KR101166851B1 - Array antenna system - Google Patents

Abstract

An array antenna system according to the present invention includes a power divider for distributing and outputting power of an input signal, a first phase shifter for adjusting and outputting a phase of a first signal from the power divider, and a second from the power divider. A second phase shifter for adjusting and outputting a phase of the signal, a coupler for generating a plurality of signals by combining signals from the first and second phase shifters in a predetermined manner, and a plurality of signals from the coupler At least one antenna feeding cell including a third phase shifter for adjusting the phase of the antenna, characterized in that to configure the antenna feeding unit by connecting the at least one antenna feeding cells in series and parallel . The present invention can optimize the radiation pattern, beam width and tilting angle of the array antenna, and as a result, there is an effect that can increase the system capacity.

Array antenna, tilt angle, beam width, vertical radiation pattern, horizontal radiation pattern

Description

Array antenna system {ARRAY ANTENNA SYSTEM}

1 is a view showing a tilt angle adjustment scheme in an array antenna system according to the prior art.

2 is a diagram showing the configuration of an antenna switching cell according to an embodiment of the present invention.

3 is a diagram illustrating a configuration of an antenna feeding cell according to an embodiment of the present invention.

4 is a simplified illustration of the output of an antenna feeding cell according to an embodiment of the invention.

5 and 6 illustrate a method of connecting an antenna feeding cell according to an embodiment of the present invention.

7 and 8 illustrate examples of adjusting the spacing between antenna elements in an array antenna system according to an exemplary embodiment of the present invention.

9 is a view showing a radiation pattern according to the distance between antenna elements in order to better understand the present invention.

10 and 11 illustrate examples of adjusting the number of antenna elements in an array antenna system according to an exemplary embodiment of the present invention.

12 is a view showing a radiation pattern according to the number of antenna elements in order to better understand the present invention.

FIG. 13 is a view illustrating tilt angle adjustment examples in an array antenna system according to an exemplary embodiment of the present invention. FIG.

14 shows the appearance of an 8x4 array antenna system according to an embodiment of the invention.

15 illustrates an example of an 8x4 array antenna system according to an embodiment of the present invention.

16 illustrates another example of an 8x4 array antenna system according to an embodiment of the present invention.

The present invention relates to an array antenna system, and more particularly, to an apparatus for adjusting a vertical radiation pattern, a horizontal radiation pattern, a beam width, and a tilting angle in an array antenna system.

 Recently, mobile communication systems are evolving from 3rd generation (3G) based on code division multiple access (CDMA) to 4th generation (4G). The standards body recommends Orthogonal Frequency Division Multiplexing (OFDM) as the fourth generation method. The OFDM method is a method of transmitting data using a multi-carrier, and a plurality of sub-carriers having mutually orthogonality to each other by converting symbol strings serially input in parallel. Multi Carrier Modulation (MCM) is a type of multi-carrier modulation that is modulated and transmitted.

As such, in the OFDM-based mobile communication system other than the frequency spreading method, the interference between the sector and the cell operates more than the conventional frequency spreading-based CDMA method. This is because, in the CDMA-based mobile communication system, despreading is performed to demodulate a signal, but there is no despreading process in the non-frequency spreading system. In addition, CDMA-based mobile communication systems require up to 15 dB of Carrier to Interference and Noise Ratio (CINR), but high-bandwidth communication systems with high MCS (Modulation and Coding Scheme) levels require high CINR to interfere with adjacent cells. You need to minimize

Minimization of such inter-cell interference can be achieved by adjusting the horizontal and vertical radiation patterns of the base station antenna and the tilting angle of the antenna. That is, the inter-sector interference can be optimized by adjusting the horizontal radiation pattern, and the inter-cell interference can be optimized by adjusting the vertical radiation pattern and the tilting angle. For example, when mounting the antenna on a structure such as a steel tower, the antenna main beam is mounted to face the horizon to increase cell coverage. However, the tilting angles of the antenna are gradually lowered and adjusted in consideration of the cross interference between the cell coverage of the other base station adjacent to the base station where the relatively weak radio wave arrives.

Figure 1 shows a tilt angle adjustment method in the array antenna system according to the prior art.

As shown, (a) shows a mechanical adjustment method, a method of adjusting the direction of the beam by mechanically tilting the antenna. And (b) shows an electrical control method, a method of controlling the direction of the beam by adjusting the phase (phase) of the antenna elements (element) using a phase shifter (phase shifter).

However, since the environment around the base station varies from place to place where the base station is installed, there are considerable difficulties and costs for the optimization of the antenna. If the optimization of the antenna can be automatically optimized according to the change in the traffic environment over time or location of the base station, an increase in base station capacity (or throughput) may be achieved.

Accordingly, an object of the present invention is to provide an apparatus for easily adjusting a vertical radiation pattern, a horizontal radiation pattern, a beam width, and a tilting angle in an array antenna system.

Another object of the present invention is to provide an array antenna system that is easy to expand.

It is still another object of the present invention to provide an apparatus for remotely controlling a vertical radiation pattern, a horizontal radiation pattern, a beam width, and a tilting angle in an array antenna system.

Another object of the present invention is to provide an apparatus for increasing the degree of freedom of the vertical radiation pattern, horizontal radiation pattern, beam width and tilt angle in the array antenna system.

 According to a preferred embodiment of the present invention for achieving the above object, in the array antenna system, a power divider for distributing and outputting the power of the input signal, and adjusting and outputting the phase of the first signal from the power divider A plurality of signals by combining a first phase shifter, a second phase shifter for adjusting and outputting a phase of the second signal from the power divider, and signals from the first and second phase shifters in a predetermined manner; And at least one antenna feeding cell including a coupler for generating a plurality of phases, and a third phase shifter for adjusting a phase of the plurality of signals from the coupler, wherein the at least one antenna feeding cells are serially connected. It is characterized by configuring the antenna feeding unit by connecting in parallel.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intention or custom of a user or an operator. Therefore, the definition should be based on the contents throughout this specification.

In general, electromagnetic waves emitted from an antenna form a beam in a specific direction. A beam refers to a direction and a shape of a specific electromagnetic wave that can be transmitted and received by an antenna and is referred to as a beam pattern or a radiation pattern. The largest beam pattern among the beam patterns emitted by the antenna is called a main lobe, and other components are called side lobes. The radiation pattern of the antenna varies depending on the type of antenna and the direction of the antenna.

The present invention described below can easily adjust the vertical (Elevation or Vertical) radiation pattern, the horizontal (Horizontal or Azimuth) radiation pattern, the beam width and the tilting angle in the array antenna system It's about structure.

2 illustrates a configuration of an antenna switching cell according to an embodiment of the present invention.

As shown, the antenna switching cell 2 includes a power divider 21, a first phase shifter 22, a second phase shifter 23, and a coupler 24. It is configured by.

Referring to FIG. 2, first, the power divider 21 distributes the input power and outputs the input power to the first phase shifter 22 and the second phase shifter 23. The first phase shifter 22 shifts the phase of the signal input from the power divider 21 by a predetermined first value and outputs the shifted phase. Here, it is assumed that the first value is 0 °. The second phase shifter 23 shifts and outputs a phase of a signal input from the power divider 21 by a predetermined second value. Here, it is assumed that the second value is 90 degrees.

The coupler 24 combines the signals from the first phase shifter 22 and the second phase shifter 23 in a predetermined manner and outputs two signals. For example, the S-scattering parameter of the coupler 24 is expressed by Equation 1 below.

In the case of using the S-parameter as shown in Equation 1, the output values of c and d are shown in Equation 2 below.

That is, when the signal of '1' is input to the antenna switching cell 2, the signal magnitude and phase at each stage are summarized as shown in Table 1 below.

a b c d The first phase Second phase 0 ° 0 °

-j / 2-1/2 0 ° 90 °

-j 0 90 ° 0 °

0 -j 90 ° 90 °

-j / 2 + 1/2

As shown in Table 1, when the phases of the first phase shifter 22 and the second phase shifter 23 are both 0 ° (or 90 °), the power output to c and d ( power) is 1/2 each and the total power is output as '1'. When the phase difference between the first phase shifter 22 and the second phase shifter 23 is 90 °, the power output to c or d becomes '1'. That is, it is possible to implement a power divider and a power switch without loss compared to an input signal.

3 illustrates a configuration of an antenna feeding cell according to an embodiment of the present invention.

As shown, the antenna feeding cell 3 comprises an antenna switching cell 2, a first phase shifter 31, a second phase shifter 32 and a phase controller 33.

Referring to FIG. 3, the first signal output from the antenna switching cell 2 described in FIG. 2 is input to the first phase shifter 31, and the second signal is transferred to the second phase shifter 32. Is entered. The controller 33 controls phase shifters in the antenna switching cell 2 and phase shift values of the first and second shifters 31 and 32.

The first phase shifter 31 shifts the phase of the first signal input from the antenna switching cell 2 by a predetermined value under the control of the controller 33 and outputs the result to the corresponding antenna element (not shown). do. The second phase shifter 32 shifts the phase of the second signal input from the antenna switching cell 2 by a predetermined value under the control of the controller 33 and outputs the result to the corresponding antenna element (not shown). do.

When the antenna feeding cell 3 is briefly expressed as shown in FIG. 4, the phase shift values of the phase shifters 22, 23, 31, and 32 are summarized in Table 2 below.

Phase Shifter (22) Phase Shifter (23) Phase Shifter (31) Phase Shifter (32) (A) of FIG. 0 ° 90 ° θ ₁ - (B) of FIG. 90 ° 0 ° - θ ₂ (C) of FIG. 0 ° (90 °) 90 ° (0 °) θ ₁ θ ₂

The present invention configures the array antenna system by connecting the above-described antenna feeding cells 3 in parallel or in parallel and in series. 5 and 6 illustrate a method of connecting the antenna feeding cell 3 according to the embodiment of the present invention. As shown, FIG. 5 illustrates a case in which the array antenna is extended by connecting the antenna feeding cells 3 in parallel, and FIG. 6 illustrates a case in which the array antenna is extended by connecting the antenna feeding cells 3 in parallel and in series. . Here, the remaining antenna feeding cells except for the antenna feeding cells 3 at the end (third stage) simply replace the antenna switching cells 2 because they perform a switching function. As such, the present invention extends the arrangement of antenna elements by properly connecting the antenna feeding cell 3 and the antenna switching cell 2.

Hereinafter, a specific embodiment of adjusting the radiation pattern and the tilting angle in the array antenna system having the above structure will be described.

First, the array antenna system according to the present invention can adjust the phase shift values of the phase shifters 22 and 23 in the antenna switching cell 2 to adjust the distance between antenna elements. The spacing between the antenna elements is closely related to the radiation pattern.

7 and 8 are diagrams showing examples of adjusting spacing between antenna elements in an array antenna system according to an exemplary embodiment of the present invention.

7 illustrates a 4-element array antenna system in which two antenna feeding cells are connected in parallel. As shown in FIG. 7, when the phase shift values of the internal phase shifters 22 and 23 are adjusted, the distance between antenna elements is increased. A 3-element 2-element array antenna (see a), a 2-element array antenna (see b) having a 2d spacing between antenna elements, and a 2-element array antenna (see c) having a spacing between antenna elements d may be implemented. . Here, d may be set to λ / 2 or less in terms of side lobe reduction.

FIG. 8 illustrates a 4-element array antenna system in which two antenna feeding cells connected in parallel to one antenna feeding cell are connected in series. FIG. 8 illustrates adjustment of phase shift values of the internal phase shifters 22 and 23. As shown, a 2-element array antenna having a 3d spacing between antenna elements (see a), a 2-element array antenna having a 2d spacing between antenna elements (see b), and a 2-element array antenna having a spacing between antenna elements d (see c).

The above-described example of adjusting the spacing between antenna elements is an example of an array antenna having four antenna elements, and an array antenna having different spacing between antenna elements may be implemented in the same manner even in an array antenna system having more antenna elements.

As such, the antenna radiation pattern is optimized by adjusting the distance between antenna elements.

9 is a view showing a radiation pattern according to the distance between the antenna elements, for better understanding of the present invention. (a) shows a radiation pattern when the spacing between antenna elements is λ, and (b) shows a radiation pattern when the spacing between antenna elements is 2λ. As shown, since different radiation patterns are shown according to the spacing between antenna elements, an optimal radiation pattern is set by adjusting the spacing between antenna elements by the method of the present invention.

Next, the array antenna system according to the present invention can adjust the number of antenna elements operated by adjusting the phase shift values of the phase shifters 22 and 23 in the antenna switching cell 2. The number of antenna elements operated is closely related to the beam width.

10 and 11 illustrate examples of adjusting the number of antenna elements in an array antenna system according to an exemplary embodiment of the present invention.

FIG. 10 illustrates a 4-element array antenna system in which two antenna feeding cells are connected in parallel. As shown in FIG. 10, when the phase shift values of the internal phase shifters 22 and 23 are adjusted, the distance between antenna elements is increased. A 2-element array antenna (see a), d, and a 4-element array antenna (see b), having a distance between antenna elements d, may be implemented.

FIG. 11 illustrates a 4-element array antenna system in which two antenna feeding cells connected in parallel to one antenna feeding cell are connected in series. FIG. 11 illustrates adjustment of phase shift values of the internal phase shifters 22 and 23. As described above, a 2-element array antenna (see a) having a distance between antenna elements d may be implemented, and a 2-element array antenna (see b) having a distance between antenna elements d may be implemented.

The above-described example of adjusting the number of antenna elements is an example of an array antenna having four antenna elements, and an array antenna having a different number of antenna elements may be implemented in the same manner even in an array antenna system having more antenna elements.

As such, the antenna radiation pattern is optimized by adjusting the number of antenna elements operated.

12 is a diagram illustrating a radiation pattern according to the number of antenna elements for better understanding of the present invention. (a) shows a radiation pattern when the number of antenna elements is 4-element, and (b) shows a radiation pattern when the number of antenna elements is 8-element. As shown, since different radiation patterns are shown according to the number of antenna elements, an optimal radiation pattern is set by adjusting the number of antenna elements by the method of the present invention.

Next, the array antenna system according to the present invention can adjust the tilting angle φ by adjusting the phase shift values of the terminal phase shifters 31 and 32 in the antenna feeding cell 3. Here, the tilt angle is closely related to the beam direction.

13 is a diagram illustrating examples of tilting angle adjustment in an array antenna system according to an exemplary embodiment of the present invention. In particular, (a) shows a 4-element array antenna system in which two antenna feeding cells are connected in parallel, and (b) shows 4-element in series with two antenna feeding cells connected in parallel to one antenna feeding cell. It shows an array antenna system.

In the 4-element array antenna system as shown in FIG. 13A, the tilting angle φ satisfies Equation 3 below.

는 하기 <수학식 4>을 만족한다.On the other hand, in the system as shown in Fig. 13 (b),

Satisfies Equation 4 below.

The tilt angle adjustment examples of the above-described antennas are examples of an array antenna having four antenna elements, and an array antenna having different tilt angles may be implemented in the same manner even in an array antenna system having more antenna elements.

14 is a view showing the appearance of the 8 × 4 array antenna system according to an embodiment of the present invention.

As shown, 8 × 4 antenna elements 141 are arranged in front of the array antenna system 140, and an antenna radome 142 covers the array surface. The lower end of the array antenna system 140 includes a port 143 through which a transmission signal is input and a port 144 through which a control signal is input.

15 illustrates an example of an 8x4 array antenna system according to an embodiment of the present invention.

As shown, the antenna feeding cells 3 are connected in three stages. One antenna feeding cell 150 is configured in the first stage, two antenna feeding cells 151 and 152 are configured in the second stage, and four antenna feeding cells 153, 154, 155, and the third stage are configured. 156 is configured.

Referring to FIG. 15, the first output of the antenna feeding cell 150 is provided to the first antenna feeding cell 151 of the second stage, and the second output is to the second antenna feeding cell 152 of the second stage. Is provided. The first output of the antenna feeding cell 151 is provided to the first antenna feeding cell 153 of the third stage, and the second output is provided to the second antenna feeding cell 154 of the third stage. Similarly, the first output of the antenna feeding cell 152 is provided to the third antenna feeding cell 155 of the third stage, and the second output is provided to the fourth antenna feeding cell 156 of the third stage.

The first output of the first antenna feeding cell 153 configured in the last stage (third stage) is provided with four antenna elements corresponding to the first row of the 8 × 4 array, and the second output is the second Four antenna elements corresponding to a row are provided. Similarly, the first output of the fourth antenna feeding cell 156 is provided with four antenna elements corresponding to the seventh row, and the second output is provided with four antenna elements corresponding to the eighth row.

In this structure, since one feed line output from the antenna feeding unit 15 is connected to four antenna elements constituting one row, the tilting angle, radiation Pattern and beamwidth can be adjusted.

16 shows another example of an 8x4 array antenna system according to an embodiment of the present invention.

As shown, the antenna feeding cells 3 are connected in five stages. The first output of the first antenna feeding cell of the last stage (5th stage) is provided to the (1,1) th antenna element in an 8x4 array, and the second output is provided to the (1,2) th antenna element. . The first output of the second antenna feeding cell of the last stage is provided to the (1,3) th antenna element, and the second output is provided to the (1,4) th antenna element.

As such, the first output of the fifteenth antenna feeding cell of the last stage is provided to the (8,1) th antenna element in an 8x4 array, and the second output is provided to the (8,2) th antenna element. The first output of the sixteenth antenna feeding cell of the last stage is provided to the (8,3) th antenna element, and the second output is provided to the (8,4) th antenna element.

In such a structure, since one feed line output from the antenna feeding unit 16 is connected to one antenna element, both the horizontal axis and the vertical axis can adjust the tilting angle, the radiation pattern, and the beam width.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

As described above, the present invention can optimize the radiation pattern, the beam width and the tilting angle of the array antenna, which has the advantage of optimizing the sector-cell interference in a system where a high modulation and coding scheme (MCS) level is used. . As a result, by optimizing the interference between the sector and the cell, it has the effect of increasing the system capacity (or throughput).

Claims (6)

An array antenna system configured by connecting a plurality of antenna feeding cells in at least one of parallel and serial manners, Comprising the plurality of antenna feeding cells constituting an antenna feeding unit, Each of the plurality of antenna feeding cells includes an antenna switching cell and a first phase shifter and a second phase shifter for shifting a phase of each of signals output from the antenna switching cell. The antenna switching cell is a power divider for distributing and outputting power of an input signal, and a third phase shifter for adjusting and outputting a phase of a first signal from the power divider, and a phase of a second signal from the power divider. And a coupler for generating a plurality of signals by combining signals from the fourth phase shifter, the third phase shifter, and the fourth phase shifter according to a predetermined method. By adjusting phase shift values of the first phase shifter and the second phase shifter, a tilting angle of the antenna is adjusted, By adjusting phase shift values of the third phase shifter and the fourth phase shifter, at least one of an interval between antenna elements to which a signal is emitted and a number of antenna elements to which a signal is emitted is determined. The difference between the phase shift values of the first phase shifter and the second phase shifter is

Here, d is the antenna spacing, λ is the wavelength, Φ means the tilting angle, The difference between the phase shift values of the third phase shifter and the fourth phase shifter is 90 ° when the power of one of the signals generated by the coupler is set to 0, and the difference between the signals generated by the coupler is 90 °. 0 ° if the power is to be distributed evenly. The method of claim 1, Wherein each of the plurality of antenna feeding cells includes a controller for adjusting phase shift values of the first phase shifter and the second phase shifter. The method of claim 1, The phase shift value of the third phase shifter and the fourth phase shifter is 0 ° or 90 °. The method of claim 1, S (scattering) parameters of the coupler is characterized in that the following formula.

The method of claim 1, And a plurality of feed lines from the antenna feeding portion are connected to the antenna elements. delete

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