阅读说明：本技术 一种基于数字可编程超表面的多源doa估计方法 (Multi-source DOA estimation method based on digital programmable super surface ) 是由 万向 王嘉伟 黄梓艾 于 2021-10-21 设计创作，主要内容包括：本发明公开了一种基于数字可编程超表面的多源DOA估计方法,包括用于调控空间电磁波的可编程超表面及利用稀疏信号恢复算法进行高精度DOA估计的过程。所述的超表面由多个集成了二极管的单元构成,单元的工作状态可以通过加载不同电压的方式来动态的改变。本发明利用数字可编程超表面产生一组随机双波束表面编码来构建感知矩阵,利用一个接收喇叭来采样多个方向的入射波信息并利用稀疏信号恢复算法对采样信息进行计算,从而得到高精度的入射角信息。本发明可以在避免复杂的移相网络及大量的传感器的条件下,实现高精度的来波方向估计同时减少采样成本。这项工作有望在雷达及无线通信领域拥有重要的应用前景。(The invention discloses a multi-source DOA estimation method based on a digital programmable super surface, which comprises a programmable super surface for regulating and controlling space electromagnetic waves and a process of carrying out high-precision DOA estimation by utilizing a sparse signal recovery algorithm. The super surface is composed of a plurality of units integrated with diodes, and the working states of the units can be dynamically changed in a mode of loading different voltages. The invention utilizes a digital programmable super surface to generate a group of random dual-beam surface codes to construct a perception matrix, utilizes a receiving loudspeaker to sample incident wave information in multiple directions and utilizes a sparse signal recovery algorithm to calculate the sampled information, thereby obtaining high-precision incident angle information. The method can realize high-precision incoming wave direction estimation and reduce sampling cost under the condition of avoiding a complex phase-shifting network and a large number of sensors. The work is expected to have important application prospect in the fields of radar and wireless communication.)

1. A multi-source DOA estimation method based on a digital programmable super surface is characterized by comprising the following steps:

step 1, generating M groups of random dual-beam surface codes by using a programmable super surface, wherein each group of dual-beam surface codes corresponds to a group of fixed dual-beam angles, and the pointing angles of each group of dual-beams are different;

the programmable super surface comprises an array formed by reflective units and a receiving loudspeaker; the array formed by the reflective units is used for generating dual-beam surface coding, and the receiving horn is used for receiving energy;

step 2, establishing a complete sensing matrix in matlab by using the M groups of surface codes generated in the step 1;

step 3, irradiating the super surface by using a standard loudspeaker, sequentially programming M groups of dual-beam surface codes into the programmable super surface by using an FPGA (field programmable gate array), and finally sampling irradiation energy by using a receiving loudspeaker to obtain M groups of sampling results;

and 4, performing projection comparison on the M groups of sampling results and the sensing matrix, and calculating obvious incoming wave angle information by adopting an OMP algorithm.

2. The multi-source DOA estimation method based on the digital programmable super surface according to claim 1, characterized in that in step 1, the reflective unit comprises a first metal copper column, a second metal copper column, a diode, a metal fan-shaped branch, and a metal patch layer, a first dielectric layer, a metal stratum of an isolation medium, a second dielectric layer, a third dielectric layer and a feed layer which are sequentially arranged from top to bottom;

the first metal copper column penetrates through the metal patch layer, the first dielectric layer, the metal stratum, the second dielectric layer, the third dielectric layer and the feed layer and is connected with the metal patch layer and the feed layer at the bottom, the metal fan-shaped branches are loaded between the feed layer and the third dielectric layer and are connected with the first metal copper column, the second metal copper column penetrates through the metal patch layer, the first dielectric layer and the metal stratum and is connected with the metal patch and the metal stratum, the diode is arranged on the surface of the metal patch layer and is connected between the first metal copper column and the second metal copper column, the state of the diode is controlled by changing the voltage between the first metal copper column and the second metal copper column, and each group of double-beam surface codes corresponds to one group of diode states.

3. The method of claim 1, wherein the receiving horn in step 1 is a standard rectangular horn.

4. The method of claim 1, wherein in step 3, for a fixed set of surface codes, the sampled signal of the receiving horn should satisfy equation (1):

wherein q is the state of the reflective cell, with a specific value of "0" or "1"; theta and phi are the angles of the incident waves, (x)_r，y_r，Z_r) To sample the relative coordinates of the phase center of the horn, N represents the incoming wave in N directions in space.

5. The multi-source DOA estimation method based on the digital programmable super surface according to the claim 1, characterized in that in the step 1, the M groups refer to 40 or more groups.

Technical Field

The invention belongs to the field of radar and electromagnetic sensing, and particularly relates to a multi-source DOA estimation method based on a digital programmable super surface.

Background

As a two-dimensional plane form of the metamaterial, the digital programmable super surface can flexibly regulate and control the spatial electromagnetic wave by virtue of the reconfigurable unit characteristics of the digital programmable super surface. Based on the characteristic, the digital programmable super surface can be used as a novel antenna type and applied to the fields of radars and communication systems. DOA estimation technology has been studied for many years as one of the key technologies in the fields of radar and wireless communication. However, the traditional DOA estimation method is based on a form of phased array antenna, and the array antenna needs a complex item shifting network structure or a large number of sensor receiving arrays. These complex hardware designs can result in high production costs and computational complexity. How to simplify the antenna array structure and realize the DOA estimation effect with high precision becomes an important problem in the field.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the defects of the prior art, the invention provides a multi-source DOA estimation method based on a digital programmable super surface. The method can realize high-precision incoming wave direction estimation and reduce sampling cost under the condition of avoiding a complex phase-shifting network and a large number of sensors.

The technical scheme is as follows: a multi-source DOA estimation method based on a digital programmable super surface is used for regulating and controlling space electromagnetic waves, and a sparse signal recovery algorithm is used for carrying out a high-precision DOA estimation process. The programmable super surface is composed of a plurality of reflective units integrated with diodes, and the working states of the reflective units can be dynamically changed by loading different voltages. The invention utilizes the digital programmable super surface to generate a series of random dual-beam surface codes to construct a perception matrix, utilizes a receiving loudspeaker to sample incident wave information in multiple directions, and utilizes a sparse signal recovery algorithm to calculate the sampled information, thereby obtaining high-precision incident angle information.

The invention discloses a multi-source DOA estimation method based on a digital programmable super surface, which comprises the following steps:

step 1, generating M groups of random dual-beam surface codes by using a programmable super surface, wherein each group of dual-beam surface codes corresponds to a group of fixed dual-beam angles, and the pointing angles of each group of dual-beams are different. The M groups mean 40 or more groups.

The programmable super surface comprises an array formed by reflective units and a receiving loudspeaker; the array of reflective cells is used to generate a dual beam surface code and the receiving horn is used to receive energy.

The reflection type unit comprises a first metal copper column, a second metal copper column, a diode, a metal fan-shaped branch knot, a metal patch layer, a first dielectric layer, a metal stratum for isolating the dielectric, a second dielectric layer, a third dielectric layer and a feed layer which are sequentially arranged from top to bottom;

the first metal copper column penetrates through the metal patch layer, the first dielectric layer, the metal stratum, the second dielectric layer, the third dielectric layer and the feed layer and is connected with the metal patch layer and the feed layer at the bottom; the metal fan-shaped branch knot is loaded between the feed layer and the third dielectric layer, is connected with the first metal copper column 7 and is used for Radio Frequency (RF) signal isolation and direct-current voltage bias; the second metal copper column penetrates through the metal patch layer, the first dielectric layer and the metal stratum to connect the metal patch and the metal stratum, the diode is arranged on the surface of the metal patch layer, the diode is connected between the first metal copper column and the second metal copper column, the state of the diode is controlled by changing the voltage between the first metal copper column and the second metal copper column, and each group of dual-beam surface codes corresponds to one group of diode states.

The invention is provided with 400 reflection units, namely 400 diodes, each diode has two states, the states of the 400 diodes correspond to a group of dual-beam surface codes, and the dynamic regulation and control of the space electromagnetic wave are realized by setting the states of the 400 diodes in the programmable super surface.

Step 2, establishing a complete sensing matrix in matlab by using the M groups of surface codes generated in the step 1; the sensing matrix represents the signal energy that incoming waves in all directions of space should sample.

And 3, irradiating the super-surface by using a standard loudspeaker, wherein the irradiation distance of the loudspeaker is far-field source irradiation. And then sequentially programming the M groups of dual-beam surface codes into the programmable super surface by using the FPGA, and finally sampling the irradiation energy by using a receiving loudspeaker to obtain M groups of sampling results. The receiving horn is a standard rectangular horn.

For a fixed set of surface codes, the sampled signal of the receiving horn should satisfy equation (1):

wherein q is the state of the reflective cell, with a specific value of "0" or "1"; theta and phi are the angles of the incident waves, (x)_r，y_r，Z_r) To sample the relative coordinates of the phase center of the horn, N represents the incoming wave in N directions in space.

And 4, performing projection comparison on the M groups of sampling results and the sensing matrix, and calculating obvious incoming wave angle information by adopting an OMP algorithm.

Has the advantages that: the invention realizes multi-source DOA estimation by utilizing the digital programmable super surface. The method provided by the invention can realize high-precision incoming wave direction estimation and reduce sampling cost under the condition of avoiding a complex phase-shifting network and a large number of sensors. The work is expected to have important application prospect in the fields of radar and wireless communication.

Drawings

FIG. 1 is a schematic structural diagram of a digitally programmable super surface provided by the present invention.

FIG. 2 is a schematic diagram of a cell structure of the digitally programmable super surface provided by the present invention.

FIG. 3 is a schematic diagram of dual beam implementation with a digitally programmable super surface

FIG. 3a is a schematic illustration of dual beam orofacial encoding.

Fig. 3b is a far field simulation schematic of a dual beam.

Fig. 3c is a schematic diagram of a simulation of the E-plane of a dual beam.

Fig. 3d is a schematic diagram of the test results for a dual beam.

FIG. 4 is a diagram of an estimation model for multi-source DOA implementation using a digitally programmable super-surface.

Fig. 5 is a cross-correlation coefficient matrix diagram for 40 sets of coding modes.

Fig. 6 is a normalized energy value matrix diagram for 40 sets of coding modes.

Fig. 7 is a graph of normalized average energy values for each angle for 40 sets of coding modes.

FIG. 8 is a graph of simulation versus actual measurement results for a single incident source.

Figure 8a is a plot of simulated sample values for a single incident source.

FIG. 8b is a graph of sample values obtained experimentally for a single incident source

FIG. 8c is a graph of DOA estimates from a single-source down-projection simulation.

FIG. 8d is a graph of DOA estimates experimentally calculated for projection under a single incident source.

FIG. 8e is a graph of DOA estimates calculated by simulation of the OMP algorithm at a single source of incidence.

FIG. 8f is a graph of experimentally calculated DOA estimates for the OMP algorithm at a single incidence source.

Fig. 9 is a graph of the comparison result between simulation and actual measurement under the condition of double incident sources.

Fig. 9a is a graph of simulated sample values under a dual-incident source.

Fig. 9b is a graph of the sample values obtained experimentally for the dual incidence source.

FIG. 9c is a DOA estimate plot from a dual-incident source down-projection simulation calculation.

FIG. 9d is a graph of DOA estimates from a dual-incident source projection experiment.

FIG. 9e is a graph of DOA estimates calculated by OMP algorithm simulation under dual incidence sources.

FIG. 9f is a graph of DOA estimates experimentally calculated for the OMP algorithm at dual incidence.

Wherein, 1, a metal patch layer; 2. a first dielectric layer; 3. a metal formation; 4. a second dielectric layer; 5. a third dielectric layer; 6. a feed layer; 7. a first copper metal pillar; 8. a second copper metal pillar; 9. a diode; 10. metal fan-shaped branch knot

Detailed Description

The technical solution of the present invention will be further explained with reference to the accompanying drawings and examples.

The invention discloses a multi-source DOA estimation method based on a digital programmable super surface, which comprises the following steps:

step 1, 40 groups of random double-beam surface codes are generated by utilizing a programmable super surface, each group of surface codes corresponds to a group of fixed double-beam angles, and the pointing angles of each group of double beams are different.

The structure of the digital programmable super surface is shown in figure 1, and the programmable super surface is an array formed by 400(20 x 20) reconfigurable reflective units. The array adopts a standard rectangular horn for empty feed, and in order to prevent the shielding effect of the feed source, the incident angle of the standard rectangular horn is set to be 45 degrees. The phase center of the standard rectangular horn is 150mm from the center of the programmable super-surface.

The structure of the reflective unit is shown in fig. 2. The reflection type unit comprises a first metal copper column 7, a second metal copper column 8, a diode 9, a metal fan-shaped branch 10, a metal patch layer 1, a first dielectric layer 2, a metal stratum 3 for isolating the dielectric, a second dielectric layer 4, a third dielectric layer 5 and a feed layer 6 which are sequentially arranged from top to bottom;

the first metal copper column 7 penetrates through the metal patch layer 1, the first dielectric layer 2, the metal stratum 3, the second dielectric layer 4, the third dielectric layer 5 and the feed layer 6, is connected with the metal patch layer 1 and the feed layer 6 at the bottom, and the metal fan-shaped branch 10 is loaded between the feed layer 6 and the third dielectric layer 5, is connected with the first metal copper column 7, and is used for Radio Frequency (RF) signal isolation and direct-current voltage bias; the second metal copper column 8 penetrates through the metal patch layer 1, the first dielectric layer 2 and the metal stratum 3 to connect the metal patch with the metal stratum 3, the diode 9 is arranged on the surface of the metal patch layer 1, the diode 9 is connected between the first metal copper column 7 and the second metal copper column 8, and the state of the diode is controlled by changing the voltage between the first metal copper column 7 and the second metal copper column 8. The dynamic regulation and control of the space electromagnetic wave are realized by setting the states of 400 diodes in the programmable super surface.

FIG. 3 is a schematic diagram of a dual beam implementation using a digitally programmable metasurface where the angles of the dual beams are 10 and-30, respectively. FIG. 3a is a face-to-face encoding for generating dual beams where different colors represent different diode switch states. Black represents a "0" state, i.e. the diode is off. White represents the "1" state, i.e. the diode is conducting. Fig. 3b is a simulated dual beam far field schematic. FIG. 3c is a schematic diagram of a simulation of the E-plane of the dual beam far field. Fig. 3d is a test effect diagram of the E-plane of the dual-beam far field, and the test effect proves that the digitally programmable super-surface provided by the invention can well realize the dual-beam effect.

And 2, establishing a complete sensing matrix by using 40 groups of surface codes in matlab, wherein the sensing matrix represents the signal energy which should be sampled by incoming waves in all directions of the space.

Fig. 5 is a cross-correlation coefficient of a perceptual matrix generated using 40 sets of codes, where the brighter the white the stronger the correlation. Simulation results show that the columns of the generated sensing matrix meet good orthogonality. Fig. 6 shows a normalized energy value matrix calculated by 40 sets of codes in the whole space, which means the magnitude of sampled energy at each angle in the space. FIG. 7 is a calculated normalized average energy value for each angle, representing a test range from-60 to 60 for random dual beams.

And 3, irradiating the super-surface by using a standard horn, wherein the irradiation distance of the standard horn is far-field source irradiation. Then, the 40 groups of double-beam surface codes are sequentially programmed into the programmable super surface by using the FPGA, and finally, the irradiation energy is sampled by using a rectangular loudspeaker.

For a fixed set of surface codes, the sampled signal of the receiving horn should satisfy equation (1):

wherein q is the state of the reflective cell, with a specific value of "0" or "1"; theta and phi are the angles of the incident waves, (x)_r，y_r，Z_r) To sample the relative coordinates of the phase center of the horn, N represents the incoming wave in N directions in space.

And 4, performing projection comparison on the 40 groups of sampling results and the sensing matrix, and calculating obvious incoming wave angle information by adopting an OMP algorithm.