Frequency selective surface antenna housing for base station antenna

Abstract

The invention provides a frequency selective surface antenna housing for a base station antenna. Comprising a first dielectric layer, a common metal layer and a second dielectric layer; the common metal layer is arranged between the first dielectric layer and the second dielectric layer; a first patch resonance unit is attached to the upper surface of the first dielectric layer, and a second patch resonance unit is attached to the lower surface of the second dielectric layer; each of the first patch resonance unit and the second patch resonance unit is composed of four groups of patch resonators, and the four groups of patch resonators are also provided with resonance grooves with the same size, thereby achieving the accurate regulation and control of the specific modes of the patch resonators, and improving the stability of the filtering performance.

Description

Technical Field

[0001] The present application relates to the field of electromagnetic field technology, and particularly to a frequency selective surface radome for base station antennas. Background Art

[0002] With the rapid development of mobile communication technology, base station antennas supporting multiple frequency bands and multiple systems have gradually become the industry mainstream. Since base station antennas are usually placed outdoors and directly affected by natural phenomena such as storms, ice and snow, and solar radiation, the accuracy of the antennas is reduced, the service life is shortened, and the working reliability is poor. To protect the antennas from the external environment, radomes are usually installed outside the antennas.

[0003] At present, radomes based on frequency selective surfaces can enhance the anti-interference ability and stealth performance of antenna systems, have the functions of passband transmission within the working frequency band and suppression outside the working frequency band, and can reduce the influence of interference frequency components.

[0004] However, the existing radomes have a high profile and poor angular stability, which affects the application effect and performance stability of base station antennas. Summary of the Invention

[0005] The present application provides a frequency selective surface radome for base station antennas to solve the technical problem of poor angular stability of radomes in the prior art.

[0006] The frequency selective surface radome for base station antennas provided by the present application includes:

[0007] A first dielectric layer, a common metal layer, and a second dielectric layer;

[0008] The common metal layer is disposed between the first dielectric layer and the second dielectric layer;

[0009] A first patch resonator unit is attached to the upper surface of the first dielectric layer, and a second patch resonator unit is attached to the lower surface of the second dielectric layer;

[0010] Both the first patch resonator unit and the second patch resonator unit are composed of four groups of patch resonators, and resonance slots of the same size are also provided on the four groups of patch resonators.

[0011] Optionally, the shapes of the four groups of patch resonators are all right-angled isosceles triangles;

[0012] The resonance slots are respectively disposed on the first right-angled side and the second right-angled side of the four groups of patch resonators.

[0013] Optionally, the four groups of patch resonators include a first patch resonator combination and a second patch resonator combination;

[0014] The first patch resonator combination includes a first patch resonator and a second patch resonator, and the second patch resonator combination includes a third patch resonator and a fourth patch resonator.

[0015] Optionally, the first patch resonator and the second patch resonator are arranged in a diagonal translation;

[0016] The third patch resonator and the fourth patch resonator are arranged in a translation along another diagonal direction.

[0017] Optionally, a first rectangular slot is formed on the common metal layer;

[0018] The position of the first rectangular slot corresponds to the position of the resonance slots formed on the four groups of patch resonators.

[0019] Optionally, the first rectangular slot has the same size as the resonance slot, and the number of the first rectangular slots is the same as the number of the resonance slots.

[0020] Optionally, four groups of second rectangular slots are further formed on the common metal layer, and the positions of the four groups of second rectangular slots respectively correspond to the hypotenuse center positions of the four groups of patch resonators.

[0021] Optionally, the size parameters of the four groups of patch resonators are all the same.

[0022] Optionally, the first dielectric layer, the common metal layer and the second dielectric layer have the same size.

[0023] Optionally, the dielectric constant of the first dielectric layer is 2.2 and the thickness is 1.57 mm;

[0024] The dielectric constant of the second dielectric layer is 2.2 and the thickness is 1.57 mm.

[0025] A frequency selective surface radome for a base station antenna provided by the present application includes a first dielectric layer, a common metal layer and a second dielectric layer; the common metal layer is arranged between the first dielectric layer and the second dielectric layer; a first patch resonator unit is attached to the upper surface of the first dielectric layer, and a second patch resonator unit is attached to the lower surface of the second dielectric layer; both the first patch resonator unit and the second patch resonator unit are composed of four groups of patch resonators, and resonance slots with the same size are further formed on the four groups of patch resonators, realizing accurate regulation of specific modes of the patch resonators and improving the stability of filtering performance. Description of the Drawings

[0026] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0027] Figure 1 Schematic three-dimensional structure diagram of the frequency selective surface radome for base station antennas provided by the present application;

[0028] Figure 2 Front view of the frequency selective surface radome for base station antennas provided by the present application;

[0029] Figure 3 Schematic diagram of the structural dimensions of the first dielectric layer and the second dielectric layer in the frequency selective surface radome for base station antennas provided by the present application;

[0030] Figure 4 Schematic diagram of the dimensions of the common metal layer in the frequency selective surface radome for base station antennas provided by the present application;

[0031] Figure 5 Simulation result diagram of Embodiment 1 of the frequency selective surface radome for base station antennas provided by the present application;

[0032] Figure 6 Simulation result diagram of Embodiment 2 of the frequency selective surface radome for base station antennas provided by the present application;

[0033] Figure 7 Simulation result diagram of Embodiment 3 of the frequency selective surface radome for base station antennas provided by the present application;

[0034] Figure 8 Simulation result diagram of Embodiment 4 of the frequency selective surface radome for base station antennas provided by the present application.

[0035] Reference numerals:

[0036] 100 - Frequency selective surface radome for base station antennas; 101 - First dielectric layer; 102 - Common metal layer; 103 - Second dielectric layer; 104 - Resonant slot; 105 - First rectangular slot; 106 - Second rectangular slot; 107 - First patch resonator; 108 - Third patch resonator; 109 - Second patch resonator; 110 - Fourth patch resonator.

[0037] Through the above-mentioned drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0038] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0039] Traditional base station radomes are mainly used to protect antennas from the external environment, but their effect on improving antenna performance is limited. Although existing frequency selective surface radomes can provide certain bandpass filtering and stealth characteristics, when their design schemes are applied to dual-bandpass and dual-polarized base station antennas, they often lead to an increase in structural complexity and a decrease in angular stability, making it difficult to meet the requirements of large-scale engineering applications. Therefore, developing a frequency selective surface radome with a low profile, dual-bandpass, dual-polarization support, and good angular stability and out-of-band rejection ability is of great significance for improving the performance of base station antenna systems.

[0040] This technical solution proposes a dual-bandpass frequency selective surface radome based on isosceles right triangle patch resonators and multi-layer structures. By optimizing the patch resonance mode, the layout of rectangular slots in the common metal layer, and the resonance coupling method, dual-bandpass, dual-polarization support, good angular stability, and excellent out-of-band interference rejection ability are achieved. While improving the anti-interference ability and stealth characteristics of the antenna system, a low-profile design is maintained, which is easy to manufacture and suitable for modern high-performance wireless communication systems.

[0041] The following uses specific embodiments to describe in detail the technical solution of the present application and how the technical solution of the present application solves the above technical problems. These several specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0042] Figure 1 FIG. is a schematic three-dimensional structure diagram of a frequency selective surface radome for a base station antenna provided by the present application. As Figure 1 shown, for the frequency selective surface radome 100 for a base station antenna, its core lies in adopting a multi-layer structure and realizing dual-bandpass characteristics through a specific patch resonator design, while having good angular stability and a low-profile feature. Its specific structure is as follows:

[0043] The frequency selective surface radome for base station antennas is composed of a first dielectric layer 101, a common metal layer 102, and a second dielectric layer 103. The first dielectric layer 101 is located at the top, and its upper surface is covered with first patch resonator units for receiving external electromagnetic waves and exciting resonance modes. The second dielectric layer 103 is located at the bottom, and its lower surface is covered with second patch resonator units. Among them, both the first patch resonator units and the second patch resonator units are composed of four groups of patch resonators, that is, four patch resonators are arranged on the upper surface of the first dielectric layer 101, and four patch resonators are arranged on the lower surface of the second dielectric layer 103 for receiving the electromagnetic waves transmitted from the first patch resonator units. Each patch resonator is of an isosceles right triangle structure, and resonance slots 104 with the same size are opened inside to optimize the electromagnetic field distribution characteristics of the resonance mode and improve the transmission performance within the working passband of the frequency selective surface radome.

[0044] Specifically, resonance slots 104 are respectively arranged on the first right-angle side and the second right-angle side of each isosceles right triangle patch resonator. This resonance slot can achieve the regulation of the TM 10 mode resonance frequency without affecting the TM 11 mode resonance frequency. Among them, TM represents the transverse magnetic (Transverse Magnetic) mode, which means that in this mode, the magnetic field of the electromagnetic wave has no component in the propagation direction, while the electric field has a component in the propagation direction. In a rectangular waveguide, the TM 10 mode is the most basic transverse magnetic mode. "10" means that in the cross-section, the electric field has a half-wave variation in one direction (usually the width direction) and no variation in the other direction (usually the height direction). This mode can propagate within a specific frequency range. The TM 11 mode means that in the cross-section, the electric field has a half-wave variation in both directions. This mode usually appears at higher frequencies because it requires higher frequencies to support this more complex field distribution.

[0045] The common metal layer 102 is located between the first and second dielectric layers 103, used to provide metal shielding characteristics, and at the same time has rectangular coupling slots starting at specific positions to regulate the transmission of electromagnetic waves. The rectangular coupling slots include four groups of first rectangular slots 105 and four groups of second rectangular slots 106. The settings of the first rectangular slots 105 and the second rectangular slots 106 can further improve the frequency selective surface radome in terms of dual-band pass and angular stability. Specifically, the first rectangular slots 105 match the resonance slots 104 on the first right-angle side and the second right-angle side of each isosceles right triangle patch resonator. Their sizes are the same as those of the resonance slots 104, and the quantities are also the same to ensure that the coupling paths between the two layers of patch resonators are consistent and ensure TM 10 and TM 11Efficient coupling between double-layer patch resonators improves the low-frequency bandpass performance and optimizes the high-frequency bandpass filtering characteristics. The second rectangular slot 106 matches the center position of the hypotenuse of the isosceles right triangle, further enhancing the energy transmission of the high-frequency mode (TM 11 ), making the high-frequency bandpass filtering more stable.

[0046] The specific steps of the frequency selective surface radome operation include: Electromagnetic waves in free space are incident on the first patch resonator unit, exciting TM 10 and TM 11 modes. The first rectangular slot 105 is located on the common metal layer 102, and its size and position match the resonant slot 104 on the first patch resonator unit, enabling the TM 10 mode and the TM 11 mode to be transmitted to the second patch resonator unit and resonate again on the second patch resonator unit. Therefore, the overall frequency selection mechanism includes the first patch resonator unit to the first rectangular slot 105 and then to the second patch resonator unit. Among them, the first rectangular slot 105 enhances the transmission of the low-frequency mode (TM 10 ), making the low-frequency passband more stable, and the second rectangular slot 106 optimizes the transmission of the high-frequency mode (TM 11 ), making the high-frequency passband more stable.

[0047] The frequency selective surface radome for base station antennas provided in this application optimizes the dual-bandpass performance and improves the angular stability by opening the first rectangular slot 105 (corresponding to the resonant slot 104) and the second rectangular slot 106 (corresponding to the center position of the hypotenuse) on the common metal layer 102, making the frequency selective surface radome suitable for modern base station antenna systems. This structure not only enhances the transmission performance of the low-frequency and high-frequency modes, but also reduces the processing complexity and improves the engineering feasibility, providing a new solution for the design of high-performance base station radomes.

[0048] Figure 2 This is the front view of the frequency selective surface radome for base station antennas provided in this application. As Figure 2 shown, the frequency selective surface radome for base station antennas adopts a multi-layer structure. While maintaining a low profile, by optimizing the size of the patch resonator, the physical parameters of the dielectric layer, and the consistency of the overall structure, it ensures efficient dual-bandpass filtering characteristics and excellent angular stability.

[0049] First, in order to ensure the consistency of the resonant characteristics, the sizes of the four groups of patch resonators need to be set to the same parameters, which can ensure that each resonator behaves the same in the same electromagnetic environment, and further ensure the same frequency response in the dual polarization directions, so as to improve the polarization stability of the frequency selective surface radome.

[0050] Secondly, since the resonators have the same size, under the coupling strength regulation of the first rectangular groove 105 and the second rectangular groove 106, their responses to the TM 10 and TM 11 modes remain consistent, thereby obtaining more stable filtering performance within the dual-frequency passband. Additionally, due to the complete size matching of all layers, the mechanical strength of the entire structure is higher, avoiding stress concentration or deformation caused by different sizes and improving the reliability of the frequency selective surface radome.

[0051] Specifically, the dielectric constants of the first dielectric layer 101 and the second dielectric layer 103 of the present invention are both 2.2, and the thicknesses are both 1.57 mm. Among them, the advantage of selecting a dielectric constant of 2.2 is that it has the effects of low reflection and high transmission efficiency at this coefficient, enabling the frequency selective surface radome to reduce the energy reflected by electromagnetic waves during transmission, thereby improving the signal transmission efficiency and the bandpass filtering performance.

[0052] On the other hand, the thickness of 1.57 mm is relatively thin, resulting in a relatively low overall thickness of the frequency selective surface radome, meeting the requirements of base station antennas for low profile and lightweight. This thickness improves the magnetic coupling efficiency between the upper patch resonator and the lower patch resonator, enabling the first rectangular groove 105 and the second rectangular groove 106 to efficiently achieve the transmission of the dual-frequency mode and improving the bandpass filtering characteristics.

[0053] From Figure 2 it can be seen that the frequency selective surface radome adopts a three-layer structure, including: upper substrate (first dielectric layer 101): 1.57 mm, dielectric constant of 2.2, common metal ground (intermediate metal layer): lower substrate (second dielectric layer 103): 1.57 mm, dielectric constant of 2.2, upper metal (upper patch resonator), lower metal (lower patch resonator). This symmetric structure can ensure more uniform electromagnetic wave transmission, and since the structures, materials, and sizes of the upper and lower layers are completely symmetric, the frequency selective surface radome will not generate directional deviation during the electromagnetic wave transmission process, further ensuring stable bandpass characteristics at different incident angles.

[0054] In addition, the resonators of the upper and lower layers both adopt the same size, and in combination with the first rectangular groove 105 and the second rectangular groove 106 of the common metal layer 102, it can ensure the dual-polarization response of the TM 10 and TM 11 modes to be consistent. Due to the complete consistency of the thickness and size of the dielectric layer, the stress distribution of the entire structure is uniform, avoiding structural bending or deformation caused by differences in interlayer thickness or size and improving the mechanical stability of the radome.

[0055] Figure 3This is a schematic diagram of the structural dimensions of the first dielectric layer and the second dielectric layer in the frequency selective surface radome for base station antennas provided by this application. As Figure 3 shown, this figure shows the unit structure of a frequency selective surface radome based on isosceles right triangle patch resonators. Its main components include: four isosceles right triangle patch resonators, two of which are placed by translation along one diagonal direction, and two are placed by translation along the other diagonal direction, and each forms a symmetric structure along the diagonal. Each patch resonator has a slotted structure inside, which is used to regulate the electromagnetic field distribution of the resonant mode and improve the filtering performance. The period parameter p represents the period of the unit structure, determines the repeated arrangement mode of the entire frequency selective surface radome, and affects the frequency selective characteristics. The gap g represents the distance between adjacent patch resonators. Exemplarily, g = 3mm, which affects the coupling strength between resonators, thereby affecting the bandwidth and resonant frequency. The patch side length l1 directly determines the resonant frequency and affects the working ranges of low frequencies and high frequencies.

[0056] Through the isosceles right triangle structure and the slotted design, precise regulation of the TM 10 and TM 11 modes is achieved, enabling the frequency selective surface radome to have dual-band pass filtering capabilities. This structure can still maintain stable frequency selective characteristics under large-angle incidence conditions, reducing the influence of the incident angle on the transmission performance. In addition, due to the symmetric layout of the four triangular resonators along two sets of diagonal directions respectively, this structure can support polarization signals in both the x direction and the y direction simultaneously, improving the communication capacity and anti-interference ability of the system.

[0057] On the other hand, the above four patch resonators can be divided into a first patch resonator combination and a second patch resonator combination, and the electromagnetic coupling characteristics are optimized through a reasonable arrangement method, improving the dual-polarization performance and angular stability. Among them, the first patch resonator combination includes the first patch resonator 107 and the second patch resonator 109, which are mainly responsible for the electromagnetic wave resonance response in the first diagonal direction, where the first diagonal direction is as Figure 3 indicated by the label in. The second patch resonator combination includes the third patch resonator 108 and the fourth patch resonator 110, which are mainly responsible for the electromagnetic wave resonance response in the second diagonal direction, where the second diagonal direction is as Figure 3 indicated by the label in. By periodically arranging the two groups of patch resonators along the first diagonal direction and the second diagonal direction respectively, the same resonance response can be formed in two orthogonal polarization diagonal directions respectively, thereby realizing the dual-polarization characteristics in two orthogonal diagonal directions.

[0058] Furthermore, the electromagnetic waves in these two diagonal polarization directions can be symmetrically decomposed into electromagnetic waves polarized along the x-axis and y-axis directions respectively, and the combination of the two sets of patch resonators has the following characteristics: The electromagnetic field distributions of the low-frequency resonance mode (TM 10 ), and the high-frequency resonance mode (TM 11 ) of the first patch resonator 107 and the second patch resonator 109 are both symmetric and periodic along the first diagonal; The electromagnetic field distributions of the low-frequency resonance mode (TM 10 ), and the high-frequency resonance mode (TM 11 ) of the third patch resonator 108 and the fourth patch resonator 110 are both symmetric and periodic along the second diagonal. Such electromagnetic wave polarization characteristics and mode electromagnetic field distribution characteristics mean that the structural layout adopted in the present invention still has dual-polarization characteristics in two orthogonal directions of the x-axis and y-axis, and this layout that takes into account both the structure and the high symmetry and periodicity of the electromagnetic field distributions of the high- and low-frequency resonance modes enables the radome to maintain stable transmission characteristics under large-angle incidence, improves the angular stability, and further can improve the channel capacity and anti-interference ability of the communication system.

[0059] The frequency selective surface radome for base station antennas provided by the present application realizes efficient dual-band filtering, wide-angle stability, dual-polarization support and low-profile design by optimizing resonator arrangement, coupling gap and period design, is applicable to modern base station antenna systems, and improves anti-interference ability and channel capacity.

[0060] Figure 4 It is a schematic diagram of the size of the common metal layer in the frequency selective surface radome for base station antennas provided by the present application. As Figure 4 shown, the main function of the common metal layer size is to provide an electromagnetic coupling channel, and the transmission characteristics of electromagnetic waves are regulated by optimizing the rectangular coupling slits on the metal layer to achieve dual-polarization dual-bandpass characteristics.

[0061] Specifically, a plurality of rectangular coupling slits are opened on the common metal layer 102 to control the transmission characteristics of electromagnetic waves. The specific functions of each size parameter are as follows: p = 54 mm, which represents the period of the frequency selective surface radome, affects the array arrangement mode of the entire radome, and determines the frequency selection characteristics. l s1 = 4 mm, which defines the coupling slit sizes in the longitudinal and transverse directions, determines the transmission efficiency of electromagnetic waves through the metal layer, and directly affects the coupling strength of the low frequency (TM 10 mode). l 21 = 10 mm, l 22 = 1 mm are used to adjust the electromagnetic transmission capabilities of different resonance modes, especially the transmission characteristics of the high-frequency mode (TM 11 ). l3 = 12.8 mm, which defines the coupling length in a specific area and optimizes the high-frequency mode (TM11 The matching effect of (). w s1 = 2mm, w s2 = 0.5mm, w s3 = 1mm, which defines the slot width and mainly controls the transmission bandwidth, enabling the frequency selective surface radome to maintain stable frequency selective characteristics within the target frequency band. l s3 = 3.5mm, which cooperates with other slot lengths to jointly optimize the dual-bandpass characteristics.

[0062] The rectangular slots in this figure are distributed around the common metal layer 102, forming strong magnetic coupling with the upper and lower patch resonators to ensure TM 10 and TM 11 modes to achieve efficient transmission within the two passbands. Centered at point O, the layout of the rectangular slots is symmetric, ensuring the dual-polarization characteristics, so that the polarization signals in the x-direction and y-direction have consistent transmission characteristics at the same frequency. The rectangular slots with an inclined angle further optimize the transmission characteristics of the incident electromagnetic wave in different polarization directions, improving the angular stability.

[0063] In summary, by reasonably designing the longitudinal and transverse rectangular slots (l s1 , l s2 ), the transmission path of low-frequency signals is optimized, and the low-frequency bandpass performance is improved. l 21 , l 22 , l3 and other parameters optimize the high-frequency resonance mode, making the high-frequency transmission efficiency higher and improving the bandpass filtering performance. In addition, this structure realizes the dual-polarization characteristics through the slots uniformly distributed along the x-axis and y-axis directions, enabling the polarization signals in the x-direction and y-direction to be transmitted, and improving the anti-interference ability. This optimized design of the common metal layer enables the frequency selective surface radome to meet the requirements of modern communication systems for efficient frequency selection, angular stability, and dual-polarization support, and has broad engineering application prospects.

[0064] Figure 5 This is the simulation result diagram of the first embodiment of the frequency selective surface radome for base station antennas provided by this application. As Figure 5 shown, it shows the simulation results of the scattering parameters of the frequency selective surface radome for base station antennas under the TE (Transverse Electric Incidence) polarized incident wave in the case of normal incidence in the electromagnetic simulation software, which is used to determine the transmission and reflection characteristics of the frequency selective surface radome for base station antennas. The main observed parameters include:

[0065] S 11 (Reflection coefficient): It represents the proportion of the incident electromagnetic wave that is reflected. The lower the value, the smaller the energy reflection, indicating that the matching effect of the radome at this frequency point is better.

[0066] S 21 (Transmission coefficient): It represents the transmission characteristics of electromagnetic waves. The higher the value, the smoother the signal can pass through the frequency selective surface radome structure.

[0067] Specifically, two passband frequencies are respectively shown at 3.7 GHz and 5.0 GHz in the figure, which proves that the frequency selective surface radome structure has dual-band pass capabilities. There are two transmission poles in each frequency band, indicating that the filtering characteristics of this frequency selective surface radome are of higher order and can provide better selectivity.

[0068] Regarding the bandwidth characteristics, it includes a low-frequency passband and a high-frequency passband. Among them, the center frequency of the low-frequency passband is 3.7 GHz, the -3dB bandwidth is from 3.60 GHz to 3.78 GHz, and the relative bandwidth is 4.7%. The center frequency of the high-frequency passband is 5.0 GHz, the -3dB bandwidth is from 4.96 GHz to 5.1 GHz, and the relative bandwidth is 2.9%. It can be seen that the low-frequency and high-frequency passband bandwidths of the frequency selective surface for base station antennas provided in this application are moderate, ensuring the stable transmission of communication signals.

[0069] In addition, regarding the transmission characteristics, by carefully observing the S 21 curve, it can be found that within the two passband ranges, the transmission coefficient is close to 0 dB, indicating that the frequency selective surface proposed in this application has extremely high transmission efficiency within the target frequency band, can effectively transmit signals, and has good suppression ability outside the passband.

[0070] Secondly, regarding the out-of-band suppression characteristics, it can be seen from the figure that in the frequency bands of 3.0–3.5 GHz and 5.2–6.0 GHz, S 21 drops below -20 dB, indicating that the radome has a strong suppression effect on interference signals in these frequency bands and improves the anti-interference ability.

[0071] The above simulation results verify the dual-band pass, low insertion loss, high selectivity, and out-of-band interference suppression capabilities of the frequency selective surface radome for base station antennas proposed in this application, providing an efficient and stable frequency selection scheme for modern wireless communication systems, which is particularly suitable for 5G communication, satellite communication, and radar stealth systems.

[0072] Figure 6 This is the simulation result diagram of the second embodiment of the frequency selective surface radome for base station antennas provided in this application. As Figure 6 shown, it shows the simulation results of the scattering parameters of the frequency selective surface radome for base station antennas under normal incidence and TM-polarized incident waves in an electromagnetic simulation software, which are used to analyze the transmission and reflection characteristics of the frequency selective surface radome in this polarization mode. The main parameters include:

[0073] S11 (Reflection coefficient), a low value (e.g., below -10 dB) indicates low reflection, and the frequency selective surface radome has good matching in this frequency band. The curve shows that at 3.7 GHz and 5.0 GHz, S 11 is below -10 dB, indicating that the frequency selective surface radome has low reflection for TM polarized waves in these two frequency bands and can allow more signals to transmit through.

[0074] S 21 (Transmission coefficient), a high value (close to 0 dB) indicates high transmission efficiency, and the frequency selective surface radome has good band-pass characteristics in this frequency band. It can be observed from the figure that near 3.7 GHz and 5.0 GHz, S 21 is relatively high (close to 0 dB), indicating that the frequency selective surface radome has good dual-band pass characteristics under the incidence of TM polarized waves.

[0075] Specifically, for the dual-band pass characteristics, the center frequencies of the two pass bands are 3.7 GHz and 5.0 GHz respectively, indicating that the frequency selective surface radome also has the ability of dual-band pass for TM polarized waves. Each pass band has two transmission poles, indicating that the structure provides higher-order selectivity and can precisely control the band-pass frequency range.

[0076] For the bandwidth characteristics, the -3 dB bandwidth is from 3.60 GHz to 3.78 GHz, and the relative bandwidth is 4.7%. The -3 dB bandwidth of the high-frequency pass band (5.0 GHz) is from 4.96 GHz to 5.1 GHz, and the relative bandwidth is 2.9%. This bandwidth is suitable for dual-band communication systems such as Wi-Fi 6 and satellite communication.

[0077] For the transmission coefficient S 21 , it is close to 0 dB within the pass band, indicating that the structure has high transmission efficiency for TM polarized waves and low insertion loss.

[0078] For the out-of-band rejection ability, in the frequency bands of 3.0 - 3.5 GHz and 5.2 - 6.0 GHz, S 21 significantly decreases, indicating that the frequency selective surface has good filtering and suppression ability for out-of-band interference signals, which helps to improve the anti-interference ability of the system.

[0079] Figure 7 This is the simulation result diagram of the third embodiment of the frequency selective surface radome for base station antennas provided by this application. As Figure 7 shown, it shows the simulation results of the scattering parameters of the frequency selective surface radome for base station antennas under the incidence of TE (Transverse Electric Incidence) polarized incident waves in the electromagnetic simulation software under the condition of large-angle incidence.

[0080] This simulation diagram shows the S ∘ transmission coefficient under different incident angles (𝜃 = 0 ∘ , 30 ∘ ), 50 21 ), which is used to determine the angular stability of the frequency selective surface radome. Among them, the center frequency and bandwidth of the passband hardly change with the incident angle. The center frequencies of the low-frequency passband (about 3.7 GHz) and the high-frequency passband (about 5.0 GHz) are basically stable. This shows that the frequency selective surface radome can still maintain stable frequency selection characteristics within a wide angular range.

[0081] In addition, the insertion loss increases slightly. When the angle increases (such as 𝜃 = 50 ∘ ), the S 21 curve drops slightly (the insertion loss increases), but the overall change is small. This indicates that the structure has strong adaptability to large-angle incidence and can still maintain a high transmission efficiency.

[0082] On the other hand, the frequency selective surface radome of the present application can maintain good dual-band characteristics under both TE (transverse electric wave) and TM (transverse magnetic wave) polarization incidences, but the performance for different polarizations is slightly different. For example, under TE incident waves, the center frequency and bandwidth of the passband are basically unchanged, and only the insertion loss increases slightly. This shows that the propagation characteristics of TE polarized waves match well with the structure and are not affected by polarization changes. Under TM incident waves, the center frequency and bandwidth of the low-frequency passband (3.7 GHz) are stable, which is the same as the performance of TE waves. The bandwidth of the high-frequency passband (5.0 GHz) has a slight shift, probably because the coupling degree between the magnetic field distribution of TM waves and the TM11 resonance mode of the frequency selective surface radome is slightly different, resulting in a slight influence on the high-frequency part.

[0083] Figure 8 This is the simulation result diagram of the fourth embodiment of the frequency selective surface radome for base station antennas provided by the present application. As Figure 8 shown, it shows the simulation results of the scattering parameters of the frequency selective surface radome for base station antennas under TM polarization incident waves in the electromagnetic simulation software under large-angle incidence.

[0084] This diagram shows the S ∘ coefficient under different incident angles (𝜃 = 0 ∘ , 30 ∘ ), 50 21 ), which is used to determine the angular stability of the frequency selective surface radome. It can be seen from the figure that the frequency selective surface radome for base station antennas has obvious transmission peaks at 3.7 GHz and 5.0 GHz, proving its dual-band passband characteristics. The frequencies of these two transmission peaks hardly change with the incident angle, indicating that the structure has good angular stability.

[0085] In addition, at 𝜃 = 0 ∘ to 𝜃 = 50 ∘ within the range, the center frequency of the passband remains basically stable, and the insertion loss (S 21 peak value) slightly increases at a large incident angle (𝜃 = 50 ∘ ), but the change range is small, indicating that the frequency selective surface radome facing the base station antenna has strong adaptability to different incident angles.

[0086] Secondly, it can be seen from the figure that in the frequency band above 5.2 GHz, S 21 significantly decreases (below -20 dB), indicating that the frequency selective surface radome can effectively suppress high-frequency interference signals and reduce interference to other systems.

[0087] The frequency selective surface radome for base station antennas proposed in this application has good angular stability. Within the incident angle range of 0 ∘ to 50 ∘ , the center frequency and bandwidth of the passband basically remain unchanged; high transmission efficiency, low insertion loss, and excellent transmission performance in the 3.7 GHz and 5.0 GHz frequency bands; excellent out-of-band interference suppression ability, significant attenuation of transmission in the frequency band above 5.2 GHz (below -40 dB), effectively reducing interference, and applicable to 5G communication, satellite communication, and stealth radar systems with wide-angle incidence.

[0088] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and the practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include known common knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only considered exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

[0089] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A frequency selective surface radome for base station antennas, characterized in that, Including: A first dielectric layer, a common metal layer, and a second dielectric layer; The common metal layer is disposed between the first dielectric layer and the second dielectric layer; A first patch resonator unit is attached to the upper surface of the first dielectric layer, and a second patch resonator unit is attached to the lower surface of the second dielectric layer; Both the first patch resonator unit and the second patch resonator unit are composed of four groups of patch resonators, and resonance slots with the same size are also provided on the four groups of patch resonators.

2. The frequency selective surface radome according to claim 1, characterized in that, The shapes of the four groups of patch resonators are all right-angled isosceles triangles; The resonance slots are respectively disposed on the first right-angled side and the second right-angled side of the four groups of patch resonators.

3. The frequency selective surface radome according to claim 2, characterized in that, The four groups of patch resonators include a first patch resonator combination and a second patch resonator combination; Wherein, the first patch resonator combination includes a first patch resonator and a second patch resonator, and the second patch resonator combination includes a third patch resonator and a fourth patch resonator.

4. The frequency selective surface radome according to claim 3, characterized in that, The first patch resonator and the second patch resonator are arranged in a translational manner along the diagonal direction; The third patch resonator and the fourth patch resonator are arranged in a translational manner along the other diagonal direction.

5. The frequency selective surface radome according to any one of claims 1 to 4, characterized in that, A first rectangular slot is provided on the common metal layer; The position of the first rectangular slot corresponds to the position where the resonance slots are provided on the four groups of patch resonators.

6. The frequency selective surface radome according to claim 5, characterized in that, The first rectangular slot has the same size as the resonance slot, and the number of the first rectangular slots is the same as the number of the resonance slots.

7. The frequency selective surface radome according to claim 5, characterized in that, Four groups of second rectangular slots are also provided on the common metal layer, and the positions of the four groups of second rectangular slots respectively correspond to the hypotenuse center positions of the four groups of patch resonators.

8. The frequency selective surface radome according to any one of claims 1 to 4, characterized in that, The size parameters of the four groups of patch resonators are all the same.

9. The frequency selective surface radome according to any one of claims 1 to 4, characterized in that, The sizes of the first dielectric layer, the common metal layer, and the second dielectric layer are the same.

10. The frequency selective surface radome according to any one of claims 1 to 4, characterized in that, The dielectric constant of the first dielectric layer is 2.2, and the thickness is 1.57 millimeters; The dielectric constant of the second dielectric layer is 2.2, and the thickness is 1.57 millimeters.

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