CN102447167B - Aerial array - Google Patents

Abstract

The invention discloses a high-frequency receiving antenna array, which includes M array elements. The spacing between the array elements can be equal or unequal. The spacing between the M array elements is d ₁ , d ₂ , .. ....d _M-1 , the relationship between array elements is: d _i =d _Mi , d _i =d _i+2 , M=2 ^N , where i is the number of the spacing between M array elements , i<M/2, N is a positive integer, and wherein, the array length is determined by the minimum working wavelength λ. When the spacing between M array elements is equal, the spacing When the spacing between the M array elements is unequal, the spacing d ₁ +...+d _M-1 ≤λ. Compared with the conventional array design method, this method can not only obtain narrower horizontal and vertical pattern than the conventional design method, and higher directivity coefficient of the receiving array, but also can make the direction of the array within the designed working frequency range The sex coefficient remains basically unchanged. At the same time, it can also realize a controllable wide zero point at any angle in the horizontal and vertical directions.

Description

antenna array

technical field

The invention generally relates to the field of antennas, in particular to a small super-directional wide-null-point high-frequency receiving antenna array, and the directivity coefficient of the array is basically unchanged within the designed working frequency range.

Background technique

In the high-frequency band (3-30MHz), due to the long wavelength of the signal, it is difficult for the conventional array design to achieve a narrower pattern, especially in the vertical direction. A wider pattern will not only affect the radar system's estimation of the signal's azimuth, the reduction of the array directivity coefficient and other indicators, but also reduce the anti-jamming ability of the system. In addition, in the high-frequency band, due to the existence of various short-wave radio stations, communication signals, atmospheric noise, industrial interference, ionospheric clutter, etc., the electromagnetic environment in the high-frequency band is very complicated. The suppression of clutter is very difficult, especially at night, which seriously affects the normal work of radar and communication systems. In order to make the radar and communication system in the high-frequency band work normally all-weather in a complex electromagnetic environment, the receiving antenna is required to have good directivity and a controllable wide zero point to achieve better signal reception. better reception and better rejection of interference and clutter.

Achieving this goal using a conventional array approach will lead to a sharp increase in the complexity and cost of the receiving array.

Contents of the invention

In order to solve the above problems, the present invention proposes a new method of receiving array design according to the characteristic that the external noise in the high-frequency band is dominant (that is, the external noise received by the radar or communication system is much higher than the internal noise of the receiver).

The present invention provides an antenna array, including M array elements, and the distances between the M array elements are d ₁ , d ₂ ,...d _M-1 respectively, and the feature is that d _i =d _Mi , d _i =d _i+2 , M=2 ^N , wherein, i is the serial number of the spacing between M array elements, i<M/2, N is a positive integer, and wherein, the spacing is determined by the minimum working wavelength λ is determined. Such a design can increase the directivity coefficient of the array and increase the power range of the radar system. In the entire application frequency band, the pattern and directivity coefficient are basically unchanged. Among them, when the spacing between M array elements is equal, the spacing

Among them, when the spacing between M array elements is unequal spacing, the spacing 2(d ₁ +...+d _M/2-1 )+d _M/2 ≤ λ, the design effect of unequal spacing and equal spacing Basically the same, you can choose according to geographical conditions, convenience and other aspects.

Among them, the antenna array works in the high-frequency band of 3-30MHz.

Wherein, the antenna array is an end-fire array.

Among them, in the xyz rectangular coordinate system, use the following formula to select the angle required to form the zero point and the length of the transposition cable: or l _i =-(d ₁ +...d _i )sinθ _i , where, is the angle between any vector on the xy plane and the x-axis, and θ is the angle between any vector on the xy plane and the z-axis.

Wherein, it further comprises: one or more phase-shifting cables and one or more synthesizers, wherein, one array element in every two array elements in the M array elements is connected to the synthesizer through a phase-shifting cable, and the other array element Connect directly to a synthesizer.

Wherein, it further comprises: a synthesizer in every two synthesizers in a plurality of synthesizers is connected to a higher-level synthesizer in a plurality of synthesizers through a phase-shifting cable in a plurality of phase-shifting cables, and another synthesizer directly Connect to more advanced synthesizers.

Among them, the number of array elements is determined by the following formula:

Among them, η ₀ is the required array efficiency.

Wherein, M=4, M=2 ^N .

Compared with the conventional array design method, this method can not only obtain narrower horizontal and vertical pattern, and higher directivity coefficient of the receiving array, but also realize controllable wide beam null. The array can better suppress interference and clutter, and improve the technical index of the system. In addition, the array can keep the pattern and directivity coefficient basically unchanged in the designed working frequency range. The array is an end-fire array, and the array can be used alone, or multiple arrays can be used to form a new array.

Description of drawings

For a full understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 shows the specific arrangement of the end-fire array according to the embodiment of the present invention under the Cartesian coordinate system;

FIG. 2 shows a structural arrangement of an antenna array of a 4-element array according to an exemplary embodiment of the present invention;

Fig. 3 shows the simulation comparison of the vertical pattern of the antenna array according to the exemplary embodiment of the present invention and the traditional antenna array under the same parameters, wherein, it shows that the operating frequency is 5, 6, 7, 8, 10MHz the vertical pattern of the antenna array, and where the designator with n is the result of the normal method of design; and

Fig. 4 shows the simulation comparison of the horizontal pattern of the antenna array according to the exemplary embodiment of the present invention and the traditional antenna array under the same parameters, wherein, it shows that the operating frequency is 5, 6, 7, 8, 10MHz The horizontal pattern of the antenna array, and therein, the designator with n is the result of conventional method design.

detailed description

The making and using of various embodiments of the invention are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable concepts that can be implemented in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

According to the characteristic that the external noise in the high-frequency band is dominant, the present invention aims at the existing high-frequency over-the-horizon radar and the receiving antenna array of the high-frequency band communication receiving system, which have wide horizontal plane and vertical plane patterns, small directivity coefficients, and poor anti-interference ability and other problems, a new array design method is proposed, which can be used for the design of end-fire arrays in high-frequency bands. Compared with arrays designed by conventional methods, it has narrower horizontal and vertical patterns and higher directivity At the same time, the pattern and directivity coefficient can be kept basically unchanged within the designed working frequency band, and the zero point can be realized at any angle in the vertical and horizontal planes.

The schematic diagram of the end-fire array is shown in Figure 1. The array is composed of M array elements, the distance between the array elements is d ₁ , d ₂ ......, d _M-1 , and the number of array elements is It is an even number, and it is required that the spacing of the array elements in the array is symmetrical to the center of the array d _i =d _Mi , and it is also required that d _i =d _i+2 (i<M/2). The spacing of the array can be equal or unequal, and the number of array units is M=2 ^N , where N is an integer. The array mainly includes: antenna element, phase-shifting cable, combiner, etc. The array is realized by multiple two-in-one power combiners. The basic block diagram of the array is shown in Figure 2.

Although the design method adopted in the present invention can improve the directivity coefficient of the array, its efficiency is reduced compared with the conventional design method. The invention provides the mathematical expression after the array is output by the power combiner and the efficiency ratio formula between the design of the invention and the conventional array design, and analyzes the characteristics of the array by using these two formulas. On this basis, the array design method of the present invention is given, and compared with the pattern designed by the conventional array method.

According to the array arrangement and structure in Figure 1 and Figure 2, after passing through the last power combiner, the expression of the pattern function of the array is:

in is a function independent of the array design. Here d _i is the distance between the antenna elements, and l _i is the length of the phase-shifting cable. Although this design method improves the directivity coefficient of the array, the efficiency of the array is reduced. Compared with the conventional end-fire array, the efficiency reduction value is:

For the designed antenna array of the present invention, two basic conditions must be guaranteed:

1. The direction diagram is not distorted;

2. The noise power output by the array is much higher than the noise inside the system, that is, greater than 10dB.

Using formula (1) and formula (2), it can be determined that the maximum radiation direction of the array is the end-fire direction, that is θ=π/2 direction. According to the two basic requirements of array design, the basic requirements for array design parameters obtained through analysis and calculation are:

1.2(d ₁ +...+d _M/2-1 )+d _M/2 ≤λ;

2.

η ₀ is the required array efficiency. Therefore, the number of array elements can be determined by formula (2).

Since the spacing of the antenna elements must meet the requirement of no distortion in the antenna pattern, the increase in the number of array elements will not only reduce the efficiency of the antenna array, but also reduce the spacing between the array elements, which will lead to mutual coupling between the array elements. increase, the efficiency further decreases. In order to obtain better design results, N=2 is usually selected. at this time,

When the arrays are arranged at equal intervals, d ₁ =d ₂ =d ₃ ≤λ/(M-1) may be taken. Use the first sine function in formula (3) to control the front-to-back lobe ratio of the pattern, and the second sine function to control the zero position in the vertical direction. If it is required to form a zero point at the rear lobe, then take l ₁ =d ₁ , and the zero point of the vertical pattern is sinθ=-l ₂ /(d ₁ +d ₂ )

Assuming that the required design frequency range is 5-10MHz, the minimum wavelength is: λ=30m, and in this example, d ₁ =d ₂ =d ₃ =7.5m≤λ/(M-1). The back lobe is taken as 0, the zero point in the vertical direction is in the direction of 10 degrees, and two zero points are also formed in the ±80 degree direction of the horizontal pattern. Therefore, l ₁ =7.5m, l ₂ =-2.6m

The direction diagrams of the horizontal plane and the vertical plane are shown in Figure 3 and Figure 4 respectively, and the following characteristics can be seen from the figure:

1. The main lobe width of the horizontal and vertical pattern is smaller than the main lobe width of the conventional end-fire array design;

2. The width of the main lobe of the pattern is basically unchanged;

3. The zero point can be formed in the specified direction of the horizontal and vertical pattern, and the zero point in the vertical direction is deeper;

4. The directivity coefficient of the array changes little;

Basic steps in array design:

1. Determine the minimum wavelength according to the selected working frequency;

2. According to the external noise environment of the selected operating frequency, utilize formula (2) to determine the allowable array loss, i.e. the efficiency of the antenna array, select the number of array elements, M=N ² ;

3. Determine the spacing between cells according to the formula:

When equally spaced: When not equally spaced: d _i ＝d _Mi ; and 2(d ₁ +…+d _M/2-1 )+d _M/2 ≤λ/2

4. Use formula (3) to select the angle required to form the zero point and the length of the transposition cable;

or l _i ＝-(d ₁ +...d _i )sinθ _i

5. Form the array according to the form shown in Figure 1, and other parts of the array, and realize it according to the method shown in Figure 2, thus obtaining the required array.

The invention is aimed at radar or communication equipment working in high frequency band (3-30MHz). Due to the existence of various short-wave radio stations, communication signals, atmospheric noise, industrial interference, ionospheric clutter, etc. in the high-frequency band, the electromagnetic environment in the high-frequency band is very complicated, and the main lobe of the antenna array pattern is relatively wide. In order to make the radar and communication system in the high-frequency band work normally all-weather in a complex electromagnetic environment, the receiving antenna is required to have good directivity and a controllable wide zero point to achieve better signal reception. better reception and better rejection of interference and clutter. According to the characteristic that the external noise in the high-frequency band is dominant (that is, the external noise received by the radar or communication system is much higher than the internal noise of the receiver), the present invention proposes a new method for designing a receiving array. Compared with conventional array design methods, this method can not only obtain narrower horizontal and vertical patterns, and a higher directivity coefficient of the receiving array, but also achieve controllable width at any angle in the horizontal and vertical directions. Beam null. The array can better suppress interference and clutter, and improve the technical index of the system. In addition, the array can keep the directivity coefficient basically unchanged in the designed operating frequency range. The array is an end-fire array, and the array can be used alone, or multiple arrays can be used to form a new array.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As those of ordinary skill in the art will understand, by means of the present invention, existing or hereafter developed processes, machines, manufactures for performing substantially the same functions or obtaining substantially the same results as the corresponding embodiments adopted according to the present invention , material components, means, methods or steps may be used in accordance with the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (6)

1. an aerial array, comprises M array element, and the spacing between a described M array element is respectively d₁、d₂、……d_M-1, its featureBe d_i＝d_M-i，d_i＝d_i+2，M＝2^N，

Wherein, i is the sequence number of the spacing between a described M array element, i < M/2, and N is positive integer,

And wherein, described spacing is determined by minimum operation wavelength λ;

Wherein, the spacing between a described M array element is unequal-interval, spacing d₁+d₂…+d_M-1≤λ。

2. aerial array according to claim 1, is characterized in that, described aerial array is operated in the high frequency of 3～30MHzWave band.

3. aerial array according to claim 1, is characterized in that, described aerial array is end-fire array.

4. aerial array according to claim 1, is characterized in that, further comprises: one or more phase shift cables withOne or more synthesizers, wherein,

An array element in a described M array element in every two adjacent array elements is connected to described synthesizer through described phase shift cable,And another array element is connected directly to described synthesizer.

5. aerial array according to claim 4, is characterized in that, further comprises: every phase in described multiple synthesizersThe phase shift cable of a synthesizer in two adjacent synthesizers in described multiple phase shift cables is connected to described multipleMore senior synthesizer in synthesizer, and another synthesizer be connected directly to described in more senior synthesizer.

6. aerial array according to claim 1, is characterized in that, M=4.