A frequency-controlled array antenna based on mirror double-wave mixing and a target detection method

Abstract

The application discloses a frequency control array antenna based on mirror image double-wave mixing, and the peak value of the radiation waveform of the frequency control array is discrete in the angle direction, so that the distance of a target can be measured according to the echo time of the peak value waveform, and the azimuth angle of the target can be obtained through the configuration of the array phase. The application solves the problem that the traditional frequency control array cannot distinguish the distance and angle information of the target, and can enhance the detection capability of the radar based on the frequency control array. The target detection method of the application can directly use multiple single-frequency wave signals to form a periodic emission waveform similar to a pulse radar, without a complex frequency synthesis and intermediate frequency signal generation system. Meanwhile, the problem that the distance and angle information of the traditional frequency control array are difficult to separate is solved.

Description

Technical Field

[0001] This invention belongs to the field of frequency-controlled array antenna technology, specifically relating to a frequency-controlled array antenna and target detection method based on mirror dual-wave mixing. Background Technology

[0002] Frequency-controlled arrays are a special type of antenna array where each antenna element emits radio frequency signals at different frequencies according to a certain pattern. This allows the beam in space to be correlated with the propagation distance, propagation angle, and propagation time, enhancing the radar's target resolution and anti-crosstalk capabilities. However, unlike traditional phased arrays that use a unified frequency source to drive the antenna, frequency-controlled arrays need to generate multiple frequency signals, and the initial phase of each signal usually needs to be consistent or have a specific distribution, which poses a challenge to the implementation of frequency-controlled arrays. Conventional frequency-controlled array implementations require multiple coherent frequency sources to generate the required frequencies, making the signal generation system complex and making it difficult to guarantee the initial phase relationship between different channels. In classic frequency-controlled arrays, the frequencies of the antenna elements are distributed in an arithmetic sequence, and the peak value of the generated radiation pattern appears as a curve correlated with both distance and angle. Therefore, using the peak echo time of this pattern for target detection cannot accurately determine the target's angular position. In some more in-depth frequency-controlled array studies, by making the radiation frequency of each antenna vary specifically over time, a radiation intensity peak value fixed at a specific distance and angle can be achieved. However, this type of method requires precise control of the radiation waveform of each antenna, which is difficult to implement in engineering. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a frequency-controlled array antenna and target detection method based on mirror dual-wave mixing. By forming interference in space through two mirror frequency-controlled array signals with opposite frequency change trends, the amplitude peak of the array radiation signal propagates only in a specific angular direction, eliminating ambiguity in the distance and angular directions and improving radar detection capability.

[0004] A frequency-controlled array antenna includes two sets of signal generation units;

[0005] The frequency of the signal generated by the first group of signal generation units at each node is from... Start by proceeding from left to right according to frequency step size. Gradually increasing; at the nth node, the frequency of the signal element is ; and the initial phase difference between adjacent nodes that generate the signal is ;

[0006] The frequency of the signal generated at each node by the second group of signal generation units is from Start by proceeding from left to right according to frequency step size. Gradually decrease; at the nth node, the frequency of the signal element is ; and the initial phase difference between adjacent nodes that generate the signal is ;

[0007] The signals generated by the two sets of signal units corresponding to the same node number are superimposed and radiated out through the antenna.

[0008] Preferably, the spacing between adjacent antennas is d equal to , For frequency The wavelength of electromagnetic waves in free space.

[0009] A target detection method based on a frequency-controlled array antenna includes:

[0010] (1) Select a phase Each of the two signal generation units generates a signal and radiates it out through the antenna;

[0011] (2) Measure the echo signal using a wide-beam receiving antenna. If a peak is detected in the echo signal, it indicates that... There is a target in the direction;

[0012] (3) Measure the time of the first peak. Then the distance from the target to the antenna array is:

[0013]

[0014] (4) If no echo peak is detected, select another phase. Repeat (1) to (3).

[0015] The present invention has the following beneficial effects:

[0016] This invention relates to a frequency-controlled array antenna based on mirrored dual-wave mixing. The peak value of the radiated waveform from the frequency-controlled array is discrete in the angular direction. Therefore, the target distance can be measured solely from the echo time of the peak waveform, and the azimuth angle of the target can be determined by configuring the array phase. This invention solves the problem that traditional frequency-controlled arrays cannot distinguish between target distance and angular information, thus enhancing the detection capability of frequency-controlled array-based radars.

[0017] The target detection method of this invention can directly construct a periodically emitted waveform similar to that of a pulse radar using multiple single-frequency wave signals, without requiring a complex frequency synthesis and intermediate frequency signal generation system. It also solves the problem of separating range and angle information in traditional frequency-controlled arrays. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the principle of the frequency-controlled array antenna of the present invention;

[0019] Figure 2 For a 16-node antenna array , Normalized radiation waveform at time;

[0020] Figure 3 and Figure 4 The waveforms are shown at t=2.01s and t=2.02s, respectively, when the waveform propagates forward. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, the frequency-controlled array antenna of the present invention includes two sets of signal generating units. In the first set, the frequency of the signal units ranges from... Start by proceeding from left to right according to frequency step size. Gradually increasing; at the nth node, the frequency of the signal element is If the array length is N, then the frequency of the last node is... .

[0023] In the other group, the frequency of the signal unit is from Start by proceeding from left to right according to frequency step size. Gradually decrease; at the nth node, the frequency of the signal element is If the array length is N, then the frequency of the last node is... .

[0024] in, , and There are no strict restrictions on the value of ; it can take any value. However, it is required that... .

[0025] The initial frequencies of the two sets of signal units are the same, and the frequency steps are also the same, but the directions of frequency change are opposite.

[0026] In addition to the frequency distribution described above, the array also possesses specific phase characteristics. Between two nodes, for both sets of signal elements, the initial frequency difference between two adjacent signal elements is... .

[0027] At each node, the output signals of the corresponding two sets of signal units are superimposed: at the first node, the frequency of the first set of units is... The signal, with the same frequency as the second group of units, is... The signals are added together; at the nth node, the frequency of the first group of units is... The signal, with the same frequency as the second group of units, is... The signals are added together.

[0028] The signal superimposed from each node is radiated out by the antennas of each node. The spacing between adjacent antennas is d. Generally, d equals... , For frequency The wavelength of electromagnetic waves in free space.

[0029] For the first array with a positively increasing frequency, the signal of its nth antenna element can be expressed as:

[0030]

[0031]

[0032] here The initial phase difference between adjacent nodes. This is a fixed phase difference that occurs during signal generation; it is a constant.

[0033] At time t, the distance from the antenna array position is R, and the deviation from the array normal is... The array factor can be calculated by summing the radiation fields of all elements. For an array with increasing positive frequency, its array factor can be written as:

[0034]

[0035]

[0036] here , where is the wave number of the electromagnetic wave of the frequency corresponding to the nth unit in free space, and c is the speed of light.

[0037] For an array with decreasing frequency, the signal of its nth antenna element can be expressed as:

[0038]

[0039]

[0040] At time t, the distance from the antenna array position is R, and the deviation from the array normal is... The array factor at a given location can be calculated by summing the radiation fields of all elements. For an array with decreasing frequency, its array factor can be written as:

[0041]

[0042]

[0043] Here, phase control is used to ensure that the phase difference between adjacent cells in the two arrays is consistent. .

[0044] Adding the array factors of the two arrays gives the total array factor:

[0045]

[0046] in,

[0047]

[0048]

[0049] here:

[0050]

[0051] The above equation shows that the electromagnetic waves generated by the two sets of signal units interfered.

[0052] The meanings of the parameters appearing in the above formula are as follows:

[0053] R represents the moment of observation; R is the distance from the observation point to the center of the array or the first cell. This indicates the angle of the observation point relative to the normal phase of the array; Indicates the center frequency; Indicates the frequency difference between adjacent units; represents the wavenumber of the electromagnetic wave of the frequency corresponding to the nth element in the array in free space; C represents the speed of light; d represents the spacing between adjacent antenna elements. This represents the initial phase difference between adjacent units.

[0054] Based on the above theory, the relationship between the radiation intensity of the frequency-controlled array proposed in the invention and the distance, angle, and propagation time can be derived, such as... Figure 2 The image shows an array of 16 nodes. , Normalized radiation waveform at time.

[0055] Figure 2 The bright spot represents the peak value of the composite radiation signal, which appears only at a specific angle. After a certain period of time, the waveform will propagate forward, as shown... Figure 3 and Figure 4 As shown.

[0056] The waveform can be seen propagating in a direction that extends into the distance.

[0057] By changing The propagation angle of the beam peak can be controlled, and it can be calculated using the following formula:

[0058]

[0059] Where K is an integer.

[0060] At time t, the condition for the beam peak to occur is:

[0061]

[0062] In the above formula, L is an integer.

[0063] Based on the characteristics of the array described above, the range and azimuth angle of the target can be detected. The specific process is as follows:

[0064] (1) Select a phase Then the antenna beam will follow It is transmitted from different angles.

[0065] (2) Measure the echo signal through a wide-beam receiving antenna. If the detected microwave signal shows a peak, it indicates that there is a target in this direction.

[0066] (3) Measure the time of the first peak. Then the distance from the target to the antenna array is:

[0067]

[0068] (4) If no echo peak is detected, select another phase. Repeat (1) to (3).

[0069] The advantage of using this method to detect targets is that it can directly construct a periodically transmitted waveform similar to that of a pulse radar using multiple single-frequency wave signals, without the need for complex frequency synthesis and intermediate frequency signal generation systems. It also solves the problem of separating range and angle information in traditional frequency-controlled arrays.

[0070] As can be seen from the beam characteristics above, the peak value of the frequency-controlled array radiation waveform of this invention is discrete in the angular direction. Therefore, the target distance can be measured solely from the echo time of the peak waveform, and the azimuth angle of the target can be determined by configuring the array phase. This invention solves the problem that traditional frequency-controlled arrays cannot distinguish between target distance and angular information, thus enhancing the detection capability of frequency-controlled array-based radars.

[0071] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A frequency-controlled array antenna, characterized by The two groups of signal generating units are used to generate signals corresponding to the same node number. The frequency of the signal generated by the first group of signal generating units on each node starts from f0and gradually increases by a frequency step Δf from left to right; at the nth node, the frequency of the signal unit is f0+(n-1)Δf; and the initial phase difference between adjacent nodes generating the signal is The frequency of the signal generated by the second group signal generating unit on each node gradually decreases from fo in accordance with a frequency step Δf from left to right; at the nth node, the frequency of the signal unit is fo-(n-1)Δf; and the initial phase difference between adjacent nodes generating the signal is The signals corresponding to the same node number generated by the two groups of signal units are superimposed and radiated through the antenna.

2. A frequency steerable array antenna as claimed in claim 1, characterized in that The interval d between the adjacent antennas is equal to λ / 2, and λ is the wavelength of the electromagnetic wave with the frequency f0 in the free space.

3. A target detection method based on the frequency-controlled array antenna of claim 1, characterized in that, The two groups of signal generating units are used to generate signals corresponding to the same node number. The signals corresponding to the same node number generated by the two groups of signal units are superimposed and radiated through the antenna. The interval d between the adjacent antennas is equal to λ / 2, and λ is the wavelength of the electromagnetic wave with the frequency f0 in the free (1) selecting a phase The two groups of signal generating units respectively generate signals and radiate them through the antennas. (2) Measure the echo signal by a wide-beam receiving antenna. If the detected echo signal appears a peak, it means that there is a target in the direction of the beam. (3) Measure the time of first peak occurrence, t r The distance of the target from the antenna array is then: R = c-t r / 2 (4) if no echo peak is detected, select other phase Repeat (1) - (3).

Images