CN115616476A - Intelligent super surface, system and method for measuring two-dimensional direction of arrival angle - Google Patents
Intelligent super surface, system and method for measuring two-dimensional direction of arrival angle Download PDFInfo
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- CN115616476A CN115616476A CN202211300451.8A CN202211300451A CN115616476A CN 115616476 A CN115616476 A CN 115616476A CN 202211300451 A CN202211300451 A CN 202211300451A CN 115616476 A CN115616476 A CN 115616476A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/04—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
Abstract
The invention discloses an intelligent super surface, a system and a method for measuring a two-dimensional direction of arrival angle. By designing a control voltage signal of each unit, the reflection phase of each unit presents periodic and mutually orthogonal phase change in space, and then the reflection phase is received by an auxiliary antenna and then is subjected to signal processing, so that a two-dimensional direction-of-arrival angle on the intelligent super surface is obtained. The invention realizes accurate two-dimensional direction-of-arrival angle estimation only by applying periodic control voltage to the super surface and one receiving antenna, compared with the method requiring n 2 The phased array system for estimating the same-scale two-dimensional direction of arrival angle of the radio frequency front end has simple structure, greatly reduces the hardware cost, is convenient for integration, can be used in radar, remote sensing and non-radarThe method has wide application prospect in a plurality of fields such as line communication and the like.
Description
Technical Field
The invention relates to an intelligent super-surface for measuring a two-dimensional direction of arrival angle, a measuring system and a method, which can be used in the fields of radar, remote sensing, wireless communication and the like.
Background
Two-dimensional direction of arrival (DOA) measurement technology is widely researched and applied as one of important technologies of radar, remote sensing and wireless communication. However, most of the existing DOA estimation methods rely on phased arrays, and the phased array technology needs multiple radio frequency front ends to receive electromagnetic waves, which undoubtedly increases hardware cost of system-level applications, so that the DOA estimation system based on the phased arrays always has the problems of high cost, high power consumption and high hardware complexity, and further popularization of the DOA estimation system is hindered. Therefore, there is a need to develop a low-cost and low-hardware complexity hardware device and related algorithm to meet the wide application of DOA technology in radar, remote sensing, and wireless communication systems.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide an intelligent super surface, a measuring system and a measuring method for measuring a two-dimensional direction of arrival (DOA), which can measure a two-dimensional incident angle of electromagnetic waves arriving at the intelligent super surface by applying mutually orthogonal time coding sequences to units on the super surface and receiving and demodulating the units by an auxiliary receiving antenna, have a real-time beam regulation function and can solve the technical problems of hardware complexity, high cost and high power consumption of the traditional DOA estimation system.
In order to solve the technical problems, the specific technical scheme of the invention is as follows:
an intelligent super-surface for measuring two-dimensional direction of arrival angles, comprising: n × n basic units, each unit comprising a three-layer structure: the first layer is formed by welding centrosymmetric metal patches of a PIN diode, the second layer is a dielectric substrate, and the third layer is a full metal layer with non-etched patterns; the metal patches on the first layer are connected with the metal layers on the third layer through metal through holes, control signals are transmitted to the metal patches from the feeder lines through the metal through holes, and the on-off of the diode is controlled by controlling the voltage of the two metal patches across the diode.
The control link consists of a Field Programmable Gate Array (FPGA) and a digital I/O module; each interface of the digital I/O module is connected to a control signal link of a unit, each unit being controllable by an independent periodic control signal.
When the unit control voltage of the intelligent super-surface is switched between 0V and 0.8V, the reflection phase of the unit can generate phase change of about 180 degrees in a frequency band of 4-5 GHz, and the amplitude is basically kept unchanged.
Each super-surface unit is modulated by periodic and orthogonal coded voltage, so that the reflection phase of the super-surface unit in space generates periodic and orthogonal continuous switching, and the time codes of the units are not influenced by each other.
Further, the material of the basic unit is a polytetrafluoroethylene F4BM high frequency antenna plate coated with copper foil on one side, the dielectric constant is 2.65, and the loss tangent is 0.001. The metal material is copper, and the thickness of the metal material is 0.018mm.
The invention also provides a two-dimensional direction-of-arrival angle measuring system, which comprises a transmitting antenna, a time modulation module, a receiving antenna and a data processing module; the time modulation module comprises the intelligent super surface; when the intelligent super surface is irradiated by incident waves, each basic unit on the intelligent super surface performs periodic time modulation on the incident waves and reflects the modulated electromagnetic waves to a free space; and a receiving antenna placed in a far field receives the reflected signal, transmits the reflected signal to a data processing module for demodulation, recovers the amplitude and phase distribution of the incident wave excited on the intelligent super surface, and estimates the two-dimensional angle of arrival.
The invention also provides a two-dimensional direction of arrival angle measuring method, which comprises the following steps:
step 1: single tone signal E i ＝e j2πft At a two-dimensional incident angle theta i And
incident on the smart metasurface, f denotes frequency and its scattering pattern is as follows:
wherein, the first and the second end of the pipe are connected with each other,
is the m-th row and the n-th column at theta and
directional scattering pattern, Γ mn (t) is the reflection coefficient of the corresponding m-th row and n-th column of the basic unit at t time, and the value thereof corresponds to n 2 The values of the m x n-th row of the order hadamard matrix;
step 2: after time modulation of each basic unit, the amplitude and phase distribution of the super-surface incident wave are modulated into an interweaved time-varying signal, and the signals are received by receiving antennas at the incoming angles theta and theta
Where received, the received signal at time t is
Through n 2 Second order T 0 For the interval sampling, the received signal can be expressed in the form of a matrix as follows:
wherein the matrix A is an n-order square matrix corresponding to the amplitude and phase information of each basic unit on the whole super surface, and is compressed into a one-dimensional vector in order to satisfy the matrix operation in the above formula
Γ is n 2 The corresponding value of the order square matrix is an n-order Hadamard matrix corresponding to the time-varying reflection coefficient of the super-surface modulation end; due to the orthogonality of the Hadamard matrix, the solvable matrix A value is solved by using the same Hadamard matrix at the receiving end, and the amplitude-phase distribution of the incident wave on the super surface is reconstructed.
And 3, step 3: the reconstructed amplitude-phase distribution matrix A of the incident wave on the super surface corresponds to a received signal matrix in the conventional phase control matrix angle measurement technology, and then the method can be adapted to a conventional arrival angle estimation algorithm, such as MUSIC, ESPRIT and the like, to calculate the arrival direction angle value of the super surface.
The invention has the following advantages:
1. the hardware complexity and cost are low: the invention provides an intelligent super surface for measuring a two-dimensional arrival angle, which comprises the following components: n × n basic units, each unit comprising a three-layer structure: the first layer is formed by welding centrosymmetric metal patches of a PIN diode, the second layer is a dielectric substrate, and the third layer is a full metal layer with non-etched patterns; the metal patches of the first layer are connected with the full metal layers of the third layer through the metal through holes, control signals are transmitted to the metal patches from the feeder lines through the metal through holes, and the on-off of the diode is controlled by controlling the voltage of the two metal patches of the diode cross.
2. Simple structure, low cost, planarization, easy other device integration: compared with the traditional phased array, the invention does not need to use a large number of electronic phase shifters or T/R components, has low cost, simple structure and high integration level, and is easy to integrate other high-frequency/plane circuits while meeting the requirements of size miniaturization and planarization.
In conclusion, the super surface designed by the invention can measure the two-dimensional direction of arrival angle on the super surface in real time, and can replace a phased array-based angle of arrival measuring system, so that the hardware complexity and the cost of the measuring system are reduced.
Drawings
FIG. 1 is a schematic diagram of a two-dimensional direction-of-arrival angle measurement of an intelligent super-surface in the present invention;
FIG. 2 is a schematic diagram of the overall structure and a schematic diagram of a local cell structure of the intelligent super surface in the present invention;
FIG. 3 is a reflection amplitude response and reflection phase response curve diagram of the intelligent super surface in the invention under different working states of the PIN diode;
FIG. 4 is a diagram of a real object of the intelligent super-surface and a two-dimensional space angle at which a two-dimensional direction of arrival angle is measured;
FIG. 5 is a schematic diagram of an architecture of an intelligent super-surface based two-dimensional direction-of-arrival angle measurement system;
FIG. 6 is a graph of the actual DOA angle of the angle α of the intelligent super surface in FIG. 4, the DOA angle measured by the intelligent super surface, and the angle error;
FIG. 7 is a graph of the actual DOA angle at β in FIG. 4, the DOA angle measured by the smart super surface, and the angle error in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
One embodiment of the invention is shown in fig. 1, and discloses an intelligent super surface for measuring a two-dimensional direction of arrival angle, wherein the super surface consists of a metal patch layer, an F4B dielectric layer and a metal back plate layer, and n × n basic units. The control voltage signal of each unit is carefully designed, so that the reflection phase of each unit presents periodic and mutually orthogonal phase change in space, and the signals are processed after being received by an auxiliary antenna.
As shown in FIG. 1, each unit of the smart meta-surface in the invention can be controlled independently by a periodic control voltage, and the m row and n column units show a time-varying reflection phase Γ under the control voltage mn (t) of (d). When a beam of electromagnetic waves with single frequency is at a two-dimensional directional angle theta i And
when the light is incident on the intelligent super surface, the intelligent super surfaceThe far-field scattering pattern of (a) is:
wherein θ and
is the angle of the reflected signal after the modulation of the intelligent super surface, d x And d y Representing the spacing between two adjacent cells along the x-axis and the y-axis. As shown in FIG. 1, after each cell is time-modulated, the amplitude and phase distribution of the incident wave on the subsurface is mapped into an interleaved time-varying signal, which is then summed at θ
And receiving by the receiving antenna arranged at the angle position. The amplitude and phase information of the incident wave on the super-surface unit is compressed into a one-dimensional vector, and the received signal can be expressed as:
wherein
Is composed of N 2 The reflection coefficients of the super-surface units at the same sampling time. In the present invention, in the case of the present invention,
the first row contains all +1 and the other rows contain the same number of hadamard matrices of +1 and-1. In this case, it is preferable that the air conditioner,
are mutually orthogonal to each other and,
the inverse of (c) also exists. Thus, the incident wave is in the superThe vector a, which is composed of the amplitude and phase distribution over the surface, can be reconstructed from the received signal. The distribution can be regarded as a received signal matrix required by a traditional DOA algorithm model, and the traditional DOA algorithm, such as a MUSIC algorithm and an ESTPT algorithm, is directly applied to calculate the two-dimensional arrival angle on the super surface.
The structure diagram of the intelligent super-surface for measuring the two-dimensional direction of arrival disclosed by the invention is shown in figure 2. The super surface consists of a metal patch layer, an F4B dielectric layer and a metal back plate layer, n x n basic units are total, and each unit comprises a three-layer structure: the top layer of the unit is welded in a gap between two centrosymmetric reflecting patches and a PIN diode (SMP 1320-040 LF), and an F4B dielectric substrate (polytetrafluoroethylene) dielectric substrate (dielectric constant is 2.65, and loss tangent is 0.001) is arranged between the top layer and the metal ground. Each metal patch structure of the top layer is connected with a control signal through a metal via hole. The structure diagram of the intelligent super surface and the unit thereof is shown in fig. 2, wherein the specific structural parameters are as follows: p =25mm, h =4mm, v =24mm, w =10.6mm, g =0.3mm.
The actual measurement curve diagram of the reflection amplitude response and the reflection phase response of the intelligent super surface in different working states of the PIN diode is shown in figure 3, the working frequency of the intelligent super surface is 4.3 GHz-4.8 GHz, 180-degree reflection phase shift is realized in the two states, and the amplitude conversion is relatively stable.
The intelligent super-surface object structure in the invention is shown in figure 4. The structure object diagram of the two-dimensional direction of arrival angle measuring system utilizing the intelligent super surface is shown in fig. 5, and the whole system consists of a transmitting antenna, a time modulation module, a receiving module and a data processing module. The time modulation module is positioned on the left side of the figure 5 and consists of the intelligent super surface and the control platform in the invention. The receiving and data processing module is located on the right side of fig. 5 and consists of a receiving antenna located in the normal direction of the intelligent super surface and connected to a high-performance SDR receiver. When the super surface is irradiated by the incident wave, each unit on the super surface performs periodic time modulation on the incident wave, wherein the modulation codes corresponding to the unit of the m-th row and the n-th column are corresponding to n 2 Values of m x n-th row of the order hadamard matrixWherein, the control voltage corresponding to 1 in the Hadamard matrix is 0.8V, and the control voltage corresponding to 0 in the Hadamard matrix is 0V. The modulated electromagnetic wave is reflected to a free space, a receiving antenna arranged in a far field receives the reflected signal, the reflected signal is transmitted to a signal processing end to be demodulated, the amplitude and phase distribution of the incident wave excited on the super surface are restored, and two-dimensional angle of arrival estimation is carried out.
Further, by utilizing the framework of the two-dimensional direction-of-arrival angle measuring system of the intelligent super-surface, the transmitting antenna transmits single-frequency electromagnetic waves of 4.5GHz, the alpha angle and the beta angle of the single-frequency electromagnetic waves are scanned from-75 degrees to +75 degrees, and angle estimation is carried out on the single-frequency electromagnetic waves through the intelligent super-surface system. Wherein, the actual direction of arrival angle of the alpha angle, the direction of arrival angle of the intelligent super-surface measurement and the angle error curve chart are shown in fig. 6, and the actual direction of arrival angle of the beta angle, the direction of arrival angle of the intelligent super-surface measurement and the angle error curve chart are shown in fig. 7. The angle of the direction of arrival measured by the intelligent super-surface and the actual angle of the direction of arrival have small errors, and the integral error is controlled within 4 degrees, thereby proving the application value of the invention.
In a word, the intelligent super-surface provided by the invention realizes the measurement of the two-dimensional direction of arrival angle only through the control of the periodic control voltage, has simple principle, simple hardware architecture, low cost and convenient integration, and has wide application prospect in a plurality of fields such as radar, remote sensing, wireless communication and the like.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. An intelligent super-surface for measuring direction of arrival angle, characterized in that: the intelligent super surface comprises n x n basic units, wherein each basic unit comprises a three-layer structure: the first layer is formed by welding two centrosymmetric metal patches of a PIN diode, the second layer is a medium substrate layer, and the third layer is an all-metal layer without etching clusters; the metal patch of the first layer is connected with the all-metal layer of the third layer through a metal through hole; each metal patch of the first layer is connected to a control signal link through a metal through hole; the whole super surface has 2 x n control signal links, and each unit is independently controlled by a periodic control voltage.
2. The intelligent super-surface for measuring a direction of arrival angle of claim 1, wherein: the basic unit of the intelligent super-surface is made of a polytetrafluoroethylene F4BM high-frequency antenna plate with a copper foil coated on one surface, the dielectric constant of the antenna plate is 2.65, and the loss tangent of the antenna plate is 0.001.
3. The intelligent super-surface for measuring a direction of arrival angle of claim 1, wherein: the control link of the intelligent super surface consists of a Field Programmable Gate Array (FPGA) and a digital I/O module; each interface of the digital I/O module is connected to a control signal link of a base unit, such that each base unit is controlled by an independent periodic control signal.
4. The intelligent super-surface for measuring a direction of arrival angle of claim 1, wherein: when the control voltage of the basic unit of the intelligent super-surface is switched between 0V and 0.8V, the reflection phase of the basic unit generates phase change of about 180 degrees in a frequency band of 4-5 GHz, and the amplitude is basically kept unchanged.
5. The intelligent super-surface for measuring a direction of arrival angle of claim 1, wherein: each basic unit is modulated by a periodic and orthogonal code voltage respectively, so that the reflection phase of the basic unit in space generates periodic and orthogonal continuous switching, and the time codes of the units are different from each other.
6. A two-dimensional direction of arrival angle measurement system is characterized by comprising a transmitting antenna, a time modulation module, a receiving antenna and a data processing module; the time modulation module comprises the intelligent super surface of any one of claims 1-5; when the intelligent super surface is irradiated by incident waves, each basic unit on the intelligent super surface periodically modulates the incident waves in time and reflects the modulated electromagnetic waves to a free space; and a receiving antenna placed in a far field receives the reflected signal, transmits the reflected signal to a data processing module for demodulation, recovers the amplitude and phase distribution of the incident wave excited on the intelligent super surface, and estimates the two-dimensional angle of arrival.
7. A two-dimensional direction-of-arrival angle measurement method based on the system of claim 6, comprising the steps of:
step 1: single tone signal E i ＝e j2πft At a two-dimensional incident angle theta i And
incident on the smart metasurface, f denotes frequency and its scattering pattern is as follows:
wherein the content of the first and second substances,
is the m-th row and the n-th column at theta and
directional scattering patterns, Γ mn (t) is the reflection coefficient of the corresponding m-th row and n-th column basic unit at t time, and the value thereof corresponds to n 2 The values of the m x n th row of the hadamard-ordered matrix;
step 2: after time modulation of each basic unit, the superThe amplitude and phase distribution of the surface incident wave is modulated into an interleaved time-varying signal, which is received by a receiving antenna at an entrance angle θ
Where received, the received signal at time t is
Through n 2 Second order T 0 After sampling at intervals, the received signal is expressed in the form of a matrix as follows:
wherein the matrix A is an n-order square matrix corresponding to the amplitude and phase information of each basic unit on the whole super surface, and is compressed into a one-dimensional vector in order to satisfy the matrix operation in the above formula
Γ is n 2 The corresponding value of the order square matrix is an n-order Hadamard matrix corresponding to the time-varying reflection coefficient of the super-surface modulation end;
and step 3: and calculating the direction-of-arrival angle value of the super-surface by using an angle-of-arrival estimation algorithm.
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| CN116299152A (en) * | 2023-03-21 | 2023-06-23 | 安徽大学 | Variable criterion variable sparse multi-target direction-of-arrival estimation method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116299152A (en) * | 2023-03-21 | 2023-06-23 | 安徽大学 | Variable criterion variable sparse multi-target direction-of-arrival estimation method |
| CN116299152B (en) * | 2023-03-21 | 2023-11-21 | 安徽大学 | Variable criterion variable sparse multi-target direction-of-arrival estimation method |
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