KR101058452B1 - Antenna Radiation Pattern Synthesis Method for High Resolution Image Radar - Google Patents

Abstract

The present invention relates to a method for synthesizing an antenna radiation pattern of a high resolution image radar. Such a method of synthesizing the antenna radiation pattern of the high resolution image radar of the present invention iteratively repeats the antenna mask template suitable for the radar geometry and the parameters of the radar system having a plurality of antenna radiation elements of a two-dimensional array structure Designing using an optimization technique; And finding an optimal distribution of amplitude and phase of the phased array antenna by using a particle swarm optimization (PSO) technique, and synthesizing an antenna radiation pattern with the designed antenna mask template.

According to the present invention, a mask template suitable for system performance is found by finding an optimal value of an aperture distribution for amplitude and phase of each antenna in a phased array antenna using an iterative optimization method and a particle swarm optimization (PSO) method. Synthesizing the antenna radiation pattern has the advantage of optimizing the performance of the phased array high resolution image radar.

Resolution, image, radar, antenna, copy, pattern, compositing, mask, template

Description

Method for composing a radiation pattern of antennas in a synthetic aperture radar system

The present invention relates to an antenna of a high resolution imaging radar (SAR), and more particularly, to iteratively optimizing an aperture distribution for amplitude and phase of each antenna in a phased array antenna and a particle swarm (PSO). Method of synthesizing antenna radiation pattern of high resolution image radar to optimize the performance of phased array high resolution image radar by finding the optimal value using the optimization technique and synthesizing the mask template and antenna radiation pattern suitable for system performance It is about.

In the case of a high resolution image radar system composed of passive antennas, the antenna pattern cannot be changed according to the geometric configuration of the image to be acquired. The antenna pattern should be synthesized by greatly reflecting the system gain. However, this method is not technically very large in the case of a high resolution image radar having a multifunction multimode. Currently, a technique for synthesizing antenna patterns required by a system using a transmission / reception module without much dependence on an operation mode and a geometric configuration has been proposed. The most important part of the system is to design the mask template of the antenna pattern according to the system parameters and the operating geometry. Since the mask template of the antenna pattern greatly influences the performance of the system, a method of optimizing the antenna template and system performance variables as a function is required.

The present invention has been made in view of the above-mentioned matters, and finds an optimal value of an aperture distribution for the amplitude and phase of each antenna in a phased array antenna using an iterative optimization method and a PSO (Particle Swarm Optimization) technique. It is an object of the present invention to provide a method of synthesizing an antenna radiation pattern of a high resolution image radar capable of optimizing the performance of a phased array high resolution image radar by synthesizing a mask template and an antenna radiation pattern suitable for performance.

In order to achieve the above object, a method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention,

a) designing an antenna mask template suitable for the parameters of the radar system and the geometrical configuration of the radar having a plurality of antenna radiation elements of a two-dimensional array structure by using an iterative optimization technique; And

b) finding the optimal distribution of the amplitude and phase of the phased array antenna using Particle Swarm Optimization (PSO), and synthesizing the antenna radiation pattern with the designed antenna mask template.

Here, the step a) (design stage of the antenna mask template),

a-1) generating a uniformly distributed antenna pattern using a Synthetic Aperture Radar (SAR) geometry variable;

a-2) calculating a distance ambiguity area simultaneously received from the side lobe pattern in the distance direction to the main lobe using the SAR geometric variable and the SAR input variable;

a-3) The final antenna by applying the distance ambiguity region calculated in the step a-2), the SAR input variable, the main lobe variable and the sublobe variable set from the radar system to the uniformly distributed antenna pattern generated in the step a-1). Determining a mask template;

a-4) calculating a range ambiguity ratio (RAR) and a noise equivalent sigma zero (NESZ) using the determined antenna mask template; And

a-5) In order to finally set the mask template for the antenna main and side lobe, the template for the antenna main lobe is determined based on the calculated NESZ and swath width, which is the main lobe variable, and the calculated RAR Determining a template for the antenna side lobe by determining a template width in the calculated distance ambiguity region using an iterative optimization technique to satisfy the value.

Here, the SAR geometric variables in step a-1) may include altitude, angle of incidence, and swath width.

In addition, the SAR input variable in step a-2) may include a pulse repetition frequency (PRF), an output power, and a pulse width.

In addition, the step b) (synthesizing the antenna radiation pattern to the antenna mask template),

b-1) Generate a certain number of particles (a combination of distribution coefficients of amplitude and phase of the transceiver module) to find an optimal distribution coefficient of amplitude and phase of the transceiver module uniformly distributed on the antenna aperture. Making;

b-2) initializing the position and velocity of the created objects;

b-3) synthesizing an antenna radiation pattern with the antenna mask template using the information of all the entities;

b-4) determining whether a mask pattern, a beam pattern, and an antenna directivity satisfy a target function for each of the objects; And

b-5) finishing the antenna radiation pattern synthesis by performing an evaluation of the adaptability for the object satisfying the target function.

Here, in synthesizing the antenna radiation pattern in the step b-3), in order to improve the speed and accuracy of the synthesis, adaptive weights are set and reflected based on the image radar parameters.

Further, in the determination of step b-4), if the mask pattern, beam pattern and antenna directivity for each of the objects do not satisfy the target function,

b-6) comparing the objective function to each other;

b-7) locally selecting the information of the best individual among the adjacent individuals based on the comparison result and simultaneously selecting the information of the best individual among all the individuals; And

b-8) further comprising resetting the position and speed of the objects based on the selected object information and reflecting them in the antenna radiation pattern synthesis.

According to the present invention, a mask template suitable for system performance is found by finding an optimal value of an aperture distribution for amplitude and phase of each antenna in a phased array antenna using an iterative optimization method and a particle swarm optimization (PSO) method. Synthesizing the antenna radiation pattern has the advantage of optimizing the performance of the phased array high resolution image radar.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Before describing the embodiment of the present invention in earnest, the configuration of the high resolution image radar system to which the method of the present invention is applied will be described in order to help the understanding of the present invention.

1 is a view showing the configuration of a high resolution image radar system composed of a phased array antenna to which the method of the present invention is applied.

Referring to FIG. 1, a high-resolution imaging radar system minimizes a change in an orientation angle of an antenna beam pattern according to frequency, an antenna radiation element 110, a transmission / reception module 120 for setting amplitude and phase values at an antenna aperture, and a frequency. True time delay (TTD) 130 as a time delay element for providing phase stability for transmitting and receiving, and a transmission / reception control module 140 for controlling frequency up / down conversion, generation of a frequency required by the radar, and overall operation and timing of the radar. It consists of

In order to synthesize an antenna pattern capable of satisfying the performance of a high resolution image radar (SAR), an optimal amplitude and phase value must be found by the transmission / reception module 120 described with reference to FIG. 1. To do this, we first need to design an antenna mask template that matches the geometry and system parameters of the phased array radar.

Then, embodiments of the present invention will be described based on the prior knowledge as described above.

2 is a flowchart illustrating the overall execution of the method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention.

Referring to FIG. 2, according to the method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention, first, a geometric configuration of a radar having a plurality of antenna radiation elements 110 having a two-dimensional array structure and a parameter of a radar system Is designed using an iterative optimization technique (step S210).

Here, iterative optimization technique selects an approximated solution from the initial value to find the optimal solution, calculates by substituting this value and evaluates whether the solution has reached the target value. The technique of finding the most optimal solution while changing. Various techniques exist depending on the method of repeatedly searching for an approximate solution, but in this embodiment, a technique for searching for an optimal solution is applied by applying a mutation characteristic, which is a characteristic of an evolutionary algorithm.

Subsequently, an antenna radiation pattern is synthesized to the designed antenna mask template by finding an optimal distribution of amplitude and phase of the phased array antenna using a particle swarm optimization (PSO) technique (step S220).

Here, the antenna mask template design process using the iterative optimization technique of step S210 will be described in more detail with reference to FIG. 3.

3 is a flowchart illustrating a process of designing an antenna mask template using an iterative optimization technique in a method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention.

Referring to FIG. 3, first, a uniformly distributed antenna pattern is generated by using a SAR (Synthetic Aperture Radar) geometry variable (step S301).

Then, using the SAR geometric variable and the SAR input variable, a distance ambiguity region simultaneously received from the side lobe pattern in the distance direction to the main lobe is calculated (step S302).

Then, the final antenna mask template is determined by applying the distance ambiguity region calculated in step S302, the SAR input variable, the main lobe variable and the sublobe variable to the uniformly distributed antenna pattern generated in step S301 (step S301). S303).

Then, the range ambiguity ratio (RAR) and noise equivalent sigma zero (NESZ) are calculated using the determined antenna mask template (step S304).

Then, in order to finally set the mask template for the antenna main lobe and the sublobe, the template for the antenna main lobe is determined based on the calculated NESZ and the swath width, which is the main lobe variable, and the calculated RAR value is determined. The template for the antenna side lobe is determined by determining the template width in the calculated distance ambiguity region using an iterative optimization technique so as to be satisfied (step S305). Here, in order to set the mask template for the antenna main and side lobe, the template for the antenna main lobe is determined based on the NESZ calculated above and the swath of the image. In addition, for the antenna side lobe, the distance ambiguity area should be calculated and the template width in the ambiguity area should be determined to satisfy the RAR value. Since the RAR value represents the sum of the signal values reflected in the ambiguity region, the optimal template can be determined only by using an iterative optimization technique.

As described above, by using the iterative optimization technique, the target function of the main leaf NESZ and the target function of the side lobe RAR can be optimized. In other words, it is possible to optimize the target functions by simultaneously controlling the main and side lobes.

Meanwhile, the SAR geometric variables in step S301 may include altitude, angle of incidence, and swath width.

In addition, the SAR input variable in step S302 may include a pulse repetition frequency (PRF), an output power, a pulse width.

4 is a diagram illustrating a SAR antenna mask template of a specific mode synthesized using an iterative optimization technique.

As shown in FIG. 4, it can be seen that there is a difference between the initial antenna mask template and the optimized antenna mask template after performing the iterative optimization technique. This shows that the optimal template can be determined.

Next, a process of synthesizing the antenna radiation pattern to the antenna mask template of step S220 will be described in more detail with reference to FIG. 5.

5 is a flowchart illustrating a process of synthesizing an antenna radiation pattern to an antenna mask template in the method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention.

Referring to FIG. 5, first, a combination having a predetermined number of particles (coefficients of amplitude and phase of a transmit / receive module) in order to find an optimal distribution coefficient of amplitude and phase of a transmit / receive module uniformly distributed on an antenna aperture. ) Is generated (step S501). That is, the number of initial objects is properly selected.

Here, in order to synthesize the antenna radiation pattern into the antenna mask template, it is necessary to find the optimal distribution coefficient of the amplitude and phase of the transmission / reception module uniformly distributed on the antenna aperture. To this end, the present invention uses the PSO technique. The PSO technique is a kind of evolutionary algorithm, which is the best of the information of the objects (where the object refers to a combination having the amplitude and phase distribution coefficients of the transmitting and receiving module and generates several objects to obtain the best one among them). The information of the object is selected in the next simulation to find the optimal distribution of amplitude and phase of the transmit / receive module.

When a predetermined number of objects are generated by the above, the position and speed of the created objects are initialized (step S502). Here, each individual evolves at random with initial position and velocity values, and the initial position and velocity represent the amplitude and phase distribution of each individual entity. It evolves by updating the equations for each position set in each object in each simulation. Here, the position of the object represents a value consisting of amplitude and phase distribution, and the velocity represents a value in which the amplitude and phase are updated in the next simulation.

Thereafter, an antenna radiation pattern is synthesized to the antenna mask template (antenna mask template determined in step S303 of FIG. 3) by using the information of all the objects (step S503).

Then, it is determined whether the mask pattern, the beam pattern and the antenna directivity satisfy the target function for each of the objects (step S504).

If the determination satisfies the target function, the antenna radiation pattern synthesis is completed by evaluating the adaptability of the object satisfying the target function (step S505).

Here, in the synthesis of the antenna radiation pattern of step S503, in order to improve the speed and accuracy of the synthesis, adaptive weights are set and reflected based on the image radar parameters (step S503-1).

Further, in the determination of the step S504, if the mask pattern, the beam pattern and the antenna directivity for each of the objects do not satisfy the target function, comparing the target function between the objects (S506) and the comparison result. Locally select the information of the best object among the adjacent objects on the basis of the step of globally selecting the information of the best object among all the objects (S507) and the position and speed of the objects based on the selected object information Resetting to reflect the antenna radiation pattern composition (S508) further.

Here, the information of the best object is shared locally between the adjacent objects, and the position and speed of the objects are reset by using the information of the best object globally among all the objects to determine the speed to be updated in the next simulation. Done. This process is performed repeatedly and continuously until the target function is finally satisfied, so that the information of the final object shows the desired antenna amplitude and phase distribution.

6 is a view showing the amplitude and phase distribution characteristics of the SAR antenna radiation pattern of a specific mode synthesized using the method of the present invention as described above.

As shown in FIG. 6, it can be seen that there is a significant difference between the Taylor distribution characteristic curve 601 and the optimization distribution characteristic curve 602 to which the iterative optimization technique is applied. As can be seen through the characteristic curve, the present invention In the present invention, by applying an iterative optimization technique, it is possible to find an optimal amplitude and phase distribution value of an antenna radiation pattern in the transmission / reception module 120 (see FIG. 1).

FIG. 7A illustrates a case in which an antenna pattern is not synthesized in an antenna mask template by using particle swarm optimization (PSO) and a weight function, and FIG. 7B illustrates a case in which an antenna pattern is efficiently synthesized in an antenna mask template. .

FIG. 8A is a diagram illustrating a range ambiguity ratio (RAR) characteristic finally analyzed using the antenna pattern synthesized in FIG. 7B, and FIG. 8B is a noise equivalent obtained finally analyzed using the antenna pattern synthesized in FIG. 7B. Sigma Zero) shows the characteristics. These results indicate that the requirements of the image radar system are significantly improved.

As described above, the method for synthesizing the antenna radiation pattern of the high resolution image radar according to the present invention uses an iterative optimization method and a particle swarm optimization (PSO) technique to determine the distribution of apertures for the amplitude and phase of each antenna in the phased array antenna. By finding the optimal value and synthesizing the mask template and antenna radiation pattern suitable for the system performance, the performance of the phased array high resolution image radar can be optimized.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Accordingly, the true scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of the same should be construed as being included in the scope of the present invention.

1 is a view showing the configuration of a high resolution image radar system composed of a phased array antenna to which the method of the present invention is applied.

Figure 2 is a flow chart showing the overall execution of the method of synthesizing the antenna radiation pattern of the high resolution image radar according to the present invention.

3 is a flowchart illustrating a process of designing an antenna mask template using an iterative optimization technique in a method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention;

4 shows a SAR antenna mask template of a particular mode synthesized using an iterative optimization technique.

5 is a flowchart illustrating a process of synthesizing an antenna radiation pattern to an antenna mask template in the method of synthesizing an antenna radiation pattern of a high resolution image radar according to the present invention;

6 shows the amplitude and phase distribution characteristics of a SAR antenna radiation pattern of a particular mode synthesized using the method of the present invention.

FIG. 7A illustrates a case in which an antenna pattern is not synthesized in an antenna mask template by using particle swarm optimization (PSO) and a weight function. FIG.

FIG. 7B illustrates a case in which an antenna pattern is efficiently synthesized in an antenna mask template using a PSO and a weight function. FIG.

FIG. 8A is a diagram showing a range ambiguity ratio (RAR) characteristic finally analyzed using the antenna pattern synthesized in FIG. 7B. FIG.

FIG. 8B is a diagram showing Noise Equivalent Sigma Zero (NESZ) characteristics finally analyzed using the antenna pattern synthesized in FIG. 7B.

<Explanation of symbols for the main parts of the drawings>

110 Antenna copy element 120 Transmit / receive module

130 ... Time Delay Element (TTD) 140 ... Transmission / Reception Control Module

Claims (7)

a) in a uniformly distributed antenna pattern generated using SAR geometric variables in a radar with multiple antenna radiators of a two-dimensional array structure, a distance ambiguity region calculated using SAR geometric variables and SAR input variables, and SAR input variables; Designing an antenna mask template determined by applying a main lobe variable and a sublobe variable set from a radar system using an iterative optimization technique; And b) finding an optimal distribution of the amplitude and phase of the phased array antenna using a Particle Swarm Optimization (PSO) technique, and synthesizing an antenna radiation pattern with the designed antenna mask template. Of antenna radiation patterns The method of claim 1, Step a) (design stage of the antenna mask template), a-1) generating a uniformly distributed antenna pattern using a Synthetic Aperture Radar (SAR) geometry variable; a-2) calculating a distance ambiguity area simultaneously received from the side lobe pattern in the distance direction to the main lobe using the SAR geometric variable and the SAR input variable; a-3) The final antenna by applying the distance ambiguity region calculated in the step a-2), the SAR input variable, the main lobe variable and the sublobe variable set from the radar system to the uniformly distributed antenna pattern generated in the step a-1). Determining a mask template; a-4) calculating a range ambiguity ratio (RAR) and a noise equivalent sigma zero (NESZ) using the determined antenna mask template; And a-5) In order to finally set the mask template for the antenna main and side lobe, the template for the antenna main lobe is determined based on the calculated NESZ and swath width, which is the main lobe variable, and the calculated RAR And determining a template for an antenna sublobe by determining a template width in the calculated distance ambiguity region using an iterative optimization technique so as to satisfy a value. The method of claim 2, The SAR geometrical variable in step a-1) includes an altitude, an angle of incidence, and a swath width. The method of claim 2, The SAR input variable in step a-2) includes a pulse repetition frequency (PRF), an output power, and a pulse width. The method of claim 1, Step b) (compositing the antenna radiation pattern to the antenna mask template), b-1) Generate a certain number of particles (a combination of distribution coefficients of amplitude and phase of the transceiver module) to find an optimal distribution coefficient of amplitude and phase of the transceiver module uniformly distributed on the antenna aperture. Doing; b-2) initializing the position and velocity of the created objects; b-3) synthesizing an antenna radiation pattern with the antenna mask template using the information of all the entities; b-4) determining whether a mask pattern, a beam pattern, and an antenna directivity satisfy a target function for each of the objects; And b-5) finalizing antenna radiation pattern synthesis by performing an adaptation evaluation on the object satisfying the target function. The method of claim 5, In synthesizing the antenna radiation pattern in step b-3), in order to improve the speed and accuracy of the synthesis, the antenna radiation pattern of the high resolution image radar is set and reflected based on an adaptive weight based on the image radar parameters. Synthesis method. The method of claim 5, In the determination of step b-4), if the mask pattern, beam pattern and antenna directivity for each of the objects do not satisfy the target function, b-6) comparing the objective function to each other; b-7) locally selecting the information of the best individual among the adjacent individuals based on the comparison result and simultaneously selecting the information of the best individual among all the individuals; And b-8) resetting the position and speed of the objects based on the selected object information to reflect the antenna radiation pattern synthesis.

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