CN117040644A - Ka frequency band passive intelligent response system and method based on amplitude coding super surface - Google Patents
Ka frequency band passive intelligent response system and method based on amplitude coding super surface Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
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- H—ELECTRICITY
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/59—Responders; Transponders
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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- H04B10/516—Details of coding or modulation
- H04B10/548—Phase or frequency modulation
- H04B10/556—Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
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- H—ELECTRICITY
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a ka frequency band passive intelligent response system and a method based on an amplitude coding super surface, wherein the system comprises the amplitude coding super surface and an FPGA control module, the amplitude coding super surface is formed into a square array by periodically arranging a plurality of basic units, and the four basic units in the center are information perception modules; the amplitude coding super-surface has the characteristic of scattering state electric adjustability, and the super-surface can be switched back and forth among a plurality of scattering states by changing the state of a PIN diode at the top of the basic unit; the information sensing module receives an external incident signal and outputs the external incident signal to the FPGA control module; and the FPGA control module performs characteristic recognition on the signals received by the super surface, and outputs current regulated and controlled in real time according to the result of signal recognition. The invention can accurately respond to the target incident signal, simultaneously reduce the RCS of the signal outside the target, realize the functions of identity recognition and electromagnetic stealth, and has the characteristics of low power consumption, light weight and easy processing.
Description
Technical Field
The invention relates to the technical field of electromagnetic functional materials, in particular to a ka frequency band passive intelligent response system and method based on an amplitude coding super surface.
Background
The target mark refers to a process of identifying the identity of the target through various technologies and means, and is a very important link in the increasingly complex electromagnetic interference environment nowadays. Particularly, with the rapid development of electromagnetic technology, various electromagnetic interference means are developed, the viability and camouflage capability of various devices are continuously enhanced, and meanwhile, the electromagnetic interference environment is increasingly complicated, so that higher requirements are required for the target identification technology at present, and accordingly, the changing practical application environment is met.
The amplitude coding super-surface is researched, the advantage that the super-surface flexibly regulates and controls the scattering state of electromagnetic waves is utilized, detection signals can be perceived, whether corresponding frequency spectrum characteristics are endowed to echoes or not is determined according to the perception result, the purpose of accurately responding to specific detection signals is achieved, and meanwhile the scattering intensity under incidence of other signals is reduced. The amplitude coding super-surface ensures the survival problem of the self while improving the target resolution capability, and realizes the low-cost, low-power consumption and miniaturized intelligent coding response tag.
For example, document 1 (a.lavrenko, b.litchfield, g.woodward and s.payson, "Design and evaluation of a compact harmonic transponder for insect tracking," IEEE microw, wirel co., vol.30, no. 4, pp. 445-448, april 2020) proposes a lightweight, miniaturized passive harmonic transponder combining a printed circuit including a diode and a tuning inductor with a dipole antenna, and re-transmitting most of the received incident signal energy back in the form of a second harmonic, thereby achieving the effect of a harmonic response, but the operating bandwidth is significantly limited due to the simple structure and the response form is single.
Document 2 (c.hilton and j.a. Nanzer, "Narrowband Passive RF Tags for Frequency-Selective Harmonic Doppler Radar Tracking," IEEE trans. Antennas Propagat, vol. 71, no. 2, pp. 1216-1222, feb. 2023) proposes a frequency selective radio frequency harmonic tag for harmonic doppler radar tracking, integrating a loop antenna, a dipole antenna, and a diode. Because the narrow-band working characteristic of the circular ring antenna can play a role of narrow-band filtering, a second-order harmonic signal is generated by utilizing the nonlinear effect of the diode and is emitted by the dipole antenna, so that the harmonic response to the incident signal with the specific frequency is realized, but the defect of single response form exists because only the second-order harmonic signal can be generated.
Disclosure of Invention
The invention aims to provide a ka frequency band passive intelligent response system and a method based on an amplitude coding super surface, which can reduce power consumption and realize electromagnetic stealth, so that a targeted intelligent coding response tag is realized in an electromagnetic interference environment.
The technical solution for realizing the purpose of the invention is as follows: the ka frequency band passive intelligent response system based on the amplitude coding super surface comprises the amplitude coding super surface and an FPGA control module, wherein:
the amplitude coding super-surface is formed by periodically arranging a plurality of basic units to form a square array, and the four basic units in the center are information sensing modules; the amplitude coding super-surface has the characteristic of scattering state electric adjustability, and the super-surface can be switched back and forth among various scattering states by changing the state of a PIN diode at the top of the basic unit; the information sensing module receives an incident signal from the outside and outputs the incident signal to the FPGA control module;
the FPGA control module comprises a signal receiving module, a signal processing module and a current output module, and can realize characteristic identification of signals received by the super surface and output current regulated and controlled in real time according to the result of signal identification.
The ka frequency band passive intelligent response method based on the amplitude coding super surface is based on the ka frequency band passive intelligent response system based on the amplitude coding super surface, and comprises the following specific steps:
step 1, an information sensing module receives an incident signal from the outside and transmits the received signal to an FPGA control module;
step 2, the FPGA control module performs feature recognition on the received signals, and outputs currents in different states according to recognition results;
and 3, the regulated output current changes the scattering state of the super surface in real time through an I/O port, so that the response of the system to the target signal and the RCS reduction of the signal outside the target are realized.
Compared with the prior art, the invention has the remarkable advantages that:
(1) The response system does not need to actively transmit response signals, and has the advantages of lower power consumption, smaller size and more flexible application compared with the active response system;
(2) The matched FPGA control module receives and recognizes external detection signals to determine whether the system works and the working mode, so that the defect of full-time working of the traditional amplitude coding super-surface is avoided, the working time of the system is greatly reduced, and the power consumption of the system is further reduced;
(3) The included amplitude coding super-surface can realize the multifunctional integrated design of signal receiving and amplitude modulation, can regulate and control the scattering state of the self in real time while receiving signals, and improves the self detection and viability by implementing RCS reduction on detection signals outside target signals.
Drawings
FIG. 1 is a schematic diagram of a ka-band passive intelligent response system based on amplitude-encoded super-surfaces in an embodiment of the invention.
FIG. 2 is a schematic diagram of an array surface structure of an amplitude-coded super-surface in an embodiment of the invention.
FIG. 3 is a schematic top view of a unit structure of an amplitude encoded super surface module according to an embodiment of the present invention.
FIG. 4 is a schematic side view of a unit structure of an amplitude encoded super surface module according to an embodiment of the present invention.
FIG. 5 is a schematic bottom view of a unit structure of an amplitude encoded super surface module according to an embodiment of the invention.
Fig. 6 is a schematic diagram of a dc feed layer in the middle of a unit structure of an amplitude encoded super surface module in an embodiment of the invention.
FIG. 7 is a graph of the change in reflectance of an amplitude encoded subsurface unit with or without a PIN diode passing current, in an embodiment of the invention.
Fig. 8 is a graph of the variation of radar cross section RCS of an amplitude encoded super surface array with or without a PIN diode passing current in an embodiment of the invention.
FIG. 9 is a schematic diagram of a circuit model responsible for detecting and amplifying signals received by a subsurface in accordance with an embodiment of the present invention.
FIG. 10 is a time domain waveform diagram of an amplitude encoded subsurface bottom output signal in accordance with an embodiment of the present invention.
Fig. 11 is a time domain waveform diagram of a signal amplified by detection in an embodiment of the present invention.
Fig. 12 is a time domain waveform diagram of a system for coding response to an external incident signal in an embodiment of the present invention.
Fig. 13 is a spectrum diagram of a coded response of a system to an external incident signal in an embodiment of the invention.
Detailed Description
It is easy to understand that various embodiments of the present invention can be envisioned by those of ordinary skill in the art without altering the true spirit of the present invention in light of the present teachings. Accordingly, the following detailed description and drawings are merely illustrative of the invention and are not intended to be exhaustive or to limit or restrict the invention.
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.
The invention provides a ka frequency band passive intelligent response system based on an amplitude coding super surface, which comprises the amplitude coding super surface and an FPGA control module, wherein:
the amplitude coding super-surface is formed by periodically arranging a plurality of basic units to form a square array, and the four basic units in the center are information sensing modules; the amplitude coding super-surface has the characteristic of scattering state electric adjustability, and the super-surface can be switched back and forth among various scattering states by changing the state of a PIN diode at the top of the basic unit; the information sensing module receives an incident signal from the outside and outputs the incident signal to the FPGA control module;
the FPGA control module comprises a signal receiving module, a signal processing module and a current output module, and can realize characteristic identification of signals received by the super surface and output current regulated and controlled in real time according to the result of signal identification.
As a specific example, the basic units in the amplitude coding super surface sequentially comprise a first layer to an eighth layer from top to bottom, wherein the eighth layer bottom of the four basic units in the information sensing module is provided with a ninth layer, which is specifically as follows:
the first layer is a metal circuit layer and consists of four groups of square ring metal patches which are arranged in a central symmetry mode and PIN diodes, wherein the PIN diodes are arranged at the positions of gaps among the square ring metal patches and are used for connecting all the square ring metal patches together; changing the state of the PIN diode by changing the current flowing through the PIN diode, so that the super-surface is switched between different scattering states;
the second layer is a first dielectric substrate;
the third layer is a metal grounding layer and provides grounding for the PIN diode;
the fourth layer is a second dielectric substrate;
the fifth layer is a direct current feed layer and consists of two metal feed lines longitudinally distributed along the square array, and provides regulated output current for the PIN diode;
the sixth layer is a third dielectric substrate;
the seventh layer is a metal grounding layer and provides grounding for the bottommost wilkinson feed network;
the eighth layer is a fourth dielectric substrate;
the ninth layer is a wilkinson feed network and is used for outputting incident wave signals received by four basic units in the information sensing module.
As a specific example, twelve metallized holes are designed in the four basic units of the information sensing module, so as to play roles of signal transmission and electrical connection; all the metallized holes can be divided into three groups according to different transmitted signals, and each group is four;
the first group of metallized holes are positioned between the first layer of metal circuit layer and the third layer of metal grounding layer, the punching positions are respectively positioned at the left half part of each group of square ring metal patches, and the centers of the four basic units are symmetrically distributed up and down to provide grounding signals for the PIN diode;
the second group of metallized holes are positioned between the first layer of metal circuit layer and the fifth layer of direct current feed layer, the punching positions are respectively positioned at the right half part of each group of square ring metal patches, and the centers of the four basic units are symmetrically distributed up and down to provide regulated output current for the PIN diode;
the third group of metallized holes are positioned between the first layer of metal circuit layer and the ninth layer of Wilkinson feed network, the punching positions are respectively positioned at the central ring edge of each group of square ring metal patches, and the centers of the four basic units are distributed in a central symmetry manner; the square annular metal patch at the top of the information sensing module receives an incident signal from the detection radar, and then the incident signal is transmitted to the Wilkinson feed network at the bottom through the third group of metalized holes, and the Wilkinson feed network gathers the received signals and outputs the signals to the FPGA control module.
As a specific example, in the amplitude coding super-surface, each array of basic units forms a subarray, each subarray is provided with an I/O port, and the real-time switching of the PIN diode between different states is ensured by regulating and controlling the input current of each array of subarrays;
by switching the on-off state of the PIN diode, the super surface realizes high scattering and low scattering states respectively, and has the electrically adjustable characteristic of the scattering state.
As a specific example, the FPGA control module includes a signal receiving module, a signal processing module, and a current output module, where:
the signal receiving module is a back-end processing circuit comprising a power amplifier and an envelope detector, and can receive the output signal at the bottom of the super surface and perform detection amplification processing;
the signal processing module reads and compares signal parameters, namely the pulse width and the pulse repetition period of the detected signal are read, and compared with prestored pulse width and pulse repetition period parameter values, if the comparison results are consistent, the signal processing module judges that the signal processing module is a friend detection signal, and if the comparison results are inconsistent, the signal processing module judges that the signal processing module is an enemy detection signal, so that the characteristic identification of the received signal is realized;
the current output module is used for simultaneously regulating and controlling the current output state of the multichannel I/O port according to the characteristic identification result of the signal and controlling the working state of the amplitude coding super surface, if the signal processing module judges that the received signal is a friend detection signal, the current output by the FPGA is subjected to time coding, and if the signal processing module judges that the received signal is an enemy detection signal, the FPGA outputs the current under single amplitude.
As a specific example, each basic unit has a length of 11mm and a width of 11mm; the basic unit works in the ka frequency band;
the first dielectric substrate to the fourth dielectric substrate are ROGERS4350 dielectric substrates, the dielectric constant is 3.66, and the dielectric loss tangent is 0.0037;
the thickness of each basic unit is 1.5mm, and the thicknesses of the first dielectric substrate to the fourth dielectric substrate are 1mm,0.2mm and 0.1mm respectively;
the variation range of the output current of the FPGA control module is 0.04-400 mA, and the precision is 0.1mA.
The invention also provides a ka frequency band passive intelligent response method based on the amplitude coding super surface, which is based on the ka frequency band passive intelligent response system based on the amplitude coding super surface, and comprises the following specific steps:
step 1, an information sensing module receives an incident signal from the outside and transmits the received signal to an FPGA control module;
step 2, the FPGA control module performs feature recognition on the received signals, and outputs currents in different states according to recognition results;
and 3, the regulated output current changes the scattering state of the super surface in real time through an I/O port, so that the response of the system to the target signal and the RCS reduction of the signal outside the target are realized.
As a specific example, in step 1, the information sensing module receives an incident signal from the outside, and transmits the received signal to the FPGA control module through the wilkinson feed network at the bottom, where the frequency range of the received signal covers the whole ka band.
As a specific example, in step 2, the FPGA control module includes a signal receiving module, a signal processing module, and a current output module, which specifically includes:
the signal receiving module is a back-end processing circuit comprising a power amplifier and an envelope detector, and can receive the output signal at the bottom of the super surface and perform detection amplification processing;
the signal processing module reads and compares signal parameters, namely the pulse width and the pulse repetition period of the detected signal are read, and compared with prestored pulse width and pulse repetition period parameter values, if the comparison results are consistent, the signal processing module judges that the signal processing module is a target detection signal, and if the comparison results are inconsistent, the signal processing module judges that the signal processing module is an external target signal, so that the characteristic identification of the received signal is realized;
the current output module is used for simultaneously regulating and controlling the current output state of the multi-channel I/O port according to the characteristic identification result of the signal and controlling the working state of the amplitude coding super-surface, if the signal processing module judges that the received signal is a target detection signal, the current output by the FPGA is subjected to time coding, and if the signal processing module judges that the received signal is an external target signal, the FPGA outputs the current under a single amplitude.
As a specific example, in step 3, the regulated output current changes the scattering state of the super surface in real time through the I/O port, so as to realize the response of the system to the target signal and the RCS reduction of the signal outside the target, specifically:
the regulation and control current output by the FPGA changes the scattering state of the super surface in real time through the I/O port;
when the FPGA outputs coded current, the scattering state of the super surface is switched back and forth according to a designed coding sequence, and specific frequency spectrum characteristics are endowed to echo signals, so that response to target signals is realized;
when the FPGA outputs current with single amplitude, the super surface keeps a low scattering state, the intensity of echo signals is reduced, and RCS reduction of signals outside the target is realized.
According to the invention, the characteristic recognition can be carried out on the signals received by the super surface, the time coding is carried out on the current signals output by the FPGA according to the result of the signal recognition, the coded current controls the scattering state of the super surface through the I/O port, so that the scattering state of the coded super surface is switched back and forth according to the designed coding sequence, and certain frequency spectrum characteristics are endowed to echo signals, so that the passive intelligent response system can accurately respond to the target incident signals, and RCS reduction is carried out on the signals outside the target, thereby realizing the functions of identity recognition and electromagnetic stealth; compared with the traditional design, the invention has the characteristics of low power consumption, light weight and easy processing.
For a clearer description of the objects, technical solutions and advantages of the present invention, reference will be made to the following detailed description taken in conjunction with the accompanying drawings and examples. It will be apparent that the examples described are preferred embodiments of the invention and are not limiting thereof.
Examples
As shown in fig. 1, this embodiment designs a ka-band passive intelligent response system based on an amplitude coding super surface, where the passive intelligent response system includes: the amplitude coding super-surface with the information sensing module can identify the super-surface receiving signal and the FPGA control module for intelligently regulating and controlling the super-surface. When the system starts to work, the linear frequency modulation pulse signal from the detection radar is received by the amplitude coding super surface, and is transmitted to the FPGA control module through the Wilkinson feed network at the bottom, the received signal is converted into a square wave pulse signal after detection and amplification processing, the FPGA is convenient for reading the pulse width and the pulse repetition period of the signal, and after that, the signal is compared with the signal parameters prestored in the system. According to the comparison result, the FPGA current output module selects and outputs the coded current or the current with single amplitude, and controls the scattering state of the amplitude coding super-surface through the I/O interface, so that the super-surface switches the scattering state back and forth or always keeps the low scattering state according to a preset coding sequence, and the coded response of the target detection signal and the electromagnetic stealth of the signal outside the target are realized.
The technical solution for realizing the invention comprises the following steps:
and step 1, the information sensing module receives an incident signal from the outside and transmits the received signal to the FPGA control module.
And 2, the FPGA control module performs feature recognition on the received signals, and outputs currents in different states according to recognition results.
And 3, the regulated output current changes the scattering state of the super surface in real time through the I/O port, so that the accurate response of the system to the target signal and the RCS reduction of the signal outside the target are realized.
Specifically, the information sensing module designed can receive an incident signal from the outside, and transmits the received signal to the FPGA control module through the Wilkinson feed network at the bottom, and the frequency range of the received signal can cover the whole ka frequency band.
Specifically, the FPGA control module designed to realize the feature recognition can be used for carrying out feature recognition on the received signals, and outputting currents in different states according to recognition results, specifically comprises the following steps:
the designed FPGA control module comprises a signal receiving module and a current output module, wherein the signal receiving module comprises a power amplifier and a rear-end processing circuit including an envelope detector, and can receive the output signal from the bottom of the super surface and perform detection amplification processing, so that the FPGA control module can conveniently read and compare signal parameters subsequently, and the characteristic identification of the received signal is realized. The current output module can realize current output regulated and controlled in real time. And receiving and reading signal parameters of the incident wave signals, comparing the signal parameters with prestored parameters of the system, outputting coded current by the FPGA if the comparison results are consistent, and outputting current with single amplitude by the FPGA if the comparison results are inconsistent.
Specifically, the designed passive intelligent response system can realize accurate response to the target signal and RCS reduction of the target external signal, and specifically comprises the following steps:
the regulation and control current output by the FPGA changes the scattering state of the super surface in real time through the I/O port, when the FPGA outputs the coded current, the scattering state of the super surface is switched back and forth according to the designed coding sequence, the specific frequency spectrum characteristic of the echo signal is endowed, and the accurate response to the target signal is realized; when the FPGA outputs current with single amplitude, the super surface keeps a low scattering state, the intensity of echo signals is reduced, and RCS reduction of signals outside the target is realized.
With reference to fig. 2 to fig. 6, this embodiment provides an amplitude coding super surface with an information sensing module, where the super surface includes a plurality of basic units, taking a unit serving as the information sensing module in the middle as an example, each basic unit sequentially includes from top to bottom:
the first layer is a metal circuit layer and consists of four groups of square ring metal patches and PIN diodes, wherein the square ring metal patches are arranged in a central symmetry mode, and the PIN diodes are arranged at the positions of gaps among the square ring patches and are connected together. By changing the current flowing through the PIN diode, the state of the PIN diode is changed, so that the super-surface unit can be switched between different states;
the second layer is a ROGERS4350 dielectric substrate;
the third layer is a metal grounding layer and provides a grounding effect for the PIN diode;
the fourth layer is a ROGERS4350 dielectric substrate;
the fifth layer is a direct current feed layer and consists of two metal feed lines distributed along the longitudinal direction of the unit, and provides regulated output current for the PIN diode;
the sixth layer is a ROGERS4350 dielectric substrate;
the seventh layer is a metal grounding layer and provides a grounding effect for the bottommost wilkinson feed network;
the eighth layer is a ROGERS4350 dielectric substrate;
the ninth layer is a wilkinson feed network, and is capable of outputting an incident wave signal received by the unit.
In addition, twelve metallized holes are designed in the basic unit to realize the functions of signal transmission and electrical connection. All the metallized holes can be divided into three groups according to the transmitted signals, and each group is four. The first group of metallized holes are positioned between the first metal circuit layer and the third grounding layer to provide grounding signals for the PIN diode. The second group of metallized holes are positioned between the first metal circuit layer and the fifth direct current feed layer and provide regulated output current for the PIN diode. The third group of metallized holes is located between the first metal circuit layer and the ninth Wilkinson feed network and is used for transmitting the incident wave signals received by the units to the feed network at the bottom.
Compared with other surrounding super-surface units, the unit serving as the information sensing module is additionally provided with a Wilkinson feed network of a ninth layer and four metallized holes positioned between the first metal circuit layer and the Wilkinson feed network of the ninth layer, so that the function of receiving external signals is realized.
Specifically, in this embodiment, the structural period of the subsurface unit is 11mm; the length of the outer edge of the square ring metal patch forming the metal circuit layer is 1.7mm, the radius of the inner edge is 1mm, and the gap between the metal patches is 0.2mm; the metal feeder lines constituting the direct current feeder layer were arranged longitudinally along the cell, with a length of 11mm and a width of 0.6mm. The line width of an alternating current feeder line forming the Wilkinson feed network is 0.2mm and 0.1mm respectively, the line length accords with the design principle of the Wilkinson feed network, the corner is designed by chamfering, the problem of discontinuous impedance of the transmission line at the corner is solved, and an isolation resistor with the resistance of 100 omega is placed between branches of the feed network and has the effect of isolating electromagnetic coupling of the branches.
Specifically, in this embodiment, the loading component of the super surface unit is an SMP1320 PIN diode and a 100Ω chip resistor, where the placement positions of the components are shown in fig. 3 and 5, and the PIN diode is equivalent to a resistance element with adjustable resistance value when the forward bias current is loaded, where the super surface is in a low scattering state; when no current is applied, the equivalent is a capacitive element with a capacitance of 0.23pF, in which case the super surface is in a highly scattering state.
Specifically, the super surface unit in this embodiment has a 9-layer structure, and is divided into four layers of ROGES4350 dielectric substrates, one metal circuit layer, one direct current feed layer, one wilkinson feed network and two metal grounding layers; the thicknesses of the four layers of the ROGERS4350 dielectric substrates are 1mm,0.2mm and 0.1mm from top to bottom in sequence, the dielectric constant of the adopted ROGERS4350 material is 3.66, and the dielectric loss tangent is 0.0037. The electrical connection and signal transmission are realized between the layers through the metallized holes.
Specifically, in this embodiment, the FPGA control module includes a signal receiving module and a current output module. The signal receiving module is a rear-end processing circuit comprising a power amplifier and an envelope detector, and can receive the output signal at the bottom of the super surface and perform detection amplification processing, so that the FPGA control module can conveniently read and compare signal parameters subsequently, and the characteristic recognition of the received signal is realized; the current output module can realize current output regulated and controlled in real time, and the working state of the amplitude coding super-surface is controlled through the I/O port.
As an optimization scheme, fig. 7 shows a graph of the change of the reflection coefficient in the presence or absence of current passing through an amplitude-coded super-surface unit in the case of both x and y polarizations. When current passes through, the diode is in a conducting state and can be equivalent to a resistance of 100 omega, and the unit shows good absorption characteristic; when no current passes through, the diode is in a cut-off state, which can be equivalent to a 2.3pF capacitor, and the cell shows good reflection characteristics. Under the x polarization condition, the unit has a 10dB regulation bandwidth of 10GHz in the ka frequency band, and reaches a reflection coefficient regulation range of 18dB in 34.5 GHz; under the y polarization condition, the unit has a 10dB regulation bandwidth of 10GHz in the ka frequency band, and reaches a reflection coefficient regulation range of 20dB in 35 GHz.
As an optimization scheme, fig. 8 shows a change curve diagram of a single-station radar cross section (single-station RCS) of an amplitude coding super-surface array under the condition that a PIN diode passes or not when electromagnetic waves are normally incident, when current passes, the diode is in a conducting state, which can be equivalent to a resistance of 100 Ω, and the array shows good low scattering characteristics; when no current passes through, the diode is in a cut-off state, which can be equivalent to a 2.3pF capacitor, and the array shows good high scattering property. The array has a 10dB RCS reduction bandwidth of 9GHz when operating in the ka band, achieving an RCS reduction of 18.5dB at 37 GHz.
As an optimization scheme, fig. 9 shows a schematic diagram of a circuit model responsible for detecting and amplifying signals received by the super surface. In order to facilitate the simulation calculation, the circuit for detecting and amplifying is connected with the multifunctional coding super-surface module. And receiving an external incident signal from the super surface, outputting the received signal to the bottom, detecting and amplifying the signal, and testing the time domain waveform of the signal under each node.
As an optimization scheme, a circuit model test result for detecting and amplifying a signal received by a super surface is shown in fig. 10-11, and in order to fit an actual application scene and an application frequency band, an external incident signal is set to be a linear frequency modulation pulse signal with a pulse width of 10ns, a pulse repetition frequency of 50MHz, a center frequency of 27GHz, a frequency modulation bandwidth of 100MHz and an amplitude of 1W; FIG. 10 shows a time domain waveform of a subsurface bottom output signal, resulting in more than half the attenuation and slight fluctuations in the intensity of the bottom output signal due to transmission loss and port reflection loss inside the subsurface; FIG. 11 shows a waveform diagram of a time domain of a signal after detection amplification, compared with the previous signal, the waveform diagram of the time domain of the signal after detection amplification filters high-frequency components, and the waveform diagram shows a square pulse signal with a pulse width of 10ns and a pulse repetition frequency of 50MHz, so that the FPGA control module is convenient for reading signal parameters such as the pulse width and the pulse repetition period of the signal subsequently, and further, the module can recognize the characteristics of an external incident signal.
As an optimization scheme, fig. 12 and fig. 13 show test results of the system for coding response to the external incident signal. For chirped signals, the reflected signal is subjected to a "1010101010" periodic code modulation, here in the form of an intra-pulse code, to produce a response code signal having certain spectral characteristics. Fig. 12 shows a time-domain waveform of the coded response signal, which is represented by a chirped signal modulated periodically within one pulse, with a modulation period of 2ns, and a corresponding modulation frequency of 500MHz, compared to the original incident signal. Fig. 13 shows a spectrum distribution diagram of the coded response signal. Compared with the initial incident signal, the generated coded response signal spectrum has a plurality of harmonic components distributed at equal intervals near the fundamental frequency, wherein the first-order harmonic is respectively positioned at 26.5GHz and 27.5GHz, the distance between the first-order harmonic and the fundamental frequency is 500MHz, and the modulation frequency set in the test can be used as an autonomously adjustable spectral characteristic to be endowed to the echo signal, so that a corresponding response effect is generated. In addition, by changing the form and content of the code, the frequency spectrum distribution of the echo signal can be correspondingly changed, so that the system can generate diversified response effects according to different conditions.
In summary, according to the amplitude coding super-surface with the information sensing module disclosed by the invention, the matched FPGA control module performs characteristic recognition on the received electromagnetic wave signals and selectively outputs the coding current, so that the scattering state of the super-surface is switched in real time, and specific frequency spectrum characteristics are given to echo signals, so that a targeted passive intelligent response system is realized, the resolution capability of radars to enemy targets in a battlefield environment is improved, and the survival problem of the system is also guaranteed.
It should be noted that the above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily contemplated by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention.
It should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes described in the context of a single embodiment or with reference to a single figure in order to streamline the invention and aid those skilled in the art in understanding the various aspects of the invention. The present invention should not, however, be construed as including features that are essential to the patent claims in the exemplary embodiments.
Claims (10)
1. The ka-band passive intelligent response system based on the amplitude coding super surface is characterized by comprising the amplitude coding super surface and an FPGA control module, wherein:
the amplitude coding super-surface is formed by periodically arranging a plurality of basic units to form a square array, and the four basic units in the center are information sensing modules; the amplitude coding super-surface has the characteristic of scattering state electric adjustability, and the super-surface can be switched back and forth among various scattering states by changing the state of a PIN diode at the top of the basic unit; the information sensing module receives an incident signal from the outside and outputs the incident signal to the FPGA control module;
the FPGA control module comprises a signal receiving module, a signal processing module and a current output module, and can realize characteristic identification of signals received by the super surface and output current regulated and controlled in real time according to the result of signal identification.
2. The ka-band passive intelligent response system based on the amplitude coding super surface according to claim 1, wherein the basic units in the amplitude coding super surface sequentially comprise a first layer to an eighth layer from top to bottom, wherein the eighth layer bottom of the four basic units in the information sensing module is provided with a ninth layer, and the system is specifically as follows:
the first layer is a metal circuit layer and consists of four groups of square ring metal patches which are arranged in a central symmetry mode and PIN diodes, wherein the PIN diodes are arranged at the positions of gaps among the square ring metal patches and are used for connecting all the square ring metal patches together; changing the state of the PIN diode by changing the current flowing through the PIN diode, so that the super-surface is switched between different scattering states;
the second layer is a first dielectric substrate;
the third layer is a metal grounding layer and provides grounding for the PIN diode;
the fourth layer is a second dielectric substrate;
the fifth layer is a direct current feed layer and consists of two metal feed lines longitudinally distributed along the square array, and provides regulated output current for the PIN diode;
the sixth layer is a third dielectric substrate;
the seventh layer is a metal grounding layer and provides grounding for the bottommost wilkinson feed network;
the eighth layer is a fourth dielectric substrate;
the ninth layer is a wilkinson feed network and is used for outputting incident wave signals received by four basic units in the information sensing module.
3. The ka-band passive intelligent response system based on the amplitude coding super-surface according to claim 2, wherein twelve metallized holes are designed in the four basic units of the information sensing module, and the system plays roles of signal transmission and electrical connection; all the metallized holes can be divided into three groups according to different transmitted signals, and each group is four;
the first group of metallized holes are positioned between the first layer of metal circuit layer and the third layer of metal grounding layer, the punching positions are respectively positioned at the left half part of each group of square ring metal patches, and the centers of the four basic units are symmetrically distributed up and down to provide grounding signals for the PIN diode;
the second group of metallized holes are positioned between the first layer of metal circuit layer and the fifth layer of direct current feed layer, the punching positions are respectively positioned at the right half part of each group of square ring metal patches, and the centers of the four basic units are symmetrically distributed up and down to provide regulated output current for the PIN diode;
the third group of metallized holes are positioned between the first layer of metal circuit layer and the ninth layer of Wilkinson feed network, the punching positions are respectively positioned at the central ring edge of each group of square ring metal patches, and the centers of the four basic units are distributed in a central symmetry manner; the square annular metal patch at the top of the information sensing module receives an incident signal from the detection radar, and then the incident signal is transmitted to the Wilkinson feed network at the bottom through the third group of metalized holes, and the Wilkinson feed network gathers the received signals and outputs the signals to the FPGA control module.
4. The ka-band passive intelligent response system based on the amplitude coding super surface according to claim 3, wherein in the amplitude coding super surface, each array of basic units forms a subarray, each subarray is provided with an I/O port, and the PIN diode is ensured to be switched between different states in real time by regulating and controlling the input current of each array of subarrays;
by switching the on-off state of the PIN diode, the super surface realizes high scattering and low scattering states respectively, and has the electrically adjustable characteristic of the scattering state.
5. The ka-band passive intelligent response system based on amplitude coding super-surface according to claim 3, wherein the FPGA control module comprises a signal receiving module, a signal processing module and a current output module, wherein:
the signal receiving module is a back-end processing circuit comprising a power amplifier and an envelope detector, and can receive the output signal at the bottom of the super surface and perform detection amplification processing;
the signal processing module reads and compares signal parameters, namely the pulse width and the pulse repetition period of the detected signal are read, and compared with prestored pulse width and pulse repetition period parameter values, if the comparison results are consistent, the signal processing module judges that the signal processing module is a friend detection signal, and if the comparison results are inconsistent, the signal processing module judges that the signal processing module is an enemy detection signal, so that the characteristic identification of the received signal is realized;
the current output module is used for simultaneously regulating and controlling the current output state of the multichannel I/O port according to the characteristic identification result of the signal and controlling the working state of the amplitude coding super surface, if the signal processing module judges that the received signal is a friend detection signal, the current output by the FPGA is subjected to time coding, and if the signal processing module judges that the received signal is an enemy detection signal, the FPGA outputs the current under single amplitude.
6. The ka-band passive intelligent response system based on amplitude-coded super-surfaces according to claim 4, wherein each basic unit is 11mm long and 11mm wide; the basic unit works in the ka frequency band;
the first dielectric substrate to the fourth dielectric substrate are ROGERS4350 dielectric substrates, the dielectric constant is 3.66, and the dielectric loss tangent is 0.0037;
the thickness of each basic unit is 1.5mm, and the thicknesses of the first dielectric substrate to the fourth dielectric substrate are 1mm,0.2mm and 0.1mm respectively;
the variation range of the output current of the FPGA control module is 0.04-400 mA, and the precision is 0.1mA.
7. The ka-band passive intelligent response method based on the amplitude coding super surface is characterized by comprising the following specific steps of:
step 1, an information sensing module receives an incident signal from the outside and transmits the received signal to an FPGA control module;
step 2, the FPGA control module performs feature recognition on the received signals, and outputs currents in different states according to recognition results;
and 3, the regulated output current changes the scattering state of the super surface in real time through an I/O port, so that the response of the system to the target signal and the RCS reduction of the signal outside the target are realized.
8. The ka-band passive intelligent response method based on amplitude coding subsurface according to claim 7, wherein in step 1, the information sensing module receives an incident signal from the outside, and transmits the received signal to the FPGA control module through a wilkinson feed network at the bottom, and the frequency range of the received signal covers the whole ka-band.
9. The ka-band passive intelligent response method based on the amplitude coding super surface according to claim 7, wherein in step 2, the FPGA control module comprises a signal receiving module, a signal processing module and a current output module, specifically:
the signal receiving module is a back-end processing circuit comprising a power amplifier and an envelope detector, and can receive the output signal at the bottom of the super surface and perform detection amplification processing;
the signal processing module reads and compares signal parameters, namely the pulse width and the pulse repetition period of the detected signal are read, and compared with prestored pulse width and pulse repetition period parameter values, if the comparison results are consistent, the signal processing module judges that the signal processing module is a target detection signal, and if the comparison results are inconsistent, the signal processing module judges that the signal processing module is an external target signal, so that the characteristic identification of the received signal is realized;
the current output module is used for simultaneously regulating and controlling the current output state of the multi-channel I/O port according to the characteristic identification result of the signal and controlling the working state of the amplitude coding super-surface, if the signal processing module judges that the received signal is a target detection signal, the current output by the FPGA is subjected to time coding, and if the signal processing module judges that the received signal is an external target signal, the FPGA outputs the current under a single amplitude.
10. The ka-band passive intelligent response method based on the amplitude coding super-surface according to claim 7, wherein in the step 3, the regulated output current changes the scattering state of the super-surface in real time through an I/O port, so as to realize the response of the system to the target signal and the RCS reduction of the target external signal, specifically:
the regulation and control current output by the FPGA changes the scattering state of the super surface in real time through the I/O port;
when the FPGA outputs coded current, the scattering state of the super surface is switched back and forth according to a designed coding sequence, and specific frequency spectrum characteristics are endowed to echo signals, so that response to target signals is realized;
when the FPGA outputs current with single amplitude, the super surface keeps a low scattering state, the intensity of echo signals is reduced, and RCS reduction of signals outside the target is realized.
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