CN-121663214-B - Cross-band multistage adjustable radar wave-absorbing structure, design method and preparation method

CN121663214BCN 121663214 BCN121663214 BCN 121663214BCN-121663214-B

Abstract

A wave-absorbing structure of a multi-stage adjustable radar with a cross-band, a design method and a preparation method belong to the technical field of electromagnetic wave regulation and control. The cross-band multistage adjustable radar wave absorbing structure is prepared by adopting a photoetching process and a magnetron sputtering process, can realize absorption of a specific wave band under an S/C/X wave band, and comprises a patterned microwave absorption layer, a chalcogenide phase change material layer, a heat bearing layer, a metal electrode layer and a flexible medium layer from top to bottom. The invention realizes the conversion of metal-insulating state by controlling the conductivity of the chalcogenide phase change material, realizes the adjustment of the Fermi level of the chalcogenide phase change material by controlling the chalcogenide phase change material, realizes the adjustment of multi-frequency band absorption, realizes perfect absorption at a plurality of specific frequency points, has a certain angle insensitivity, has a simple structure of the chalcogenide phase change material layer, meets the requirement of mass production and processing, expands the application of the phase change material in the GHz field, and has the advantages of flexible design, electric adjustability, wide application range and the like.

Inventors

Cao tun
CHENG ZEXU
GAO HONGZE
YANG YIXIAO
JIA JINGYUAN
SU YING
CHEN ZIJIAN
LIAN MENG
LIU KUAN
ZHANG LEI
LIU JIAN
CAO GAOFENG
ZHENG CHUANG
ZHANG MINGQI

Assignees

大连理工大学

Dates

Publication Date: 20260508
Application Date: 20260205

Claims (10)

1. The cross-band multistage adjustable radar wave absorbing structure is characterized in that the cross-band multistage adjustable radar wave absorbing structure is prepared by adopting a photoetching process and a magnetron sputtering process, can realize absorption of a preset wave band under an S/C/X wave band, and comprises a patterned microwave absorbing layer, a chalcogenide phase change material layer, a heat bearing layer, a metal electrode layer and a flexible medium layer from top to bottom in sequence; The thickness of the patterned microwave absorption layer is 18-36 micrometers, the side length is 10-15 millimeters, and the material is selected from copper; the thickness of the chalcogenide phase change material layer is in the range of 20-50 nanometers, and the material is selected from GeTe, seTe or GeSbSeTe; the thickness of the heat-bearing layer is 40-70 nanometers, and the material is selected from tungsten, gold or copper; The thickness of the metal electrode layer is in the range of 70-100 nanometers, and the material is selected from gold or copper; the thickness of the flexible medium layer is 30-800 micrometers, and the material is selected from polyimide or flexible glass.
2. A method of designing a multi-level tunable radar absorbing structure in a cross-band according to claim 1, comprising the steps of: the first step is to build a mathematical model of the dielectric constant of the chalcogenide phase change material, and the specific steps are: when considering the thermal effect, the heat receiving capacity of the chalcogenide phase change material is proportional to the square of the resistance and voltage of the material, and the mathematical model is: (1) Wherein V is the crystallization rate, V 0 is the factor before the index, E a is the crystallization activation energy, k is the Boltzmann constant, T is the absolute temperature, R m is the resistance of the chalcogenide phase change material, V is the equivalent voltage, and T 0 is the initial temperature of the chalcogenide phase change material; assuming a crystallization critical time, integrating the crystallization rate with time to obtain a regulation and control parameter t for controlling the chalcogenide phase change material to finish crystalline state transformation; Secondly, constructing a flexible radar wave-absorbing structure based on the chalcogenide phase change material according to a mathematical model of the dielectric constant of the chalcogenide phase change material, wherein the wave-absorbing range and the wave-absorbing efficiency in the working bandwidth are used as parameters according to an optimized structure, and the flexible radar wave-absorbing structure is specific to: Step 2.1, determining a flexible radar wave-absorbing structure according to the regulation and control parameters obtained in the first step, and working according to the minimum frequency of the flexible radar wave-absorbing structure Determining a theoretical minimum thickness h of the flexible radar wave-absorbing structure, and optimally calculating the thickness of each layer in the flexible radar wave-absorbing structure; Step 2.2, establishing a flexible radar wave-absorbing structure model, namely sequentially forming a patterned microwave absorbing layer, a chalcogenide phase change material layer, a heat bearing layer, a metal electrode layer and a flexible medium layer from top to bottom, constructing an equivalent circuit model through electromagnetic simulation, and obtaining an analytic relationship between the reflection coefficient of the flexible radar wave-absorbing structure model and the geometric dimension of the patterned microwave absorbing layer according to the equivalent circuit model of the flexible radar wave-absorbing structure; And 2.3, according to the analysis relation obtained in the step 2.2, using the minimum value of the wave absorption rate within a certain frequency band as an optimization target, using the thickness, the length and width geometric dimensions of the patterned microwave absorption layer, the thickness of the chalcogenide phase change material layer, the heat bearing layer, the metal electrode layer and the flexible medium layer in the flexible radar wave absorption structure model as independent variables, performing simulation verification by adopting a time domain finite difference method to optimize the whole flexible radar wave absorption structure model, and finally obtaining the geometric parameters of each layer of the patterned microwave absorption layer, the chalcogenide phase change material layer, the heat bearing layer, the metal electrode layer and the flexible medium layer in the flexible radar wave absorption structure.
3. The method for designing a multi-stage adjustable radar absorbing structure according to claim 2, wherein in the first step, the adjustment and control parameter t is obtained by the formula (2): (2) Wherein a is a constant representing time, and b is a correction coefficient representing equivalent voltage.
4. The method for designing a multi-level tunable radar absorbing structure according to claim 3, wherein in the second step: In the step 2.1, the theoretical minimum thickness h, h=of the flexible radar absorbing structure Wherein Is the wavelength corresponding to the minimum operating frequency; The step 2.2 is specifically as follows: Step 2.2.1, calculating the value of the equivalent total resistance R of the equivalent circuit model; (3) Wherein R is the equivalent total resistance, S is the area of the patterned microwave absorbing layer, A is the area of the patterned microwave absorbing layer through which current flows, R 21 is the square resistance of the wave absorbing structure forming the resonance part; step 2.2.2, calculating an equivalent lumped inductance L and an equivalent lumped capacitance C of the equivalent circuit model; (4) Wherein L 0 、C 0 is the equivalent inductance and capacitance of the wave absorbing layer in the air, epsilon r is the equivalent dielectric constant of the whole flexible radar wave absorbing structure; Establishing an equivalent impedance Z r of the patterned microwave absorbing layer into a R, C, L series model according to the equivalent lumped inductance L and the equivalent lumped capacitance C, as shown in a formula (5); (5) Wherein Z r is the equivalent impedance of the patterned microwave absorbing layer, R is the equivalent total resistance, ω is the angular frequency, L is the inductance, and C is the capacitance; expressed as imaginary units; Step 2.2.3, calculating the input impedance Z in and the reflection coefficient of the whole flexible radar wave-absorbing structure Reflection coefficient of the whole wave-absorbing structure The method comprises the following steps: (8) Wherein, the Is the reflection coefficient and Z 0 is the transmission characteristic impedance.
5. The method for designing a multi-stage tunable radar absorbing structure in accordance with claim 4, wherein the input impedance Z in and the reflection coefficient in step 2.2.3 are as follows The calculation formula of (2) is as follows: The input impedance Z in is equivalent to the parallel connection of the absorbing layer impedance Z r and the bottom plate equivalent impedance Z d , as shown in formula (6): (6) Wherein Z d is obtained by a formula (7); (7) wherein Z 0 is the transmission characteristic impedance; Is free space wave number; Is the physical thickness of the dielectric layer; Is the relative dielectric constant of the bottom plate; Is the relative dielectric constant of air.
6. A method for preparing the cross-band multistage adjustable radar absorbing structure according to claim 1, comprising the following steps: Firstly, taking a flexible dielectric layer as a substrate, and preprocessing the flexible dielectric layer; secondly, processing a heat bearing layer and a metal electrode layer, and specifically: Step 2.1, spin coating photoresist on the top of the flexible dielectric layer, and controlling the thickness of the photoresist to be 500-650nm by controlling the rotation time and the rotation speed of a spin coater; step 2.2, placing the heat-bearing layer and the metal electrode layer patterning photoetching mask plate into a photoetching machine, exposing photoresist on the flexible medium layer, and then placing the exposed flexible medium layer into a developing solution for soaking to obtain photoetching patterns of the heat-bearing layer and the metal electrode layer; 2.3, respectively taking tungsten metal and aluminum oxide as target materials, and carrying out multilayer film accurate deposition by adopting magnetron sputtering equipment; Step 2.4, realizing the regulation and control of each layer thickness by accurately controlling the deposition time through a step-by-step deposition strategy, and realizing the sequential deposition of metal electrode layers and heat-bearing layers with different thicknesses; and thirdly, processing the chalcogenide phase change material layer based on the processing result of the second step, specifically: step 3.1, spin-coating photoresist on the surface of the whole structure treated in the second step, wherein the surface comprises an unpatterned area of the flexible dielectric layer, and the thickness of the photoresist is 100-200nm; Step 3.2, placing the patterned photoetching mask of the chalcogenide phase-change material layer into a photoetching machine, exposing photoresist on the flexible medium layer, and then placing the exposed flexible medium layer into a developing solution for soaking to obtain a photoetching pattern of the chalcogenide phase-change material layer; step 3.3, using the chalcogenide phase change material as a target material, adopting magnetron sputtering equipment to deposit a chalcogenide phase change material layer, and realizing the thickness regulation of the chalcogenide phase change material layer by precisely controlling the deposition time; fourthly, preparing a patterned microwave absorbing layer by adopting a magnetron sputtering method based on the processing result of the third step, and specifically: step 4.1, spin-coating photoresist on the surface of the whole structure treated in the third step, wherein the surface comprises an unpatterned area of the flexible dielectric layer; step 4.2, placing the photoetching mask plate of the patterning microwave absorption layer into a photoetching machine, exposing the photoresist on the flexible medium layer for 5-8s, and then placing the exposed flexible medium layer into a developing solution for soaking to obtain the photoetching pattern of the patterning microwave absorption layer; and 4.3, precisely depositing the patterned microwave absorption layer by using copper Cu as a target material and precisely controlling the deposition time to realize the thickness regulation of the patterned microwave absorption layer.
7. The method for preparing the cross-band multistage adjustable radar absorbing structure according to claim 6, wherein the first step is specifically as follows: step 1.1, taking a flexible dielectric layer as a substrate, and baking the flexible dielectric layer at a high temperature of 400-500 ℃ in a low-oxygen environment; And 1.2, soaking the flexible medium layer in isopropanol solution, placing the flexible medium layer in an ultrasonic cleaner to ultrasonically clean the surface of the substrate, and wiping the surface of the substrate with deionized water after the cleaning is finished.
8. The method for preparing a multi-stage adjustable radar absorbing structure according to claim 7, wherein in the second step: In the step 2.1, the heating treatment temperature is 100-150 ℃ and the time is 2-3 minutes, and the photoresist is hardened to enable the photoresist to be more tightly attached to the substrate, wherein the photoresist is LOR3A; In the step 2.2, the exposure time is 5-8s, and the soaking time is 5-10s; In the step 2.3, the deposition parameters are that the background vacuum of the cavity is less than or equal to 5 multiplied by 10 -4 Pa, the flow rate of working gas is 4.5-5.5 mtorr, the sputtering power is 70-90W, the sputtering temperature is 80-150 ℃, the distance between the flexible medium layer and the target is 80-120 mm, the rotation speed of the flexible medium layer is 15-25 rpm, and the magnetic field strength is 0.09-0.11T.
9. The method for preparing a multi-stage adjustable radar absorbing structure according to claim 8, wherein in the third step: In the step 3.1, the thickness of the photoresist is controlled to be 100-200nm by controlling the rotation time and the rotation speed of a spin coater, a flexible medium layer coated with the photoresist is placed on a heating table after spin coating is finished, the heating temperature is 100-150 ℃, the heating time is 2-3 minutes, and the photoresist is hardened to enable the photoresist to be more tightly attached to a substrate, wherein the photoresist is LOR3A; In the step 3.2, the exposure time is 5-8s, and the soaking time is 5-10s; In the step 3.3, the deposition parameters are that the background vacuum of the chamber is controlled to be less than or equal to 5 multiplied by 10 -4 Pa, the flow rate of working gas is 4.5-5.5 mtorr, the sputtering power is 100-130W, the temperature of the flexible medium layer is 80-150 ℃, the distance between the flexible medium layer and the target is 80-120 mm, the rotating speed of the flexible medium layer is 15-25 rpm, and the magnetic field strength is 0.09-0.11T.
10. The method for preparing a multi-stage adjustable radar absorbing structure according to claim 9, wherein in the fourth step: In the step 4.1, the thickness of the photoresist is controlled to be 18-30 mu m by controlling the rotation time and the rotation speed of a spin coater, a flexible medium layer coated with the photoresist is placed on a heating table after spin coating is finished, the heating temperature is 100-150 ℃, the heating time is 2-3 minutes, and the photoresist is hardened to enable the photoresist to be more tightly attached to a substrate, wherein the photoresist is LOR3A; In the step 4.2, the exposure time is 5-8s, and the soaking time is 20-40s; In the step 4.3, the deposition parameters are that the background vacuum of the chamber is controlled to be less than or equal to 5 multiplied by 10 -4 Pa, the flow rate of working gas is 4.5-5.5 mtorr, the sputtering power is 50-100W, the sputtering temperature is 80-150 ℃, the distance between the flexible medium layer and the target is 80-120 mm, the rotation speed of the flexible medium layer is 15-25 rpm, and the magnetic field strength is 0.09-0.11T.

Description

Cross-band multistage adjustable radar wave-absorbing structure, design method and preparation method Technical Field The invention belongs to the technical field of electromagnetic wave regulation and control, and relates to a cross-band multistage adjustable radar wave absorbing structure, a design method and a preparation method, in particular to a cross-band multistage adjustable flexible radar wave absorbing structure based on a chalcogenide phase change material, a design method and a preparation method. Background The radar wave absorbing structure is a key technology for realizing stealth of weapon equipment, and can effectively reduce the probability of finding and tracking a target by a radar wave detection means, and avoid the target from being intercepted or greatly shortening the detected distance. The advantages and disadvantages of the radar wave-absorbing stealth technology directly determine the survival and sudden prevention capability of weapon equipment on a battlefield, and concern the trend of war. The metamaterial is a composite material with an artificial structure, and has important application value in the technical field of efficient wave absorption due to unique properties such as negative refractive index, zero refractive index and super absorption. The metamaterial radar wave absorbing structure can realize radar wave absorption within a certain frequency range by designing different types of structures, and can not be changed once the structure is prepared, and can only work within a fixed frequency range. Aiming at the broadband radar stealth requirement of weapon equipment in the whole operational flow, a broadband sandwich structure based on a dual-band super surface is disclosed in Chinese patent No. CN202310732302.7, the dual-band broadband wave transmission is realized, and the broadband radar stealth structure has the characteristic of large-angle stability. The Chinese patent CN202311458848.4 discloses a super surface absorber, a device and application thereof, and has the ultra-wideband absorption effect. The topological shape of the wave absorber cannot be changed after being fixed, so that the wave absorber can only work in a fixed frequency range, and the practical application of the wave absorber structure is severely restricted. The Chinese patent CN201910887551.7 discloses a graphene-based microwave band dynamic adjustable absorber and a preparation method thereof, wherein the square resistance of graphene is dynamically controlled by a direct-current voltage source, so that the regulation and control of the wave frequency point of absorption are realized. The Chinese patent CN202311215016.X discloses an amplitude-adjustable wave-absorbing structure controlled by a varactor. The capacitance value of the varactor in the parallel resonance microstrip branch is adjusted to realize the adjustment of the resistance value of the load resistor in the main resonance structure, thereby realizing the effective adjustment of the wave absorption amplitude. The two passive tunable devices have the defects of complex welding and numerous feeder lines, and are unfavorable for reconfigurable characteristics and common surface application. When the technology is applied to engineering, the stealth effect is limited, the band adjustment capability is insufficient, the materials are hard materials, and the integration difficulty with the surface of equipment is high. Therefore, development of a wave absorbing structure of a cross-band adjustable flexible radar is urgently needed. The chalcogenide phase change material has non-volatility (the maintenance of crystalline phase state does not need external energy to maintain), and the refractive index and conductivity difference between different crystalline phase states are large, so that the chalcogenide phase change material becomes an important means for realizing dynamic regulation and control of the electromagnetic characteristics of the metamaterial. Therefore, the chalcogenide phase change material and the flexible wave absorbing structure are combined to form the cross-band adjustable flexible radar wave absorbing structure based on the chalcogenide phase change material, low-power consumption active regulation and control of wave absorbing frequency points can be achieved, a new thought is provided for regulation and control of cross-band wave absorbing performance, and full-band stealth capacity of weapon equipment is effectively improved. Disclosure of Invention The invention mainly solves the technical problems of overcoming the defects of the prior method, and provides a cross-band multistage adjustable radar wave absorbing structure, a design method and a preparation method, aiming at the problems that the traditional radar wave absorbing structure can not realize flexible regulation and control, has narrower frequency band, is fixed and is not suitable for complex curved surface occasions, and the like, the invention u