CN114639965A - Wave-transparent material with signal focusing function and preparation method thereof - Google Patents

Wave-transparent material with signal focusing function and preparation method thereof Download PDF

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Publication number
CN114639965A
CN114639965A CN202210245771.1A CN202210245771A CN114639965A CN 114639965 A CN114639965 A CN 114639965A CN 202210245771 A CN202210245771 A CN 202210245771A CN 114639965 A CN114639965 A CN 114639965A
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dielectric constant
wave
less
transparent material
resins
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钱桂芳
吴敏
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Ningbo University
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Ningbo University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/10—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Laminated Bodies (AREA)
  • Details Of Aerials (AREA)

Abstract

The invention provides a wave-transparent material with a signal focusing function and a preparation method thereof, belonging to the field of high polymer materials and communication equipment materials. The novel wave-transmitting material is prepared by laminating two resins with the dielectric constant difference less than 3. In the pressing process, the two resins mutually permeate to form a dielectric constant gradient. The gradient value of the dielectric constant of the formed material is decreased from one surface of the high dielectric constant material before lamination to one surface of the low dielectric constant material before lamination. The two resins having a difference in dielectric constant of less than 3 constituting the material are two thermoplastic resins capable of being heat-blended, each having a dielectric constant of less than 4 and a difference in dielectric constant of more than 0.5 and less than 1.8, particularly a polyether sulfone resin and a polypropylene resin having a bisphenol A structure in the main chain. The wave-transmitting material can be used for manufacturing the antenna housing, and the manufactured antenna housing has a signal focusing effect.

Description

Wave-transparent material with signal focusing function and preparation method thereof
Technical Field
The invention belongs to the field of high polymer materials and communication equipment materials, and relates to a wave-transmitting material, in particular to a preparation method of the wave-transmitting material and the prepared wave-transmitting material.
Background
The wave-transparent material is a dielectric material with two conductive surfaces and low loss and distortion when electromagnetic waves pass through the dielectric material. The main applications are the manufacture of various radomes, the protection of antennas for radars and other electronic devices against the harmful effects of the external environment. Such as: the airborne radome of the airplane is mostly made of glass fiber reinforced plastics and a composite sandwich structure thereof, the radomes (panels) of air defense missiles, sea defense missiles and other tactical missiles are mostly made of polytetrafluoroethylene or glass fiber reinforced polytetrafluoroethylene, and the antenna window materials of strategic missiles undergo the development processes of quartz glass, puncture high silica cloth reinforced silicon dioxide and three-dimensional quartz reinforced silicon dioxide. In general, the smaller the dielectric loss of the material, the thinner the wall of the housing, the less energy is absorbed and thus the greater the power transmission coefficient.
With the continuous development of communication technology, 5G base stations/micro stations, mobile phones, antennas, loT terminals, etc. have been widely used in life. Since the above facilities are generally installed in the open air, it is usually necessary to add a wave-transparent plastic casing or a bracket sheet on the above facilities to better protect the facilities from the external environment. The frequency band mainly used in the current 5G communication market is divided into two parts, namely a 5G-sub6 frequency band (617 MHz-6 GHz) and a 5G-mmW frequency band (26.5 GHz-40 GHz), which not only requires that the wave-transmitting material has high wave-transmitting rate in a specific stage, but also provides certain requirements and requirements for the wave-transmitting performance of the wave-transmitting material in broadband and high frequency bands.
At present, most of the wave-transmitting material structures of the millimeter wave antenna housing are sandwich structure composite materials, such as foam sandwich structure composite materials or honeycomb sandwich structure composite materials. The skin layer of the foam sandwich structure composite material structure is generally a fiber-reinforced thermosetting resin material, the core layer is generally a thermosetting rigid foam, such as PMI foam, and the problems of difficult recovery, difficult processing and forming, low processing precision and the like exist, and besides the problems of processing and recovery and the like, the material cannot meet the additional integrated effects of signal focusing and the like. In order to solve the processing problem, some manufacturers and organizations provide some solutions, for example, patent CN103660410 discloses a wave-transparent core material for a radome, a preparation method and a use thereof, wherein a skin of the radome is made of a fiber-reinforced thermoplastic composite material, and a core layer is made of foamed polyurethane, phenolic resin or epoxy resin. The thermoplastic resin of the skin material in the method is polyolefin, thermoplastic polyester and polyamide. Patent CN 110539539539 discloses a wave-transparent material for a millimeter wave antenna housing and a molding method thereof. The thermoplastic high-flame-retardant polyether sulfone resin material is adopted, the problem of material recovery can be well solved, a sandwich structure is still adopted, namely the sandwich structure is formed by adhering a core material and a covering by using an adhesive, the sandwich structure is easy to delaminate in a complex environment for a long time, the service life and the wave-transmitting effect of the radome are influenced, and the cost of raw materials is high. Patent CN112549666 discloses an integrated broadband high-wave-transmission material developed and designed for the broadband electromagnetic wave frequency band of 600MHz to 300GHz by adopting the green environmental protection integrated molding foaming technology and the freeze finishing technology. The developed wave-transparent material is integrally formed, so that a breakthrough is made from the material, and the technical bottleneck that the communication antenna housing is only suitable for low-frequency and narrow-frequency bands and cannot be suitable for millimeter wave bands is solved.
However, the above scheme mainly solves the problem of the high-frequency high-wave-transmission material from the aspect of macrostructure regulation, and even if the structure of the material is improved, the signal is only better transmitted, and the signal cannot be focused and amplified.
Disclosure of Invention
In order to ensure the wave-transmitting performance of the material and focus signals, the invention provides a preparation method of a wave-transmitting material and the wave-transmitting material prepared by the same.
In a first aspect, the present invention provides a wave-transparent material having a signal focusing effect.
The novel wave-transmitting material is prepared by laminating two resins with the dielectric constant difference less than 3. The two resins mutually permeate in the pressing process to form a dielectric constant gradient. The gradient value of the dielectric constant of the formed material is decreased from one surface of the high dielectric constant material before lamination to one surface of the low dielectric constant material before lamination.
The two resins with the dielectric constant difference less than 3 can be polyether sulfone, polypropylene, polystyrene, polyethylene, polylactic acid, polyurethane, polymethyl methacrylate, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polyimide, polyphenylene sulfide, polyetherimide and other thermoplastic polymers, and copolymers or blends thereof.
The two resins with the dielectric constant difference of less than 3 are particularly polyethersulfone and polypropylene, wherein the polyethersulfone is preferably polyethersulfone with a main chain containing a bisphenol A structure.
The two resins having a difference in dielectric constant of less than 3, preferably two resins having a difference in dielectric constant of less than 2, and more preferably two thermoplastic resins having a dielectric constant of less than 2, which are capable of being heat blended. In particular two thermoplastic resins capable of being heat blended, each having a dielectric constant of less than 4 and a difference of more than 0.5 and less than 1.8.
The obtained sheet is subjected to a process such as foaming, and the dielectric constant of the obtained material can be further reduced.
In a second aspect, the invention provides a method for preparing a wave-transparent material with a signal focusing function. Is prepared by the following steps:
step 1, respectively pressing a material A with a high dielectric constant and a material B with a low dielectric constant and a dielectric constant value difference less than 3 with the material A into sheets;
step 2, stacking the material A sheet and the material B sheet up and down, and pressing into tablets;
and 3, preparing the sheet pressed in the step 2 into a flat plate type or spherical surface type or conical or cuboid cover type or cube cover type by adopting the processes of foaming and/or plastic sucking, mold hot pressing and the like.
The materials A and B are preferably thermoplastic plastics, including polyethersulfone, polypropylene, polystyrene, polyethylene, polylactic acid, thermoplastic polyurethane and the like, in particular polyethersulfone, polypropylene, polyethylene, polystyrene and the like with the dielectric constant of less than 3.
The pressed sheet in the step 1 can be formed by rolling the granules into a sheet after the granules are extruded by a double screw.
The tabletting in the step 1 and the step 2 can be carried out by normal-temperature rolling, hot pressing of a flat vulcanizing machine and the like.
The thickness of the sheet produced in step 1 is between 0.01 and 100 mm, preferably between 1 and 20 mm.
And (3) pressing into tablets in the step 2, for example, a hot pressing method is adopted, the pressing temperature is the temperature at which the material A and the material B can be softened and blended, and the tablets can be obtained through a twin-screw extrusion test, and the temperature at which two phases of the two materials are well melted is the optimal temperature by blending the two materials through twin-screw extrusion. The good phase fusion can be judged by scanning electron microscope pictures, the mixed material slices are observed by a scanning electron microscope, and the two materials can be judged to be good phase fusion without obvious single-phase aggregation.
The processing in step 3 is to be a flat plate type, a spherical surface type, a conical type, a rectangular parallelepiped cover type, a square cover type, or the like, and preferably the outer surface of the cover, i.e., the surface through which the signal is incident from outside to inside first, is the surface with a low dielectric constant.
In a third aspect, the present invention provides:
a communication device comprises the wave-transparent material. In one embodiment the communication device is a millimeter wave radome.
The invention has the beneficial effects that the prepared wave-transmitting material ensures low dielectric loss, and simultaneously adopts a calendering and permeating method to form a dielectric constant gradient in the material, so that incident signals can be refracted after passing through the antenna housing made of the material, and the effect of signal gain amplification is achieved. Under the high-frequency band communication scenes such as 5G communication and the like, the signal intensity loss is in direct proportion to the frequency and the dielectric permittivity, and the signal gain is realized by a simple method while the low dielectric loss is realized. Meanwhile, compared with a method for directly bonding two or more materials or other methods equivalent to direct bonding, the method provided by the invention has no obvious phase interface, so that the loss of signals when the signals are incident on different interfaces is reduced, the strength and the efficiency of the signals are improved, and the practicability is improved. On the other hand, the method provided by the invention can finish the manufacture of the device by simple equipment and process, thereby reducing the production cost and having better practicability compared with other methods. The preferable polyether sulfone resin with the bisphenol A structure not only has low dielectric constant and good compatibility with other thermoplastic resins, but also contains oxygen and other polar functional groups, provides sites for polar action and hydrogen bond action, and provides great convenience for further bonding and other processing steps of materials.
Drawings
Fig. 1 is a schematic distribution diagram of two types of polymer structural units in the wave-transparent material of the present invention. Wherein 1 is a material structure with high dielectric constant, and 2 is a material structure with low dielectric constant. The dashed lines in the figure represent the material mass, and the symbol densities indicated at 1 and 2 illustrate the distribution of the two material structures in the shaped material mass.
Fig. 2 is a sequence diagram showing two sheets stacked before pressing, wherein 1 is a material having a high dielectric constant and 2 is a material having a low dielectric constant.
Fig. 3 is a graph showing the dielectric constant of the wave-transparent material produced from the high dielectric constant surface to the low dielectric constant surface.
Detailed Description
The present invention is described in detail below with reference to specific examples, which are provided to assist those skilled in the art in further understanding the present invention, but are not intended to limit the present invention in any way.
Example 1
A wave-transmitting material is composed of two polymer materials as follows:
the material A is polyether sulfone with the following structure:
Figure DEST_PATH_IMAGE001
its weight average molecular weight Mw=6000, dielectric constant 2.9 at 1MHz test frequency;
the material B is polypropylene PP, polypropylene resin with the trade name of Novolen 1040RC of Lummus company is adopted, and the dielectric constant is actually measured to be 2.1 under the frequency of 1 MHz.
Extruding the material A and the material B with twin screw and rolling to obtain 5mm thick sheets, placing the sheets on the sheet layer, and vulcanizing at 10Mpa and 150 deg.C with a flat vulcanizing machineHot pressing under the conditions to obtain a sheet of 7mm thickness. Placing the obtained sheet into a die cavity of a multilayer die-pressing foaming machine, and filling supercritical CO2And keeping the temperature and the pressure at 165 ℃ under the pressure of 10MPa for 20min, and then quickly opening the die to release the pressure to obtain the finished wave-transmitting material.
Comparative example 1
Compared with example 1, the difference is that a 7mm thick sheet is made of the same polyether sulfone resin as in example 1, and supercritical foaming is carried out to obtain a finished material.
Comparative example 2
Compared with example 1, the difference is that a 7mm thick sheet is made of the same polypropylene PP resin as in example 1, and the sheet is subjected to supercritical foaming to obtain a finished material.
The dielectric constants of the material sheets in example 1 and comparative examples 1 and 2 were sampled and tested at different thicknesses by connecting parallel plate molds with a network analyzer to obtain the dielectric constant of the material of example 1 decreasing from one surface (high dielectric constant surface) to the other surface (second dielectric constant surface), as shown in fig. 3. In contrast, the dielectric constant of the materials in comparative example 1 and comparative example 2 did not change from one side to the other.
The network analyzer was used to connect two horn antennas, and the free space method was used to measure the intensity of the signal incident at an angle of 30 ° at 700MHz through the materials of example 1, comparative example 1 and comparative example 2, respectively, and the signal intensity through the material of example 1 was found to be the strongest, and the signal intensity through the materials of comparative example 1 and comparative example 2 was found to be 75% and 82% of the intensity through the material of example 1, respectively.
Example 2
The material obtained in the example 1 is subjected to mold processing by a plastic suction method at 200 ℃ to obtain a curved cover with a curvature radius of 1m and a low dielectric constant surface positioned on a convex surface, namely an outer surface, and the antenna cover with the signal focusing function is obtained.
Comparative example 3
Compared with example 2, the radome having the same radius of curvature was manufactured using the material obtained in comparative example 1.
Comparative example 4
As compared with example 2, the radome having the same radius of curvature was manufactured using the material obtained in comparative example 2.
And connecting the millimeter wave frequency spreading head and the two horn-shaped antennas by using a network analyzer, and respectively measuring the strength of the incident W-band signal from the convex surface and the received W-band signal from the concave surface by using a free space method. Different incident angles were used to test the incident angle coverage at which the received signal strength was 50% of the transmitted signal strength. Through tests, the coverage range of the incident angle of the antenna housing manufactured by the method of the embodiment 2 is the largest, and the incident angle ranges of the comparative example 3 and the comparative example 4 are 72% and 78% of the embodiment 2 respectively.
It can be seen from the examples and comparative examples that the material of the present invention not only allows the communication signal to pass well, but also realizes the effective focusing of the signal. The radome manufacturing in the embodiment can also adopt an additional housing mode to ensure the strength of the finished radome, and similar changes also belong to the protection scope of the invention.

Claims (10)

1. A wave-transparent material with signal focusing function is prepared by pressing two resins with dielectric constant difference less than 3, and two resins are mutually permeated in pressing process to form dielectric constant gradient, and the value of the formed material dielectric constant gradient is decreased from one surface of high dielectric constant material before pressing to one surface of low dielectric constant material before pressing.
2. The wave-transparent material having a signal focusing effect according to claim 1, wherein the two resins having a difference in dielectric constant of less than 3 constituting the material are two thermoplastic resins capable of being heat-blended, each having a dielectric constant of less than 4 per se and a difference in dielectric constant of more than 0.5 and less than 1.8.
3. The wave-transparent material with signal focusing function according to claim 1, wherein the two resins with the dielectric constant difference less than 3 are polyethersulfone, polypropylene, polystyrene, polyethylene, polylactic acid, polyurethane, polymethyl methacrylate, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polyimide, polyphenylene sulfide, polyetherimide, and copolymers or blends thereof.
4. The wave-transparent material with signal focusing function according to claim 1, characterized by being composed of polyethersulfone and polypropylene having dielectric constants differing by less than 3.
5. The wave-transparent material with signal focusing function according to claim 4, wherein the polyethersulfone constituting the material is polyethersulfone having a main chain containing a bisphenol A structure.
6. A method for preparing a wave-transparent material with a signal focusing function is characterized by comprising the following steps of:
step 1, respectively pressing a material A with a high dielectric constant and a material B with a low dielectric constant and a dielectric constant value difference less than 3 with the material A into sheets;
step 2, stacking the material A sheet and the material B sheet up and down, and pressing into tablets;
and 3, preparing the sheet pressed in the step 2 into a flat plate type or a spherical surface type or a conical shape or a rectangular parallelepiped cover type or a cubic cover type by adopting a foaming and/or plastic sucking and/or mold hot pressing process.
7. The method for preparing the wave-transparent material with signal focusing function according to claim 6, wherein the pressing in step 1 and step 2 is performed by normal temperature rolling, hot rolling or press pressing with a press vulcanizer.
8. The method according to claim 6, wherein the thickness of the pressed sheet in step 1 is 0.01-100 mm.
9. A communication device comprising the wave-transparent material of claim 1.
10. A communication device according to claim 9, wherein the communication device is a millimeter wave radome.
CN202210245771.1A 2022-03-14 2022-03-14 Wave-transparent material with signal focusing function and preparation method thereof Pending CN114639965A (en)

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