Three-dimensional frequency selective surface (FSS), antenna system, and base station

Abstract

The present application relates to the technical field of wireless communications, and provides a three-dimensional FSS. The present application provides a three-dimensional FSS compatible with an irregular metal boundary. Each three-dimensional FSS comprises a plurality of three-dimensional FSS units. Each unit comprises a metal plate, a base plate, and a metal boundary assembly. The base plate penetrates through the metal plate in a crossed mode. A metal pattern and a metal strip are formed on the base plate. The metal boundary assembly in each three-dimensional FSS unit is irregularly distributed on the metal plate, that is, the sizes, shapes, numbers, and orientations of the metal boundary assemblies of the three-dimensional FSS units can be inconsistent. A feed network and a phase shifter can be placed in each metal boundary assembly. In this way, according to a three-dimensional FSS architecture provided by the present application, different metal parts can be arranged on horizontal metal plates to form different metal boundaries, so that the problems that the metal parts such as the feed network and the phase shifter are not evenly distributed on the FSS, periodic unit boundaries are thus not normalized, and FSS performance deterioration is prone to occurring can be solved, thereby ensuring that the designed three-dimensional FSS has stable performance.

Description

A three-dimensional frequency selective surface FSS, antenna system and base station

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on March 22, 2024, with application number 202410339800.X and application name “A three-dimensional frequency selective surface FSS, antenna system and base station”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of wireless communication technology, and in particular to a three-dimensional frequency selective surface (FSS), an antenna system, and a base station. Background Art

[0003] With the advent of the 5G era, base station sites face challenges such as limited tower space and overloaded antennas. To address this issue, existing technologies have proposed a minimalist solution that integrates active and passive antennas in a modular manner. This solution integrates the 5G Massive MIMO AAU and 2 / 3 / 4G passive antennas into one, with a frequency selective surface (FSS) placed between the two antennas. This surface is electromagnetically transparent to the active antenna and reflects the passive antenna. This solution can significantly reduce the use of antenna space resources, effectively increase the height of the 5G AAU, enhance 5G coverage, and improve 5G user experience. However, this solution faces new challenges, such as the uneven distribution of metal components such as the feed network and phase shifters on the front and back of the FSS, and the non-uniform boundaries of the FSS periodic units, which can easily lead to FSS performance degradation. Summary of the Invention

[0004] This application provides a three-dimensional FSS, antenna system, and base station compatible with various metal boundaries. This three-dimensional FSS maintains stable performance even when metal components such as feed networks and phase shifters are irregularly distributed on the front and back of the FSS and when periodic unit boundaries are non-uniform.

[0005] In the first aspect, the present application provides a three-dimensional frequency selective surface (FSS) that is compatible with a variety of metal boundaries. The three-dimensional FSS includes multiple three-dimensional FSS units, each three-dimensional FSS unit includes a substrate and a metal plate, and at least a portion of the multiple three-dimensional FSS units also includes at least one metal boundary component; one or more substrates pass through the metal plate, and the metal boundary components of the multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate.

[0006] It should be noted that the number of substrates can be two. After crossing, the substrates pass through the metal plate at a certain angle, and the metal boundary components are distributed along the boundary of the metal plate. Irregular distribution of metal boundary components means that they are not distributed according to a specific pattern, which is different from the uniform distribution of metal boundary components in each three-dimensional FSS unit. Irregular placement here includes the non-uniform structure of the metal boundary components themselves, that is, inconsistent size, shape, quantity, etc.; it also includes inconsistent distribution position on the metal plate, that is, inconsistent orientation, distribution on the upper or lower surface of the metal plate, etc.

[0007] In this application, the metal boundary components of multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate. Through simulation and actual testing, it is found that the three-dimensional FSS in this application has very good consistency when the metal boundary components are irregularly distributed, and can also reduce the insertion loss fluctuation within the passband and obtain higher out-of-band suppression.

[0008] In an optional embodiment, the plurality of substrates are two substrates, and the two substrates cross and pass through the metal plate. Therefore, it can be seen that the two substrates can provide polarization in two directions, achieving a dual-polarization effect, thereby allowing signals in two polarization directions to pass through.

[0009] In an optional embodiment, the sizes of the metal boundary components of the multiple three-dimensional FSS units are not completely the same, so that the metal boundary components of the multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate.

[0010] In an optional embodiment, the size of the metal boundary component includes a height of the metal boundary component, the height of the metal boundary component is less than a quarter of a wavelength, and the wavelength is a wavelength corresponding to a passband center frequency.

[0011] It should be noted that the dimensions of the metal boundary components within each 3D FSS unit can be different, or even partially different. The dimensions of the metal boundary components can be understood as the size of the metal boundary components, including their height. Typically, the height of the metal component does not exceed the height of the metal ring and dipole.

[0012] In this application, metal boundary components of different sizes of multiple three-dimensional FSS units are distributed on the surface of the metal plate. Through simulation and actual testing, it is found that the three-dimensional FSS in this application has very good consistency even when the metal boundary components have different sizes. The three-dimensional FSS has good robustness, the insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high suppression. It solves the problem that when metal components such as feeding networks or phase shifters of different sizes are placed in the metal boundary components and distributed on the metal plate, the boundaries of the periodic units are not normalized, thereby causing the FSS performance to deteriorate.

[0013] In an optional embodiment, the numbers of the metal boundary components of the multiple three-dimensional FSS units are not exactly the same, so that the metal boundary components of the multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate.

[0014] It should be noted that the number of metal boundary components in the multiple 3D FSS units constituting the 3D FSS may be different, or may be partially different. For example, among 10 3D FSS units, the number of metal boundary components in one or more 3D FSS units may be different.

[0015] In the present application, different numbers of metal boundary components of multiple three-dimensional FSS units are distributed on the surface of the metal plate. Through simulation and actual testing, it is found that the three-dimensional FSS of the present application has very good consistency even when there are different numbers of metal boundary components. The insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high suppression. This solves the problem that when different numbers of metal components such as feeding networks or phase shifters placed in the metal boundary components are distributed on the metal plate, the boundaries of the periodic units are not normalized, thereby causing the FSS performance to deteriorate.

[0016] In an optional embodiment, the metal boundary components of the multiple three-dimensional FSS units have different orientations, so that the metal boundary components of the multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate.

[0017] It should be noted that the orientations of the metal boundary components within the multiple 3D FSS units that comprise the 3D FSS can be completely or partially different. Specifically, the orientation of the metal boundary components can be parallel to or perpendicular to an edge of the metal plate, i.e., the metal boundary components form a certain angle with the edge of the metal plate. When metal boundaries of varying heights are arranged parallel to or perpendicular to the edge of the metal plate, the FSS exhibits excellent robustness, with minimal insertion loss fluctuations within the passband and high suppression in the stopband.

[0018] In the present application, metal boundary components of multiple three-dimensional FSS units with different orientations are distributed on the surface of the metal plate. Through simulation and actual testing, it is found that the three-dimensional FSS of the present application has very good consistency even when the metal boundary components have different orientations. The insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high out-of-band suppression. This solves the problem that when metal components such as feeding networks or phase shifters with different orientations placed in the metal boundary components are distributed on the metal plate, the boundaries of the periodic units are not normalized, thereby causing the FSS performance to deteriorate.

[0019] In an optional embodiment, the shapes of the metal boundary components of the multiple three-dimensional FSS units are not completely the same, so that the metal boundary components of the multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate.

[0020] It should be noted that the shapes of the metal boundary components in the multiple 3D FSS units constituting the 3D FSS may all be different, or may be partially different, and may be a cuboid, a cylinder, or other shapes.

[0021] In the present application, metal boundary components of different shapes of multiple three-dimensional FSS units are distributed on the surface of the metal plate. Through simulation and actual testing, it is found that the three-dimensional FSS of the present application has very good consistency even when the metal boundary components have different shapes. The insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high out-of-band suppression. This solves the problem that when metal components such as feeding networks or phase shifters of different shapes placed in the metal boundary components are distributed on the metal plate, the boundaries of the periodic units are not normalized, thereby causing the FSS performance to deteriorate.

[0022] In an optional implementation, there is space inside the metal boundary component, a feeding network and / or a phase shifter is placed inside the metal boundary component, or the metal boundary component has a hollow structure.

[0023] As can be seen, the hollow structure can be used to house a feed network, connecting the RF signal to the array elements, forming a path for RF signal transmission. Phase shifters can also be placed within the hollow structure to alter the phase of the signal passing through it. Even with irregularly distributed metal components like the feed network or phase shifters, good performance can still be achieved. Furthermore, metal boundary components can isolate the effects of the phase shifter or feed network on the 3D FSS unit.

[0024] In an optional embodiment, the interior of the metal boundary component is a solid structure. Through simulation and actual testing, it is found that the metal boundary component can achieve the same effect as a hollow structure when it is a solid structure.

[0025] In an optional embodiment, the metal boundary components of the plurality of three-dimensional FSS units are located on the upper surface and / or the lower surface of the metal plate.

[0026] It should be noted that the metal boundary components in the three-dimensional FSS unit are all located on the upper surface or the lower surface of the metal plate, or are partially located on the upper surface and partially located on the lower surface.

[0027] It can be seen from this that each three-dimensional FSS unit is compatible with metal boundary components irregularly distributed on the upper and lower surfaces of the metal plate, so that the three-dimensional FSS has very good consistency even when the metal boundary components are irregularly distributed on the metal plate. The insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high out-of-band suppression. This solves the problem that when metal components such as the feeding network or phase shifter are irregularly placed in the metal boundary component and distributed on the metal plate, the periodic unit boundaries are not normalized, thereby causing the FSS performance to deteriorate.

[0028] In an optional embodiment, the substrate has a metal pattern, and the metal pattern is a metal ring.

[0029] In an optional embodiment, the substrate has a metal pattern, and the metal pattern is a metal ring and a dipole.

[0030] In an optional embodiment, the substrate has a metal pattern, and the metal pattern is a dipole.

[0031] It should be noted that the number of substrates that make up a three-dimensional FSS unit can be two or more, and each substrate has a metal pattern. The metal pattern can be a metal ring, including a circular metal ring and a rectangular metal ring. The specific shape of the metal ring is not limited in this application. The effect of the metal ring can also be achieved when the pattern is a dipole. It can be seen that the structure of vertically crossed substrates with different metal patterns has good response consistency to different metal boundaries, extremely small insertion loss fluctuations in the passband, and high out-of-band suppression can be achieved in the stopband. The two modes are transmitted independently and do not interfere with each other.

[0032] In an optional embodiment, there is a gap in the metal ring, and the gap is located in the middle of the substrate in the vertical direction.

[0033] In an optional embodiment, there is a gap in the dipole, and the gap is located in the middle of the substrate in the vertical direction.

[0034] It can be seen from this that by setting a gap in the metal ring or dipole on the substrate of the three-dimensional FSS unit, the physical connection between the upper and lower structures of the horizontal metal plate is cut off, and each response is a half ring. By introducing the gap, the electrical connection realizes dual resonance and effectively expands the bandwidth.

[0035] In an optional embodiment, the substrate further includes at least one metal strip, for example, coupling metal strips are provided above and below the metal ring and the dipole.

[0036] It should be noted that a gap is provided in the middle of the metal ring and / or the dipole. In the present application, the gap is in a "Z" shape, but may also be in other shapes that can produce an equivalent capacitance effect.

[0037] It can be seen that by introducing metal strips to generate electromagnetic coupling with the metal ring below, and optimizing the size and position, the passband matching can be improved, the large-angle incidence performance can be improved, and the wave transmission performance can be improved.

[0038] In a second aspect, the present application provides an antenna system, which includes the three-dimensional frequency selective surface FSS of the first aspect, a first frequency band radiation element array, a second frequency band radiation element array, a second frequency band radiation element array and a reflector.

[0039] It should be noted that the antenna system may be a radiating element array with only two frequency bands or a radiating element array with three frequency bands, and the present invention does not limit the number of radiating element arrays.

[0040] The above-mentioned first-band radiation element array, second-band radiation element array, three-dimensional FSS and third-band radiation element array are arranged in sequence, that is, the above-mentioned three-dimensional FSS is arranged between the second-band radiation element array and the third-band radiation element array. Specifically, the number of three-dimensional FSS is not limited in this application. The above-mentioned three-dimensional FSS is used to reflect the signals of the first and second-band radiation element arrays, and transmit the signals of the third-band radiation element array. Specifically, the above-mentioned signals include transmitted signals and received signals. It can be seen that the cavity equipped with a feeding network or a phase shifter is arranged on the frequency selective surface, and the signal of the third-band radiation element array has less insertion loss when it is transmitted from the above-mentioned frequency selective surface, which is beneficial to improving the signal quality of the antenna system.

[0041] Furthermore, the three-dimensional FSS architecture proposed in this application can adapt to the layout of different metal components on the horizontal metal plate to form irregular metal boundaries, solve the problem of uneven distribution of metal components such as the feeding network and phase shifter on the front and back sides of the FSS, resulting in non-uniform periodic unit boundaries and deterioration of FSS performance, and ensure that the designed three-dimensional FSS has stable performance.

[0042] In a third aspect, the present application provides a base station, which includes the antenna system of the second aspect and a radio frequency module connected to the antenna system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1a is a schematic diagram of a base station application scenario provided by this application;

[0044] FIG1b is a schematic structural diagram of a base station antenna feeding system provided by the present application;

[0045] FIG1c is a schematic structural diagram of a base station antenna system provided by the present application;

[0046] FIG1d is a schematic diagram of a three-dimensional FSS structure provided by this application;

[0047] FIG1e is a schematic diagram of a partial structure of a three-dimensional FSS provided by the present application;

[0048] FIG1f is a schematic structural diagram of a three-dimensional FSS unit structure provided by the present application;

[0049] FIG1g is a schematic structural diagram of another three-dimensional FSS unit structure provided by the present application;

[0050] FIG1h is a schematic structural diagram of another three-dimensional FSS unit structure provided by the present application;

[0051] FIG2 a is a TE transmission characteristic diagram of a three-dimensional FSS unit provided by the present application;

[0052] FIG2 b is a TM transmission characteristic diagram of a three-dimensional FSS unit provided by the present application;

[0053] FIG2c is a TE transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0054] FIG2 d is a TM transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0055] FIG3a is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0056] FIG3 b is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0057] FIG3 c is a TE transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0058] FIG3 d is a TM transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0059] FIG4a is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0060] FIG4 b is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0061] FIG4 c is a TE transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0062] FIG4 d is a TM transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0063] FIG5a is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0064] FIG5 b is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0065] FIG6a is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0066] FIG6 b is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0067] FIG6 c is a TE transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0068] FIG6 d is a TM transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0069] FIG7 a is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0070] FIG7 b is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0071] FIG7 c is a TE transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0072] FIG7 d is a TM transmission characteristic diagram of another three-dimensional FSS unit provided by the present application;

[0073] FIG8a is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0074] FIG8 b is a schematic diagram of another three-dimensional FSS unit structure provided by the present application;

[0075] FIG9 is a schematic diagram of another three-dimensional FSS unit structure provided by this application. DETAILED DESCRIPTION

[0076] First, some expressions that may appear in this application are explained.

[0077] "At least one" means one or more, while "a plurality" means two or more.

[0078] "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural.

[0079] Furthermore, the terms "comprises," "includes," and "having" as used in the description of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not limited to the listed steps or units but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to the process, method, product, or apparatus.

[0080] Next, a brief introduction is given to the terms involved in the embodiments of this application.

[0081] 1. Antenna

[0082] The antenna may include one or more of a radiating unit, a reflector (or base plate, antenna panel), a feed network (or power distribution network), and a radome. Among them, the antenna element may constitute the radiating unit of the antenna. The antenna element may be simply referred to as an element, which has the function of guiding and amplifying electromagnetic waves. The feed network implements the feeding function, and feeding means power supply. In the field of antennas, feeding can be directed to supplying power to the antenna, or in other words, providing energy. The function of the feed network is to feed the signal to each radiating unit of the antenna according to a certain amplitude and phase, or to feed the signal received from each radiating unit to the signal processing unit of the base station according to a certain amplitude and phase. The feed network is usually composed of a controlled impedance transmission line, and the feed network may include devices such as phase shifters.

[0083] 2. Frequency selective surface (FSS)

[0084] An FSS is a two-dimensional periodic array structure that effectively controls the transmission and reflection of incident electromagnetic waves. It can act as a spatial filter, exhibiting distinct bandpass or bandstop filtering characteristics when interacting with electromagnetic waves. FSSs exhibit specific frequency selectivity. There are generally two types of FSSs: one that transmits incident waves under resonance, and the other that reflects incident waves under resonance.

[0085] 3. Base Station

[0086] The base station in the embodiment of the present application can be a device for communicating with a terminal device, including a base transceiver station (BTS) in a global system for mobile communications (GSM) system or a code division multiple access (CDMA), or a node B (NB) in a wideband code division multiple access (WCDMA) system, or an evolved Node B (eNB or eNodeB) in an LTE system, or a wireless controller in a cloud radio access network (CRAN) scenario, or the base station can include a relay station, an access point, a vehicle-mounted device, a wearable device, a base station in a future 5G network, or a base station in a future evolved public land mobile network (PLMN) network, etc., and the embodiment of the present application is not limited.

[0087] 4. Electromagnetic transparency: It means that electromagnetic waves can pass through a certain material or component without obvious changes.

[0088] 5. Electromagnetic shielding: refers to the use of materials or technologies to prevent radio waves from penetrating or interfering with specific spaces or equipment.

[0089] 6. Transverse Electric Wave (TE wave): The direction of the electric field in the electromagnetic wave is perpendicular to the propagation direction of the electromagnetic wave.

[0090] 7. Transverse Magnetic Wave (TM wave): The direction of the magnetic field in the electromagnetic wave is perpendicular to the propagation direction of the electromagnetic wave.

[0091] 8. Multiple Input Multiple Output (MIMO): This system uses multiple antennas at both the transmitter and receiver, creating multiple channels between the transmitter and receiver. This system can significantly increase channel capacity and boost data transmission rates.

[0092] 9. Phase shifter: A device that adjusts the phase of a wave. A common phase shifter circuit consists of resistors, reactance components, nonlinear elements, and active devices. When a sinusoidal signal passes through a phase shifter, its phase changes. By adjusting the circuit parameters, an ideal phase shifter can continuously change the phase of the passing signal between 0° and 360° without changing the signal's amplitude. In other words, the signal passes through undistorted, but its phase is altered.

[0093] 10. Feed network: Also known as the power distribution network, this is a crucial component of base station antennas. Its primary function is to connect the signal at the antenna end to the array elements, forming a path for RF signal transmission. This process requires impedance matching and amplitude and phase distribution. Feed networks come in a variety of types, including microstrip lines, coaxial cables, and air-plane lines. These lines are responsible for transmitting the electrical signals sent by the device to the antenna elements.

[0094] In order to make the purpose, technical solutions and advantages of the present invention more clear and distinct, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0095] To facilitate understanding of the antenna system and base station antenna feed system provided in the embodiments of the present application, the following describes its application scenario. Figure 1a illustrates an example. As shown in Figure 1a, the application scenario may include a base station and a terminal. Wireless communication can be achieved between the base station and the terminal. The base station can be located in a base station subsystem (BBS), a terrestrial radio access network (UMTS terrestrial radio access network, UTRAN) or an evolved universal terrestrial radio access network (EUTRAN), and is used to provide cell coverage of wireless signals to enable communication between terminal devices and wireless networks. Specifically, the base station can be a base transceiver station (BTS) in a global system for mobile communications (GSM) or a (code division multiple access, CDMA) system, or a node B (NB) in a wideband code division multiple access (WCDMA) system, or an evolutionary node B (eNB or eNodeB) in a long term evolution (LTE) system, or a wireless controller in a cloud radio access network (CRAN) scenario. Alternatively, the base station can also be a relay station, an access point, an on-board device, a wearable device, a g-node (gNodeB or gNB) in a new radio (NR) system, or a base station in a future evolved network, etc., and the embodiments of the present application are not limited thereto.

[0096] Figure 1b shows a possible schematic diagram of the structure of a base station antenna feed system. A base station antenna feed system typically includes an antenna system 1, a mast 2, an antenna adjustment bracket 3, and other structures. The base station antenna system 1 includes a radome 11. This radome 11 has excellent electrical properties for electromagnetic wave penetration and mechanical properties that can withstand harsh external environments, thereby protecting the antenna system 1 from external environmental influences. The antenna system 1 can be mounted on a mast 2 or a tower via the antenna adjustment bracket 3 to facilitate signal reception or transmission by the antenna system 1. The base station may also include a radio frequency processing unit 5 and a baseband processing unit 6. For example, the radio frequency processing unit 5 may be used to perform frequency selection, amplification, and down-conversion on signals received by the antenna system 1, converting them into intermediate frequency signals or baseband signals and transmitting them to the baseband processing unit 6. Alternatively, the radio frequency processing unit 5 may be used to convert baseband signals or intermediate frequency signals into electromagnetic waves through the antenna system 1 after up-conversion and amplification, and then transmit them. The baseband processing unit 6 may be connected to the feed network of the antenna system 1 via the radio frequency processing unit 5. In some embodiments, the radio frequency processing unit 5 may also be referred to as a remote radio unit (RRU), and the baseband processing unit 6 may also be referred to as a baseband unit (BBU).

[0097] As shown in Figure 1c, it is a schematic diagram of a base station antenna system provided by the present application. The first frequency band radiation element array, the second frequency band radiation element array, the three-dimensional FSS, the third frequency band radiation element array and the reflector are arranged in sequence from top to bottom. The three-dimensional FSS is composed of multiple three-dimensional FSS units, and the three-dimensional FSS unit includes a substrate, a metal plate and a metal boundary component. In a possible implementation, the three-dimensional FSS is arranged between the second frequency band radiation element array and the third frequency band radiation element array, and the three-dimensional FSS is used to reflect the signal of the first frequency band radiation element array, the signal of the second frequency band radiation element array, and transmit the signal of the third frequency band radiation element array. The signal of the first frequency band radiation element array specifically includes the signal received by the first frequency band radiation element array and the signal transmitted by the first frequency band radiation element array; the signal of the second frequency band radiation element array specifically includes the signal received by the second frequency band radiation element array and the signal transmitted by the second frequency band radiation element array; the signal of the third frequency band radiation element array specifically includes the signal received by the third frequency band radiation element array and the signal transmitted by the third frequency band radiation element array. The three-dimensional FSS reflects signals from the first-band and second-band radiating elements, while transmitting signals from the third-band radiating elements. In this solution, by setting up a three-dimensional FSS, the first-band radiating element array and the second-band radiating element array can be stacked in a direction perpendicular to the pole. In other words, the first-band radiating element array, the second-band radiating element array, and the third-band radiating element array are arranged side by side (SBS), thereby improving the integration of the antenna system within a single roof space.

[0098] Figure 1d shows a schematic diagram of a three-dimensional FSS structure provided by this application. The three-dimensional FSS comprises multiple three-dimensional FSS units, each of which includes a substrate, a metal plate, and a metal boundary component. The substrate intersects and passes through the metal plate, and the metal boundary components are irregularly distributed on the surface of the metal plate. The metal boundary components of the multiple three-dimensional FSS units in the three-dimensional FSS differ in at least one of the number, shape, size, and orientation, addressing the issue of irregular periodic three-dimensional FSS unit boundaries causing degraded FSS performance.

[0099] As shown in Figure 1e, the present application provides a schematic diagram of a partial structure of a three-dimensional FSS. In order to more clearly show the metal boundary components of each three-dimensional FSS unit, the present application provides a schematic diagram of the structure of the metal boundary components and metal plate of a three-dimensional FSS. The metal boundary components are irregularly distributed on the metal plate. The number of metal boundary components of multiple three-dimensional FSS units of the three-dimensional FSS is different. Some three-dimensional FSS units have 0, some have 1, and others have multiple metal boundary components. The sizes of the three-dimensional FSS units are also different. The height of the metal boundary components of some three-dimensional FSS units is all 0, the height of the metal boundary components of other three-dimensional FSS units is all H, the height of the metal boundary components of other three-dimensional FSS units is all 2H, and the height of the metal boundary components of other three-dimensional FSS units includes a combination of 0, H and 2H. It should be noted that H here represents a certain value, and the height H can be any value. 2H means that the height is twice that of H. The height of the metal boundary components provided in this application is only for illustration, and this application does not limit the height of the metal boundary components. The orientations of the 3D FSS cells are also different. The metal boundary components of some 3D FSS cells are parallel to the edge of the metal plate, while the metal boundary components of other 3D FSS cells are perpendicular to the edge of the metal plate.

[0100] As shown in FIG1f , it is a schematic diagram of a three-dimensional FSS unit structure provided by the present application with a metal boundary component height of 0.

[0101] In this embodiment, the substrate is placed vertically across the metal plate, and the metal pattern on the substrate consists of a rectangular ring or a structure similar to a rectangular ring. Two metal strips are provided above and below the rectangular ring respectively. A gap is provided in the middle of the rectangular ring. This application is in the shape of a "Z", which can be a cross-finger or other shape. A structure that produces an equivalent capacitance effect can be used. Coupling metal strips are provided above and below the ring. A groove is provided on the horizontal metal plate for passing through the substrate printed with the metal pattern and forming a three-dimensional structure with it. The height of the metal boundary component on the metal plate is 0.

[0102] As shown in FIG1g , it is a schematic diagram of a three-dimensional FSS unit structure with a metal boundary component height H provided by the present application.

[0103] In this embodiment, the height of the metal boundary component is H, and the other basic structures are the same as those of the embodiment of FIG. 1 f .

[0104] As shown in FIG1h , it is a schematic diagram of a three-dimensional FSS unit structure with a metal boundary component height of 2H provided by the present application.

[0105] In this embodiment, the height of the metal boundary component is 2H, and the other basic structures are the same as those of the embodiment of FIG. 1 f .

[0106] FIG2 a is a diagram of TE transmission characteristics when the heights of the metal boundary components are 0, H, and 2H, respectively;

[0107] Before analyzing TE transmission characteristics, it's important to note that TE waves are transverse electric waves, meaning they are electromagnetic waves in which the direction of the electric field is perpendicular to the direction of propagation. This example analyzes the transmission characteristics of transverse electric waves when the metal boundary component heights are 0, 1H, and 2H, respectively.

[0108] Before analyzing the transmission characteristic diagram, it should be noted that when the transmission coefficient is near 0dB, it indicates that it has a good passband for transverse electric waves. When the transmission coefficient is below -20dB, it has a good stopband for transverse electric waves.

[0109] The passband is the frequency band within which signals within a certain frequency range can pass through the 3D FSS. Within the passband, the 3D FSS does not significantly attenuate the signal amplitude. The stopband is the frequency band within which signals in another frequency range are reflected. The key difference between the passband and the stopband lies in the signal's ability to pass through the 3D FSS. Signals within the passband can pass through the 3D FSS without significant amplitude attenuation within the frequency range, while signals within the stopband are reflected by the 3D FSS.

[0110] When the height of the metal boundary component is 0, H, and 2H, and the transverse radio wave signal transmission angle is 0 degrees, the transmission coefficients within the stopband range are approximately -30dB, -35dB, and -40dB, respectively, indicating good suppression characteristics. As illustrated in Figure 1c, when the transverse radio wave signal frequencies of the first and second frequency band radiating element arrays are low, the three-dimensional FSS in the antenna system has a good suppression effect on the first and second frequency band radiating element arrays. The three-dimensional FSS is able to reflect the transverse radio wave signals of the first two frequency bands, thereby preventing the transverse radio wave signals of the first two frequency bands from passing through the three-dimensional FSS. At the same time, the transmission coefficients within the passband range are all around 0dB, indicating good passband characteristics. As illustrated in Figure 1c, when the signal frequency of the third frequency band radiating element array is high, the three-dimensional FSS is able to allow the transverse radio wave signal of the third frequency band radiating element array to pass through.

[0111] It can be seen from this that the three-dimensional FSS provided in this application is compatible with metal boundaries of different heights, has very good consistency, has extremely small insertion loss fluctuations in the passband, and can achieve high out-of-band suppression in the stopband.

[0112] FIG2 b is a diagram showing the TM transmission characteristics when the heights of the metal boundary components are 0, H, and 2H, respectively.

[0113] Before analyzing TM transmission characteristics, it's important to note that TM waves are transverse magnetic waves, meaning they are electromagnetic waves in which the direction of the magnetic field is perpendicular to the direction of propagation. This example analyzes the transmission characteristics of transverse magnetic waves when the metal boundary component heights are 0, 1H, and 2H, respectively.

[0114] When the heights of the metal boundary components are 0, H, and 2H, and the transverse magnetic wave signal is incident at a 0-degree angle, the transmission coefficient within the stopband range is around -30dB, indicating good stopband characteristics. As illustrated in Figure 1c, when the transverse magnetic wave signals of the first and second frequency band radiating element arrays are of a certain frequency magnitude, the 3D FSS in the antenna system exhibits good stopband characteristics for the first and second frequency band radiating element arrays. The 3D FSS is able to reflect the transverse magnetic wave signals of the first two frequency bands, thereby preventing the transverse magnetic wave signals of the first two frequency bands from passing through the 3D FSS. The transmission coefficient within the passband range is around 0dB, indicating good passband characteristics. As illustrated in Figure 1c, when the signal of the third frequency band radiating element array is of a certain frequency magnitude, the 3D FSS is able to pass the transverse magnetic wave signal of the third frequency band radiating element array.

[0115] It can be seen from this that the three-dimensional FSS provided in this application is compatible with metal boundaries of different heights, has very good consistency, has extremely small insertion loss fluctuations in the passband, and can achieve high out-of-band suppression in the stopband.

[0116] Figure 2c is a TE transmission characteristic diagram when the incident angle is 60 degrees and the heights of the metal boundary components are 0, H, and 2H respectively;

[0117] When the height of the metal boundary component is 0, H, and 2H, and the transverse radio wave signal is incident at a 60-degree angle, the transmission coefficients within the stopband range are approximately -35dB, -40dB, and -48dB, respectively, indicating good stopband characteristics. As illustrated in Figure 1c, when the transverse radio wave signals of the first and second frequency band radiating element arrays are of a certain frequency magnitude, the three-dimensional FSS in the antenna system has good stopband characteristics for the first and second frequency band radiating element arrays. The three-dimensional FSS is able to reflect the transverse radio wave signals of the first two frequency bands, thereby preventing the transverse radio wave signals of the first two frequency bands from passing through the three-dimensional FSS. The transmission coefficients within the passband range are all around 0dB, indicating good passband characteristics. As illustrated in Figure 1c, when the signal of the third frequency band radiating element array is of a certain frequency magnitude, the three-dimensional FSS is able to pass the transverse radio wave signal of the third frequency band radiating element array.

[0118] As can be seen, the 3D FSS provided by this application is compatible with metal edges of varying heights, exhibits excellent consistency, minimizes insertion loss fluctuation within the passband, and achieves high out-of-band suppression in the stopband. Furthermore, the TE and TM transmission characteristics are excellent at 0 and 60 degrees of incidence, respectively, demonstrating excellent angular stability.

[0119] Figure 2d is a graph of TM transmission characteristics when the incident angle is 60 degrees and the heights of the metal boundary components are 0, H, and 2H, respectively.

[0120] When the metal boundary component heights are 0, H, and 2H, and the transverse magnetic wave signal is incident at a 60-degree angle, the transmission coefficients within the stopband range are approximately -48dB, -38dB, and -32dB, respectively, demonstrating good stopband characteristics. As illustrated in Figure 1c, when the transverse magnetic wave signals from the first and second frequency band radiating element arrays are of a certain frequency magnitude, the 3D FSS in the antenna system exhibits good stopband characteristics for the first and second frequency band radiating element arrays. The 3D FSS is able to reflect the transverse magnetic wave signals from the first and second frequency band radiating element arrays, preventing them from passing through the 3D FSS. The transmission coefficients within the on-off range are all around 0dB, demonstrating good passband characteristics. As illustrated in Figure 1c, when the signal from the third frequency band radiating element array is of a certain frequency magnitude, the 3D FSS is able to pass the transverse magnetic wave signals from the third frequency band radiating element array.

[0121] As can be seen, the 3D FSS provided by this application is compatible with metal edges of varying heights, exhibits excellent consistency, minimizes insertion loss fluctuation within the passband, and achieves high out-of-band suppression in the stopband. Furthermore, the TE and TM transmission characteristics are excellent at 0 and 60 degrees of incidence, respectively, demonstrating good angular stability.

[0122] In one possible implementation, as shown in FIG. 3 a and FIG. 3 b , the coupling structures above and below the rectangular ring in the substrate have only one metal strip.

[0123] FIG3 a is a schematic diagram showing a structure in which the coupling structure above and below the rectangular ring has only one metal strip and the height of the metal boundary component is 0, that is, there is no metal block.

[0124] Figure 3b is a schematic diagram of a structure in which the coupling structure above and below the rectangular ring has only one metal strip, and the height of the metal boundary component is 2H. In this embodiment, the height of the metal boundary component is 2H, and the other structures are the same as those of the embodiment of Figure 3a.

[0125] Figure 3c is a TE transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment; Figure 3d is a TM transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment. As shown in Figures 3c and 3d, when the metal boundary component height is 0 and 2H, and when the signal transmission angle is 0 degrees, the transmission coefficients within the stopband range in both the TE and TM transmission characteristic diagrams are below -20dB. Specifically, when the metal boundary component height is 0, the low-frequency region image in the TE transmission characteristic diagram is approximately -30dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -30dB. When the metal boundary component height is 2H, the low-frequency region image in the TE transmission characteristic diagram is approximately -40dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -30dB. This indicates that metal boundary components with a height of 0 or 2H have good stopband characteristics. Furthermore, the transmission coefficients within the passband range are both around 0dB, indicating that metal boundary components with a height of 0 or 2H have good passband characteristics.

[0126] It can be seen from this that the three-dimensional FSS provided in this application is compatible with metal boundaries of different heights. When there is only one metal strip in the coupling structure above and below the rectangular ring, the consistency is still very good, the insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high out-of-band suppression.

[0127] In one possible implementation, the coupling structures above and below the rectangular ring in the substrate include multiple metal strips.

[0128] FIG4 a is a schematic diagram of a structure in which the coupling structure above and below the metal ring has three metal strips and the height of the metal boundary component is 0. ...

[0129] FIG4 b is a schematic diagram of a structure in which the coupling structure above and below the metal ring has three metal strips and the height of the metal boundary component is 2H.

[0130] Figure 4c is a TE transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment; Figure 4d is a TM transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment. As shown in Figures 4c and 4d, when the metal boundary component height is 0 and 2H, and when the signal transmission angle is 0 degrees, the transmission coefficients within the passband range in both the TE and TM transmission characteristic diagrams are below -20dB. Specifically, when the metal boundary component height is 0, the low-frequency region image in the TE transmission characteristic diagram is approximately -30dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -30dB. When the metal boundary component height is 2H, for example, 8mm, the low-frequency region image in the TM transmission characteristic diagram is approximately -40dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -30dB. This indicates that metal boundary components with a height of 0 or 2H have good stopband characteristics. The transmission coefficients within the stopband range are both around 0dB, indicating that metal boundary components with a height of 0 or 2H have good passband characteristics.

[0131] It can be seen from this that the three-dimensional FSS provided in this application is compatible with metal boundaries of different heights. When there are three metal strips in the coupling structure above and below the rectangular ring, the consistency is still very good, the insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high out-of-band suppression.

[0132] Figures 5a and 5b illustrate a three-dimensional FSS unit structure, provided by this application, featuring a rectangular ring with seamless center-positioned metal boundary components of varying heights. In this embodiment, the coupling structure above and below the rectangular ring in the substrate comprises one or more metal strips, with no gap in the center of the rectangular ring.

[0133] FIG5 a is a schematic diagram showing a structure in which there is no gap in the middle of the rectangular ring, there are two metal strips in the coupling structure above and below the rectangular ring in the substrate, and the height of the metal boundary component is 0. FIG5 a is a schematic diagram showing a structure in which the middle of the rectangular ring has no gap, there are two metal strips in the coupling structure above and below the rectangular ring in the substrate, and the height of the metal boundary component is 0.

[0134] FIG5 b is a schematic diagram showing a structure in which there is no gap in the middle of the rectangular ring, there are two metal strips in the coupling structure above and below the rectangular ring in the substrate, and the height of the metal boundary component is H. FIG5 b is a schematic diagram showing a structure in which the middle of the rectangular ring has no gap, there are two metal strips in the coupling structure above and below the rectangular ring in the substrate, and the height of the metal boundary component is H.

[0135] It can be seen from this that the three-dimensional FSS provided in this application is compatible with metal boundaries of different heights. When there are two metal strips in the coupling structure above and below the rectangular ring and there is no gap in the middle position of the rectangular ring, the consistency is still very good, the insertion loss fluctuation in the passband is extremely small, and the stopband can achieve high out-of-band suppression.

[0136] As shown in FIG6a and FIG6b, it is a schematic diagram of the three-dimensional FSS unit structure of metal boundary components with different placement directions and different heights provided by the present application.

[0137] In this embodiment, a substrate is placed vertically across a metal plate. The metal pattern on the substrate consists of a rectangular ring or a structure similar to a rectangular ring, with a gap (here in a "Z" shape, but it can be a cross-finger or other shape that produces an equivalent capacitance effect) in the middle of the rectangular ring. Two coupling metal strips are placed above and below the ring. A slot is cut into the horizontal metal plate for passing through the substrate with the metal pattern and forming a three-dimensional structure with it. Metal blocks placed in different orientations are distributed on both sides of the metal plate to form a metal boundary component.

[0138] In a possible implementation, as shown in FIG6 a , the metal boundary components of the three-dimensional FSS unit structure are respectively arranged horizontally and vertically with an edge line of the metal plate, with a height of 0.

[0139] In a possible implementation, as shown in FIG6 b , the metal boundary components of the three-dimensional FSS unit structure are respectively arranged horizontally and vertically with respect to an edge line of the metal plate, with a height of H.

[0140] Figure 6c is a TE transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment; Figure 6d is a TM transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment. As shown in Figures 6c and 6d, when the metal boundary component height is 0 and H, and when the signal transmission angle is 0 degrees, the transmission coefficients within the stopband range in both the TE and TM transmission characteristic diagrams are below -20dB. Specifically, when the metal boundary component height is 0, the low-frequency region image in the TE transmission characteristic diagram is approximately -30dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -30dB. When the metal boundary component height is H, for example, 5mm, the low-frequency region image in the TM transmission characteristic diagram is approximately -38dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -38dB. This indicates that the metal boundary component height of 0 or H has good stopband characteristics. The transmission coefficients within the passband range are both around 0dB, indicating that the metal boundary component height of 0 or H has good passband characteristics. By comparison, it can be found that the irregular periodic three-dimensional FSS set in both the horizontal and vertical directions can also be compatible with metal boundaries of different heights. The FSS has good robustness, small insertion loss fluctuation in the passband, and high suppression in the stopband.

[0141] As shown in FIG. 7 a and FIG. 7 b , they are schematic diagrams of a three-dimensional FSS unit structure of a substrate having a rectangular ring and a dipole metal pattern provided by the present application.

[0142] In this embodiment, the substrate is placed vertically across the metal plate. The metal pattern on the substrate has a rectangular ring or a structure similar to a rectangular ring, and there is also a dipole (the bent form is used to compensate for the electrical length). A gap is provided in the middle of the vertical transmission part. This embodiment is a "Z" shape, which can be a cross-finger or other shape, as long as it produces an equivalent capacitance effect. Similarly, coupling metal strips are provided above and below the ring and the dipole. A slot is provided on the horizontal metal plate for passing through the substrate printed with the metal pattern and forming a three-dimensional structure with it. Metal boundary components of different heights are distributed on both sides of the metal plate.

[0143] In one possible embodiment, as shown in FIG. 7 a , the height of the metal boundary component of the three-dimensional FSS unit structure is zero.

[0144] In one possible embodiment, as shown in FIG7 b , the height of the metal boundary component of the three-dimensional FSS unit structure is H.

[0145] Figure 7c is a TE transmission characteristic diagram of a three-dimensional FSS unit provided in this embodiment; Figure 7d is a TM transmission characteristic diagram of another three-dimensional FSS unit provided in this embodiment. As shown in Figures 7c and 7d, when the metal boundary component height is 0 and H, and when the signal transmission angle is 0 degrees, the transmission coefficients within the stopband range in both the TE and TM transmission characteristic diagrams are below -20dB. Specifically, when the metal boundary component height is 0, the low-frequency region image in the TE transmission characteristic diagram is approximately -30dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -35dB. When the metal boundary component height is H, for example, 8mm, the low-frequency region image in the TM transmission characteristic diagram is approximately -42dB, and the low-frequency region image in the TM transmission characteristic diagram is approximately -35dB. This indicates that the metal boundary component height of 0 or H has good stopband characteristics. The transmission coefficients within the passband range are both around 0dB, indicating that the metal boundary component height of 0 or H has good passband characteristics. Comparison reveals that the vertically intersecting structure of substrates with different metal patterns exhibits consistent response to different metal boundaries, minimal insertion loss fluctuation within the passband, and high out-of-band suppression in the stopband. The two modes transmit independently without interfering with each other.

[0146] As shown in FIG8a and FIG8b, it is a schematic diagram of the three-dimensional FSS unit structure of a substrate with a rectangular ring and a dipole metal pattern provided by the present application.

[0147] In this embodiment, a substrate is placed vertically across a metal plate. The metal pattern on the substrate consists of a rectangular ring or a structure similar to a rectangular ring, along with a dipole (bent to compensate for electrical length), with no gap in the middle of the vertical transmission section. Similarly, coupling metal strips are provided above and below the ring and dipole. A slot is provided in the horizontal metal plate to pass through the substrate with the printed metal pattern and form a three-dimensional structure with it. Metal boundary components of varying heights are distributed on both sides of the metal plate.

[0148] In one possible embodiment, as shown in FIG8 a , the height of the metal boundary component of the three-dimensional FSS unit structure is zero.

[0149] In one possible embodiment, as shown in FIG8 b , the height of the metal boundary component of the three-dimensional FSS unit structure is H.

[0150] As shown in FIG9 , it is a schematic diagram of a three-dimensional FSS unit structure provided by this application.

[0151] In this embodiment, the three-dimensional FSS unit structure can be said to be the three-dimensional FSS unit structure in any of the above embodiments. The difference is that the orientation of the metal boundary components in the three-dimensional FSS unit structure is different. As shown in Figure 9, this embodiment provides a schematic diagram in which the metal boundary component has a height of H and is placed at a certain angle to the metal plate boundary.

Claims

1. A three-dimensional frequency selective surface (FSS) compatible with various metal boundaries, characterized by: The three-dimensional FSS includes multiple three-dimensional FSS units, each of which includes a substrate and a metal plate, and at least a portion of the multiple three-dimensional FSS units also includes at least one metal boundary component; the one or more substrates pass through the metal plate, and the metal boundary components of the multiple three-dimensional FSS units are irregularly distributed on the surface of the metal plate.

2. The three-dimensional FSS according to claim 1, characterized in that The plurality of substrates are two substrates, and the two substrates cross and pass through the metal plate.

3. The three-dimensional FSS according to claim 1 or 2, characterized in that The metal boundary components of the three-dimensional FSS cells are not all the same size.

4. The three-dimensional FSS according to claim 3, characterized in that The size of the metal boundary component includes the height of the metal boundary component, and the height of the metal boundary component is less than a quarter of a wavelength, where the wavelength is a wavelength corresponding to a passband center frequency.

5. The three-dimensional FSS according to any one of claims 1 to 4, characterized in that: The numbers of the metal boundary components of the plurality of three-dimensional FSS units are not exactly the same.

6. The three-dimensional FSS according to any one of claims 1 to 5, characterized in that: The metal boundary components of the plurality of three-dimensional FSS units are not all oriented in the same direction.

7. The three-dimensional FSS according to any one of claims 1 to 6, characterized in that: The metal boundary components of the plurality of three-dimensional FSS units are not all the same in shape.

8. The three-dimensional FSS according to any one of claims 1 to 7, characterized in that: There is a space inside the metal boundary component, and a feed line and / or a phase shifter are placed inside the metal boundary component, or the metal boundary component is a hollow structure.

9. The three-dimensional FSS according to any one of claims 1 to 7, characterized in that: The metal boundary component is a solid structure.

10. The three-dimensional FSS according to any one of claims 1 to 9, characterized in that: The metal boundary components of the plurality of three-dimensional FSS units are located on an upper surface and / or a lower surface of the metal plate.

11. The three-dimensional FSS according to any one of claims 1 to 10, characterized in that: The substrate has a metal pattern, and the metal pattern is a metal ring.

12. The three-dimensional FSS according to claim 11, characterized in that The metal pattern also includes a dipole.

13. The three-dimensional FSS according to any one of claims 1 to 10, characterized in that: The substrate has a metal pattern, and the metal pattern is a dipole.

14. The three-dimensional FSS according to claim 11, characterized in that The metal ring has a gap therein, and the gap is located in the middle of the substrate in a vertical direction.

15. The three-dimensional FSS according to claim 12 or 13, characterized in that There is a gap in the dipole, and the gap is located in the middle of the substrate in the vertical direction.

16. The three-dimensional FSS according to any one of claims 1 to 15, characterized in that: The substrate further includes at least one metal strip.

17. An antenna system, characterized in that: It comprises a first frequency band radiation unit array, a second frequency band radiation unit array, the three-dimensional FSS according to any one of claims 1 to 16, a third frequency band radiation unit array and a reflection plate.

18. A base station, characterized in that: It comprises the antenna system as claimed in claim 17 and a radio frequency module connected to the antenna system.

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