CN115133277A

CN115133277A - Antenna radiation arm, antenna radiation unit and multi-frequency array antenna

Info

Publication number: CN115133277A
Application number: CN202210600550.1A
Authority: CN
Inventors: 盖伊·约瑟夫; 高永杰; 岳彩龙; 梁兆标; 刘木林; 惠俊明
Original assignee: Tongyu Zhongshan Wireless Technology Research Institute Co ltd; Tongyu Communication Inc
Current assignee: Tongyu Zhongshan Wireless Technology Research Institute Co ltd; Tongyu Communication Inc
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2022-09-30

Abstract

Each pair of dipoles of the antenna radiation unit comprises two oppositely arranged antenna radiation arms, each antenna radiation arm is provided with an annular conductive structure, and the conductive structure is provided with an inductive circuit structure for prolonging the electrical length of the antenna radiation arm, so that the miniaturization of the physical size is realized, the first frequency band electrical signals can be conducted, the second frequency band electrical signals can be filtered, the mutual coupling between array elements is reduced in the design environment with limited array height and space, and the influence of the low-frequency antenna on the radiation performance of the high-frequency antenna is reduced. The antenna radiation arm comprises a driving arm and a parasitic arm, wherein the driving arm is connected with the feed balun and is provided with two radiation branches; two ends of the parasitic arm are respectively opposite to the two radiation branches of the driving arm, and the parasitic arm is encircled to form the annular conductive structure; the two radiation branches of the driving arm are respectively coupled to two ends of the parasitic arm through a capacitance structure and resonate the first frequency band electric signal, so that the impedance bandwidth is widened.

Description

Antenna radiation arm, antenna radiation unit and multi-frequency array antenna

Technical Field

The invention relates to a base station antenna, in particular to an antenna radiation arm, an antenna radiation unit and a multi-frequency array antenna.

Background

Cellular base station antennas typically have low and high frequency arrays that lie in the same reflection plane. The method can be realized by staggering the low-frequency array elements and the high-frequency array elements or arranging the low-frequency array elements and the high-frequency array elements in a coaxial array. In the continuous pursuit of low-profile base station antennas, the shape and size of the radiating elements are required to be small, and the spacing between the high-frequency and low-frequency elements is required to be reduced. Especially for base station antenna systems requiring radiating elements with wide frequency band and high gain, it may be necessary to use multiple coupled radiating elements, which may broaden the bandwidth coverage compared to a single antenna element. In this respect, dipole and patch antennas may produce good results, such as is very useful in BTS antenna arrays with stacked coupled radiators.

In such a base station antenna structure, the low frequency element is usually located above the high frequency element, and the dipole arms are spread out in a radiating plane that is co-aperture with the high frequency antenna. When the low frequency unit and the high frequency unit are close to each other, strong mutual coupling can generate various adverse effects, the bandwidth coverage of the antenna is reduced, and the radiation performance of the antenna in two frequency bands is reduced. Thus, the problem facing BTS antennas remains how to design low profile antenna elements with a broad frequency band for low frequency arrays while at the same time having minimal impact on the high frequency array to achieve the desired radiation performance of the co-aperture base station antenna.

Disclosure of Invention

The invention aims to provide an antenna radiation arm, an antenna radiation unit and a multi-frequency array antenna which can reduce the influence of a low-frequency antenna on the radiation performance of a high-frequency antenna.

The technical scheme adopted by the invention for solving the technical problems is as follows: an antenna radiation arm is provided with an annular conductive structure, an inductive circuit structure for prolonging the electrical length of the conductive structure is arranged on the conductive structure, so that the antenna radiation arm can conduct a first frequency band electrical signal and filter a second frequency band electrical signal, the antenna radiation arm comprises a driving arm and a parasitic arm, the driving arm is connected with a feed balun and is provided with two radiation branches; two ends of the parasitic arm are respectively opposite to the two radiation branches of the driving arm, and the two radiation branches are encircled to form the annular conductive structure; the two radiation branches of the driving arm are respectively coupled to two ends of the parasitic arm through a capacitance structure and form resonance to the first frequency band electric signals.

The driving arm is coupled with the feed balun and resonates the first frequency band electric signal.

One or more inductive circuit structures are distributed on the parasitic arm and/or the driving arm.

Furthermore, a plurality of inductive circuit structures distributed on the parasitic arm are arranged at intervals, so that a current zero point is generated on the parasitic arm aiming at the second frequency band electric signal.

And two ends of the parasitic arm are provided with auxiliary branches which extend towards the inner side of the closed-loop conductive structure and are used for changing the electrical length of the closed-loop conductive structure.

And the auxiliary branch is provided with an inductive circuit structure for changing the electric length.

The two ends of the parasitic arm are connected through a bridge circuit.

The invention also provides an antenna radiation unit, which comprises two pairs of dipoles, wherein each pair of dipoles comprises two antenna radiation arms which are oppositely arranged.

The invention also provides a multi-frequency array antenna, which comprises one or more first radiation units and one or more second radiation units, wherein the first radiation units are provided with the antenna radiation unit structures; the first radiating unit works in a first frequency band, the second radiating unit works in a second frequency band, the frequency of the second frequency band is greater than that of the first frequency band, and the plane where the first radiating unit is located above the second radiating unit and shows wave-transparent characteristics to the second frequency band radiated waves.

The second radiation unit is provided with a plurality of rows and a plurality of columns, and the first radiation unit is staggered with the second radiation unit in the row and column directions.

The invention has the beneficial effects that: the antenna radiation arm is provided with the inductive circuit structure to prolong the electrical length of the annular conductive structure, so that the miniaturization of physical size is realized, the conduction of the electrical signals of the working frequency band is met, the electrical signals of a higher frequency band can be filtered, the radiation structure is electrically transparent to other antenna radiation structures working at the higher frequency band, the mutual coupling between array elements can be reduced in the design environment with limited array height and space, and the influence of a low-frequency antenna on the radiation performance of a high-frequency antenna is reduced. The antenna radiation arm is divided into a driving arm and a parasitic arm, and energy from the driving arm is coupled to the parasitic arm through a capacitor structure to generate resonance in the working frequency band, so that the impedance bandwidth is widened.

Drawings

Fig. 1 is a portion of the radiating arm of the antenna of the present invention.

Fig. 2 is a schematic view of an antenna radiating arm of the present invention.

Fig. 3 is a schematic diagram of a pair of dipoles formed by two antenna radiating arms according to the present invention.

Fig. 4 is an embodiment of the antenna radiating element of the present invention.

Fig. 5 is a side view of the radiating element of the antenna of the present invention.

Fig. 6 is a side view of the dual band antenna of the present invention.

Fig. 7 is a schematic diagram of a dual-frequency dual-polarized array antenna of the present invention.

Fig. 8 is a schematic layout diagram of the dual-frequency dual-polarized antenna array according to the present invention.

Fig. 9 is a bandwidth response of the antenna sub-array of fig. 8.

Fig. 10 is a row sub-element bandwidth response of the antenna shown in fig. 8.

FIG. 11 is the horizontal planar gain of a low band column-45 polarized subarray for each frequency point in the 690MHz-960MHz frequency band.

FIG. 12 is a low band column-45 ° polarising subarray vertical plane gain for each frequency point in the 690MHz-960MHz frequency band

FIG. 13 is a horizontal planar gain plot of a low band column +45 polarized subarray for each frequency point in the 690MHz-960MHz range.

FIG. 14 is a plot of the low band column +45 ° polarising subarray vertical in-plane gain for each frequency point in the range 690MHz to 960 MHz.

FIG. 15 shows the horizontal plane gain of the high-band 8-array element column-45 ° polarizator sub-array for each frequency point in the frequency band range of 1427MHz to 2690 MHz.

FIG. 16 is the vertical planar gain of a high band 8 array element column-45 ° polarizator sub-array for each frequency point in the 1427MHz-2690MHz frequency band.

FIG. 17 shows the horizontal gain of the high-band 8-array element column + 45-degree polarizator sub-array for each frequency point in the frequency band range of 1427MHz to 2690 MHz.

FIG. 18 shows the vertical planar gain of the high band 8 array element column +45 ° polarizator sub-array for each frequency point in the frequency band range of 1427MHz-2690 MHz.

Fig. 19 is a second embodiment of the antenna radiating element of the present invention.

Fig. 20 is a third embodiment of the antenna radiating element of the present invention.

The mark in the figure is: 1. antenna radiating arm, 2, inductive circuit structure, 3, capacitive structure, 4, driving 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 Description

The technical scheme of the invention is clearly and completely described below with reference to the accompanying drawings and the detailed description. The specific contents listed in the following examples are not limited to the technical features necessary for solving the technical problems to be solved by the technical solutions described in the claims. Meanwhile, the list is that the embodiment is only a part of the present invention, and not all embodiments.

As shown in fig. 1 and 2, the conductive surface of the radiating arm of the antenna of the present invention has a loop-shaped conductive structure with a series of electrically reactive segments spaced apart on the conductive structure. The element or line with inductive properties may extend the electrical length of the conductive structure, allowing it to be miniaturized in physical dimensions while having sufficient electrical length, and the antenna radiating arm may extend over a distance much less than half the lowest operating wavelength of the antenna. For example inductive circuit configuration 2 in fig. 1 and L in fig. 2 ₀ 、L ₁ 、L ₂ 、L ₃ 、L ₄ The structure can adopt a bent transmission line or other slow wave structures. The inductive circuit structures 2 arranged at intervals are arranged to prolong the electrical length, so that the antenna radiation arm can filter the induced current formed on the antenna radiation arm by the second frequency band while working in the first frequency band, thereby reducing the interference.

As shown in fig. 3, two antenna radiating arms are oppositely arranged to form a pair of dipoles. The two pairs of dipoles are arranged crosswise and constitute, as shown in fig. 4, a ± 45 ° polarized antenna radiating element operating in a first frequency band, the conductive surface of which allows the radiated waves of a second frequency band to pass through.

In the dual-band array antenna embodiment shown in fig. 6 and 7, the low-frequency radiating element 11 has an antenna radiating arm structure according to the present invention. With the transmission line structure of the antenna radiating arm and the inductive circuit structure arranged, for example, in the form of a slow-wave structure, the induced high-frequency signal current from the high-frequency radiating element 10 is caused to travel a relatively long path within a relatively short physical distance with respect to the operating wavelength of said high-frequency radiating element, and a plurality of surface current nulls, which are equivalent to open points on the transmission line, are formed on the structure. Such open points may create isolated short transmission line segments that appear as close to the coupling stub or open conductive surface to the high frequency radiated wave, thus allowing the high frequency radiated wave to pass through the conductive surface of the antenna radiating arm without interference. The plane formed by the extension of the low-frequency radiating element 11 has the characteristic of electric transparency for the radiation wave emitted by the high-frequency radiating element 10 below the plane, so that the coupling effect of the low-frequency band and high-frequency band antennas is reduced, and the low-frequency radiating element is prevented from generating adverse effects on the performance of the high-frequency radiating element below the low-frequency radiating element.

As shown in fig. 2 to 5, the antenna radiation arm 1 is divided into a driving arm 4 and a parasitic arm 6. The drive arm 4 is connected to a feed balun 7, and is fed by the feed balun 7. The driving arm 4 extends from the feeding end to both sides to form two symmetrical radiating branches 5. The parasitic arm 6 is in a semi-enclosed structure, and two ends of the parasitic arm are respectively opposite to the two radiation branches 5 of the driving arm 4 and enclose an annular conductive structure with the driving arm 4. The two radiating branches 5 are coupled to the two ends of the parasitic arm 6 by means of elements or lines having capacitive characteristics, such as C0 shown in fig. 2 and the capacitive structure 3 shown in fig. 3 and 4, which may be in the form of interdigital capacitors or other capacitive structures. The capacitive structure 3 resonates by coupling energy from the first frequency band of the dipole driving arm to the parasitic arm of the dipole, thereby widening the impedance bandwidth. The parasitic arm may be configured to have an equivalent electrical length that is close to a half wavelength of the resonant mode of the frequency band.

The drive arm 4 may be provided with an inductive circuit structure 2 to change the electrical length, if necessary. The number of inductive circuit structures 2 on the driving arm 4 or the parasitic arm 6 may be one or more, as desired.

As shown in fig. 4, auxiliary branches 9 may be further provided at both ends of the parasitic arm 6, and the auxiliary branches 9 extend toward the inner side of the closed-loop conductive structure, so as to further extend the electrical length of the parasitic arm 6. Furthermore, the auxiliary branch 9 may be provided with an inductive circuit configuration for varying the electrical length. This auxiliary branch 9, together with the inductive circuit structure of the parasitic arm 6, serves to extend the electrical length of the arm in the second frequency band, e.g. the high frequency band, so as to create a current zero on each folded arm of the dipole, thereby minimizing the effect of the low frequency radiating element on the high frequency radiating element in the antenna configuration shown in fig. 7.

The driving arm 4 of the antenna radiation arm 1 can be connected with the feed balun 7 in a coupling mode, so that the dipole antenna radiation unit shows double resonance response, wherein the first resonance mode is generated by the driving arm coupled to the feed balun structure, and the second resonance mode is generated by the capacitive coupling of the driving arm to the parasitic arm, so that the antenna radiation unit obtains better performance.

The antenna radiation unit with the antenna radiation arm structure mainly aims at the problem that an upper radiation unit in a multi-frequency array antenna interferes with a lower radiation unit. The number and the array mode of the radiating units are set according to the antenna requirements. For example, one or more first radiating elements, and one or more second radiating elements, and are arrayed on a reflector plate. The first radiating unit works in a first frequency band with lower frequency, and the second radiating unit works in a second frequency band with higher frequency. The plane of the first radiation unit with lower working frequency is arranged above the second radiation unit. The first radiating unit adopts the structure of the antenna radiating unit, so that the first radiating unit has wave-transparent characteristics on the second frequency band radiating waves, and the interference can be reduced. In a multi-frequency array antenna having more frequency bands, following this principle, the radiation element located above always has an antenna radiation arm structure that exhibits wave-transparent characteristics for the radiation wave of the operating frequency band of the radiation element below.

Fig. 9 illustrates a multi-band base station antenna model having a high-frequency sub-array and a low-frequency sub-array, where the high-frequency radiating element 10 and the low-frequency radiating element 11 have a plurality of rows and a plurality of columns, the low-frequency radiating element is staggered from the high-frequency radiating element in the row and column directions, and the radiating arm of the low-frequency radiating element is shielded above the high-frequency radiating element. The low-frequency radiation unit covers a frequency band within a range of 690MHz-960MHz, and return loss is higher than 14 dB. At 700MHz, the cross-section of each 45 polarization element is 0.32 x 0.26 x. The return loss of the high-frequency radiation unit covering the 1400 MHz-2690MHz frequency band is more than 14 dB. If conventional or prior art dipole antennas are used to meet these bandwidth requirements, cross-coupling, impedance mismatch, pattern distortion, and gain degradation in the high band may result due to the large amplitude spanned by the low band elements over the high band elements, and the significant reflection and diffraction of the radiated wave at the metal surface of the low band elements. The lowest operating wavelength of the low band of 960MHz is about 1.5 times the lowest operating wavelength of the high band, and therefore mutual coupling between the low and high frequency components can have a significant impact on high frequency antenna performance. With the antenna radiating element having the antenna radiating arm structure of the present invention, a long current path is established through a slow-wave structure integrated in its radiating arm on the low-frequency antenna element, minimizing reflection and diffraction of high-frequency signals on its radiating surface, thereby reducing high-order mode resonances throughout the high-band frequency range. At the same time, the phase current from the high frequency element is filtered out and effectively prevented from being formed on the radiation arm of the low frequency element, thereby minimizing reflection and diffraction of the high frequency band radiation wave. As shown in fig. 9-18, the bandwidth response, represented by the S-parameter frequency, scans the various frequency bands. In fig. 9, an S-parameter curve denoted by (Pi, Pi) represents port reflection coefficients in a column sub-array of low-band elements; (Pi, Pj) respectively represent port-to-port isolation between elements of the row sub-array. The S-parameters for the high frequency sweep in fig. 10 are represented in the same manner as for the low and high frequency antennas. According to the test result, the antenna array adopting the structure has good performance, and completely meets the requirements of miniaturization and high performance of the antenna.

The transmission line structure of the antenna radiating arm 1 and the specific form of the inductive circuit structure therein can be adapted as desired. For example, as shown in fig. 19, a pair of auxiliary dipoles 19 extend from the drive arm 4 at a position where the auxiliary dipoles are connected to the feed balun, so as to enhance the antenna radiation performance. Alternatively, as shown in fig. 20, both ends of the parasitic arm 6 corresponding to the radiation branches 5 of the driving arm are connected by the bridge circuit 17, and one end of the parasitic arm 6 remote from the driving arm is set as an open end which is opened. It will be apparent to those skilled in the art that the geometry and location of each slow wave structure integrated in the radiating surface of the disclosed low band antenna elements and critical to their miniaturization can be modified and optimized for a given interleaved multi-band antenna array to meet specific performance requirements. This can be done using commercial electromagnetic simulation software and parameterized algorithms.

The above description of the specific embodiments is only for the purpose of helping understanding the technical idea of the present invention and the core idea thereof, and although the technical solution is described and illustrated herein using the specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and detail may be made therein by those skilled in the art without departing from the technical spirit of the present invention. Such modifications and substitutions are intended to be included within the scope of the present invention.

Claims

1. An antenna radiating arm, characterized by: the antenna radiation arm (1) comprises a drive arm (4) and a parasitic arm (6), wherein the drive arm (4) is connected with a feed balun (7) and is provided with two radiation branches (5); two ends of the parasitic arm (6) are respectively opposite to the two radiation branches (5) of the driving arm (4) and surround to form the annular conductive structure; two radiation branches (5) of the driving arm (4) are respectively coupled to two ends of the parasitic arm (6) through the capacitor structure (2) and resonate for the first frequency band electric signals.

2. An antenna radiating arm according to claim 1, wherein: the driving arm (4) is coupled with the feed balun (7) and resonates the electric signal of the first frequency band.

3. An antenna radiating arm according to claim 1, wherein: one or more inductive circuit structures (2) are distributed on the parasitic arm (6) and/or the driving arm (4).

4. An antenna radiating arm according to claim 3, wherein: the inductive circuit structures (2) distributed on the parasitic arm (6) are arranged at intervals, so that a current zero point is generated on the parasitic arm aiming at the electric signal of the second frequency band.

5. An antenna radiating arm according to claim 1, wherein: and auxiliary branches (9) which extend towards the inner side of the closed loop conducting structure and are used for changing the electrical length of the closed loop conducting structure are arranged at two ends of the parasitic arm (6).

6. An antenna radiating arm according to claim 5, wherein: and an inductive circuit structure for changing the electric length is arranged on the auxiliary branch (9).

7. An antenna radiating arm according to claim 1, wherein: the two ends of the parasitic arm (6) are connected through a bridge circuit (17).

8. An antenna radiating element, characterized by: comprising two pairs of dipoles, each pair comprising two oppositely arranged antenna radiating arms according to any of claims 1-7.

9. A multi-frequency array antenna, comprising: comprising one or more first radiating elements having the antenna radiating element structure of claim 6, and one or more second radiating elements; the first radiating unit works in a first frequency band, the second radiating unit works in a second frequency band, the frequency of the second frequency band is greater than that of the first frequency band, and a plane where the first radiating unit is located above the second radiating unit and shows wave-transparent characteristics to the second frequency band radiating waves.

10. The multi-frequency array antenna of claim 9, wherein: the second radiation unit is provided with a plurality of rows and a plurality of columns, and the first radiation unit is staggered with the second radiation unit in the row and column directions.