Multi-band common-caliber base station antenna

Abstract

The invention particularly relates to a multi-band common-caliber base station antenna which comprises a low-frequency antenna, an intermediate-frequency antenna and a high-dual-band antenna which are coaxially placed on the upper surface of a metal floor from top to bottom. Wherein the low-frequency antenna and the intermediate-frequency antenna are both composed of three layers of composite wave-transparent structures, the middle layer serves as a radiation structure of the antenna, electromagnetic waves are radiated outwards through direct feed of a feeder line, the upper layer and the lower layer are additional electromagnetic structures, and the three layers are combined into a wave-transparent structure with the frequency selection characteristic. The radiation effect and the matching characteristic of the antenna are almost not influenced by the introduction of an additional electromagnetic structure; the intermediate-frequency antenna has a wave-transparent characteristic for the high-dual-frequency antenna below the intermediate-frequency antenna, and the low-frequency antenna has a wave-transparent characteristic for the intermediate-frequency antenna and the high-dual-frequency antenna below the low-frequency antenna; the high-dual-frequency antenna is located at the bottom of the array; the multiband common-caliber base station antenna realizes stable radiation in four working frequency bands, and has the characteristics of multiband, wide bandwidth, small mutual interference, simple structure and the like.

Description

Technical Field

[0001] The present invention relates to the field of mobile communication technology base station array antennas, and in particular to a multi-band common-aperture base station antenna. Background Art

[0002] At present, mobile communication technology is booming. The commercialization of the fifth generation mobile communication technology (5G) and the planning of the future 6G technology can allow people to experience the convenience brought by high-speed Internet applications anytime and anywhere, and realize the interconnection of all things. However, this does not mean that traditional 3G and 4G communications will no longer be carried out. On the contrary, the traditional standard system and the communication system with high-speed transmission function can be used in combination with each other. In the future, mobile communications will face the coexistence of 3G, 4G, 5G and even 6G for a long time. This means that the mobile communication network will face multi-band communication operations and the density of base stations will continue to increase, resulting in tight site space. At the same time, the operation and maintenance of base stations will be overwhelmed. Integrating antennas of multiple frequency bands into one, using an array to achieve multi-network coverage, and the antennas of each frequency band can work relatively independently, is a more ideal solution to alleviate the shortage of antenna resources, improve resource utilization and reduce costs. The development and application of dual-band or even multi-band base station arrays has become an inevitable trend of communication systems, and common-aperture antenna technology has emerged.

[0003] Taking the design of dual-band co-aperture antennas as an example, for dipole antennas, the antenna size and profile height are positively correlated with the working wavelength, which means that antennas working at low frequencies often have larger apertures and higher profiles. Placing low-frequency antennas between high-frequency antenna units can achieve the coexistence of antennas in multiple frequency bands without increasing the aperture size and profile height. However, the larger low-frequency antenna will inevitably block the high-frequency antenna in space, affecting the normal radiation of electromagnetic waves from the high-frequency antenna, causing distortion of the high-frequency antenna's radiation pattern, and affecting antenna performance. How to overcome the distortion of the antenna pattern caused by spatial occlusion is a hot issue that needs to be solved in the field of co-aperture antennas.

[0004] To solve this problem, the low-frequency antenna needs to be designed to be electromagnetically transparent to the high-frequency antenna, which can be achieved by introducing a frequency selective surface into the original low-frequency antenna radiation structure. In addition, the development of dual-frequency co-aperture antennas is no longer sufficient to meet the needs of multi-band communications, so there is an urgent need to develop and research multi-band co-aperture antenna arrays. Expanding to multi-frequency arrays requires low-frequency antennas to be electromagnetically transparent in multiple frequency bands, which places higher demands on the design of frequency selective surfaces. Therefore, it is necessary to design a low-frequency antenna with multi-band electromagnetic transparency and develop a multi-band co-aperture antenna array to support the coexistence of multi-band communications.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] The present invention provides a multi-band co-aperture base station antenna based on a composite wave-transparent structure, which can realize a multi-band co-aperture antenna array, support the coexistence of multi-band communications, meet the needs of multi-band high-performance communications, and thus overcome the limitations of the prior art.

[0007] Other features and advantages of the present invention will become apparent from the following detailed description, or may be learned in part by practice of the present invention.

[0008] According to a first aspect of the present invention, there is provided a multi-band common aperture base station antenna, comprising:

[0009] The low-frequency antenna, the medium-frequency antenna, and the high-frequency dual-frequency antenna are coaxially placed above the metal floor from top to bottom;

[0010] The low-frequency antenna and the intermediate-frequency antenna are both composite wave-transmitting structures composed of three layers of electromagnetic surfaces; when the electromagnetic waves of the high dual-frequency antenna are irradiated on the intermediate-frequency antenna and the low-frequency antenna, the composite wave-transmitting structure is excited and exhibits electromagnetic transparency, thereby realizing normal radiation of electromagnetic waves in the two high-frequency bands and suppressing the distortion of the directional pattern caused by space obstruction; when the electromagnetic waves of the intermediate-frequency antenna are irradiated on the low-frequency antenna, the composite wave-transmitting structure of the low-frequency antenna is excited and exhibits electromagnetic transparency, thereby realizing normal radiation of the intermediate-frequency electromagnetic waves.

[0011] In some exemplary embodiments, the low-frequency antenna includes a low-frequency first electromagnetic surface, a low-frequency second electromagnetic surface and a low-frequency third electromagnetic surface placed from top to bottom, with adjacent two surfaces separated by air layers with the same interval; wherein the low-frequency first electromagnetic surface and the low-frequency third electromagnetic surface have the same structure.

[0012] In some exemplary embodiments, the low-frequency first electromagnetic surface includes a low-frequency first dielectric substrate and a low-frequency first folded square ring metal structure printed on its lower surface; the low-frequency first folded square ring metal structure constitutes a low-frequency first square ring array in a 3×3 arrangement, and the low-frequency first square ring array constitutes a metal structure on the lower surface of the low-frequency first dielectric substrate in a 2×2 arrangement; the low-frequency first square ring array is divided into a low-frequency first radiation square ring group and a low-frequency second radiation square ring group placed diagonally opposite to each other to achieve a ±45° polarized radiation function.

[0013] In some exemplary embodiments, the low-frequency first folded square ring metal structure includes a low-frequency outer square ring strip, a low-frequency middle square ring strip, and a low-frequency inner square ring strip that are coaxially nested.

[0014] In some exemplary embodiments, the low-frequency second electromagnetic surface includes a low-frequency second dielectric substrate and a low-frequency first square ring metal structure printed on its lower surface, and a low-frequency first Y-type feed line and a low-frequency second Y-type feed line that cross each other and are printed on its upper surface;

[0015] The low-frequency first Y-type feeder transfers the energy input by the low-frequency first coaxial line to the low-frequency first radiating square ring group by coupling; the low-frequency second Y-type feeder transfers the energy input by the second coaxial line to the low-frequency second radiating square ring group by coupling; one end of the low-frequency first coaxial line is connected to the low-frequency first Y-type feeder, and the other end is connected to the bottom of the metal floor; one end of the low-frequency second coaxial line is connected to the second Y-type feeder, and the other end is connected to the bottom of the metal floor.

[0016] In some exemplary embodiments, the intermediate frequency antenna includes an intermediate frequency first electromagnetic surface, an intermediate frequency second electromagnetic surface and an intermediate frequency third electromagnetic surface placed from top to bottom; adjacent ones are separated by air layers with the same interval; wherein the intermediate frequency first electromagnetic surface and the intermediate frequency third electromagnetic surface have the same structure.

[0017] In some exemplary embodiments, the intermediate frequency first electromagnetic surface includes an intermediate frequency first dielectric substrate and an intermediate frequency first folded square ring metal structure printed on its lower surface; the first folded square ring metal structure constitutes an intermediate frequency first square ring array in a 3×3 arrangement, and the intermediate frequency first square ring array constitutes a metal structure on the lower surface of the intermediate frequency first dielectric substrate in a 2×2 arrangement; the intermediate frequency first square ring array is divided into an intermediate frequency first radiation square ring group and an intermediate frequency second radiation square ring group placed diagonally opposite each other to achieve a radiation function of ±45° polarization.

[0018] In some exemplary embodiments, the first folded square ring metal structure includes a coaxially nested intermediate frequency outer square ring strip and an intermediate frequency inner square ring strip.

[0019] In some exemplary embodiments, the intermediate frequency second electromagnetic surface includes an intermediate frequency second dielectric substrate and an intermediate frequency first square ring metal structure printed on its lower surface, and an intermediate frequency first Y-type feed line and an intermediate frequency second Y-type feed line that cross each other and are printed on its upper surface;

[0020] The first intermediate frequency Y-type feeder transmits the energy input by the first intermediate frequency coaxial line to the first intermediate frequency radiating square ring group by coupling; the second intermediate frequency Y-type feeder transmits the energy input by the second intermediate frequency coaxial line to the second intermediate frequency radiating square ring group by coupling; one end of the first intermediate frequency coaxial line is connected to the first intermediate frequency Y-type feeder, and the other end is connected to the bottom of the metal floor; one end of the second intermediate frequency coaxial line is connected to the second intermediate frequency Y-type feeder passing through the intermediate frequency, and the other end is connected to the bottom of the metal floor.

[0021] In some exemplary embodiments, the high dual-frequency antenna includes a high dual-frequency first dielectric substrate and a parasitic patch printed on its upper surface, a high-frequency second dielectric substrate and a radiation patch printed on its lower surface; the high dual-frequency first dielectric substrate is located above the high dual-frequency second dielectric substrate.

[0022] The multi-band common aperture base station antenna based on the composite electromagnetic transparent structure provided by the embodiment of the present invention improves the radiation structure of the antenna, and together with the additional electromagnetic surface, forms a composite wave-transmitting structure with multi-band broadband response, suppresses the problem of antenna pattern distortion and failure to radiate normally caused by space shielding, and realizes the low mutual interference collaborative work of multi-band multi-antenna array under common aperture. The array has the characteristics of multi-frequency coordination, stable radiation, simple structure, and easy design.

[0023] Compared with the existing technology, it has the following advantages:

[0024] 1) The four-band common aperture base station antenna proposed in the present invention does not carry any circuit elements, but is only composed of a dielectric substrate and metal etched thereon, which can achieve stable radiation of multiple antennas in their respective frequency bands. In addition, there is no need to introduce auxiliary structures to stabilize the radiation performance of low-frequency antennas.

[0025] 2) The present invention combines the radiation patches of the low-frequency antenna and the medium-frequency antenna with the additional electromagnetic surface to form a second-order filtering structure with broadband wave-transmitting characteristics. At the same time, the additional electromagnetic surface is designed to have multiple resonant frequency points, and together with the antenna radiation patch, it forms a composite wave-transmitting structure with multi-frequency response, realizing multi-band operation.

[0026] 3) In the present invention, the two layers of additional electromagnetic structure introduced in the intermediate frequency antenna have dual-frequency resonance characteristics and are electromagnetically transparent to the high dual-frequency antenna; the two layers of additional electromagnetic structure introduced in the low frequency antenna have triple-frequency resonance characteristics and are electromagnetically transparent to both the high dual-frequency antenna and the intermediate frequency antenna. This avoids mutual shielding between different antennas, and the array can achieve stable radiation in four working frequency bands.

[0027] 4) The introduction of additional electromagnetic structures does not affect the original radiation performance and matching performance of the low-frequency antenna and the medium-frequency antenna while achieving the conformal shape of the radiation pattern.

[0028] 5) The present invention achieves a multi-band transmission effect by directly improving the low-frequency array and the intermediate frequency, without increasing the array spacing and stacking the array to reduce the shielding effect of the low-frequency antenna; the antennas in the array proposed by the present invention are placed on the same reflective floor without increasing the cross-sectional height of the array; the use of dielectric plates with high dielectric constants and structures that require precision processing technology are avoided, reducing processing difficulty and cost.

[0029] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present invention, and together with the specification are used to explain the principles of the present invention. Obviously, the accompanying drawings described below are only some embodiments of the present invention, and for those of ordinary skill in the art, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0031] Figure 1 The overall structure diagram of a multi-band common-aperture base station antenna array based on a composite wave-transmitting structure according to an exemplary embodiment of the present invention is schematically shown;

[0032] Figure 2 A side view schematically shows a multi-band common-aperture base station antenna array based on a composite wave-transmitting structure according to an exemplary embodiment of the present invention;

[0033] Figure 3 The overall structure diagram of the low-frequency antenna of the multi-band common-aperture base station antenna array based on the composite wave-transmitting structure according to the exemplary embodiment of the present invention is schematically shown;

[0034] Figure 4 Schematic diagrams showing the structure of a low-frequency antenna according to an exemplary embodiment of the present invention: (a) a first dielectric substrate printed metal structure diagram; (b) a second dielectric substrate printed metal structure diagram; (c) a third dielectric substrate printed metal structure diagram;

[0035] Figure 5 The overall structure of the intermediate frequency antenna according to the exemplary embodiment of the present invention is schematically shown;

[0036] Figure 6 Schematic diagrams showing the structure of an intermediate frequency antenna according to an exemplary embodiment of the present invention: (a) a first dielectric substrate printed metal structure diagram; (b) a second dielectric substrate printed metal structure diagram; (c) a third dielectric substrate printed metal structure diagram;

[0037] Figure 7 Schematically showing the structure of a high frequency antenna according to an exemplary embodiment of the present invention; (a) overall structure diagram; (b) second dielectric substrate and printed metal structure diagram;

[0038] Figure 8 A port marking diagram schematically illustrates a multi-band common-aperture base station antenna array based on a composite wave-transmitting structure according to an exemplary embodiment of the present invention;

[0039] Fig. 9Schematic diagrams of electromagnetic wave radiation: (a) schematic diagram of electromagnetic wave radiation of a multi-band common-aperture base station antenna array of a traditional solution; (b) schematic diagram of electromagnetic wave radiation of a multi-band common-aperture base station antenna array of the present invention;

[0040] Fig.10 The following are comparison diagrams of simulation results: (a) at 4.8 GHz, when the azimuth angle φ = 0° and 90°, the elevation angle θ = -90° to 90°, and the port 5 and port 8 are differentially fed, the radiation patterns of a single high dual-frequency antenna, the array of the present invention, and a traditional array are compared; (b) at 5 GHz, when the azimuth angle φ = 0° and 90°, the elevation angle θ = -90° to 90°, and the port 5 and port 8 are differentially fed, the radiation patterns of a single high dual-frequency antenna, the array of the present invention, and a traditional array are compared; (c) at 3.4 GHz, when the azimuth angle φ = 0° and 90°, the elevation angle θ = -90° to 90°, and the port 5 and port 8 are differentially fed, the radiation patterns of a single high dual-frequency antenna, the array of the present invention, and a traditional array are compared. Compared with the directional pattern in the traditional array; (d) at 3.6GHz, when the azimuth angle φ = 0° and 90°, the elevation angle θ = -90° to 90°, and the port 5 and port 8 are differentially fed, the directional pattern of the single high dual-frequency antenna, the array of the present invention and the traditional array is compared; (e) at 1.8GHz, when the azimuth angle φ = 0° and 90°, the elevation angle θ = -90° to 90°, and the port 3 is fed, the directional pattern of the single intermediate frequency antenna, the array of the present invention and the traditional array is compared; (f) at 2GHz, when the azimuth angle φ = 0° and 90°, the elevation angle θ = -90° to 90°, and the port 3 is fed, the directional pattern of the single intermediate frequency antenna, the array of the present invention and the traditional array is compared;

[0041] Fig.11 The frequency responses of the composite wave-transmitting structure are as follows: (a) The frequency response of the composite wave-transmitting structure with three-band wave-transmitting function used in low-frequency antennas; (b) The frequency response of the composite wave-transmitting structure with dual-band wave-transmitting function used in medium-frequency antennas.

[0042] In the figure: 1- low frequency antenna; 2- low frequency first electromagnetic surface; 3- low frequency second electromagnetic surface; 4- low frequency third electromagnetic surface; 5- intermediate frequency antenna; 6- intermediate frequency first electromagnetic surface; 7- intermediate frequency second electromagnetic surface; 8- intermediate frequency third electromagnetic surface; 9- high dual frequency antenna; 10- metal floor; 11- low frequency first Y-type feeder; 12- low frequency second Y-type feeder; 13- low frequency first coaxial line; 14- low frequency second coaxial line; 15- intermediate frequency first Y-type feeder; 16- intermediate frequency second Y-type feeder; 17- intermediate frequency first coaxial line; 18- intermediate frequency second coaxial line; 21- low frequency first dielectric substrate; 22- low frequency first folded square ring Metal structure; 23-low frequency first square ring array; 24-low frequency outer square ring strip; 25-low frequency middle square ring strip; 26-low frequency inner square ring strip; 27-low frequency first radiation square ring group; 28-low frequency second radiation square ring group; 31-low frequency second dielectric substrate; 32-low frequency first square ring metal structure; 33-low frequency second square ring array; 41-low frequency third dielectric substrate; 42-low frequency second folded square ring metal structure; 43-low frequency third ring array; 44-low frequency third radiation square ring group; 45-low frequency fourth radiation square ring group; 61-intermediate frequency antenna first dielectric substrate; 62-intermediate frequency first folded square ring metal structure; 63 -IF first square ring array; 64-IF outer square ring strip; 65-IF inner square ring strip; 66-IF first radiating square ring group; 67-IF second radiating square ring group; 71-IF second dielectric substrate; 72-IF first square ring metal structure; 73-IF second square ring array; 81-IF third dielectric substrate; 82-IF second folded square ring metal structure; 83-IF third ring array; 84-IF third radiating square ring group; 85-IF fourth radiating square ring group; 91-high dual-frequency first dielectric substrate; 92-parasitic patch; 921-parasitic patch chamfer; 922-parasitic patch center circular gap; 93-high The second dual-frequency dielectric substrate; 94-radiation patch; 941-radiation patch chamfer; 942-radiation patch edge rectangular gap; 95-high dual-frequency first L-type feeder group; 951-high dual-frequency first L-type bent feeder; 952-high dual-frequency second L-type bent feeder; 96-high dual-frequency second L-type feeder group; 961-high dual-frequency third L-type bent feeder; 962-high dual-frequency fourth L-type bent feeder; 97-high dual-frequency first coaxial feeder group; 971-high dual-frequency first coaxial line; 972-high dual-frequency second coaxial line; 98-high dual-frequency second coaxial feeder group; 981-high dual-frequency third coaxial line; 982-high dual-frequency fourth coaxial line. DETAILED DESCRIPTION

[0043] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present invention will be more comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0044] In addition, the accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0045] A multi-band common-aperture base station antenna array comprises a plurality of antennas operating in different frequency bands arranged in a stack, wherein an intermediate frequency antenna is located above a high dual-frequency antenna, and a low frequency antenna is located above the intermediate frequency antenna; the orthographic projection of the intermediate frequency antenna partially or completely overlaps with the orthographic projection of the high dual-frequency antenna on a reflector, and the orthographic projection of the low frequency antenna partially or completely overlaps with the orthographic projections of the intermediate frequency antenna and the high dual-frequency antenna on the reflector; when electromagnetic waves from the high dual-frequency antenna irradiate the intermediate frequency antenna and the low frequency antenna, a composite wave-transparent structure is excited, exhibiting electromagnetic transparency, achieving normal radiation of electromagnetic waves in two high frequency bands, and suppressing the problem of pattern distortion caused by spatial shielding; when electromagnetic waves from the intermediate frequency antenna irradiate the low frequency antenna, the composite wave-transparent structure of the low frequency antenna is excited, exhibiting electromagnetic transparency, and achieving normal radiation of intermediate frequency electromagnetic waves.

[0046] like Figure 1 As shown, an embodiment of the present invention provides a multi-band co-aperture base station antenna, specifically a four-band dual-polarization co-aperture base station antenna, including a low-frequency antenna 1, an intermediate-frequency antenna 5, and a high dual-frequency antenna 9 coaxially placed on the upper surface of a metal floor 10. The low-frequency antenna 1 is a composite wave-transmitting structure composed of three layers of electromagnetic surfaces, including a low-frequency first electromagnetic surface 2, a low-frequency second electromagnetic surface 3, and a low-frequency third electromagnetic surface 4, wherein the low-frequency second electromagnetic surface 3 acts as a radiation structure of the antenna, and is connected to a feeding structure for feeding; the intermediate-frequency antenna 5 is a composite wave-transmitting structure composed of three layers of electromagnetic surfaces, including an intermediate-frequency first electromagnetic surface 6, an intermediate-frequency second electromagnetic surface 7, and an intermediate-frequency third electromagnetic surface 8, wherein the intermediate-frequency second electromagnetic surface 7 acts as a radiation structure of the antenna, and is connected to a feeding structure for feeding. The low-frequency antenna 1 is located at the top of the array; the intermediate-frequency antenna 5 is located below the low-frequency antenna 1; and the high dual-frequency antenna 9 is located below the intermediate-frequency antenna 5, that is, at the bottom of the entire array.

[0047] Specifically, the low frequency antenna 1 operates at 0.78-1.08 GHz, the medium frequency antenna 5 operates at 1.7-2.1 GHz, and the high dual frequency antenna 9 operates at 3.3-3.5 GHz and 4.7-4.9 GHz.

[0048] like Figure 3 As shown, the low-frequency antenna 1 is located at the top of the array, and includes a low-frequency first electromagnetic surface 2, a low-frequency second electromagnetic surface 3 and a low-frequency third electromagnetic surface 4, wherein the low-frequency first electromagnetic surface 2 includes a low-frequency first folded square ring metal structure 22 printed on the lower surface of a low-frequency first dielectric substrate 21; the low-frequency antenna second electromagnetic surface 3 includes a low-frequency second dielectric substrate 31 and a low-frequency first square ring metal structure 32 printed on the lower surface; the low-frequency third electromagnetic surface 4 includes a low-frequency third dielectric substrate 41 and a low-frequency second folded square ring metal structure 42 printed on the lower surface thereof. The low-frequency third electromagnetic surface 4 is exactly the same as the low-frequency first electromagnetic surface 2. The first dielectric substrate 21, the second dielectric substrate 31 and the third dielectric substrate 41 are separated by air layers with the same spacing.

[0049] like Figure 4 As shown, the metal pattern printed on the lower surface of the first dielectric substrate 21 of the low-frequency antenna is a low-frequency first folded square ring metal structure 22. The low-frequency first folded square ring metal structure 22 includes a coaxially nested low-frequency outer square ring strip 24, a low-frequency middle square ring strip 25 and a low-frequency inner square ring strip 26. The low-frequency first folded square ring metal structure 22 is arranged in a 3×3 manner to form a low-frequency first square ring array 23. Further, the low-frequency first square ring array 23 is arranged in a 2×2 manner to form a metal structure on the lower surface of the first dielectric substrate 21.

[0050] Furthermore, the first square ring array 23 is divided into a low-frequency first radiation square ring group 27 and a low-frequency second radiation square ring group 28 which are placed diagonally opposite to each other to achieve the radiation function of ±45° polarization.

[0051] like Figure 4 As shown, the metal pattern printed on the lower surface of the low-frequency second dielectric substrate 31 is a low-frequency first square ring metal structure 32, and the low-frequency first square ring metal structure 32 is arranged in a 3×3 manner to form a second square ring array 33; further, the second square ring array 33 is arranged in a 2×2 manner to form a metal structure on the lower surface of the low-frequency second dielectric substrate 31.

[0052] A low-frequency first Y-type feeder 11 and a low-frequency second Y-type feeder 12 are printed in the middle of the upper surface of the low-frequency second dielectric substrate 31. The low-frequency first Y-type feeder 11 transfers the energy input by the low-frequency first coaxial line 13 to the low-frequency first radiation square ring group 27 in the form of coupling; the low-frequency second Y-type feeder 12 transfers the energy input by the low-frequency second coaxial line 14 to the low-frequency second radiation square ring group 28 in the form of coupling; one end of the low-frequency first coaxial line 13 passes through the low-frequency second dielectric substrate 31 to be connected with the low-frequency first Y-type feeder 11, and the other end passes through the low-frequency third dielectric substrate 4 in sequence. 1. The intermediate frequency first dielectric substrate 61, the intermediate frequency second dielectric substrate 71, the intermediate frequency third dielectric substrate 81, the high dual-frequency first dielectric substrate 91, and the high dual-frequency second dielectric substrate 93 are connected to the bottom of the metal floor 10. One end of the low frequency second coaxial line 14 passes through the low frequency second dielectric substrate 31 to connect with the low frequency second Y-type feeder 12, and the other end passes through the low frequency third dielectric substrate 41, the intermediate frequency first dielectric substrate 61, the intermediate frequency second dielectric substrate 71, the intermediate frequency third dielectric substrate 81, and the high dual-frequency first dielectric substrate 91, and the high dual-frequency second dielectric substrate 93 in sequence to connect to the bottom of the metal floor 10. The metal structure printed on the lower surface of the low frequency first dielectric substrate 21 and the low frequency third dielectric substrate 41 has almost no effect on radiation.

[0053] like Figure 4 As shown, the low-frequency third dielectric substrate 41 and the low-frequency second folded square ring metal structure 42 on its lower surface are completely identical to the low-frequency first dielectric substrate 21 and the low-frequency first folded square ring metal structure 2 on its lower surface.

[0054] Specifically, the low-frequency first dielectric substrate 21, the low-frequency second dielectric substrate 31 and the low-frequency third dielectric substrate 41 are all 0.8 mm thick F4BM300 plates, with a dielectric constant of 3.0 and a loss tangent of 0.0018, and the adjacent dielectric substrates are separated by an air layer of 4.2 mm. When the composite wave-transmitting structure of the low-frequency antenna resonates, three wave-transmitting frequency bands covering the working frequency bands of the medium-frequency antenna and the high dual-frequency antenna are generated, and a second-order broadband resonance is formed, which expands the wave-transmitting bandwidth.

[0055] like Figure 5As shown, the intermediate frequency antenna 5 is located below the low frequency antenna 1, and includes the intermediate frequency antenna first electromagnetic surface 6, the intermediate frequency antenna second electromagnetic surface 7 and the intermediate frequency third electromagnetic surface 8; wherein the intermediate frequency antenna first electromagnetic surface 6 includes the intermediate frequency first dielectric substrate 61 and the intermediate frequency first folded square ring metal structure 62 printed on its lower surface; the intermediate frequency antenna second electromagnetic surface 7 includes the intermediate frequency second dielectric substrate 71 and the intermediate frequency first square ring metal structure 72 printed on its lower surface; the intermediate frequency third electromagnetic surface 8 includes the intermediate frequency third dielectric substrate 81 and the intermediate frequency second folded square ring metal structure 82 printed on its lower surface. The intermediate frequency third electromagnetic surface 8 is exactly the same as the intermediate frequency first electromagnetic surface 6. The first dielectric substrate 61, the second dielectric substrate 71 and the third dielectric substrate 81 are separated by air layers with the same spacing.

[0056] like Figure 6 As shown, the metal pattern printed on the lower surface of the first dielectric substrate 61 of the intermediate frequency antenna is an intermediate frequency first folded square ring metal structure 62. The intermediate frequency first folded square ring metal structure 62 includes a coaxially nested intermediate frequency outer square ring strip 64 and an intermediate frequency inner square ring strip 65. The intermediate frequency first folded square ring metal structure 62 is arranged in a 2×2 manner to form an intermediate frequency first square ring array 63. Further, the intermediate frequency first square ring array 63 is arranged in a 2×2 manner to form a metal structure on the lower surface of the intermediate frequency first dielectric substrate 61.

[0057] Furthermore, the intermediate frequency first square ring array 63 is divided into an intermediate frequency first radiation square ring group 66 and an intermediate frequency second radiation square ring group 67 which are diagonally opposite to each other to achieve the radiation function of ±45° polarization.

[0058] like Figure 6 As shown, the metal pattern printed on the lower surface of the intermediate frequency second dielectric substrate 71 is the intermediate frequency first square ring metal structure 72. The intermediate frequency first square ring metal structure 72 is arranged in a 2×2 manner to form an intermediate frequency second square ring array 73. Further, the intermediate frequency second square ring array 73 is arranged in a 2×2 manner to form a metal structure on the lower surface of the intermediate frequency second dielectric substrate 71.

[0059] A first intermediate frequency Y-type feeder 15 and a second intermediate frequency Y-type feeder 16 that cross each other are printed in the middle position on the upper surface of the second intermediate frequency dielectric substrate 71. The first intermediate frequency Y-type feeder 15 transfers the energy input by the first intermediate frequency coaxial line 17 to the first intermediate frequency radiation square ring group 66 by coupling; the second intermediate frequency Y-type feeder 16 transfers the energy input by the second intermediate frequency coaxial line 18 to the second low frequency radiation square ring group 67 by coupling; one end of the first intermediate frequency coaxial line 17 passes through the second intermediate frequency dielectric substrate 61 to be connected to the first intermediate frequency Y-type feeder 15, and the other end passes through the third intermediate frequency dielectric substrate 81, the first high dual-frequency dielectric substrate 91, and the second high dual-frequency dielectric substrate 93 to be connected to the bottom of the metal floor 10; one end of the second intermediate frequency coaxial line 18 passes through the second intermediate frequency dielectric substrate 71 to be connected to the second intermediate frequency Y-type feeder 16, and the other end passes through the third intermediate frequency dielectric substrate 81, the first high dual-frequency dielectric substrate 91, and the second high dual-frequency dielectric substrate 93 to be connected to the bottom of the metal floor 10. The metal structures printed on the lower surfaces of the first dielectric substrate 61 and the third dielectric substrate 81 have almost no effect on radiation.

[0060] like Figure 6 As shown, the intermediate frequency third dielectric substrate 81 and the intermediate frequency second folded square ring metal structure 82 on its lower surface are completely identical to the intermediate frequency first dielectric substrate 61 and the intermediate frequency first folded square ring metal structure 62 on its lower surface.

[0061] Specifically, the first intermediate frequency dielectric substrate 61, the second intermediate frequency dielectric substrate 71 and the third intermediate frequency dielectric substrate 81 are all 0.5 mm thick F4BM220 plates, with a dielectric constant of 2.2 and a loss tangent of 0.001. The two adjacent layers of dielectric substrates are separated by an air layer with a spacing of 2.9 mm. When the composite wave-transmitting structure of the intermediate frequency antenna resonates, two wave-transmitting frequency bands covering the working frequency band of the high dual-frequency antenna are generated, and a second-order broadband resonance is formed at the same time, which expands the wave-transmitting bandwidth. The metal structure printed on the lower surface of the first intermediate frequency dielectric substrate 61 and the third intermediate frequency dielectric substrate 81 has almost no effect on the antenna radiation.

[0062] like Figure 7 As shown, the high dual-frequency antenna 9 is located below the intermediate frequency antenna 5, and includes a high dual-frequency first dielectric substrate 91 and a parasitic patch 921 printed on its upper surface, a high dual-frequency second dielectric substrate 93 and a radiation patch 941 printed on its lower surface; the high dual-frequency first dielectric substrate 91 is located above the high dual-frequency second dielectric substrate 93.

[0063] Specifically, the two dielectric substrates of the high-frequency antenna 9 are both 0.8 mm thick FR4 plates, with a dielectric constant of 4.4 and a loss tangent of 0.02. The two dielectric substrates are separated by an air layer with a spacing of 6.7 mm.

[0064] The upper surface of the high dual-frequency second dielectric substrate 93 is printed with a first L-shaped feed line group 95 and a second L-shaped feed line group 96 placed orthogonally. The two groups of feed lines excite the high dual-frequency antenna through differential feeding to achieve dual-polarization radiation; the first L-shaped feed line group 95 includes two high dual-frequency first L-shaped bent feeding structures 951 and a high dual-frequency second L-shaped bent feed line 952 of the same structure; the high dual-frequency first L-shaped bent feed line 951 and the high dual-frequency second L-shaped bent feed line 952 transfer the energy in the high dual-frequency first coaxial line 971 and the high dual-frequency second coaxial line 972 to the radiation patch 94 through coupling, wherein the input signals in the high dual-frequency first coaxial line 971 and the high dual-frequency second coaxial line 972 have the same amplitude and opposite phase. The structure of the high dual-frequency second L-shaped feed line group 96 is exactly the same as that of the high dual-frequency first L-shaped feed line group 95, including a high dual-frequency third L-shaped bent feed line 961 and a high dual-frequency fourth L-shaped bent feed line 962. The high dual-frequency third L-shaped bent feed line 961 and the high dual-frequency fourth L-shaped bent feed line 962 transfer the energy in the high dual-frequency third coaxial line 981 and the high dual-frequency fourth coaxial line 982 to the radiation patch 94 through coupling, wherein the amplitude of the input signal in the high dual-frequency third coaxial line 981 and the high dual-frequency fourth coaxial line 982 is the same, and the phase is opposite.

[0065] The four-band common-aperture base station antenna array proposed by the present invention does not carry any additional circuit elements. All electromagnetic structures are composed only of a dielectric substrate and metal etched on its surface. It has a simple structure and wide design freedom. The introduction of additional electromagnetic structures does not affect the original radiation performance and matching performance of the antenna on the basis of achieving directional pattern conformity. Finally, the array achieves stable radiation and matching in the four working frequency bands.

[0066] Fig. 9 (a) is a schematic diagram of electromagnetic wave radiation of a traditional common-aperture base station array antenna. The antennas of each frequency band are placed on a common reflective floor. The low-frequency antenna with a higher profile is located at the top of the array, followed by the medium-frequency antenna, and the high dual-frequency antenna is located at the bottom of the array. Due to spatial obstruction, the low-frequency antenna and the medium-frequency antenna will generate secondary radiation under the excitation of the high dual-frequency antenna, affecting the normal radiation of the high dual-frequency antenna and causing directional pattern distortion. Similarly, the low-frequency antenna will also generate secondary radiation under the excitation of the medium-frequency antenna, affecting the radiation performance of the medium-frequency antenna. The different antennas in the array affect each other and are difficult to operate in coordination.

[0067] Fig. 9(b) is a schematic diagram of electromagnetic wave radiation of the multi-band common aperture base station antenna array of the present invention, in which a multi-layer composite electromagnetic transparent structure is introduced into the low-frequency antenna and the medium-frequency antenna to realize a multi-band electromagnetic transparent design. Among them, the composite wave-transparent structure formed by the medium-frequency antenna has a wave-transparent window in two high-frequency bands, which suppresses the shielding of the high dual-frequency antenna and realizes the directional pattern preservation of the high dual-frequency antenna. The composite wave-transparent structure formed by the low-frequency antenna not only has a wave-transparent window in two high-frequency bands, but also realizes wave-transparent performance in the medium-frequency band, and at the same time realizes the directional pattern preservation of the high dual-frequency antenna and the medium-frequency antenna.

[0068] The effect of the present invention can be further illustrated by the following simulation:

[0069] 1. Simulation software:

[0070] Commercial Ansoft HFSS19.2 software.

[0071] 2. Simulation content:

[0072] Simulation 1:

[0073] Fig.10 (a) shows the high dual-frequency antenna of the present invention when the azimuth angle φ = 0° and 90° and the elevation angle θ = -90° to 90°. Figure 8 The middle ports are numbered as port 5 and port 8 for differential feeding excitation, and the normalized radiation pattern of the high dual-frequency antenna at 4.8GHz. It includes 1. The radiation pattern of the high dual-frequency antenna only; 2. The radiation pattern of the high dual-frequency antenna under the three-band electromagnetically transparent low-frequency antenna based on the composite wave-transparent structure proposed in the present invention, and the dual-band electromagnetically transparent intermediate-frequency antenna; 3. The radiation pattern of the high dual-frequency antenna under the traditional low-frequency antenna and the intermediate-frequency antenna, wherein the radiation structure of the traditional low-frequency antenna and the intermediate-frequency antenna is a rectangular patch with the same size as the antenna in the present invention.

[0074] like Fig.10 As shown in (a), the directional pattern of the high-frequency dual-frequency antenna in the traditional array is significantly distorted within the range of ±60° in the axial direction, and the gain and beam width are both deteriorated; while the directional pattern of the high-frequency dual-frequency antenna in the array of the present invention is not significantly distorted, and is almost the same as the directional pattern when there is only the high-frequency dual-frequency antenna. This shows that the low-frequency antenna and the medium-frequency antenna of the present invention have achieved "electromagnetic transparency" to the high-frequency dual-frequency antenna.

[0075] Simulation 2:

[0076] Fig.10 (b) shows the high dual-frequency antenna of the present invention when the azimuth angle φ = 0° and 90° and the elevation angle θ = -90° to 90°. Figure 8The middle ports are numbered as port 5 and port 8 for differential feeding excitation, and the normalized radiation pattern of the high dual-frequency antenna at 5.0GHz. It includes 1. The radiation pattern of the high dual-frequency antenna only; 2. The radiation pattern of the high dual-frequency antenna under the three-band electromagnetically transparent low-frequency antenna based on the composite wave-transparent structure proposed in the present invention, and the dual-band electromagnetically transparent intermediate-frequency antenna; 3. The radiation pattern of the high dual-frequency antenna under the traditional low-frequency antenna and the intermediate-frequency antenna, wherein the radiation structure of the traditional low-frequency antenna and the intermediate-frequency antenna is a rectangular patch with the same size as the antenna in the present invention.

[0077] like Fig.10 As shown in (b), the directional pattern of the high dual-frequency antenna in the traditional array is significantly distorted within the range of ±60° in the axial direction, and the gain and beam width are both deteriorated; while the directional pattern of the high dual-frequency antenna in the array of the present invention is not significantly distorted, and is almost the same as the directional pattern when there is only the high dual-frequency antenna. This shows that the low-frequency antenna and the medium-frequency antenna of the present invention have achieved "electromagnetic transparency" to the high dual-frequency antenna.

[0078] Simulation 3:

[0079] Fig.10 (c) shows the high dual-frequency antenna of the present invention when the azimuth angle φ = 0° and 90° and the elevation angle θ = -90° to 90°. Figure 8 The middle ports are numbered as port 5 and port 8 for differential feeding excitation, and the normalized radiation pattern of the high dual-frequency antenna at 3.4GHz. It includes 1. The radiation pattern of the high dual-frequency antenna only; 2. The radiation pattern of the high dual-frequency antenna under the three-band electromagnetically transparent low-frequency antenna based on the composite wave-transparent structure proposed in the present invention, and the dual-band electromagnetically transparent intermediate-frequency antenna; 3. The radiation pattern of the high dual-frequency antenna under the traditional low-frequency antenna and the intermediate-frequency antenna, wherein the radiation structure of the traditional low-frequency antenna and the intermediate-frequency antenna is a rectangular patch with the same size as the antenna in the present invention.

[0080] like Fig.10 As shown in (c), the radiation pattern of the high dual-frequency antenna in the traditional array is obviously distorted within the range of ±60° in the axial direction, and the gain decrease is as large as 18dB; while the radiation pattern of the high dual-frequency antenna in the array of the present invention does not show obvious distortion, and is almost consistent with the radiation pattern when there is only the high dual-frequency antenna, thereby achieving stable radiation.

[0081] Simulation 4:

[0082] Fig.10 (d) shows the high dual-frequency antenna of the present invention when the azimuth angle φ = 0° and 90° and the elevation angle θ = -90° to 90°. Figure 8The middle ports are numbered as port 5 and port 8 for differential feeding excitation, and the normalized radiation pattern of the high dual-frequency antenna at 3.6GHz. It includes 1. The radiation pattern of the high dual-frequency antenna only; 2. The radiation pattern of the high dual-frequency antenna under the three-band electromagnetically transparent low-frequency antenna based on the composite wave-transparent structure proposed in the present invention, and the dual-band electromagnetically transparent intermediate-frequency antenna; 3. The radiation pattern of the high dual-frequency antenna under the traditional low-frequency antenna and the intermediate-frequency antenna, wherein the radiation structure of the traditional low-frequency antenna and the intermediate-frequency antenna is a rectangular patch with the same size as the antenna in the present invention.

[0083] like Fig.10 As shown in (d), the radiation pattern of the high dual-frequency antenna in the traditional array is seriously distorted within the range of ±60° in the axial direction, and even a split petal phenomenon occurs, and the gain is significantly reduced; while the radiation pattern of the high dual-frequency antenna in the array of the present invention does not show obvious distortion, and is almost consistent with the radiation pattern when there is only the high dual-frequency antenna, achieving stable radiation.

[0084] Simulation 5:

[0085] Fig.10 (e) shows the intermediate frequency antenna of the present invention when the azimuth angle φ = 0° and 90° and the elevation angle θ = -90° to 90°. Figure 8 The port numbered as port 3 is excited, and the normalized radiation pattern of the intermediate frequency antenna at 1.8 GHz. It includes 1. The radiation pattern of the intermediate frequency antenna only; 2. The radiation pattern of the intermediate frequency antenna under the three-band electromagnetic transparent low-frequency antenna based on the composite wave-transmitting structure proposed in the present invention; 3. The radiation pattern of the intermediate frequency antenna under the traditional low-frequency antenna, where the radiation structure of the traditional low-frequency antenna is a rectangular patch with the same size as the antenna in the present invention.

[0086] like Fig.10 As shown in (e), the directional pattern of the intermediate frequency antenna in the traditional array is obviously distorted, and the beam width becomes narrower; while the directional pattern of the intermediate frequency antenna in the array of the present invention is not obviously distorted, and is almost the same as the directional pattern when there is only the intermediate frequency antenna. This shows that the intermediate and low frequency antennas of the present invention achieve "electromagnetic transparency" to the intermediate dual frequency antenna.

[0087] Simulation 6:

[0088] Fig.10 (f) shows the intermediate frequency antenna of the present invention when the azimuth angle φ = 0° and 90° and the elevation angle θ = -90° to 90°. Figure 8The port numbered as port 3 is excited, and the normalized radiation pattern of the intermediate frequency antenna at 2.0 GHz is obtained. The radiation pattern includes 1. the radiation pattern of the intermediate frequency antenna only; 2. the radiation pattern of the intermediate frequency antenna under the three-band electromagnetic transparent low-frequency antenna based on the composite wave-transmitting structure proposed in the present invention; 3. the radiation pattern of the intermediate frequency antenna under the traditional low-frequency antenna, wherein the radiation structure of the traditional low-frequency antenna is a rectangular patch with the same size as the antenna in the present invention.

[0089] like Fig.10 As shown in (f), the directional pattern of the intermediate frequency antenna in the traditional array is obviously distorted, and the beam width becomes narrower; while the directional pattern of the intermediate frequency antenna in the array of the present invention is not obviously distorted, and is almost the same as the directional pattern when there is only the intermediate frequency antenna. This shows that the intermediate and low frequency antennas of the present invention achieve "electromagnetic transparency" to the intermediate dual frequency antenna.

[0090] Fig.11 (a) is the frequency response of the composite wave-transmitting structure with three-band wave-transmitting function used in the low-frequency antenna of the present invention. Its transmission coefficient is greater than -1dB in the three frequency bands of 1.7-2.1GHz, 3.3-3.5GHz and 4.7-4.9GHz, achieving a good wave-transmitting effect.

[0091] Fig.11 (b) is the frequency response of the composite wave-transmitting structure with dual-band wave-transmitting function used in the intermediate frequency antenna of the present invention. Its transmission coefficient is greater than -1dB in the two frequency bands of 3.3-3.5GHz and 4.7-4.9GHz, achieving a good wave-transmitting effect.

[0092] The above description is only one embodiment of the present invention and does not constitute any limitation to the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be regarded as excluding other embodiments, including the specific features, structures, materials or characteristics described in the present invention can be combined and modified in any one or more embodiments in a suitable manner. Obviously, for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structures of the present invention, but these modifications and changes based on the ideas of the present invention are still within the claims and protection scope of the present invention.

Claims

1. A multi-band common aperture base station antenna, characterized in that: include: A low frequency antenna (1), a medium frequency antenna (5) and a high dual frequency antenna (9) are coaxially placed above a metal floor (10) from top to bottom; The low-frequency antenna (1) and the intermediate-frequency antenna (5) are both composite wave-transmitting structures composed of three layers of electromagnetic surfaces; when the electromagnetic waves of the high dual-frequency antenna (9) are irradiated onto the intermediate-frequency antenna (5) and the low-frequency antenna (1), the composite wave-transmitting structure is excited and exhibits electromagnetic transparency, thereby achieving normal radiation of electromagnetic waves in the two high-frequency bands and suppressing the problem of directional pattern distortion caused by spatial shielding; when the electromagnetic waves of the intermediate-frequency antenna (5) are irradiated onto the low-frequency antenna (1), the composite wave-transmitting structure of the low-frequency antenna (1) is excited and exhibits electromagnetic transparency, thereby achieving normal radiation of the intermediate-frequency electromagnetic waves.

2. The multi-band common aperture base station antenna according to claim 1, characterized in that: The low-frequency antenna (1) comprises a low-frequency first electromagnetic surface (2), a low-frequency second electromagnetic surface (3) and a low-frequency third electromagnetic surface (4) arranged from top to bottom, with adjacent two surfaces separated by air layers of equal spacing; wherein the low-frequency first electromagnetic surface (2) and the low-frequency third electromagnetic surface (4) have the same structure.

3. The multi-band common aperture base station antenna according to claim 2, characterized in that: The low-frequency first electromagnetic surface (2) comprises a low-frequency first dielectric substrate (21) and a low-frequency first folded square ring metal structure (22) printed on its lower surface; the low-frequency first folded square ring metal structure (22) forms a low-frequency first square ring array (23) in a 3×3 arrangement, and the low-frequency first square ring array (23) forms a metal structure on the lower surface of the low-frequency first dielectric substrate (21) in a 2×2 arrangement; the low-frequency first square ring array (23) is divided into a low-frequency first radiation square ring group (27) and a low-frequency second radiation square ring group (28) which are arranged diagonally to each other, so as to realize a radiation function of ±45° polarization.

4. The multi-band common aperture base station antenna according to claim 3, characterized in that: The low-frequency first folded square ring metal structure (22) comprises a coaxially nested low-frequency outer square ring strip (24), a low-frequency middle square ring strip (25) and a low-frequency inner square ring strip (26).

5. The multi-band common aperture base station antenna according to claim 3, characterized in that: The low-frequency second electromagnetic surface (3) comprises a low-frequency second dielectric substrate (31), a low-frequency first square ring metal structure (32) printed on its lower surface, and a low-frequency first Y-type feeder (11) and a low-frequency second Y-type feeder (12) printed on its upper surface that cross each other; The low-frequency first Y-type feeder (11) transmits the energy input from the low-frequency first coaxial line (13) to the low-frequency first radiation square ring group (27) in the form of coupling; the low-frequency second Y-type feeder (12) transmits the energy input from the second coaxial line (14) to the low-frequency second radiation square ring group (28) in the form of coupling; one end of the low-frequency first coaxial line (13) is connected to the low-frequency first Y-type feeder (11), and the other end is connected to the bottom of the metal floor (10); one end of the low-frequency second coaxial line (14) is connected to the second Y-type feeder (12), and the other end is connected to the bottom of the metal floor (10).

6. The multi-band common aperture base station antenna according to claim 1, characterized in that: The intermediate frequency antenna (5) comprises an intermediate frequency first electromagnetic surface (6), an intermediate frequency second electromagnetic surface (7) and an intermediate frequency third electromagnetic surface (8) arranged from top to bottom; the two adjacent intermediate frequency surfaces are separated by an air layer with the same spacing; wherein the intermediate frequency first electromagnetic surface (6) and the intermediate frequency third electromagnetic surface (8) have the same structure.

7. The multi-band common aperture base station antenna according to claim 6, characterized in that: The intermediate frequency first electromagnetic surface (6) comprises an intermediate frequency first dielectric substrate (61) and an intermediate frequency first folded square ring metal structure (62) printed on its lower surface; the first folded square ring metal structure (62) forms an intermediate frequency first square ring array (63) in a 2×2 arrangement, and the intermediate frequency first square ring array (63) forms a metal structure on the lower surface of the intermediate frequency first dielectric substrate (61) in a 2×2 arrangement; the intermediate frequency first square ring array (63) is divided into an intermediate frequency first radiation square ring group (66) and an intermediate frequency second radiation square ring group (67) which are arranged diagonally to each other, so as to realize a radiation function of ±45° polarization.

8. The multi-band common aperture base station antenna according to claim 7, characterized in that: The first folded square ring metal structure (62) comprises a coaxially nested intermediate frequency outer square ring strip (64) and an intermediate frequency inner square ring strip (65).

9. The multi-band common aperture base station antenna according to claim 6, characterized in that: The intermediate frequency second electromagnetic surface (7) comprises an intermediate frequency second dielectric substrate (71), an intermediate frequency first square ring metal structure (73) printed on its lower surface, and an intermediate frequency first Y-type feeder (15) and an intermediate frequency second Y-type feeder (16) printed on its upper surface that cross each other; The intermediate frequency first Y-type feeder (15) transmits the energy input from the intermediate frequency first coaxial line (17) to the intermediate frequency first radiation square ring group (66) in the form of coupling; the intermediate frequency second Y-type feeder (16) transmits the energy input from the intermediate frequency second coaxial line (18) to the intermediate frequency second radiation square ring group (67) in the form of coupling; one end of the intermediate frequency first coaxial line (17) is connected to the intermediate frequency first Y-type feeder (15), and the other end is connected to the bottom of the metal floor (10); one end of the intermediate frequency second coaxial line (18) is connected to the intermediate frequency second Y-type feeder (16) passing through, and the other end is connected to the bottom of the metal floor (10).

10. The multi-band common aperture base station antenna according to claim 1, characterized in that: The high dual-frequency antenna (9) comprises a high dual-frequency first dielectric substrate (91) and a parasitic patch (92) printed on its upper surface, a high-frequency second dielectric substrate (93) and a radiation patch (94) printed on its lower surface; the high dual-frequency first dielectric substrate (91) is located above the high dual-frequency second dielectric substrate (93).

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