Broadband wave-transparent base station antenna based on multi-technology mixing

Abstract

The invention provides a broadband wave-transparent base station antenna based on multi-technology mixing, relates to the technical field of microwave and millimeter wave communication, and solves the technical problems that most of staggered base station antenna design schemes in the prior art are relatively narrow in wave-transparent bandwidth, and broadband work is difficult to realize. According to the technical scheme, an L-shaped filtering branch knot is added to an annular dipole arm, and a narrow-band wave-transparent frequency point located near 2.6 GHz is introduced; on the basis, a 2 * 2 patch type frequency selective surface is introduced, and a second wave-transparent frequency point located at 2.18 GHz is introduced; a parasitic band is added, and a third wave-transparent frequency point located at 1.8 GHz is introduced; according to the broadband low-frequency antenna, the wave-transparent effect in the broadband band of 1.7 GHz to 2.7 GHz is achieved, meanwhile, the-15 dB broadband impedance bandwidth of the low-frequency antenna itself in the range of 690 MHz to 960 MHz is kept, and the three wave-transparent structures are mutually independent, do not interfere with one another and are convenient to regulate and control.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave communication technology, specifically to a broadband transparent wave base station antenna based on a combination of multiple technologies. Background Technology

[0002] With the rapid development of fifth-generation mobile communication systems (5G), base station antennas, as key front-end devices in wireless communication links, directly affect network coverage, spectral efficiency, and system capacity. Traditional single-band base station antennas are insufficient to meet the demands of modern communication systems for high frequencies and large bandwidths, leading to the evolution of base station antennas towards multi-standard, multi-band designs. Shared aperture design provides a reasonable solution. Based on different array schemes for high and low frequency antennas, shared aperture technology can be divided into four types: side-by-side, stacked, nested, and interleaved.

[0003] In a side-by-side co-aperture base station antenna design, the high-frequency and low-frequency antennas are arranged at a certain spacing. The relatively large distance between them results in minimal interference, but the overall antenna width is large, failing to meet miniaturization requirements. Stacked designs place the high-frequency antennas vertically, including low-top-high-bottom and low-bottom-high-top configurations. Low-top-high-bottom configurations lead to severe low-frequency scattering interference, while low-bottom-high-top configurations result in excessively high antenna profiles. Nested designs embed the high-frequency antenna within the low-frequency antenna, significantly improving space utilization, but are limited by the frequency ratio of the high and low frequencies, resulting in poor design flexibility. Interleaved designs further shorten the spacing between the high and low frequency antennas, even to the point where the low-frequency antenna blocks the high-frequency antenna, but this also increases interference between them. Due to its design flexibility and high degree of array freedom, the interleaved design has become the most widely used array scheme for co-aperture base station antennas. Solving the interference problem in interleaved designs is the most promising research direction for co-aperture base station antennas.

[0004] Existing interleaved common-aperture base station antennas typically require low-frequency elements to have transmittance to high-frequency elements, meaning they should not interfere with the radiation performance of the high-frequency antenna. Current transmittance technologies mainly include adding filter stubs, frequency selective surfaces, chokes, and parasitic structures to the low-frequency elements. Low-frequency antenna designs based on frequency selective surfaces allow for independent control of transmittance and antenna impedance performance, but their transmittance bandwidth is narrow, resulting in weak transmittance and preventing broadband operation. Low-frequency antenna designs based on filter stubs offer strong single-frequency transmittance but also suffer from narrow transmittance bandwidth. Using a single structure achieves only a narrow transmittance band. Further, combining multiple technologies can extend the transmittance bandwidth; however, simple combinations, such as connecting multiple filter stubs of different sizes in series on the element arm, often lead to interference between the original transmittance structures due to crosstalk from high-frequency induced currents. This complicates transmittance performance control, significantly increasing design complexity and making it difficult to adjust; it also affects the antenna's impedance performance, hindering impedance matching. Summary of the Invention

[0005] Therefore, this invention solves the technical problem that most existing interleaved base station antenna designs have narrow transmission bandwidths, making it difficult to achieve broadband operation. The broadband transparent base station antenna based on a multi-technology hybrid design provided by this invention differs from traditional, relatively simple transparent structures. This invention uses three independently adjustable transparent structures, achieved by adding "L"-shaped filter stubs to the low-frequency vibrator arm and loading parasitic strips on the frequency selection surface and the back of the substrate. These three non-interfering technologies are loaded in parallel on the vibrator arm, achieving a -15dB broadband impedance bandwidth of 690MHz-960MHz at low frequencies, while simultaneously providing wide-band transmission of 1.7GHz-2.7GHz at high frequencies.

[0006] The present invention provides a broadband transparent base station antenna based on a multi-technology hybrid approach, comprising: a rectangular reflective ground and a low-frequency radiating element disposed in the middle region thereof; multiple sets of high-frequency radiating elements are uniformly disposed on the rectangular reflective ground region surrounding the low-frequency radiating element.

[0007] Furthermore, the low-frequency radiation unit includes a feeding structure disposed on a rectangular reflective ground, the feeding structure being connected to the dielectric substrate via a balun; a radiation arm is disposed on the upper surface of the dielectric substrate; a frequency selective surface unit is disposed on the dielectric substrate region within the radiation arm; and a parasitic strip structure is disposed on the lower surface of the dielectric substrate.

[0008] Furthermore, the radiating arms are octagonal frame structures, with four sets arranged in a grid pattern on the dielectric substrate; each set of radiating arms has multiple sets of L-shaped filter branches on its inner edge.

[0009] Furthermore, the filter stub is connected in parallel to the radiating arm.

[0010] Furthermore, the frequency selective surface unit is a 2x2 patch-type frequency selective surface.

[0011] Furthermore, the lower surface of the dielectric substrate is provided with parasitic strip structures corresponding to each group of radiating arm regions.

[0012] Furthermore, the high-frequency radiating unit includes a radiator and a non-metallic structure, with the radiator separated from the rectangular reflective ground by the non-metallic structure. Specifically, the non-metallic structure is made of Arlon AD300A, with a dielectric constant of 3 and a loss tangent of 0.002.

[0013] Furthermore, the radiating arm, balun, feed structure, filter stub, frequency selective surface unit, and parasitic strip structure are all made of copper.

[0014] Furthermore, the dielectric substrate has a dielectric constant of 4.7 and a loss tangent of 0.02.

[0015] Furthermore, the filter stubs are arranged on the four sides of the radiating arm, front, back, left, and right, with two sets of L-shaped filter stubs arranged symmetrically on each side.

[0016] The present invention has the following advantages over the prior art:

[0017] 1. This invention provides a broadband transparent base station antenna based on a multi-technology hybrid approach. By adding an "L"-shaped filter stub to the ring dipole arm (radiating arm), a narrowband transparent frequency point near 2.6 GHz is introduced. Then, a 2*2 patch-type frequency selective surface is introduced, introducing a second transparent frequency point near 2.18 GHz. Subsequently, by adding a parasitic strip below the ring dipole arm, a third transparent frequency point at 1.8 GHz is introduced. These three transparent structures are loaded in parallel on the low-frequency dipole arm, operating independently and without interference. This ultimately achieves a -15 dB broadband impedance bandwidth of 690 MHz to 960 MHz at low frequencies, while simultaneously achieving a broadband transparent effect in the high-frequency 1.7 GHz to 2.7 GHz band.

[0018] 2. This invention provides a broadband transparent base station antenna based on a hybrid multi-technology approach. Unlike traditional, relatively simple transparent structures, this invention uses three independently adjustable transparent structures. This is achieved by adding "L"-shaped filter stubs to the radiating arm and loading parasitic strips on the frequency selection surface and the back of the substrate. These three non-interfering technologies are loaded in parallel on the radiating arm, achieving a -15dB broadband impedance bandwidth of 690MHz-960MHz at low frequencies, while simultaneously providing wide-band transparency of 1.7GHz-2.7GHz at high frequencies.

[0019] 3. This invention provides a broadband transparent base station antenna based on a multi-technology hybrid approach, achieving excellent broadband wave transmission. This invention achieves a wideband wave transmission effect within the 1.7 GHz - 2.7 GHz frequency band by using a combination of three independent control technologies: filter stubs, frequency selective surfaces, and parasitic metal strips. Simultaneously, it maintains the -15dB broadband impedance bandwidth of the low-frequency antenna itself within the 690MHz-960MHz range. The three wave transmission structures are independent of each other, do not interfere with each other, and are easy to control. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a top view of the present invention;

[0023] Figure 3 This is a schematic diagram of the low-frequency radiation unit structure of the present invention;

[0024] Figure 4 This is a top view of the dielectric substrate of the present invention;

[0025] Figure 5 This is a bottom view of the dielectric substrate of the present invention;

[0026] Figure 6 This is a schematic diagram of the high-frequency radiation unit structure of the present invention;

[0027] Figure 7 This is a diagram showing the normalized RCS values ​​corresponding to the frequency-selective surface units of the present invention.

[0028] Figure 8 This is the radiation pattern of the HB unit of the present invention;

[0029] Figure 9 This is a comparison diagram of the HB 3dB beamwidth of the present invention;

[0030] Figure 10 This is a diagram of the S-parameters of the LB antenna of the present invention;

[0031] Figure 11 This is a gain diagram of the LB antenna of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Low-frequency radiating unit; 2. High-frequency radiating unit; 3. Rectangular reflective ground; 4. Dielectric substrate; 11. Radiating arm; 12. Balun; 13. Feeding structure; 14. Filter stub; 15. Frequency selective surface unit; 16. Parasitic strip structure; 17. Radiator; 18. Non-metallic structure. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Example 1

[0037] Figure 1 This is a schematic diagram of the overall structure of the broadband transparent base station antenna provided in this embodiment, which includes a low-frequency radiating element 1, a high-frequency radiating element 2, and a rectangular reflective ground 3. Figure 2 As shown, in the top view, a high-frequency radiation unit 2 is provided at each of the four corners of the low-frequency radiation unit 1. The overall height of the low-frequency radiation unit 1 is 80mm, and its planar dimensions are 130mm × 130mm.

[0038] like Figure 3As shown, the dielectric substrate 4 region is a perspective view, so the parasitic strip structure 16 on the lower surface of the dielectric substrate 4 can be seen. The low-frequency radiating unit 1 includes four radiating arms 11, baluns 12 for supporting the radiating arms 11, a feeding structure 13 for feeding the radiating arms 11, filter stubs 14, 2*2 patch-type frequency selective surface units 15, and parasitic strip structure 16. The radiating arms 11, baluns 12, feeding structure 13, filter stubs 14, 2*2 patch-type frequency selective surface units 15, and parasitic strip structure 16 are all made of copper and are printed on a dielectric substrate made of FR4 (dielectric constant 4.7, loss tangent 0.02). The filter stubs 14 are connected in parallel to the radiating arms 11 and are all located on the upper surface of the dielectric substrate 4. They can be equivalent to an LC parallel resonator, with their long side equivalent to an inductor and the distance between them and the radiating arms 11 equivalent to C, providing a narrow-band filtering effect. The patch-type frequency selective surface unit 15 is arranged in a 2*2 pattern at the center of the inner side of the radiating arm, on the upper surface of the dielectric substrate 4. Together with the radiating arm 11, it forms an LC parallel resonance, providing good wave transmission performance with low pass and high impedance. The parasitic strip structure 16 is located directly below the low-frequency radiating arm 11, on the lower surface of the dielectric substrate, at the corresponding position of the low-frequency radiating arm. Figure 4 and Figure 5 The top and bottom views of dielectric substrate 4 are shown. Figure 6 As shown, the high-frequency radiation unit 2 includes a main radiator 17 and a non-metallic structure 18. The radiator 17 is separated from the rectangular reflective ground 3 by the non-metallic structure 18, and remains ungrounded.

[0039] Most existing interleaved base station antenna designs have narrow transmission bandwidths, making it difficult to achieve broadband operation. Mainstream transmission techniques include adding filter stubs to the low-frequency dipole arm, frequency selective surfaces, chokes, and parasitic structures. However, using any single one of these structures only achieves a narrow-band filtering effect. Further, by combining multiple techniques, the transmission bandwidth can be extended. However, simply mixing multiple techniques, such as connecting various filter stubs of different sizes in series on the dipole arm, often leads to mutual interference of the original transmission structures due to crosstalk from high-frequency induced currents. This makes controlling the transmission performance complex and difficult, significantly increasing design complexity and making it hard to control. It also affects the antenna's own impedance performance, hindering impedance matching.

[0040] This invention proposes an interleaved common-aperture base station antenna that combines three independently tunable wave transmission technologies: filter stubs, frequency selective surfaces, and parasitic strips. By adding an "L"-shaped filter stub to the ring dipole arm, a narrow-band wave transmission frequency near 2.6 GHz is introduced. Then, a 2*2 patch-type frequency selective surface is introduced, introducing a second wave transmission frequency near 2.18 GHz. Subsequently, by adding a parasitic strip below the ring dipole arm, a third wave transmission frequency at 1.8 GHz is introduced. These three wave transmission structures are loaded in parallel on the low-frequency dipole arm, operating independently and without interference. This achieves a wide impedance bandwidth of -15 dB for the low-frequency range of 690 MHz to 960 MHz, while simultaneously achieving a wide wave transmission effect for the high-frequency range of 1.7 GHz to 2.7 GHz.

[0041] Radar Cross Section (RCS) is a crucial concept in radar stealth technology; it's a physical quantity that measures a target's ability to scatter electromagnetic waves. The radar target and the scattered energy can be expressed as the product of an effective area and the incident power density; this area is commonly called the radar cross section. Generally, an antenna with a normalized RCS value ≤ -6dB is considered to have good wave transmission performance. The normalized RCS value of this invention is as follows: Figure 6 As shown.

[0042] Figure 8 The radiation patterns of the HB element under two different conditions are presented. It can be clearly seen that the proposed LB element with a hybrid structure of filter stubs, frequency-selective surfaces, and parasitic stripes can effectively recover the HB radiation pattern with almost no impact on gain. Therefore, this study demonstrates that the proposed multi-technology hybrid ring LB element can effectively recover the HB radiation pattern. The comparison of the 3dB beamwidth of the high-frequency antenna when the low-frequency antenna of this invention is placed in a 1:4 interleaved array is shown in the figure. Figure 9 As shown, after adding the designed low-frequency antenna, the 3dB beamwidth of the high-frequency antenna remains very stable without any obvious abrupt change, verifying the reliability of its transmission performance across the entire frequency band. When the low-frequency antenna is not loaded with a frequency-selective surface, the high-frequency beamwidth exhibits a significant dip around 2.1GHz. When the low-frequency antenna is not loaded with a filter stub, the high-frequency beamwidth increases around 2.5GHz, deteriorating the transmission performance. When the low-frequency antenna is not loaded with a back parasitic strip, it can be seen that the high-frequency beamwidth around 1.8GHz increases, showing poor agreement with the high-frequency dipole beamwidth without the low-frequency antenna.

[0043] The low-frequency antenna performance of the present invention is as follows: Figure 10 , Figure 11As shown, the VSWR is less than 1.4 (S11 & S22 are approximately -15dB), the bandwidth range is 690 MHz ~ 960 MHz, and the low-frequency antenna gain is greater than 7.8dB. It can be seen that the low-frequency antenna itself is working normally.

[0044] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A broadband transparent-wave base station antenna based on a multi-technology hybrid approach, characterized in that, include: A rectangular reflective ground (3), and a low-frequency radiating unit (1) disposed in the middle region thereof; Multiple sets of high-frequency radiation units (2) are uniformly arranged on the rectangular reflective ground (3) area around the low-frequency radiation unit (1).

2. The broadband transparent base station antenna based on multi-technology hybrid technology according to claim 1, characterized in that, The low-frequency radiation unit (1) includes a feeding structure (13) disposed on a rectangular reflective ground (3), the feeding structure (13) being connected to the dielectric substrate (4) via a balun (12); a radiation arm (11) is disposed on the upper surface of the dielectric substrate (4); a frequency selective surface unit (15) is disposed on the region of the dielectric substrate (4) within the radiation arm (11); and a parasitic strip structure (16) is disposed on the lower surface of the dielectric substrate (4).

3. The broadband transparent base station antenna based on multi-technology hybrid technology according to claim 2, characterized in that, The radiation arm (11) is an octagonal frame structure, and there are four sets of them on the dielectric substrate (4) arranged in a grid pattern; each set of radiation arm (11) has multiple sets of L-shaped filter branches (14) on the inner side of its edge.

4. The broadband transparent base station antenna based on multi-technology hybrid technology according to claim 3, characterized in that, The filter stub (14) is connected in parallel to the radiating arm (11).

5. The broadband transparent base station antenna based on multi-technology hybridization according to claim 4, characterized in that, The frequency selective surface unit (15) is a 2x2 patch-type frequency selective surface.

6. The broadband transparent base station antenna based on multi-technology hybridization according to claim 5, characterized in that, The lower surface of the dielectric substrate (4) is provided with parasitic strip structures (16) corresponding to the region of each group of radiating arms (11).

7. The broadband transparent base station antenna based on multi-technology hybrid technology according to claim 6, characterized in that, The high-frequency radiation unit (2) includes a radiator (17) and a non-metallic structure (18), with the radiator (17) separated from the rectangular reflective ground (3) by the non-metallic structure (18).

8. The broadband transparent base station antenna based on multi-technology hybrid technology according to claim 7, characterized in that, The radiating arm (11), balun (12), feed structure (13), filter stub (14), frequency selective surface unit (15), and parasitic strip structure (16) are all made of copper.

9. The broadband transparent base station antenna based on multi-technology hybrid technology according to claim 8, characterized in that, The dielectric constant of the dielectric substrate (4) is 4.7 and the loss tangent is 0.

02.

10. The broadband transparent base station antenna based on multi-technology hybridization according to claim 9, characterized in that, The filter stubs (14) are set on the four sides of the front, back, left and right of the radiating arm (11), and two sets of L-shaped filter stubs (14) are set on each side and are symmetrical to each other.

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