongated flat body 110 may be symmetrically arranged such that a first arm 113a and a last arm 113b of the elongated flat body 110 point to a same half-space as shown in Figures 1 or 3, for example.

[0066] The elongated flat body 110 may comprise a first main surface 110a as shown in Figure 1 facing one antenna of the two antennas 210, 220 and a second main surface 110b opposite to the first main surface 110a. These two main surfaces 110a, 110b may be delimited by two lateral surfaces 110c, 1 lOd as shown in Figure 1 that form edges with the two main surfaces 110a, 110b. The elongated flat body 110 may comprises one or more slots and / or protrusions at the first main surface 110a and / or the second main surface 110b of the elongated flat body 110 as shown in Figure 8 (protrusions) and Figure 9 (slots).

[0067] The slots and / or protrusions may break up a surface structure of the first main surface 110a and / or the second main surface 110b and may be configured to produce further diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor 100 to increase the destructive interference.

[0068] The two antennas 210, 220 may comprise phased array antennas capable to steer a radiated beam inside a certain field of view and / or dual polarized antennas.

[0069] The elongated flat body 110 may be built with one or a combination of the following materials: a metal, a metal alloy, metallized plastic and a lossy material.

[0070] A lossy material is a material that dissipates energy of electromagnetic energy passing through it. The lossy material can be, for example, a lossy dielectric. A lossy dielectric can be described as a medium where some fraction of the electromagnetic wave power is lost as the wave propagates. This power loss is due to poor conduction. A lossy dielectric offers a partially conducting medium with conductivity unequal to zero. The lossy dielectric can be represented by its conductivity, permeability and permittivity parameters. The elongated flat body 110 may be formed as one or a combination of the following: a single piece lOOf as shown in the upper part of Figure 6, for example, a stack of multiple slices 100g as shown in the lower part of Figure 6, for example, an alignment of multiple pieces lOOh, lOOi aligned along the longitudinal axis 111 as shown in the upper and lower parts of Figure 7, for example.

[0071] The antenna system 200 may comprise one or more second radio frequency inhibitors 100c as shown in Figure 4, for example, arranged next to the radio frequency inhibitor 100a between the two antennas 210, 220. These additional RF inhibitors 100c can increase the isolation efficiency.

[0072] The elongated flat body 110 may be formed according to a sine wave shape as shown in Figure 1, for example, or a zig-zag shape as shown in the upper part of Figure 5, for example, or another modified analytical shape along the longitudinal axis 111.

[0073] The two antennas 210, 220 may be arranged with the radio frequency inhibitor 100 on a same ground plane 201 as shown in Figure 1. The two antennas 210, 220 may share a same radome 202. The ground plane 201 is represented by the top surface of the box to which the two antennas 210, 220 are attached as can be seen from Figure 1. The ground plane 201 can be a printed circuit board, for example, or any other kind of plate where the antennas 210, 220 can be fixed.

[0074] A radome is a structural, weatherproof enclosure that protects the RF antenna. The radome is constructed of material transparent to radio waves. Radomes protect the antenna from weather and conceal antenna electronic equipment from view. Radomes can be constructed in several shapes - spherical, geodesic, planar, etc. depending on the particular application, using various construction materials such as fiberglass, polytetrafluoroethylene (PTFE)-coated fabric, and others.

[0075] The antenna system 200 shown in Figure 1 introduces a solution to increase the isolation between co-located antennas that share the same mechanic (same ground plane 201) and possibly the same radome 202, involving the implementation of a Defected Scattering Fence (DSF), also referred to as RF inhibitor 100 in this disclosure. The DSF 100 is purposefully designed to disrupt the direct propagation of electromagnetic waves between antennas, with a primary focus on minimizing mutual coupling.

[0076] The geometric shape of the DSF 100 plays a pivotal role in its functionality, featuring a non-straight pattern. The systematic optimization of barrier thickness, arm length, and bevel angles through numerical simulations ensures an effective disruption of electromagnetic wave propagation.

[0077] In the embodiment shown in Figure 1 and most of the other Figures, a sinusoidal pattern is selected. The sinusoidal pattern, coupled with these optimized dimensions, contributes to the DSF's ability to adapt, and perform optimally for different antenna systems and steering angles. The sinusoidal septum of the DSF 100 is engineered to induce multiple diffraction points. As incident waves interact with this geometric feature, they produce diffracted waves with random phases. This intentional random-phase distribution is pivotal for achieving and exploiting the principles of destructive interference. The DSF 100 is configured to cancel out contributions from diffracted waves. As the number of diffracted waves increases, their random-phase contributions tend to nullify each other, resulting in a substantial reduction in the overall electromagnetic field at the receiving antenna.

[0078] The disclosed solution can be implemented in several different manners as shown in Figures 2 to 9, for example. Figure 2 shows a 3-dimensional representation of a radio frequency inhibitor 100a according to an embodiment and a top view of the radio frequency inhibitor 100a. Figure 2 shows an example of a a Defected Scattering Fence (DSF) 100a or RF inhibitor 100a, respectively, with asymmetric arms 113a, 113b, each characterized by bevel angles set at 45°. The asymmetric arms 113a, 113b, featuring a bevel angle of 45°, bring a unique geometric dynamic to the DSF 100a. The 45° bevel angles are strategically chosen through comprehensive numerical simulations and optimizations, ensuring that this configuration adapts effectively across a range of antenna systems. The asymmetry introduces a specific geometric feature, enhancing the DSF's adaptability to different operational scenarios and system requirements.

[0079] The bevel angle 114b shown in Figure 2 is half of the curvature angle 114 described above with respect to Figure 1, and also depicted in the bottom part of Figure 2.

[0080] The asymmetric arms 113a, 113b mean that a first arm 113a and a last arm 113b of the elongated flat body 110 point to different half-spaces, e.g., in different directions, here in Figure 2 to the top and the bottom.

[0081] Figure 3 shows a 3-dimensional representation of a radio frequency inhibitor 100b according to an embodiment and a top view of the radio frequency inhibitor 100b.

[0082] In Figure 3, a distinct configuration of the Defected Scattering Fence (DSF) or RF inhibitor 100b with symmetric arms 113a, 113b is shown, each characterized by bevel angles set at 30°. This configuration represents a meticulous design choice aimed at optimizing mutual coupling reduction between antennas. The symmetric arms 113a, 113b, with their precisely calibrated bevel angles 114b, contribute to the overall geometric precision of the DSF 100b. The 30° bevel angles 114b are chosen based on thorough numerical simulations and optimizations, ensuring that this configuration performs optimally across various antenna systems. This adaptability enhances the versatility of the RF inhibitor 100a shown in Figure 2, making it a robust solution for different operational scenarios and system requirements.

[0083] Both symmetric and asymmetric DSF configurations can be used independently or in various combinations, with different bevel angles, thicknesses, heights, providing versatility for standalone deployment or customized configurations.

[0084] Figured shows a 3 -dimensional representation of two radio frequency inhibitors 100a, 100c placed next to each other according to an embodiment and a top view of the two radio frequency inhibitors 100a, 100c.

[0085] In the example of Figure 4, the Defected Scattering Fence (DSF) or RF inhibitor is further enhanced through a thoughtful combination of barriers 100a, 100c featuring both symmetric and asymmetric arms 113a, 113b. The dual configuration approach introduces barriers 100c with symmetric arms, characterized by bevel angles 114b of 30°, and barriers 100a with asymmetric arms, featuring bevel angles 114b of 45°. This strategic duality allows for the optimization of DSF performance across different antenna systems, ensuring adaptability to varying steering angles.

[0086] Figure 5 shows a 3-dimensional representation of a radio frequency inhibitor lOOd according to an embodiment, a 3- dimensional representation of a radio frequency inhibitor lOOe according to another embodiment and a top view of the radio frequency inhibitor lOOe.

[0087] In the examples of Figure 5, the pattern of the Defected Scattering Fence (DSF) or RF inhibitor lOOd, lOOe is modified to furtherly increase the degrees of freedom of the design. The upper part of Figure 5 shows an RF inhibitor lOOd having a zigzag shape. The both lower parts of Figure 5 show an RF inhibitor lOOe having a modified analytical shape. Any combination of the embodiments described here with respect to Figures 1 to 9 can be applied to create the RF inhibitor.

[0088] Figure 6 shows a 3-dimensional representation of a radio frequency inhibitor lOOf according to an embodiment and a 3- dimensional representation of a radio frequency inhibitor 100g according to another embodiment.

[0089] The DFS or RF inhibitor can be manufactured in many different ways, as depicted in Figure 6, for example a) as a single piece of metal or any metallized material (e.g., metallized plastic, 3D printed parts, etc.) as forthe exemplary RF inhibitor lOOf shown on top of Figure 6; b) by stacking multiple slices in order to achieve the desired height as for the exemplary RF inhibitor 100g shown on bottom of Figure 6; c) by aligning multiple small modules, placed side-by-side in order to achieve the desired length as for the exemplary RF inhibitor lOOh shown at the top of Figure 7; or d) as a combination of b) and c) as shown by the exemplary RF inhibitor lOOi at the bottom of Figure 7.

[0090] The Defected Scattering Fence (DSF) or RF inhibitor can be built with a combination of different materials like - but not limited to - the following examples: a) Metal only; b) Lossy material only; and c) Metal and Lossy material.

[0091] Figure 7 shows a 3-dimensional representation of a radio frequency inhibitor lOOh according to an embodiment and a 3- dimensional representation of a radio frequency inhibitor lOOi according to another embodiment.

[0092] The DFS or RF inhibitor lOOh shown on top of Figure 7 can be manufactured by aligning multiple small modules, placed side- by-side in order to achieve the desired length. In this example four small modules are placed side-by-side, but any other number can be used as well.

[0093] The DFS or RF inhibitor lOOi shown on bottom of Figure 7 can be manufactured by stacking multiple slices in order to achieve the desired height and by aligning multiple small modules, placed side-by-side in order to achieve the desired length. In this example four small modules are placed side-by-side and five slices are stacked above each other, but any other numbers can be used as well.

[0094] Figure 8 shows a 3-dimensional representation of a radio frequency inhibitor lOOj according to an embodiment. The DFS or RF inhibitor lOOj comprises multiple protrusions 118 as depicted in Figure 8. These protrusions 118 can be applied to any structure of the RF inhibitor shown in the above Figures 1 to 7.

[0095] Figure 9 shows a 3-dimensional representation of a radio frequency inhibitor 100k according to an embodiment. The DFS or RF inhibitor 100k comprises multiple slots 119 as depicted in Figure 8. These slots 119 can be applied to any structure of the RF inhibitor shown in the above Figures 1 to 8. The slots 119 can be applied in combination with the protrusions 118 shown in Figure 8.

[0096] Figure 10 shows a performance diagram of an antenna system 200 according to the disclosure.

[0097] The disclosed antenna system 200 was implemented in a practical scenario, comprising two patch antenna arrays with MxN dimensions equal to 8x8, resulting in a total of 64 elements in each array (with a spacing around 0.51am in horizontal and 0.651am in vertical). The arrays were installed on a metal chassis, which also serves as a shared ground plane 201 between the two antennas 210, 220 as shown in Figure 1. Additionally, both phased arrays share the same single-layer radome 202.

[0098] The implementation of the two identified optimized solution within the antennas system 200 is depicted in Figure 1 and described above with respect to Figure 1. In order to evaluate the effectiveness of the disclosed solution, numerical simulations were performed employing a full-wave approach that implemented the Finite Element Method (FEM). The simulations were conducted within the 24.25-25.5 GHz frequency range, considering an array-to-array distance of 50mm. Specifically, the simulations of the two arrays placed inside the metal chassis and in the presence of the radome were performed. The effectiveness of the presented solution can be demonstrated by comparing the results with and without the identified DSF, which served to enhance the isolation between the two antennas 210, 220.

[0099] The effect of the DSF 100 can be easily shown by looking at the electric field that propagates in the antenna system volume. The presence of the DSF 100 is clearly reducing the «waveguide» effect created between the GND plane and the Radome

[0100] The total isolation between the antennas 210, 220 is a parameter investigated to determine the efficacy of the identified decoupling solution. In this regard, the total isolation (in terms of S21) between antennas at different beam steering angles was examined, both in the absence of decoupling structures and with the identified decoupling solutions.

[0101] A demonstration of the improvement provided by the Defected Scattering Fence 100 with respect to a straight barrier with the same width / height is shown in Figure 10, for the broadside beam only. It can be clearly seen from Figure 10 (curve 303) that the DSF 100 outperforms a straight barrier (curve 302) over a quite large frequency band (24.25-25GHz). The reference curve 301 shows the case where no fence is used. A demonstration of the improvement provided by the DSF has been carried out also for a large set of steering directions. When the two arrays steer their beams in a certain Field of View, the DSF 100 brings a noticeable improvement of the isolation: for the 95% of the cases the DSF 100 provides an isolation improvement higher than lOdB (not depicted in Figure 10).An exemplary case of a Defected Scattering Fence 100 implemented to increase the isolation between two horn antennas sharing the same ground plane (with and without the presence of a Radome on top) was also tested (not depicted in Figure 10). The results have shown a clear isolation improvement.

[0102] The presented solution can be applied to a vast number of products, like but not limited to Base Station Antennas (Active and Passive), Antennas for Hot-spots, Antennas for Repeaters and Second-hop relays. Every antenna product with two or more radiating sections that can be operated independently and that need a certain isolation between the radiating sections can be a use-case of this disclosure.

[0103] The disclosed DSF can also be integrated into a commercial Active Antenna Unit (AAU).

[0104] The disclosed solution can be applied to any antenna system that requires to guarantee a certain level of isolation between two or more radiating sections (e.g., MIMO, Full-Duplex, ISAC). The radiating section can be either a static-beam antenna or a beamforming / beam-steering / beam-switching antenna (e.g., phased array). This means that the presented solution can be applied to 5G Base Station Antenna as well as Wi-Fi routers / repeaters.

[0105] Another important feature of the disclosed RF inhibitor or DSF is related to its capability to reduce the Side Lobe Level (SLL) by providing a kind of shielding effect, without compromising the main beam and the level of Cross Polarization Discrimination (XPD).

[0106] While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

[0107] Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

[0108] Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

[0109] Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the disclosure beyond those described herein. While the disclosure has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the disclosure. It is therefore to be understood that within the scope of the appended claims and their equivalents, the disclosure may be practiced otherwise than as specifically described herein.

Claims

CLAIMS1. An antenna system (200) comprising: two antennas (210, 220) arranged next to each other; and a radio frequency inhibitor (100) arranged between the two antennas (210, 220) for inhibiting propagation of electromagnetic waves between the two antennas (210, 220), the radio frequency inhibitor (100) comprising: an elongated flat body (110) extending along a longitudinal axis (111) between the two antennas (210, 220), the elongated flat body (110) comprising a plurality of corrugated sections (112) with beveled edges (113), wherein the corrugated sections (112) are arranged to form a wavy structure along the longitudinal axis (111), wherein the corrugated sections (112) are configured to produce diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor (100) to achieve destructive interference and to thereby inhibit the propagation of the electromagnetic waves between the two antennas (210, 220).

2. The antenna system (200) of claim 1 , wherein at least two corrugated sections (112) of the elongated flat body (110) have a different size and / or a different curvature with respect to each other.

3. The antenna system (200) of claim 1 or 2, wherein each corrugated section (112) comprises two arms (113a, 113b) that are arranged next to each other; wherein one arm (113a) of a corrugated section (112) merges into a corresponding arm (113a) of an adjacent corrugated section (112).

4. The antenna system (200) of claim 3, wherein each corrugated section (112) is defined by a curvature angle (114) between the two arms (113a, 113b) of the corrugated section, and a length (115), a height (116) and a depth (117) of a respective arm of the two arms (113a, 113b).

5. The antenna system (200) of claim 4, wherein at least two of the following parameters are different for at least two corrugated sections (112) of the plurality of corrugated sections (112): the curvature angle (114) between the two arms (113a, 113b), the length (115) of the two arms (113a, 113b), the height ( 116) of the two arms (113a, 113b), and the depth (117) of the two arms (113a, 113b).

6. The antenna system (200) of any of claims 3 to 5, wherein the arms (113a, 113b) ofthe elongated flat body ( 110) are asymmetrically arranged such that a first arm (113a) and a last arm (113b) of the elongated flat body (110) point to different half-spaces; or wherein the arms (113a, 113b) of the elongated flat body (110) are symmetrically arranged such that a first arm (113a) and a last arm (113b) of the elongated flat body (110) point to a same half-space.

7. The antenna system (200) of any of the preceding claims, wherein the elongated flat body (110) comprises a first main surface (110a) facing one antenna of the two antennas (210, 220) and a second main surface (110b) opposite to the first main surface (110a), wherein the two main surfaces(110a, 110b) are delimited by two lateral surfaces (110c, HOd) that form edges with the two main surfaces (110a, 110b).

8. The antenna system (200) of claim 7, wherein the elongated flat body (110) comprises one or more slots (119) and / or protrusions (118) at the first main surface (110a) and / or the second main surface (110b) of the elongated flat body (110).

9. The antenna system (200) of claim 8, wherein the slots (119) and / or protrusions (118) are breaking up a surface structure of the first main surface (110a) and / or the second main surface (110b) and are configured to produce further diffractions on the propagation of the electromagnetic waves encountering the radio frequency inhibitor (100) to increase the destructive interference.

10. The antenna system (200) of any of the preceding claims, wherein the two antennas (210, 220) comprise phased array antennas capable to steer a radiated beam inside a certain field of view and / or dual polarized antennas.

11. The antenna system (200) of any of the preceding claims, wherein the elongated flat body (110) is built with one or a combination of the following materials: a metal, a metal alloy, metallized plastic and a lossy material.

12. The antenna system (200) of any of the preceding claims, wherein the elongated flat body (110) is formed as one or a combination of the following: a single piece (1001), a stack of multiple slices (100g); an alignment of multiple pieces (lOOh, lOOi) aligned along the longitudinal axis (111).

13. The antenna system (200) of any of the preceding claims, comprising: at least one second radio frequency inhibitor (100c) arranged next to the radio frequency inhibitor (100a) between the two antennas (210, 220).

14. The antenna system (200) of any of the preceding claims, wherein the elongated flat body (110) is formed according to a sine wave shape or a zig-zag shape or another modified analytical shape along the longitudinal axis.

15. The antenna system (200) of any of the preceding claims, wherein the two antennas (210, 220) are arranged with the radio frequency inhibitor (100) on a same ground plane (201); and / or wherein the two antennas (210, 220) share a same radome (202).

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