Multi-loop antenna and loop antenna type powerless radio

Abstract

To provide a multi-loop antenna that is excellent in portability and can adjust a resonance frequency by an element other than an antenna wire material, and a loop antenna type unpowered radio.SOLUTION: A conductive antenna wire material is inserted in a loop tube in a state of being wound for multiple times. In the tube, separately from the antenna wire material, a conductive, dielectric, or insulative solid, a granular material, a wire, a liquid, gel, or a gas (except normal temperature ordinary humidity air) are filled or installed. Then the above problems are solved.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multi-loop antenna with adjustable resonant frequency and a loop antenna type power-less radio. [Background technology]

[0002] When using a radio in an emergency such as a disaster, there is a concern that the batteries that power the radio will run out and you will not be able to listen to the radio halfway through. There are also hand-crank powered radios, but they require a lot of effort to generate power, and they are noisy and have problems with the deterioration of the radio's built-in rechargeable batteries. Meanwhile, listening to internet radio using a smartphone carries the risk of the network becoming unstable during a disaster, making it impossible to listen to the radio, and listening to internet radio also consumes a lot of power on the smartphone.

[0003] Furthermore, crystal radios have been known as power-free radios that do not require batteries, and methods have been proposed for connecting crystal radios to mobile phones (see, for example, Patent Document 1). However, due to their structure, crystal radios are difficult to make lightweight and compact, which makes them less portable. This makes them difficult to carry around in case of an emergency or to carry far away when evacuating.

[0004] On the other hand, multi-loop antennas, which are constructed by winding antenna wire into a coil, are also well known as antennas used in radios, radio wave generators, etc. (see, for example, Patent Document 2). However, with conventional multi-loop antennas, the resonant frequency could only be adjusted by changing the material and wire diameter of the antenna wire, the diameter and number of turns of the coil, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-35052 [Patent Document 2] International Publication No. 2020 / 138022 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to solve the problems of the above-mentioned conventional technology, and in summary, to provide a multi-loop antenna and a loop antenna type non-powered radio that are highly portable and allow the resonant frequency to be adjusted using elements other than the antenna wire. [Means for solving the problem]

[0007] The inventor solved the above problem by inserting a conductive antenna wire wound multiple times into the loop-shaped tube, and filling or installing a conductive, dielectric or insulating solid, powder, wire, liquid, gel or gas (excluding air at room temperature and humidity) inside the tube, separate from the antenna wire (the effects will be described later).

[0008] Furthermore, in the present invention, by filling the tube with a conductive or insulating liquid, gel, or powder, the resonance frequency can be adjusted without impairing the flexibility of the tube.

[0009] In addition, in the present invention, a transparent or semi-transparent material is used for the tube, and a luminous material, a fluorescent material or a coloring material is used as the conductive, dielectric or insulating liquid, gel or powder or granule, thereby making it possible to impart luminous properties or coloring. In particular, when a luminous material is used, visibility at night is high.

[0010] In addition, in the present invention, the resonant frequency can be shifted by inserting an independent conductive wire, separate from the antenna wire, into the tube in a state of being wound once or multiple times.

[0011] In the present invention, the resonant frequency can be shifted by applying a conductive paint to the outer or inner surface of the tube, or by making the tube itself conductive.

[0012] In addition, in the present invention, the resonant frequency can be shifted by providing a conductive sheet inside the loop of the tube.

[0013] In addition, in the present invention, a loop antenna type power-free radio can be configured by providing the multi-loop antenna with a tuning circuit, a demodulation circuit, and a microphone circuit and connecting a microphone output terminal to the microphone circuit. [Effects of the Invention]

[0014] The multi-loop antenna of the present invention can adjust the dielectric constant by injecting a conductive or insulating filler into the tube into which the antenna wire is inserted, allowing the resonant frequency to be adjusted using factors other than the antenna wire. Furthermore, the loop antenna-type power-free radio of the present invention is lightweight and can be made compact by multi-wrapping it using a flexible tube, making it portable in preparation for emergencies such as disasters and easy to carry during evacuation. Furthermore, when connected to a smartphone or other device, the smartphone only needs to amplify and output the audio signal, thereby reducing the smartphone's power consumption. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a multi-loop antenna and a loop antenna type power-less radio according to a first embodiment of the present invention; [Figure 2] 1 is a cross-sectional view taken along the line A1-A1 showing the internal structure of a tube according to a first embodiment of the present invention. [Figure 3] FIG. 10 is a schematic diagram showing a multi-loop antenna according to a second embodiment of the present invention. [Figure 4] 10 is a cross-sectional view taken along line A2-A2 showing the internal structure of a tube according to a second embodiment of the present invention. FIG. [Figure 5] FIG. 10 is a schematic diagram showing a multi-loop antenna according to a third embodiment of the present invention. [Figure 6]10 is a cross-sectional view taken along line A3-A3 showing the internal structure of a tube according to a third embodiment of the present invention. FIG. [Figure 7] 10 is a schematic diagram showing a usage mode of a multi-loop antenna in a third embodiment of the present invention. FIG. [Figure 8] 10 is a graph showing test results of the multi-loop antenna according to the third embodiment of the present invention. [Figure 9] 10 is a graph showing test results of the multi-loop antenna according to the third embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing a multi-loop antenna according to a fourth embodiment of the present invention. [Figure 11] FIG. 10 is a schematic diagram showing a modification of the multi-loop antenna in the fourth embodiment of the present invention. [Figure 12] FIG. 10 is a schematic diagram showing a modification of the multi-loop antenna in the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] "First embodiment" A first embodiment of the present invention will be described with reference to Figs. 1 and 2. In the drawings, the symbol R indicates a loop antenna type power-less radio, and the symbol M indicates a multi-loop antenna. The symbol 1 indicates a tube, and the symbol 2 indicates an antenna wire. The symbol 3 indicates a connection circuit, and the symbol 4 indicates a filler. The symbol 5 indicates a plug, and the symbol 6 indicates a microphone output terminal.

[0017] "Configuration of loop antenna type non-powered radio and multi-loop antenna" [1] Basic configuration The basic configuration of this embodiment will be described. The multi-loop antenna M of this embodiment is configured by bending a tube 1 into a loop as shown in Fig. 1, inserting a conductive antenna wire 2 wound multiple times in a coil shape into the curved tube 1, and connecting a start end 21 and a finish end 22 of the antenna wire 2 arranged outside the tube 1 to a connection circuit 3. As a result, when a propagating radio wave is received, power generated in the coiled antenna wire 2 at a predetermined resonant frequency is output to the connection circuit 3. Furthermore, a flexible resin is injected into the tube 1 as a filler 4, and both ends of the tube 1 are sealed with plugs 5. This allows the dielectric constant to be adjusted by the filler 4 injected into the tube 1, thereby raising or lowering the resonant frequency of the antenna.

[0018] The loop antenna type power-free radio R of this embodiment is configured by providing a tuning circuit 31, a demodulation circuit 32, and a microphone circuit 33 in the connection circuit 3 of the multi-loop antenna M, and further connecting a microphone output terminal 6 to the microphone circuit 33. This allows it to be connected to a smartphone, portable music device, PDA, car navigation system, or other electronic device with a speaker or audio output terminal for use during emergencies, etc. In particular, because the loop antenna type power-free radio R of this embodiment does not require power for radio reception or audio signal output, power consumption on the electronic device can be limited to the power consumed for amplifying the audio signal and outputting the audio signal when listening with earphones, allowing for continuous radio listening for long periods of time.

[0019] [2] About tubes [2-1] Tube shape and dimensions Next, each component will be described. First, in this embodiment, the tube 1 has a circular cross-sectional shape, but the cross-sectional shape may be angular, elliptical, or other shapes as long as it has a hollow portion for inserting the antenna wire 2. Regarding the loop shape of the tube 1, although the tube 1 is circular in this embodiment, it may also be angular, elliptical, or other shapes. Furthermore, in this embodiment, the flexible tube 1 is curved into a circular shape, but a tube 1 that has been pre-formed into a loop shape can also be used. The cross-sectional dimensions of the tube 1 can be changed as appropriate depending on the diameter and number of turns of the antenna wire 2 to be inserted. The length of the tube 1 can also be changed as appropriate depending on the coil diameter of the antenna wire 2.

[0020] [2-2] Tube material Although polyethylene is used as the material for the tube 1 in this embodiment, other flexible resin materials such as polyurethane, polypropylene, polyvinyl chloride, and PET can also be used. More flexible materials include natural rubber, synthetic rubber, silicone rubber, thermoplastic elastomers, soft resins, organic polymers, inorganic polymers, natural polymers, synthetic polymers, semi-synthetic polymers, and composites thereof. By constructing the tube 1 from a flexible material, the tube 1 can be deformed into a multi-wound (double or quintuple) state for compactness, improving the portability of the multi-loop antenna M. For example, the multi-loop antenna M can be stored in a name holder with a neck strap, or the multi-loop antenna M itself can be carried as a neck strap. The tube 1 can also be bellows-shaped to enhance its flexibility. Note that, in this specification, the "flexibility" of the tube 1 refers to the property of the tube 1 to bend elastically under external force, and the "flexibility" of the tube 1 refers to the property of the tube 1 to deform in shape under external force.

[0021] Furthermore, if a transparent or translucent material is used for the tube 1 as in this embodiment, the filler 4 can be seen from the outside, and the filler 4 can be imparted with luminous or fluorescent properties or colored. This also makes it possible to suppress deterioration of the luminous material or coloring material compared to applying it to the outside of the tube 1. Of course, the material for the tube 1 can also be opaque, and functional additives or pigments for decorative purposes can also be mixed into the main material of the tube 1. Furthermore, by enclosing a luminous material within the tube 1, the disaster prevention radio becomes easier to find in the dark at night.

[0022] [3] Antenna wire [3-1] Antenna wire material Next, the antenna wire 2 is preferably made of a flexible conductive material, such as a wire made by twisting together one or more types of conductive materials, such as Litz twisted wire, metal wire, conductive fiber, or carbon fiber. It is preferable to use a conductive wire that is coated with an insulating material, such as a synthetic polymer material, such as vinyl chloride, a semi-synthetic polymer material, or a natural polymer material, such as silk thread.

[0023] [3-2] Coil shape of antenna wire In this embodiment, the antenna wire 2 is inserted into the tube 1 in a state where it is wound twice, but the coil shape, coil diameter, and number of turns of the antenna wire 2 can be changed appropriately depending on the target resonance frequency. Furthermore, the coil shape of the antenna wire 2 can be changed appropriately depending on the shape of the tube 1 into which the antenna wire 2 is inserted, and not only the circular shape as in this embodiment but also a square shape, an elliptical shape, etc. can be adopted.

[0024] [4] Connection circuit Next, with regard to the connection circuit 3, the present embodiment employs a configuration for the connection circuit 3 to be used as a power-less radio, but when the multi-loop antenna M is used as a power generator, the circuit configuration can also be such that the power generated in the antenna wire 2 is output to the outside. Specifically, by appropriately connecting circuits such as a resistor circuit, a rectifier circuit, a tuning capacitor circuit, a matching circuit, and a storage circuit, the connection circuit 3 can be used as a power source for various information devices, such as communication devices such as radio receivers, LED lighting devices, and detection devices such as sensors that acquire observation data.

[0025] [5] About fillings [5-1]Solid / semisolid Next, in this embodiment, a silicone-based soft resin is used for the filler 4, which is mixed with a phosphorescent material and then injected into the tube 1 and solidified. This allows the position of the antenna wire 2 to be fixed while maintaining the deformability of the tube 1, thereby preventing inductance changes due to vibration, etc. Other solid fillers 4 that achieve similar effects include natural rubber, synthetic rubber, silicone rubber, urethane rubber, thermoplastic elastomers, soft resins, organic polymers, inorganic polymers, natural polymers, synthetic polymers, semi-synthetic polymers, polymer electrolytes, and composite materials of these. Furthermore, conductive, dielectric, or insulating solids or gels (semi-solids) can be used as the filler 4.

[0026] Alternatively, powder or granular material can be used as the solid filler 4. For example, powder or granular material of inorganic compounds such as iron sand or metal oxides, or organic compounds, can be used. In this case, if the tube 1 is transparent, the appearance and texture when touched can be changed by changing the particle size of the powder (for example, by making it granular). Furthermore, if the tube 1 is to be transparent or translucent, it is possible to impart phosphorescent or fluorescent properties or color by mixing phosphorescent materials, fluorescent materials, luminescent materials, or coloring materials such as pigments, dyes, and paints into the filler 4. Furthermore, by placing the filler 4 around the antenna wire 2, changes in the dielectric constant of the antenna wire 2 due to moisture, etc., can be prevented.

[0027] [5-2]Liquid A conductive or insulating liquid can be used as the filler 4, such as water, electrolyte, oil, organic solvent, or a mixture thereof. Even when a liquid filler 4 is used, the movement of the antenna wire 2 can be suppressed, thereby suppressing changes in inductance due to vibrations and preventing changes in the dielectric constant of the antenna wire 2 due to moisture. When the tube 1 is to be transparent or translucent, the liquid filler 4 can be mixed with phosphorescent or fluorescent materials, luminescent materials, coloring materials such as pigments, dyes, and paints, decorative materials that move in the liquid, air bubbles, etc., to impart phosphorescent or fluorescent properties, or to color or decorate the tube.

[0028] [5-3] Electrochemically responsive materials When an electrochemically responsive solid, gel, or liquid is used as the filler 4, electrodes are placed at both ends of the tube 1 (at the plug 5 in this embodiment) so as to be in contact with the filler 4, and the resonant frequency can be shifted by connecting these electrodes directly or by connecting a resistor or capacitor (not shown). When an electrolyte is used as the filler 4, a marker signal can be applied to the electrodes at both ends of the tube 1 to mix the signal with the resonant frequency of the antenna wire 2. Examples of electrochemically responsive solids, gels, and liquids include iron sand, metal powder, metal oxide, conductive powder, polymer electrolyte, electrolytic solution, and MR fluid.

[0029] [5-4] Gas A gas (excluding air at room temperature and humidity) can be used as the filler 4 and injected into the tube 1 in a sealed state, thereby reducing changes in the dielectric constant of the antenna wire 2 due to changes in humidity, etc. Sealing the inside of the tube 1 also prevents oxidation of the antenna wire. Gases that can be used as the filler 4 include inert gases such as nitrogen gas, carbon dioxide, and argon gas, oxygen gas, dry air, and saturated water vapor.

[0030] [6] About the stopper Next, the stopper 5 may be any material capable of sealing the inside of the tube 1, and a flexible elastomer or soft resin can be suitably used. When an electrochemically responsive substance is used as the filler 4, it is preferable to use a conductor at least in the portion of the stopper 5 that comes into contact with the filler 4. When a solid filler 4 is used and can be held in the tube 1 without sealing, the stopper 5 is not an essential component.

[0031] [7] Microphone output terminal Next, the microphone output terminal 6 can be of a standard compatible with smartphones and other electronic devices. A combo jack that also functions as an earphone input terminal can be used as the microphone output terminal 6. In this case, the radio audio signal received by the multi-loop antenna can be amplified by a smartphone or other device and output from the combo jack to earphones, allowing you to listen to the radio at an appropriate volume.

[0032] Second Embodiment [1] Basic configuration A second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The multi-loop antenna M of this embodiment is configured by inserting a conductive independent wire 7, separate from the antenna wire 2, into a tube 1 in a wound state, and connecting the start end 71 and end end 72 of the independent wire 7 housed within the tube 1 to a conductive circuit 8 outside the tube 1. This allows the resonant frequency to be shifted by electrically connecting the start end 71 and end end 72 of the independent wire 7. The conductive circuit 8 can be connected to a resistor or capacitor to cause a frequency change. Furthermore, by turning the connection on and off with a switch, the frequency change can be caused at any timing (for example, when changing the radio reception band from long wave to medium wave, medium wave to short wave, or long wave to short wave, or when using a medium wave radio as a short wave radio). The antenna wire 2 and the independent wire 7 inside the tube 1 are electrically insulated from each other.

[0033] [2] About independent wire The independent wire 2 is preferably made of a flexible conductive material, such as a wire made by twisting together one or more types of conductive materials, such as Litz twisted wire, metal wire, conductive fiber, or carbon fiber. The conductive wire is preferably coated with an insulating material, such as a synthetic polymer material such as vinyl chloride, a semi-synthetic polymer material, or a natural polymer material such as silk thread. In this embodiment, the independent wire 7 is inserted with one winding, but it can also be inserted with multiple windings. A frequency change can also occur when the starting end 71 and the ending end 72 of the independent wire 7 are directly connected without the conductive circuit 8. The other configurations are the same as those of the first embodiment.

[0034] [Effectiveness Demonstration Test (1)] A demonstration test of the effects of this embodiment will be described with reference to FIGS. 3 and 4. In this test, a polyethylene tube with an outer diameter of 20 mm and a wall thickness of 1 mm was used as tube 1, forming a circular loop with an inner diameter of 620 mm. A seven-turn antenna wire 2 and a single-turn independent wire 7 were inserted into tube 1, and the start end 71 and end end 72 of independent wire 7 were connected by a toggle switch, which serves as conductive circuit 8, to fabricate a multi-loop antenna M. The connection between the start end 71 and end end 72 of independent wire 7 was turned on and off by the toggle switch to measure the change in resonant frequency. The resonant frequency shifted significantly from 522-1053 kHz to 876-1820 kHz. Furthermore, when the independent wire 7 was wound twice and measured again, the resonant frequency shifted even more significantly from 522-1053 kHz to 1112-2262 kHz. This confirmed that the frequency shift increased with the number of turns of independent wire 7, resulting in a shift to a higher frequency. In this test, Litz twisted wire (40 strands) covered with insulating material was used for the antenna wire 2 and the independent wire 7. A variable capacitor connected in parallel was used for the connection circuit, and the resonance frequency was measured by connecting an impedance analyzer (IM3570; manufactured by Hioki E.E. Corporation) and a vector network analyzer (NanoVNA-H4).

[0035] "Third Embodiment" [1] Basic configuration A third embodiment of the present invention will be described with reference to FIGS. 5 to 8. In the multi-loop antenna M of this embodiment, as shown in FIGS. 5 and 6, the outer circumferential surface of the main body 11 of the tube 1 is coated with a conductive material to form a conductive layer 12. Furthermore, ring-shaped electrodes 13 are provided at both ends of the tube 1 in contact with the conductive layer 12, and these are connected to a conductive circuit 8. This electrically connects the outer circumferential surfaces of both ends of the tube 1, thereby shifting the resonant frequency. Examples of conductive materials that can be used to coat the outer circumferential surface of the tube 1 include conductive paint (such as a carbon-based conductive paint) that can be applied to the outer circumferential surface of the tube 1 and conductive stickers that can be attached to the outer circumferential surface. In this embodiment, the entire outer circumferential surface of the tube 1 is coated with a conductive material; however, it is sufficient to coat at least a portion of the outer circumferential surface. The main body 11 of the tube 1 is an insulating material made of transparent polyurethane. The conductive circuit 8 is the same as in the second embodiment.

[0036] [2] Ring-shaped electrode In this embodiment, ring electrodes 13 are provided on both ends of the tube 1, but if two conductive layers 12 on the tube 1 are directly connected, the ring electrodes 13 are not essential components. In this embodiment, as shown in FIG. 7, at least one of the two ring electrodes 13 is configured to be slidable along the length of the tube 1, allowing any two points on the conductive layers 12 to be electrically connected. This allows the frequency shift width to be changed by changing the relative positions of the two ring electrodes 13. Well-known conductors can be used for the ring electrodes 13.

[0037] 7, when the two ring electrodes 13 of the tube 1 are electrically connected, the resonant frequency shifts to a higher frequency. The amount of shift varies depending on the distance between the two ring electrodes 13 on the tube 1, and the greater the angle θ between the center of the loop of the tube 1 and the line connecting each ring electrode 13, the greater the amount of shift.

[0038] [Effectiveness Demonstration Test (2)] A demonstration test of the effects of this embodiment will be described with reference to FIGS. 5 to 9. In this test, a transparent polyurethane tube with an outer diameter of 8 mm and a wall thickness of 1.5 mm was used as the main body 11 of the tube 1, and a circular loop with an inner diameter of 620 mm was fabricated. A Litz twisted wire (20 strands) wound seven times as the antenna wire 2 was inserted into the tube 1, and a phosphorescent material (strontium aluminate, Luminova (registered trademark) by Nemoto Specialty Chemical Co., Ltd.) was filled in to fabricate a multi-loop antenna M. A multi-loop antenna M was also fabricated by replacing the antenna wire 2 with another Litz twisted wire (40 strands). A conductive copper foil tape (50 μm thick, 14 mm wide) was attached to the outer periphery of the main body 11 of each of these tubes 1 to form a conductive layer 12, and a pair of ring-shaped electrodes 13, 13 were attached to the outer periphery of the tube 1. As shown in Figure 7, one of the pair of ring-shaped electrodes 13·13 attached to the outer periphery of the tube 1 was slid along the tube 1 to change the angle θ from 0 to 360 degrees, and the change in resonant frequency was measured. Figure 8 shows the measurement results for a multi-loop antenna M with 20 Litz twisted wires, and Figure 9 shows the measurement results for a multi-loop antenna M with 40 Litz twisted wires. In both cases, a variable capacitor was connected in parallel to the connection circuit 3, and the resonant frequency of the parallel resonant circuit was measured. As can be seen from these results, the resonant frequency increases as the angle θ increases, that is, as the relative distance between the electrodes increases. These measurement results confirmed that there is a causal relationship between the distance between the two electrodes and changes in resonant frequency.

[0039] In this test, the resonant frequency ranges of the multi-loop antenna M made of 20-strand and 40-strand Litz twisted wires before the copper foil was attached were measured. The ranges were 524–1037 kHz for the 20-strand Litz twisted wire and 563–1432 kHz for the 40-strand Litz twisted wire. Therefore, the resonant frequency of each antenna was set to its maximum. These test results demonstrate that forming a conductive layer 12 on the outer surface of the tube 1 allows the resonant frequency to be adjusted beyond the upper limit of the resonant frequency of an antenna without a conductive layer. Furthermore, the multi-loop antenna M filled with phosphorescent material without the copper foil tape (the first embodiment shown in Figures 1 and 2 ) glows in the dark, confirming that the multi-loop antenna M, rolled up and shrunk into a triple loop, can be easily found in the dark and its presence can be easily noticed. This test also confirmed that the tube 1 can function as a radio even when filled with phosphorescent material.

[0040] "Fourth embodiment" [1] Basic configuration A fourth embodiment of the present invention will be described with reference to Figs. 10 to 12. The multi-loop antenna M of this embodiment is configured by providing a conductive sheet 9 inside the loops of a tube 1, as shown in Fig. 9. This allows the resonant frequency to be shifted, and the amount of shift can be adjusted by changing the shape of the conductive sheet 9 and its placement relative to the tube 1. Furthermore, by hanging the multi-loop antenna M on a wall or slope made of a conductive material, or on a wall or slope to which the conductive sheet 9 is attached, it can be used as an antenna or radio with a variable tuning frequency.

[0041] The conductive sheet 9 may be a sheet made of a conductive material such as metal or carbon, or a sheet made of a non-conductive sheet such as paper or resin film as a base material with a conductive layer formed on the surface. Methods for forming a conductive layer on the surface of a non-conductive sheet include attaching metal foil, metal plating, and applying conductive paint. The shape of the conductive sheet 9 may be other than circular, and may also be oval or rectangular.

[0042] [2] Adjusting the resonant frequency shift [2-1] Placement of conductive sheets The resonant frequency can be adjusted by changing the position of the conductive sheet relative to the tube, and when the conductive layer 13 is not formed on the outer surface of the tube 1, the frequency shift is largest when the conductive sheet 1 is positioned on the same plane as the inner loop of the tube 1. When the conductive layer 13 is formed on the outer surface of the tube 1, the frequency shift is largest when the conductive sheet 9 is positioned in contact with the conductive layer 13 of the tube 1.

[0043] [Effectiveness Demonstration Test (3)] A demonstration test of the effects of this embodiment will be described with reference to FIG. 10 . In this test, a polyethylene tube with an outer diameter of 20 mm and a wall thickness of 1 mm was used as the main body 11 of the tube 1, and an aluminum layer was formed on the outer surface of the main body 11 as the conductive layer 12. Furthermore, this tube 1 was formed into a circular loop with an inner diameter of 620 mm. Two turns of the antenna wire 2 were inserted into this tube 1, and a conductive sheet 9 was used, which was a circular cardboard sheet with an outer diameter of 600 mm and aluminum foil attached. This conductive sheet 9 was placed on the same plane as the loops of the tube 1 but not in contact with the loops, thereby creating a multi-loop antenna M. The resonant frequency was measured, and the placement of the conductive sheet 9 significantly shifted the resonant frequency from 581-1495 kHz to 758-2026 kHz. Furthermore, the frequency shift increased as the conductive sheet 9 was moved closer to the tube 1. In this test, 40 strands of Litz twisted wire were inserted into the tube 1 as the antenna wire 2, with seven turns. The connection circuit used a variable capacitor connected in parallel, and the resonance frequency was measured by connecting an impedance analyzer (IM3570; manufactured by Hioki E.E. Corporation) and a vector network analyzer (NanoVNA-H4).

[0044] [Effectiveness Demonstration Test (4)] A demonstration test of the effects of this embodiment will be described (not shown). In this test, a polyethylene tube with an outer diameter of 20 mm and a wall thickness of 1 mm was used as the main body 11 of the tube 1, and an aluminum layer was formed on the outer surface of the main body 11 as the conductive layer 12. Furthermore, this tube 1 was formed into a circular loop with an inner diameter of 620 mm. Seven turns of the antenna wire 2 were inserted into this tube 1, and a conductive sheet 9 made of a circular cardboard sheet with an outer diameter of 800 mm and aluminum foil attached to it was placed under the tube 1 in contact with the loop, thereby producing a multi-loop antenna M. Then, when the resonant frequency was measured, the placement of the conductive sheet 9 significantly shifted the resonant frequency from 640-1613 kHz to 1634-4059 kHz. In this test, 7 turns of Litz twisted wire (40 strands) were inserted into the tube 1 as the antenna wire 2. The connection circuit used a variable capacitor connected in parallel, and the resonance frequency was measured by connecting an impedance analyzer (IM3570; manufactured by Hioki E.E. Corporation) and a vector network analyzer (NanoVNA-H4).

[0045] [2-2] Conductive sheet area The resonant frequency can also be adjusted by changing the area of ​​the conductive sheet 9; reducing the area of ​​the conductive sheet 9 reduces the frequency shift. For example, if the conductive sheet 9 is designed to be adjustable like a folding fan, as shown in Figure 11, the smaller the opening angle θ (opening angle + cutting angle = 360°) of the conductive sheet 9, the lower the upper limit frequency of the resonant frequency. Therefore, the resonant frequency can be easily adjusted by changing the shape of the conductive sheet 9. Furthermore, if a conductive layer 13 is formed on the outer surface of the tube 1, connecting the conductive sheet 9 and the conductive layer 13 of the tube 1 to a switch circuit 81 can electrically connect the two by turning the switch circuit 81 on and off, thereby increasing the upper limit frequency of the resonant frequency. The switch circuit 81 can also be replaced with another conductive circuit 8.

[0046] [Effectiveness Demonstration Test (5)] In the multi-loop antenna M of this embodiment, the change in resonant frequency was examined for a configuration in which the diameter of the conductive sheet 9 was adjusted to match the inner diameter of the loop of the tube 1 (as shown in FIG. 12(a)), a configuration in which the diameter of the conductive sheet 9 was cut out to match the inner diameter of the loop of the tube 1 (as shown in FIG. 12(b)), and a configuration in which the diameter of the conductive sheet 9 was larger than the inner diameter of the loop of the tube 1 (as shown in FIG. 12(c)). The resonant frequency shift was in the order (c) > (a) > (b). This confirmed that the frequency shift increases in proportion to the area of ​​the conductive sheet 1, regardless of its shape. In this test, a polyethylene tube was used for the tube 1, and a conductive sheet 9 made of cardboard with aluminum foil attached was used. Furthermore, a Litz twisted wire (40 strands) was inserted into the tube 1 with seven turns as the antenna wire 2. [Explanation of symbols]

[0047] 1 tube 11 Main body 12 Conductive layer 13 electrodes 2 Antenna wire 21 Beginning 22 Termination 3 Connection circuit 31 Tuned circuit 32 Demodulation Circuit 33 Microphone Circuit 4 Filling 5 Plug body 6 Microphone output terminal 7 Independent wire rod 71 Beginning 72 Termination 8 Continuity circuit 81 Switch Circuit 9 Conductive sheet M Multi-loop antenna R Unpowered radio

Claims

1. A multi-loop antenna in which a conductive antenna wire is inserted into a flexible loop-shaped tube in a state where it is wound multiple times, and the tube is filled with a dielectric or insulating solid, powder, wire, liquid, gel or gas (excluding air at room temperature and humidity) separate from the antenna wire while maintaining the flexibility of the tube.

2. 2. The multi-loop antenna according to claim 1, wherein the tube is transparent or semi-transparent, and the dielectric or insulating liquid, gel, or powder is a phosphorescent material, a fluorescent material, or a coloring material.

3. A multi-loop antenna is provided in which a conductive antenna wire is inserted into a loop-shaped tube in a state where it is wound multiple times, and an independent conductive wire, separate from the antenna wire, is inserted into the tube in a state where it is wound one or multiple times.

4. 4. The multi-loop antenna according to claim 3, wherein said tube is filled with a dielectric or insulating liquid, gel, powder or gas (except air at normal temperature and humidity).

5. A multi-loop antenna in which a conductive antenna wire is inserted into a loop-shaped tube made of an insulating main body in a state where it is wound multiple times, and a conductive layer is formed on the outer or inner surface of the tube.

6. A multi-loop antenna in which a conductive antenna wire is inserted into a loop-shaped tube in a state where it is wound multiple times, and a conductive sheet is provided inside the loop of the tube.

7. A loop antenna type non-powered radio using the multi-loop antenna according to any one of claims 1 to 6, comprising a tuning circuit, a demodulation circuit and a microphone circuit, and a microphone output terminal connected to the microphone circuit.

Images