CN107681270B - Base station antenna and beam shaping method thereof - Google Patents

Abstract

The invention is applied to the wave beam shaping method of the base station antenna, the corresponding array element of two rows of antennas of different channels realizes the wave beam superposition through the weak coupling bridge, four ports of the said weak coupling bridge connect two rows of antenna array feeder cables and corresponding array elements of two rows of antenna arrays separately, make up the binary subarray, adopt the said weak coupling bridge to carry on the wave beam shaping to the said binary subarray, when one of them is a channel of use, the array element of another channel feeds in the weak electric signal through the coupling end and stimulates, and reach the necessary horizontal half-power angle through the wave beam superposition with the corresponding array element in the main feed array of the channel of use. The invention creatively provides a binary subarray which is grouped by using a weak coupling bridge, and a required horizontal half-power angle is realized by optimizing a binary subarray combined configuration scheme; the consistency of the horizontal half-power angle is obviously improved, the design interval of the horizontal half-power angle is expanded, and the front-to-back ratio and cross polarization of the antenna are improved to a certain extent.

Description

Base station antenna and beam shaping method thereof

【Technical field】

The present invention relates to the field of communication technologies, and in particular, to a base station antenna and a beam shaping method thereof.

【Background technique】

With the development of miniaturization, the isolation of multi-channel antennas has become a technical problem in the design of base station antennas. The coupling between the channel elements seriously affects the radiation pattern of the antenna, such as: widening of the horizontal half-power angle, decrease of gain, deterioration of front-to-back ratio, deterioration of cross-polarization, etc. The development of communication technology has put forward higher and higher requirements for the shape of the radiation beam. For the macro base station antenna, not only the requirements of gain and downtilt angle, but also the horizontal half-power angle must be consistent, which must fall within the specified angle range. , so as to meet the requirements of reducing noise and improving spatial diversity. Base station antennas need to minimize the signal overlap area while ensuring signal coverage, which requires more precise radiation pattern control - not only to meet the requirements of cross-polarization, front-to-back ratio and sidelobe suppression, but also the half-power angle. It must be limited to the specified interval, and some special applications even impose stricter requirements on the beam shape.

At present, most base station antennas are divided into several independent systems according to frequency, polarization direction and independent ESC, and each system is usually composed of a row of array elements with the same frequency. For a system, the vertical direction is a linear array, and the corresponding half-power angle is mainly determined by the number and spacing of the array elements; while there is only one array element in the horizontal direction, the corresponding half-power angle can only be controlled by the boundary. The above-mentioned reality determines that the optimization of the half-power angle in the horizontal direction has become a difficult problem in the design of base station antennas. Due to the staggered arrangement of high and low frequency array elements and the hybrid array method, the influence on the high frequency half power angle must be taken into account when optimizing the low frequency half power angle; conversely, the high frequency half power angle must also be taken into account when optimizing the high frequency half power angle angle influence. Not only that, the miniaturization of the base station antenna makes the coupling between the systems more and more serious. The electromagnetic coupling between the array elements between two adjacent columns, especially the electromagnetic coupling between the low-frequency array elements, causes the radiation beam to deform seriously, and the horizontal The wave width widens and the gain decreases. The general design process in the prior art is as follows: by optimizing the reflective plate flanging, isolation strips, raising the array elements, bending the floor, slotting the floor, and loading parasitic elements, the radiation pattern of each array element can reach the target. Require. Although this design method can make the overall performance of the antenna meet the standard, however, the design is difficult, the optimization parameters are many, and there are many uncertain factors, especially when the antenna size and performance requirements are more stringent, it is difficult to meet all requirements at the same time only by optimizing the boundary. item indicator. Simply relying on the optimized boundary, in many cases the horizontal half-power angle is too wide to meet the design specifications; using a common 3dB bridge to "borrow" a unit from another channel to compress the bandwidth will make the half-power angle too narrow, and at the same time cause Beam distortion is severe. To solve the above design problems.

Therefore, it is necessary to provide a base station antenna with miniaturization, superior performance, low cost, low loss, high isolation, wide beam, and realizing the required half-power angle, and a beam-shaping method thereof.

[Content of the invention]

The purpose of the present invention is to provide a base station antenna with wide beam, high isolation and superior performance and a beam shaping method thereof.

For realizing the object of the present invention, the following technical solutions are provided:

The present invention provides a base station antenna, which includes at least two columns of coaxially arranged radiating element arrays, and also includes cables respectively feeding the two columns of radiating elements, the cables radiating from the two columns through a weakly coupled bridge The units are connected and the beams of the radiating units are shaped by the weakly coupled bridge.

Preferably, the weakly coupled bridge is implemented by using two microstrip lines, including a coupling section, a transition section and four ports, the four ports respectively include an input end, a coupling end, a straight-through end, and an isolation end, and two microstrip lines are used. The strip lines are paralleled in the coupling section, and impedance matching is achieved in the transition section.

Preferably, the four ports of the weakly coupled electrical bridge are respectively connected to two columns of antenna array feed cables and corresponding array elements of the two columns of antenna arrays to form a binary sub-array.

Preferably, the feed cables of the two columns of radiation units are respectively connected to the input end and the isolation end of the weakly coupled bridge, the coupling end and the straight end are respectively connected to the two columns of radiation units, and the isolation end is connected to the input end and the input end respectively. Terminals remain highly isolated.

Preferably, the weakly coupled bridge is prepared by a single-layer double-sided PCB board, and the feeding point between it and the cable is welded on the front side of the PCB board, and the cable is routed from the back side of the PCB board.

The present invention also provides a beam shaping method applied to a base station antenna. The beam shaping method is applied to the base station antenna as described above. The corresponding array elements of two columns of antennas in different channels realize beam superposition through a weakly coupled bridge. The four ports of the coupling bridge respectively include an input end, a coupling end, a straight-through end and an isolation end, and the four ports are respectively connected with two columns of antenna array feed cables and corresponding array elements of the two columns of antenna arrays to form a binary sub-array, When the weak coupling bridge is used to beam shape the binary sub-array, when one of the channels is the used channel, the array elements of the other channel are excited by feeding weak electrical signals through the coupling end, which is different from the main channel of the used channel. The corresponding array elements in the feeding column can achieve the required horizontal half-power angle through beam stacking.

Preferably, the weakly coupled bridge is connected to the phase shifters of the feed cables of the two columns of the antenna array.

Preferably, the coupling coefficient of the weakly coupled bridge is -20dB to -10dB.

Preferably, before using the weakly coupled electric bridge to perform beam shaping on the binary sub-array, it further includes the step of judging whether to load the weakly coupled electric bridge to the binary sub-array, which includes:

Read the electric field simulation results of the excitation of each port;

For each binary sub-array combination, the corresponding pattern data is obtained by linear superposition;

Compare the data with the predetermined index, and calculate the fitness corresponding to the binary subarray combination;

Implement binary particle swarm optimization for the above process.

Preferably, the algorithm in the judgment process adopts a string composed of 0 and 1 to represent the arrangement and combination of binary sub-arrays, respectively representing that the binary sub-array is selected or not selected. For example: 0 means that the binary sub-array is selected, and the corresponding oscillators are connected by the weakly coupled bridge, 1 means that the binary sub-array is not selected, and the corresponding oscillator is not connected to the weakly coupled bridge; or vice versa.

Compared with the prior art, the present invention has the following advantages:

The invention discloses a two-column multiplexing horizontal beam half-power angle consistency solution based on a weakly coupled bridge. By adopting the present invention, the horizontal half-power angle is realized by beam-reshaping, and the required Horizontal half-power angle; at the same time, the front-to-back ratio and cross-polarization are also improved to some extent.

The invention creatively proposes to construct a grouped binary sub-array by using a weakly coupled electric bridge, and realize the required horizontal half-power angle by optimizing the combination configuration scheme of the binary sub-array; The coupling end applies a weak excitation signal to the other channel to cancel the influence of the coupling between the array elements and the boundary. The boundary optimization is replaced by the beam stacking, and the difficult boundary optimization problem is transformed into an easier beam stacking problem. The antenna design is freed from complicated boundary optimization, which greatly reduces the design difficulty and shortens the product design cycle; significantly improves the consistency of the horizontal half-power angle and expands the design range of the horizontal half-power angle. In addition, the invention patent improves the front-to-back ratio and cross-polarization of the antenna to a certain extent. The high and low frequency array elements in the base station antenna of the invention do not affect each other, the simulation process is simplified, and the low-cost horizontal half-power angle consistency solution is convenient for batch deployment in the base station antenna array.

【Description of drawings】

FIG. 1 is a schematic diagram of an embodiment of a base station antenna according to the present invention;

2 is a schematic diagram of a dual-column shared beam shaping method according to the present invention;

FIG. 3 is a binary optimization process based on the binary particle swarm optimization algorithm of the present invention.

【Detailed ways】

Please refer to FIG. 1 , which is a schematic diagram of an embodiment of a base station antenna according to the present invention, which includes at least two arrays of radiating elements with independent ESCs, each of the radiating element arrays includes a high-frequency radiating element 200 and a low-frequency radiating element 100 , and the dual frequencies are coaxial. The array antenna further includes cables 410 and 420 for feeding the high-frequency radiation unit and the low-frequency radiation unit respectively, wherein the cable 410 for feeding the low-frequency radiation unit 100 is connected to the two columns of radiation units through the weak coupling bridge 300 . The low frequency radiating elements in the array are connected, and the beams of the radiating elements are shaped by the weakly coupled bridge 300 . Further, the weakly coupled bridge 300 is connected to the phase shifters of the feed cables of the two arrays of antenna arrays. The low-frequency radiation unit may be a medium-low frequency radiation unit.

In this embodiment, beamforming is performed on the mid-low frequency part of the 698-960 MHz and 1710-2690 MHz dual-frequency two-coaxial arrays, so as to improve the half-power angle consistency in the horizontal direction. In the two-column dual-frequency coaxial array with this structure, the two-column independent ESCs are limited by the internal space of the antenna, and a strong electromagnetic coupling occurs between the two columns, in which the coupling between the low-frequency oscillators is particularly serious. The boundary optimization method is difficult to meet the design index of the low-frequency horizontal half-power angle. The invention makes the low-frequency vibrators of the dual-frequency coaxial array form a reciprocal binary group through a weakly coupled electric bridge, and converts the difficult boundary optimization problem into a binary array horizontal beamforming problem. The length optimizes its phase to achieve the desired horizontal half-power angle.

In this embodiment, the weakly coupled bridge is implemented by using two microstrip lines, including a coupling section, a transition section, and four ports. The four ports respectively include an input end, a coupling end, a straight-through end, and an isolation end. A microstrip line is paralleled in the coupling section, and impedance matching is achieved in the transition section. The four ports of the weakly coupled electric bridge are respectively connected with two columns of antenna array feed cables and corresponding array elements of the two columns of antenna arrays to form a plurality of binary sub-arrays.

Specifically, the feed cables of the two columns of radiation elements are respectively connected to the input end and the isolation end of the weakly coupled bridge, the coupling end and the through end are respectively connected to the two columns of radiation array elements, and the isolation end is connected to the The inputs are kept highly isolated. The two arrays of radiating array elements and the feeding network are reciprocal.

The coupling coefficient of the weakly coupled bridge preferably ranges from -20dB to -10dB, and the operating frequency is 690 to 960MHz.

Specifically, the weakly coupled bridge is prepared by using a single-layer double-sided PCB board, and the feeding point between it and the cable is welded on the front side of the PCB board, and the cable is routed from the back side of the PCB board. The PCB boards connected to the weakly coupled bridges with different polarization directions are installed back to each other, the dielectric relative permittivity of the coupling bridge is 3.0, the thickness of the PCB substrate is 0.76mm, the copper foil on the back of the PCB board is grounded, and the thickness of the copper foil is 0.035mm.

Note: The figure only shows the possible insertion positions of the weakly coupled bridge. In practical applications, the configuration of the weakly coupled bridge is related to the coupling coefficient, the power division ratio of the phase shifter, the column spacing, and the number of array elements contained in a single column. The optimized configuration scheme needs to be obtained after optimization through the optimization algorithm process.

Please refer to FIG. 2 and FIG. 3 in conjunction with the base station antenna in the embodiment of FIG. 1 to illustrate the beam shaping method. The beam shaping method is applied to the base station antenna as described above. As shown in FIG. i=1,...N, N is a natural number), the right column oscillator i (i=1,...N, N is a natural number), the corresponding array elements of the two columns of antennas of different channels pass through a 13dB weakly coupled bridge (i=1 ,...N, N is a natural number) to realize beam superposition, the four ports of the weakly coupled bridge respectively include an input end P1, a coupling end P3, a straight end P2, and an isolation end P4, and the four ports are respectively connected to two columns of antennas The array feeder cable and the corresponding array elements of the two-column antenna array form a binary sub-array, and when the weakly coupled bridge is used to beam-shape the binary sub-array, when one channel is the used channel, the other channel is used. The array element of the channel is excited by feeding a weak electrical signal through the coupling end, and the corresponding array element in the main feeding column of the channel is superimposed to achieve the required horizontal half-power angle through beam superposition. The specific data shows that the coupling coefficient S(P4, P1) between the input end P1 and the isolation end P4 is <-25dB, the coupling coefficient S(P2, P1) between the input end P1 and the straight end P2 is > -0.4dB, and the input end P1 and the The coupling coefficient of the coupling end P3 is -13.3<S(P3, P1)<-12.8dB.

For example, the base station antenna includes two channels: left and right. When the left channel is used, the array elements in the right channel are excited by feeding weak electrical signals through the coupling end, and the corresponding array elements in the left main feed array are superimposed by beams. The required horizontal half-power angle is required; on the contrary, when the right channel is used, the array element in the left channel is fed with a weak electrical signal through the coupling end for excitation, and the corresponding array element in the right main feeding array is superimposed to achieve the required horizontal half-power angle. Power angle requirements.

It can be analyzed from FIG. 2 that the smooth implementation of the present invention depends on the optimal combination of the coupling coefficient of the weakly coupled bridge and the binary group. As shown in FIG. 3 , before using the weakly coupled electric bridge to perform beam shaping on the binary sub-array, it further includes a step of judging whether to load the weakly coupled electric bridge to the binary sub-array, which includes:

1) Read the simulation results of the electric field excited by each port respectively;

2) For each binary sub-array combination, obtain corresponding pattern data through linear superposition;

3) comparing the data with a predetermined index, and calculating the fitness corresponding to the binary subarray combination;

4) Implement binary particle swarm optimization for the above process.

Figure 3 is a binary optimization design process based on binary particle swarm optimization algorithm. Taking the 698-960MHz/1710-2690MHz coaxial two-coaxial antenna shown in Figure 1 as an example, in this embodiment, the 698-960MHz low frequency band adopts the two-column shared horizontal beam shaping method of the weakly coupled bridge. The algorithm uses a string consisting of 0 and 1 to represent the binary sub-array permutation and combination, representing the binary sub-array being selected or unselected, respectively. For example: 0 means that the binary sub-array is selected, and the corresponding oscillators are connected by the weakly coupled bridge, 1 means that the binary sub-array is not selected, and the corresponding oscillator is not connected to the weakly coupled bridge; or vice versa.

For example: "{10101}" means that the 1st, 3rd and 5th pairs of oscillators are connected by bridges, while the 2nd and 4th pairs of oscillators do not have bridges. The binary particle swarm optimization (Binary Particle Swarm Optimization) is used to optimize various permutations and combinations of binary groups. The optimization process is shown in Figure 3. First, read the electric field simulation results rEx/rEy/rEz excited by each port respectively, For each combination of binary groups, the corresponding pattern data can be obtained by linear superposition, compare the data with the design indicators, calculate the fitness corresponding to the binary groups, and implement binary particle swarm optimization on the above process to obtain binary data. optimal configuration for the group. In summary, the two-tuple optimization process shown in Figure 3 solves the problem of which oscillators the weakly coupled bridge is loaded on.

Furthermore, in order to achieve precise control of the horizontal half-power angle without deforming the beam, and considering the manufacturing process and cost, the bridge coupling coefficient is more appropriate in the range of -20dB to -10dB. For the flexibility of the implementation effect, different coupling coefficients can be selected, such as: -10dB/-13dB/-16dB series of weakly coupled bridges.

The invention discloses a double-column sharing shaping scheme for base station antennas based on a weakly coupled electric bridge, which adopts a completely different strategy from the traditional design method of eliminating coupling by optimizing the boundary. The two array elements form a one-to-one corresponding binary array group, and the required horizontal half-power angle is realized by the method of beam shaping, thereby greatly reducing the design difficulty of the horizontal half-power angle.

It should be pointed out that the beam-reshaping scheme disclosed in the present invention is fundamentally different from what is commonly referred to as beam-forming technology. The present invention realizes a specific horizontal half-power angle by optimizing the coupling coefficient of the weakly coupled bridge and the combination of the two-tuple; and the beamforming adjusts the beam shape and direction by optimizing the phase of the array element. Furthermore, the present invention has the following features: 1) A number of binary sub-arrays are established between two channels of the independent ESC through a weakly coupled bridge. The coupling coefficient of the weakly coupled bridge is usually below -10dB. For the flexibility of the application, a series of weakly coupled bridges with different coupling coefficients can be designed; 2) By flexibly configuring the coupling coefficient of the bridge and arranging the two-tuple The combination is optimized to achieve the desired horizontal half-power angle.

The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto, and any equivalent transformation based on the technical solutions of the present invention falls within the protection scope of the present invention.

Claims (6)

1. A base station antenna, characterized in that it comprises at least two rows of radiating element arrays of independent ESCs, and also comprises cables respectively feeding the two rows of radiating elements, and the cables are connected to the radiating elements through a weakly coupled bridge. The two columns of radiation units are connected, and the beams of the radiation units are shaped by the weakly coupled bridge; The beam shaping method applied to the base station antenna is as follows: the corresponding array elements of the two columns of antennas of different channels realize beam superposition through the weakly coupled bridge, and the coupling coefficient of the coupled bridge is -20dB to -10dB. The ports respectively include an input end, a coupling end, a straight-through end, and an isolated end. The four ports are respectively connected to two columns of antenna array feed cables and corresponding array elements of the two columns of antenna arrays to form a binary sub-array. When the phase shifter of the feed cable is connected to the weakly coupled bridge to perform beam shaping on the binary sub-array, when one of the channels is the used channel, the array element of the other channel feeds the weak electrical signal through the coupling end to perform beam shaping. Excitation, and the corresponding array elements in the main feed column of the channel are superimposed to achieve the required horizontal half-power angle; Before using the weakly coupled electric bridge to perform beam shaping on the binary sub-array, it also includes the step of judging whether to load the weakly coupled electric bridge to the binary sub-array, which includes: Step 1.1, read the simulation results of the electric field that each port is excited respectively; Step 1.2. For each binary sub-array combination, obtain the corresponding pattern data through linear superposition; Step 1.3, compare the data with the predetermined index, and calculate the fitness corresponding to the binary subarray combination; Step 1.4, implement binary particle swarm optimization for steps 1.1-1.3. 2. The base station antenna according to claim 1, wherein the weakly coupled electric bridge is realized by two microstrip lines, comprising a coupling section, a transition section and four ports, and the four ports respectively include an input terminal , coupling end, straight end, isolation end, two microstrip lines are parallel in the coupling section, and impedance matching is achieved in the transition section. 3. The base station antenna as claimed in claim 2, wherein the four ports of the weakly coupled bridge are respectively connected to two columns of antenna array feed cables and corresponding array elements of the two columns of antenna arrays to form a binary sub-array . 4. The base station antenna according to claim 3, wherein the isolation terminal and the input terminal are kept highly isolated. 5. The base station antenna as claimed in claim 4, wherein the weakly coupled electric bridge is prepared by using a single-layer double-sided PCB board, and the feed point between the cable and the cable is welded on the front side of the PCB board, and the cable is connected from the back side of the PCB board. Traces. 6. A kind of base station antenna as claimed in claim 1, it is characterized in that, the algorithm in the described judgment flow adopts the character string formed by 0 and 1 to represent the arrangement and combination of binary sub-arrays, respectively representing that the binary sub-array is selected or Not selected.

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