An antenna radiating arm, an antenna radiating unit and a multi-frequency array antenna

Abstract

An antenna radiation arm, an antenna radiation unit and a multi-frequency array antenna, each pair of dipoles of the antenna radiation unit comprises two oppositely arranged antenna radiation arms, the antenna radiation arms have a ring-shaped conductive structure, and an inductive circuit structure is arranged on the conductive structure to extend the electrical length of the conductive structure, which realizes the miniaturization of the physical size on the one hand, and enables the antenna to pass through the first frequency band signal and filter out the second frequency band signal on the other hand, reduces the mutual coupling between the array elements in the design environment with limited array height and space, and reduces the influence of the low-frequency antenna on the high-frequency antenna radiation performance. The antenna radiation arm comprises a driving arm and a parasitic arm, the driving arm is connected to a feed balun and has two radiation branches; the two ends of the parasitic arm are opposite to the two radiation branches of the driving arm, and enclose the ring-shaped conductive structure; the two radiation branches of the driving arm are coupled to the two ends of the parasitic arm through a capacitive structure, and form a resonance to the first frequency band signal, thereby widening the impedance bandwidth.

Description

Technical Field

[0001] This invention relates to base station antennas, specifically to an antenna radiating arm, an antenna radiating element, and a multi-frequency array antenna. Background Technology

[0002] Cellular base station antennas typically consist of low-frequency and high-frequency arrays located on the same reflecting plane. This can be achieved by staggering the low-frequency and high-frequency elements or arranging them in a coaxial array. The continuous pursuit of low-profile base station antennas demands smaller radiating element dimensions and reduced spacing between high- and low-frequency elements. Particularly for base station antenna systems requiring wide-bandwidth and high-gain radiating elements, multiple coupled radiating elements may be necessary, which can broaden the bandwidth coverage compared to single antenna elements. In this regard, dipole antennas and patch antennas can be effective, for example, in BTS antenna arrays with stacked coupled radiators.

[0003] In this type of base station antenna structure, the low-frequency element is typically located above the high-frequency element, and the dipole arm extends on the radiation plane sharing the same aperture as the high-frequency antenna. When the low-frequency and high-frequency elements are close together, strong mutual coupling can cause various adverse effects, reducing the antenna's bandwidth coverage and radiation performance in both frequency bands. Therefore, the challenge facing BTS antennas remains how to design low-profile antenna elements with a wide bandwidth for the low-frequency array while minimizing the impact on the high-frequency array, in order to achieve the radiation performance required for a common-aperture base station antenna. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an antenna radiating arm, an antenna radiating element, and a multi-frequency array antenna that can reduce the influence of low-frequency antennas on the radiation performance of high-frequency antennas.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: an antenna radiating arm, which has a ring-shaped conductive structure, and an inductive circuit structure that extends its electrical length on the conductive structure, so that it can conduct a first frequency band electrical signal and filter out a second frequency band electrical signal. The antenna radiating arm includes a driving arm and a parasitic arm. The driving arm is connected to a feed balun and has two radiating branches. The two ends of the parasitic arm are respectively opposite to the two radiating branches of the driving arm, forming the ring-shaped conductive structure. The two radiating branches of the driving arm are respectively coupled to the two ends of the parasitic arm through a capacitor structure, and resonate with the first frequency band electrical signal.

[0006] The drive arm is coupled to the power supply balun and resonates with the first frequency band electrical signal.

[0007] The inductive circuit structure has one or more distributed on the parasitic arm and / or the driving arm.

[0008] Furthermore, multiple inductive circuit structures distributed on the parasitic arm are spaced apart from each other, so that the parasitic arm generates a current zero point in response to the second frequency band electrical signal.

[0009] The parasitic arm has auxiliary branches at both ends that extend into the closed-loop conductive structure to change its electrical length.

[0010] The auxiliary branch is equipped with an inductive circuit structure for changing the electrical length.

[0011] The two ends of the parasitic arm are connected by a bridging circuit.

[0012] The present invention also provides an antenna radiating element comprising two pairs of dipoles, each pair of dipoles comprising two oppositely arranged antenna radiating arms as described above.

[0013] The present invention also provides a multi-frequency array antenna, comprising one or more first radiating elements having the antenna radiating element structure described above, and one or more second radiating elements; the first radiating element operates in a first frequency band, the second radiating element operates in a second frequency band, and the frequency of the second frequency band is greater than that of the first frequency band; the plane on which the first radiating element is located is above the second radiating element, and exhibits wave transmission characteristics for the radiated waves of the second frequency band.

[0014] The second radiating unit has multiple rows and columns, and the first radiating unit is offset from the second radiating unit in the direction of rows and columns.

[0015] The beneficial effects of this invention are as follows: The antenna radiating arm extends the electrical length of its annular conductive structure by setting an inductive circuit structure. On the one hand, this achieves miniaturization of the physical size; on the other hand, while ensuring the conduction of electrical signals in its operating frequency band, it can filter out electrical signals in higher frequency bands, making the radiating structure electrically transparent to other antenna radiating structures operating in higher frequency bands. This reduces the mutual coupling between array elements in design environments with limited array height and space, and reduces the impact of low-frequency antennas on the radiation performance of high-frequency antennas. The antenna radiating arm is divided into a driving arm and a parasitic arm. Energy from the driving arm is coupled to the parasitic arm through a capacitor structure, generating resonance in its operating frequency band, thereby widening the impedance bandwidth. Attached Figure Description

[0016] Figure 1 It is part of the antenna radiating arm of this invention.

[0017] Figure 2 This is a schematic diagram of an antenna radiating arm of the present invention.

[0018] Figure 3 This is a schematic diagram of a pair of dipoles composed of two antenna radiating arms of the present invention.

[0019] Figure 4 This is one embodiment of the antenna radiating element of the present invention.

[0020] Figure 5 This is a side view of the antenna radiating element of the present invention.

[0021] Figure 6 This is a side view of the dual-frequency antenna of the present invention.

[0022] Figure 7 This is a schematic diagram of the dual-frequency dual-polarization array antenna of the present invention.

[0023] Figure 8 This is a schematic diagram of the dual-frequency dual-polarized antenna array arrangement of the present invention.

[0024] Figure 9 yes Figure 8 The bandwidth response of the antenna subarray shown.

[0025] Figure 10 yes Figure 8 The antenna shown has a row subarray bandwidth response.

[0026] Figure 11 It is the horizontal plane gain of the low-frequency band column -45° polarization subarray at various frequency points within the 690MHz - 960MHz frequency band range.

[0027] Figure 12 It is the low-frequency band column -45° polarizer array vertical plane gain at various frequency points within the 690MHz - 960MHz frequency band range.

[0028] Figure 13 It is a horizontal plane gain diagram of the low-frequency band column +45° polarization subarray at various frequency points in the range of 690MHz - 960MHz.

[0029] Figure 14 It is a gain diagram of the vertical plane of the low-frequency band column +45° polarization subarray at various frequency points in the range of 690MHz - 960MHz.

[0030] Figure 15 It is the horizontal plane gain of the high-frequency 8-element array -45° polarization subarray at various frequency points within the 1427MHz-2690MHz frequency band.

[0031] Figure 16 It is the vertical plane gain of the high-frequency 8-element array -45° polarization subarray at various frequency points within the 1427MHz-2690MHz frequency band.

[0032] Figure 17It is the horizontal gain of the high-frequency 8-element array + 45° polarization subarray at various frequency points within the 1427MHz-2690MHz frequency band.

[0033] Figure 18 It is the vertical plane gain of the high-frequency 8-element array + 45° polarization subarray at various frequency points within the 1427MHz-2690MHz frequency band.

[0034] Figure 19 This is the second embodiment of the antenna radiating element of the present invention.

[0035] Figure 20 This is the third embodiment of the antenna radiating element of the present invention.

[0036] The diagram is labeled as follows: 1. Antenna radiating arm, 2. Inductive circuit structure, 3. Capacitor structure, 4. Drive arm, 5. Radiating branch, 6. Parasitic arm, 7. Feed balun, 8. Feed port, 9. Auxiliary branch, 10. High-frequency radiating element, 11. Low-frequency radiating element, 12. Reflector, 13. High-frequency element column, 14. High-frequency element row, 15. Low-frequency element column, 16. Low-frequency element row, 17. Bridge circuit, 18. Open end, 19. Auxiliary dipole. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. The specific contents listed in the following embodiments are not limited to the technical features necessary to solve the technical problem described in the claims. Furthermore, the enumerations are merely a part of the present invention, and not all of the embodiments.

[0038] like Figure 1 and 2 As shown, the conductive surface of the antenna radiating arm of the present invention has a ring-shaped conductive structure with a series of spaced-apart electrical response characteristic segments. Components or lines with inductive characteristics can extend the electrical length of the conductive structure, enabling miniaturization of the physical size while maintaining sufficient electrical length. The extension distance of the antenna radiating arm can be much less than half the minimum operating wavelength of the antenna. For example... Figure 1 Inductive circuit structure 2 and Figure 2 As shown, L0, L1, L2, L3, and L4 can be structurally constructed using bent transmission lines or other slow-wave structures. By extending the electrical length through multiple phase-spaced inductive circuit structures 2, the antenna radiating arm can filter out the induced current formed on it by the radiating arm in the second frequency band while operating in the first frequency band, thereby reducing interference.

[0039] like Figure 3 As shown, the two antenna radiating arms are arranged opposite each other, forming a pair of dipoles. The two pairs of dipoles are arranged crosswise, as shown... Figure 4 The antenna radiating element shown is polarized at ±45°. This antenna radiating element operates in the first frequency band, and its conductive surface allows radiated waves from the second frequency band to pass through.

[0040] exist Figure 6 and 7 In the illustrated dual-band array antenna embodiment, the low-frequency radiating element 11 has the antenna radiating arm structure described in this invention. Utilizing the transmission line structure of this antenna radiating arm and the inductive circuit structure, such as a slow-wave structure, the induced high-frequency signal current from the high-frequency radiating element 10 travels a relatively long path within a relatively short physical distance relative to the operating wavelength of the high-frequency radiating element, and multiple surface current zeros are formed on this structure, equivalent to open-circuit points on the transmission line. These open-circuit points can generate isolated short transmission line segments, appearing as near-coupled short stubs or disconnected conductive surfaces to high-frequency radiated waves, thus allowing high-frequency radiated waves to pass through the conductive surface of the antenna radiating arm without interference. The plane extended by the low-frequency radiating element 11 is electrically transparent to the radiated waves emitted by the high-frequency radiating element 10 below it, reducing the coupling effect between the low-frequency and high-frequency band antennas and preventing the low-frequency radiating element from adversely affecting the performance of the high-frequency radiating element below it.

[0041] like Figure 2 As shown in Figure 5, the antenna radiating arm 1 is divided into two parts: a driving arm 4 and a parasitic arm 6. The driving arm 4 is connected to the feed balun 7 and is fed by the feed balun 7. The driving arm 4 extends from the feed end to both sides, forming two symmetrical radiating branches 5. The parasitic arm 6 has a semi-enclosed structure, with its two ends facing the two radiating branches 5 of the driving arm 4, forming a ring-shaped conductive structure with the driving arm 4. The two radiating branches 5 are coupled to the two ends of the parasitic arm 6 through components or lines with capacitive characteristics, such as… Figure 2 The C0 shown and Figure 3 and 4 The capacitor structure 3 shown can be an interdigitated capacitor or other capacitor structures. Capacitor structure 3 widens the impedance bandwidth by coupling energy from the first frequency band of the dipole driving arm to the parasitic arm of the dipole. The parasitic arm can be configured to have an equivalent electrical length close to half the wavelength of the resonant mode of that frequency band.

[0042] The electrical length can also be changed by setting an inductive circuit structure 2 on the drive arm 4 as needed. The number of inductive circuit structures 2 on the drive arm 4 or the parasitic arm 6 can be set as needed, and can be one or more.

[0043] like Figure 4As shown, auxiliary branches 9 can also be provided at both ends of the parasitic arm 6. These auxiliary branches 9 extend inwards into the closed-loop conductive structure, further extending the electrical length of the parasitic arm 6. Furthermore, an inductive circuit structure for changing the electrical length can also be provided on the auxiliary branches 9. These auxiliary branches 9, together with the inductive circuit structure of the parasitic arm 6, are used to extend the electrical length of the arm in the second frequency band (e.g., the high-frequency band) to generate a current zero point on each folded arm of the dipole, thereby minimizing the impact of the low-frequency radiation unit on the... Figure 7 The influence of the high-frequency radiating element in the antenna configuration shown.

[0044] The driving arm 4 of the antenna radiating arm 1 can be connected to the feed balun 7 by coupling, so that the dipole antenna radiating element exhibits a dual resonant response. The first resonant mode is generated by the driving arm coupled to the feed balun structure, and the second resonant mode is generated by the capacitive coupling from the driving arm to the parasitic arm, so that the antenna radiating element obtains better performance.

[0045] The antenna radiating element of this invention, featuring the aforementioned antenna radiating arm structure, primarily addresses the interference problem of upper radiating elements to lower radiating elements in multi-frequency array antennas. The number and array configuration of the radiating elements are determined according to antenna requirements. For example, one or more first radiating elements and one or more second radiating elements are arranged in an array on a reflector. The first radiating elements operate in a lower frequency first band, while the second radiating elements operate in a higher frequency second band. The unfolded plane of the radiating arm of the lower-frequency first radiating element is located above the second radiating element. By employing the aforementioned antenna radiating element structure, the first radiating element exhibits transparency characteristics to the second frequency band radiated waves, thus reducing interference. In multi-frequency array antennas with more frequency bands, following this principle, the upper radiating element always has an antenna radiating arm structure that exhibits transparency characteristics to the radiated waves of the operating frequency band of the radiating elements below it.

[0046] Figure 9The described model is a multi-band base station antenna with high-frequency and low-frequency subarrays. The high-frequency radiating element 10 and the low-frequency radiating element 11 have multiple rows and columns. The low-frequency radiating elements are offset from the high-frequency radiating elements in the row and column directions, and the radiating arms of the low-frequency radiating elements shield the high-frequency radiating elements. The low-frequency radiating elements cover a frequency band of 690MHz to 960MHz, with a return loss higher than 14dB. At 700MHz, the profile of each 45° polarization element is 0.32λ multiplied by 0.26λ. The high-frequency radiating elements covering the 1400MHz to 2690MHz band have a return loss exceeding 14dB. If conventional or existing dipole antennas are used to meet these bandwidth requirements, the large span of the low-frequency band elements above the high-frequency band elements, and the significant reflection and diffraction of the radiated waves on the metal surfaces of the low-frequency band elements, will lead to mutual coupling, impedance mismatch, pattern distortion, and a decrease in gain in the high-frequency band. The lowest operating wavelength in the low-frequency band (960 MHz) is approximately 1.5 times that of the lowest operating wavelength in the high-frequency band. Therefore, the mutual coupling between low-frequency and high-frequency components can significantly affect the performance of high-frequency antennas. By employing an antenna radiating element with the radiating arm structure described in this invention, a long current path is established through a slow-wave structure integrated into the radiating arm of the low-frequency antenna element. This minimizes the reflection and diffraction of high-frequency signals on its radiating surface, thereby reducing higher-order mode resonances across the entire high-frequency band. Simultaneously, phase currents from the high-frequency components are filtered out and effectively prevented from forming on the radiating arm of the low-frequency components, thus minimizing the reflection and diffraction of high-frequency band radiated waves. Figure 9 — Figure 18 As shown, the bandwidth response, represented by the S-parameter frequency, scans each frequency band. Figure 9 In Figure 10, the S-parameter curve represented by (Pi, Pi) indicates the port reflection coefficient in the row subarray of the low-frequency band element; (Pi, Pj) represent the port-to-port isolation between elements in the row subarray, respectively. The S-parameter representation for high-frequency scanning in Figure 10 is the same as that for low-frequency and high-frequency antennas. According to the test results, the antenna array using the structure described in this invention has good performance and fully meets the requirements for antenna miniaturization and high performance.

[0047] The transmission line structure of antenna radiating arm 1 and the specific form of its inductive circuit structure can be adjusted as needed. For example... Figure 19 As shown, on the drive arm 4, a pair of auxiliary dipoles 19 extend from the location where it connects to the feed balun to enhance the antenna radiation performance. Or as... Figure 20The parasitic arm 6 is shown to be connected to the two ends of the radiating branch 5 of the driving arm via a bridging circuit 17, with the end of the parasitic arm 6 furthest from the driving arm being set as an open end. It will be apparent to those skilled in the art that the geometry and position of each slow-wave structure integrated into the radiating surface of the disclosed low-frequency band antenna element, and which is crucial for its miniaturization, can be modified and optimized for a given interleaved multi-band antenna array to meet specific performance requirements. This can be accomplished using commercial electromagnetic simulation software and parametric algorithms.

[0048] The above description of specific embodiments is only for the purpose of helping to understand the technical concept and core idea of ​​the present invention. Although specific preferred embodiments have been used to describe and illustrate the technical solutions, they should not be construed as limiting the present invention itself. Those skilled in the art can make various changes in form and detail without departing from the technical concept of the present invention. These easily conceived changes or substitutions should all be covered within the protection scope of the present invention.

Claims

1. An antenna radiating arm having a ring-shaped conductive structure, the antenna radiating arm (1) comprising a driving arm (4) and a parasitic arm (6), the driving arm (4) being connected to a feed balun (7) and having two radiating branches (5); the two ends of the parasitic arm (6) being opposite to the two radiating branches (5) of the driving arm (4), respectively, forming the ring-shaped conductive structure, characterized in that: The conductive structure is provided with multiple inductive circuit structures (2) in the form of slow wave structures that extend its electrical length, so that the induced high-frequency signal current from the high-frequency radiation unit travels a relatively long path within a physical distance that is relatively short relative to the working wavelength of the high-frequency radiation unit, and multiple surface current zeros are formed on the structure, so that it can conduct low-frequency first frequency band electrical signals and filter out high-frequency second frequency band electrical signals. The inductive circuit structure (2) is distributed in multiple ways on the parasitic arm (6) and the driving arm (4); the multiple inductive circuit structures (2) distributed on the parasitic arm (6) are spaced apart from each other, so that the parasitic arm generates a current zero point for the second frequency band electrical signal; The drive arm (4) is coupled to the feed balun (7) and resonates with the first frequency band electrical signal. The two radiating branches (5) of the drive arm (4) are coupled to the two ends of the parasitic arm (6) through the capacitor structure (3) and resonate with the first frequency band electrical signal, so that the dipole antenna radiating element exhibits a double resonance response. The parasitic arm (6) has auxiliary branches (9) extending into the inner side of the annular conductive structure at both ends facing the driving arm (4) to change its electrical length. The auxiliary branches (9) are provided with inductive circuit structures for changing the electrical length. On the drive arm (4), a pair of auxiliary dipoles (19) extend from the location where it is connected to the feed balun to enhance the antenna radiation performance.

2. An antenna radiating element, characterized in that: It includes two pairs of dipoles, each pair of dipoles including two oppositely arranged antenna radiating arms as described in claim 1.

3. A multi-frequency array antenna, characterized in that: It includes one or more first radiating elements having the antenna radiating element structure of claim 2, and one or more second radiating elements; the first radiating element operates in a first frequency band, the second radiating element operates in a second frequency band, and the frequency of the second frequency band is greater than that of the first frequency band; the plane on which the first radiating element is located is above the second radiating element, and exhibits wave transmission characteristics for the radiated waves of the second frequency band.

4. A multi-frequency array antenna as described in claim 3, characterized in that: The second radiating unit has multiple rows and columns, and the first radiating unit is offset from the second radiating unit in the direction of rows and columns.

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