A radio frequency device

Abstract

A radio frequency device is characterized by having a spiral antenna and a radio frequency module, a first end of the spiral antenna is electrically connected with a radio frequency interface of the radio frequency module; the structure of the spiral antenna comprises a core material and a spiral conductor wound and fixed on the outer periphery of the core material; the material of the spiral conductor is single or multiple bundled metalized fibers or metal wires or carbon fiber wires, and the radius of each metalized fiber, metal wire or carbon fiber wire is less than 5 times of the skin depth when the radio frequency signal frequency is transmitted on the metalized fiber, metal wire or carbon fiber wire; the spiral antenna has an extremely high quality factor, thereby obtaining several times of communication distance compared with traditional spiral antenna under the same power.

Description

TECHNICAL FIELD

[0001] The present application relates to a radio frequency device using a spiral antenna, and more particularly to a method for implementing a spiral antenna. The improved spiral antenna disclosed in the present application has a communication efficiency and a communication distance that are several times higher than those of a conventional spiral antenna at the same power, and has a greatly improved production efficiency and a lower cost. BACKGROUND

[0002] A spring-shaped spiral antenna has the characteristics of a wide frequency band, circular polarization, high gain, and a compact structure. Therefore, a radio frequency device using such a spiral antenna is generally used in the field of communication, such as a walkie-talkie, an electronic tag in a tire inner bag, a vehicle-mounted communication device, and the like. In particular, when D / λ<0.18 (D is the outer diameter of the spiral antenna, and λ is the wavelength of the communication baseband), the spiral antenna has a significant gain improvement in the normal plane (a direction perpendicular to the spiral axis), which can greatly improve the communication distance.

[0003] A conventional spiral antenna generally uses a steel material with a diameter of 0.15-1.5 mm and a copper-plated surface, which is wound on demand by a spring production machine and cut into sections for production. The communication frequency of civilian, police, and military use is 300 MHz-6 GHz. The skin depth on a pure copper antenna is 0.0045-0.0015 mm (4.5-1.5 um), and the skin depth on an iron-based antenna is 0.0004-0.00012 mm (0.4-0.12 um). Therefore, the Q value (quality factor, the greater the value, the higher the antenna efficiency) of the conventional spiral antenna is only 3-6 (related to the communication frequency), and the ability to radiate or receive electromagnetic waves is relatively weak.

[0004] On the other hand, the conventional spiral antenna is very hard and difficult to use in scenarios that will be deformed, such as clothing and soft furniture, and is also difficult to use in scenarios that need to be fixed in a twisted manner, such as a vehicle frame. On the other hand, the conventional spiral antenna is prone to plastic deformation, which can cause significant changes in the Q value, the center frequency, the bandwidth, and the lobe diagram, and thus the antenna is disabled.

[0005] Therefore, there is a need in the society for an improved spiral antenna that can greatly improve the Q value while maintaining the size and other electrical characteristics substantially unchanged, and also greatly increase the flexibility. SUMMARY

[0006] The application discloses a radio frequency device, characterized in that it has a spiral antenna and a radio frequency module, the first end of the spiral antenna is electrically connected with the radio frequency interface of the radio frequency module; the radio frequency module has the function of outputting radio frequency electric signals, receiving radio frequency electric signals or both; the structure of the spiral antenna includes a core material and a spiral conductor wound and fixed on the outer periphery of the core material, the spiral conductor is made of single or multiple bundled metalized fibers or metal wires or carbon fiber wires; in order to improve the Q value, the radius of the single metalized fiber, the metal wire or the carbon fiber wire is <5 times of the skin depth of the radio frequency signal when the radio frequency signal is transmitted on the metalized fiber, the metal wire or the carbon fiber wire, for example, for the frequency band of 868-915 Mhz, the skin depth of copper is about 3 um, so the radius of the metalized fiber, the metal wire or the carbon fiber wire is <15 um; considering the ferromagnetic materials such as manganese, iron, nickel or related alloys, which can seriously reduce the skin depth, for example, for the frequency band of 868-915 Mhz, the skin depth of iron is only 0.1 um, which leads to the fact that mass production is impossible, therefore the relative magnetic permeability of the metal of the metalized fiber or the metal wire is <5, and the resistivity is <5x10 -8 Ω·m, one of copper, aluminum, silver, gold or an alloy is adopted; when the metalized fiber is used as the spiral conductor, the resistivity of the single metalized fiber is <100 Ω / cm, and the structural feature on the cross section is that at least two materials are coaxially distributed, the two materials are A material and B material respectively, and the B material is wrapped on the outer periphery of the A material; the key point is that the axial thermal expansion coefficient of the A material in the range of-40 DEG C to + 150 DEG C is <25x10 -6 / ℃, the A material can be aramid fiber or carbon fiber wire or basalt fiber or modified glass fiber, and the B material is one of copper, silver, aluminum, gold or an alloy.

[0007] Because the resistance of the single metalized fiber, the metal wire or the carbon fiber wire is large, which leads to a small Q value, therefore, a more optimal design is to use multiple metalized fibers, metal wires or carbon fiber wires, and the outer diameter of each metalized fiber, metal wire or carbon fiber wire is ≤2 times of the skin depth, for example, for the frequency band of 868-915 Mhz, the skin depth of copper is about 3 um, so the radius of the metalized fiber, the metal wire or the carbon fiber wire is ≤6 um.

[0008] And in order to avoid the multiple metalized fibers, metal wires or carbon fiber lines close contact with each other to form a similar single thicker conductor, resulting in more obvious skin impedance effect, the outer surface of each of the multiple bundled metalized fibers, metal wires or carbon fiber lines used to make the spiral conductor has an insulating layer with a resistivity > 0.01 Ω·m; when the spiral conductor uses metalized fibers or metal wires, the insulating layer material includes oxides or reduced substances generated on the surface of the metalized fibers or the metal wires through oxidation or reduction reactions, or organic compounds with a molecular weight of less than 1 million; when the spiral conductor uses carbon fiber lines, the insulating layer material includes one or a combination of diamond, silicon carbide, carbon nitride, and organic compounds with a molecular weight of less than 1 million.

[0009] Because the resistivity of carbon fiber is at least 60 times higher than that of copper, it will significantly affect the Q value and power of the antenna, and the resistivity of the high modulus type carbon fiber suitable for winding is 3 million times that of copper, making it more difficult to use for making antennas. Therefore, preferably, the spiral conductor selects metalized fibers or metal wires as the material.

[0010] And to make a metal wire with a radius < 3um, only gold is suitable, which is not acceptable from a cost perspective; at the same time, a 1-meter length of 10um diameter single crystal copper wire is sold in batches for about 2 yuan RMB, and taking the 868~915Mhz frequency band as an example, if high efficiency 10mW of radio frequency power needs to be transmitted (generally used for vehicle automatic toll electronic tags), about 500 10um single crystal copper wires with a length of 8.5cm are needed to make a 1 / 4 wavelength antenna, and the material cost needs to be 75 yuan, which is obviously also impossible to popularize. And the metalized fiber with the same electrical indicators is only 0.3~0.5 yuan (while the traditional spiral antenna with the same electrical performance costs 1~3 yuan), which obviously has the possibility of popularization.

[0011] Therefore, the optimal choice is to use metalized fiber lines as the material of the spiral conductor, the outer diameter of each metalized fiber is < 30um and the resistivity is lower than 100 Ω / cm, and the structural feature is to have at least two materials, A material and B material, and at least the longitudinal thermal expansion coefficient of A material in the range of -40℃ to +150℃ is < 25x10 -6 / ℃ (not greater than the thermal expansion coefficient of conventional conductive metals such as copper, aluminum, silver, gold), A material can be aramid or carbon fiber or basalt fiber or modified glass fiber; and at least B material is a conductor with a resistivity < 5x10 -8 Ω·m, and B material can be one of copper, silver, aluminum, gold or an alloy.

[0012] More preferably, the metalized fiber uses cross-linking chelation or single crystal growth method to tightly bind continuous B material on the surface of A material, and through A material to achieve high strength along the fiber axis, avoiding B material being pulled apart under tension. For example, using 5um diameter aramid as A material, and using 2.5um thick copper as B material, the strength along the axis is increased by 3~10 times compared with 10um diameter single crystal copper, so it is more suitable for use in various environments.

[0013] There are three methods for winding the spiral conductor on the core material, the first is to tightly wrap the spiral conductor material and a plurality of insulated wires around the outer periphery of the core material in a woven mesh manner, the outer diameter of the insulated wire is close to that of the spiral conductor material; the second is to tightly wrap the spiral conductor material and a plurality of insulated wires around the outer periphery of the core material after being spirally wound side by side, and then use the first insulating outer layer, the outer diameter of the insulated wire is close to that of the spiral conductor material, and the first insulating outer layer is one or a combination of woven mesh, hot melt adhesive, glue; the third is, first cover the outer periphery of the spiral conductor material with a second insulating outer layer, the second insulating outer layer has one of the properties of hot melt adhesion, solution softening adhesion or non-adhesion, then wind the spiral conductor around the outer periphery of the core material, and finally use one of the following three ways to complete the fixation: heating and melting the second insulating outer layer to adhere to the outer periphery of the core material, soaking the second insulating outer layer to adhere to the outer periphery of the core material, or tightly wrapping the spiral conductor and the core material with a third insulating outer layer, the third insulating outer layer is one or a combination of woven mesh, hot melt adhesive, glue.

[0014] Because the spiral conductor is made of very fine material, it is difficult to shape once it is out of the wound state, leading to difficulty in automatic welding, crimping or fixing to the radio frequency interface through other means to achieve electrical connection. In order to mass-produce automatically, the spiral antenna must be wound and fixed on a very long core material first, and then cut according to needs, so the end of the cut spiral antenna may appear the spiral conductor out of the wound state. Therefore, the first end of the spiral antenna has a fixed terminal, the fixed terminal has the characteristics of mechanically clamping the spiral conductor and the core material at the same time and electrically connecting the spiral conductor, and the fixed terminal and the radio frequency interface of the radio frequency module are electrically connected by one or more of welding, riveting, and crimping.

[0015] For the application field that needs to consider the flexibility of the helical antenna, the core material is a flexible material, and the material of the core material is one or a combination of materials with a dielectric constant change rate of < 25% after being wet. The helical antenna radio frequency device made in this way can be sewn on clothes for close-fitting use, can be attached to the surface of the frame along the curve of the frame, can be fixed into a special shape to make a complex super-helical antenna structure to achieve a specific lobe pattern, and can be fixed on a special elastic body to change the electrical properties due to the deformation of the elastic body, thereby becoming a radio frequency sensor device that simultaneously communicates externally and detects the deformation amount of the elastic body.

[0016] According to actual tests, for the ultra-high frequency tire inner bag electronic tag in the 868-915 Mhz frequency band, the sample made of the helical antenna with the specifications of 500 roots of the aramid material A and the copper material B as the helical conductor has a communication distance increased by 400% (from 0.5 meters to 2.5 meters) compared with the traditional product on the market with the same mechanical structure and made of a copper-plated steel spring as the helical antenna, the production efficiency is expected to be increased by 30% (the annual output of one production line is increased from 5 million to 6.5 million), the defective rate is reduced from 0.8% to 0.1%, and the cost is reduced by about 15% (from 2 yuan to 1.71 yuan).

[0017] According to actual tests, for the ultra-high frequency clothing electronic tag in the 868-915 Mhz frequency band, the sample made of the helical antenna with the specifications of 400 roots of the aramid material A and the copper material B as the helical conductor wound outside the aramid core material has a communication distance increased by 500% (from 0.3 meters to 1.8 meters) compared with the traditional product on the market with a larger size and difficult to bend, solves the problem of inaccurate clothing management during mass washing, and can be used as a user's armband for identity recognition and tracking in parts of mines, factory areas, and military camps where it is inconvenient to set up cameras and fingerprint recognition areas.

[0018] Therefore, the helical antenna radio frequency device has the beneficial effects of greatly improving the Q value to obtain multiple communication distances, greatly increasing the flexibility, and expanding the application range and application experience of the helical antenna radio frequency device while keeping the size basically unchanged, keeping other electrical properties basically unchanged, and having more advantageous costs.

[0019] DRAWINGS

[0020] Figure 1 is the first embodiment of the present application.

[0021] Figure 2 is the second embodiment of the present application.

[0022] Figure 3is a first embodiment of the spiral conductor according to the present application.

[0023] Figure 4 is a first embodiment of the spiral antenna according to the present application.

[0024] Figure 5 is a second embodiment of the spiral antenna according to the present application.

[0025] Figure 6 is a third embodiment of the spiral antenna according to the present application.

[0026] Figure 7 is a flowchart of the automatic production process according to the present application. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and do not limit the application range of the present application. For those skilled in the art, the present application can be applied to other similar scenarios without creative labor according to these drawings. As shown in the specification and claims, unless the context clearly indicates otherwise, the words "one", "a", "an", and / or "the" do not specifically refer to the singular, but also can include the plural. Generally, the terms "comprise" or "include" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements. The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment".

[0028] Figure 1 The spiral antenna 1 according to Figure 4 is electrically connected to the radio frequency module 2 to make a first embodiment of the radio frequency device disclosed by the present application, which is a monopole antenna type radio frequency device, such as a walkie-talkie. Figure 2 The spiral antenna 1 according to Figure 4 is electrically connected to the radio frequency module 2 to make a second embodiment of the radio frequency device disclosed by the present application, which is a dipole antenna type radio frequency device, such as a tire inner bag electronic tag.

[0029] In Figure 1 and Figure 2 , the spiral antenna 1 has a fixed terminal 15, which is made of a metal flat ribbon with multiple rows of pins. When producing the spiral antenna 1, the fixed terminal 15 is looped around one end of the spiral antenna 1, and the multiple rows of pins pierce through the first insulating outer layer 14 in Figure 4 to make close electrical contact with the spiral conductor 12, or pierce throughFigure 6 second insulating outer layer 16 in the second embodiment is in close electrical contact with the helical conductor 12, or in close electrical contact with the helical conductor 12 directly. Figure 5 The fixed terminal 15 is then electrically connected to the radio frequency interface 21 of the radio frequency module 2 by welding, crimping, riveting or other methods.

[0030] Figure 4 Figure 5 Figure 6 are three different methods of implementing the helical antenna 1. In Figure 4 the helical conductor 12 is helically wound side by side with a plurality of insulating wires 13 close to the outer diameter of the helical conductor 12 on the outer periphery of the core material 12, and then wrapped tightly with a first insulating outer layer 14 made of TPEE material. Figure 5 In the second embodiment, the helical conductor 12 is wrapped tightly with a plurality of insulating wires 13 close to the outer diameter of the helical conductor 12 in a meshed manner on the outer periphery of the core material 11. Figure 6 In the third embodiment, a second insulating outer layer 16 is first covered on the outer periphery of the helical conductor 12, the second insulating outer layer 16 is made of PU material with hot melting property, and then the helical conductor 12 is wound on the outer periphery of the core material 11 and heated to melt the second insulating outer layer 16 so that adjacent second insulating outer layers 16 are fused with each other, and the melted second insulating outer layer 16 also adheres to the core material 11. When the temperature decreases to below the melting temperature of the second insulating outer layer 16, the helical conductor 12 of each turn is firmly wound and fixed to the core material 11 to form the helical antenna 1.

[0031] Figure 3 The cross-sectional view of the metalized fiber is shown in

[0032] In the fourth embodiment, the intermediate form of the helical antenna 1 is a roll of helical conductor 12, insulating wire 13 and first insulating outer layer 14 wound and fixed on the flexible core material 11, and the flexible core material 11 is aramid fiber. The steps of producing the radio frequency device are as follows: first step 31, winding the intermediate form of the helical antenna 1 after unwinding and winding the fixed terminal 15 on the intermediate form of the helical antenna 1 at a set interval; second step 32, cutting the intermediate form of the helical antenna 1 to form the helical antenna 1 according to the set; third step 33, electrically connecting the helical antenna 1 with the radio frequency module 2 to form the radio frequency device. Figure 7 Figure 4 In the fourth embodiment, the intermediate form of the helical antenna 1 is a roll of helical conductor 12, insulating wire 13 and first insulating outer layer 14 wound and fixed on the flexible core material 11, and the flexible core material 11 is aramid fiber. The steps of producing the radio frequency device are as follows: first step 31, winding the intermediate form of the helical antenna 1 after unwinding and winding the fixed terminal 15 on the intermediate form of the helical antenna 1 at a set interval; second step 32, cutting the intermediate form of the helical antenna 1 to form the helical antenna 1 according to the set; third step 33, electrically connecting the helical antenna 1 with the radio frequency module 2 to form the radio frequency device.​​​

Claims

1. A radio frequency device, characterized in that, It has a helical antenna and an RF module, wherein the first end of the helical antenna is electrically connected to the RF interface of the RF module; The radio frequency module has the function of outputting radio frequency electrical signals or receiving radio frequency electrical signals, or both. The structure of the helical antenna includes a core material and a helical conductor wound around and fixed to the outer periphery of the core material. The material of the spiral conductor is a single or multiple bundled metallized fibers, metal wires, or carbon fiber wires, and the radius of each metallized fiber, metal wire, or carbon fiber wire is less than 5 times the skin depth when the radio frequency signal is transmitted on the metallized fiber, metal wire, or carbon fiber wire. The relative permeability of the metal in the metallized fiber or the metal wire is <5, and the resistivity is <5×10⁻⁶. -8 Ω·m, made of one or an alloy of copper, aluminum, silver, and gold; The resistivity of a single metallized fiber is <100Ω / cm, and the structural feature of the cross-section is that at least two materials are coaxially distributed, namely material A and material B, wherein material B is wrapped around the periphery of material A; Material A has an axial thermal expansion coefficient of <25x10⁻⁶ within the temperature range of -40℃ to +150℃. -6 / ℃, Material A can be aramid, carbon fiber, basalt fiber, or modified glass fiber; Material B is one of copper, silver, aluminum, or gold, or an alloy thereof.

2. The radio frequency device according to claim 1, characterized in that, The spiral conductor is made of multiple bundles of metallized fibers, metal wires or carbon fiber wires, and the outer surface of each metallized fiber, metal wire or carbon fiber wire has an insulating layer with a resistivity >0.01 Ω·m. When the helical conductor is made of metallized fiber or metal wire, the insulating layer material is an oxide generated on the surface of the metallized fiber or metal wire through an oxidation reaction, or the insulating layer material is an organic compound with a molecular weight of less than 1 million. When the helical conductor is made of carbon fiber wire, the insulating layer material includes one or a combination of diamond, silicon carbide, carbon nitride, and organic compounds with a molecular weight of less than 1 million.

3. The radio frequency device according to claim 1, characterized in that, The spiral conductor is wound and fixed to the outer periphery of the core material by weaving the material of the spiral conductor and multiple insulating wires into a mesh and tightly wrapping them around the outer periphery of the core material. The outer diameter of the insulating wires is close to that of the material of the spiral conductor.

4. The radio frequency device according to claim 1, characterized in that, The spiral conductor is wound and fixed to the outer periphery of the core material by spirally winding the material of the spiral conductor and multiple insulating wires side by side around the outer periphery of the core material, and then tightly wrapping it with a first insulating outer layer. The outer diameter of the insulating wires is close to that of the material of the spiral conductor. The first insulating outer layer is one or a combination of woven mesh, hot melt adhesive, and glue.

5. The radio frequency device according to claim 1, characterized in that, The spiral conductor is wound and fixed to the outer periphery of the core material in the following manner: First, a second insulating outer layer is covered on the outer periphery of the spiral conductor material. The second insulating outer layer has one of the following properties: it can be heat-melted into an adhesive, it can be softened into an adhesive in a solution, or it cannot be adhesive. Then, the spiral conductor is wound around the outer periphery of the core material. Finally, the fixing is completed by one of the following three methods: heating and melting the second insulating outer layer to adhere it to the outer periphery of the core material, immersing it in a solution and then adhering the second insulating outer layer to the outer periphery of the core material, or tightly wrapping the spiral conductor and the core material with a third insulating outer layer. The third insulating outer layer is one or a combination of woven mesh, hot melt adhesive, and glue.

6. The radio frequency device according to claim 1, characterized in that, The first end of the helical antenna has a fixed terminal, which has the characteristic of mechanically clamping the helical conductor and the core material while simultaneously electrically connecting to the helical conductor. The fixed terminal and the radio frequency interface of the radio frequency module are electrically connected by one or more of welding, riveting, and crimping.

7. The radio frequency device according to claim 1, characterized in that, The core material is a flexible material, and the core material is one or a combination of materials whose dielectric constant changes by less than 25% after being exposed to moisture.

8. The radio frequency device according to claim 1, characterized in that, It also has an outer casing that encloses the helical antenna and the radio frequency module. The outer casing is enclosed by spraying liquid colloid onto the outer surface of the helical antenna and the radio frequency module and then curing it. Alternatively, the spiral antenna and the radio frequency module can be immersed in a liquid colloid and then cured to form a solid shape. Alternatively, the spiral antenna and the radio frequency module can be injection molded into a mold. Alternatively, the spiral antenna and the radio frequency module can be mechanically placed into a pre-formed housing and fixed in place. Alternatively, a flexible sheet-like outer shell can be used to wrap or cover the helical antenna and the radio frequency module.

9. The radio frequency device according to claim 1, characterized in that, The spiral antenna has an intermediate form during automated production. The operator obtains the spiral antenna by cutting the intermediate form to the required length. The intermediate form is a long strip with a length much longer than the length of a single spiral antenna, in which the spiral conductor is continuously wound and fixed around the outer periphery of a single core material.

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