Television antenna device with coaxial cable

Abstract

This cable comprises: a first shield part that has at least one line for transmitting signals or power and is provided outside the line; a first layer that is provided so as to cover the outer circumference of the first shield part and is composed of a member which absorbs radio waves; a second shield part provided outside the first layer; a second layer that is provided so as to cover the outer circumference of the second shield part and is composed of a member which absorbs radio waves; and an insulating resin that covers the outer side of the second layer.

Description

[Technical field]

[0001] This technology is For television reception With coaxial cable Television The present invention relates to an antenna device. [Background technology]

[0002] A coaxial cable used in connection with a conventional balanced antenna generates various problems because the shield wire of the outer conductor is connected to the ground of the connected device such as a television receiver. One problem is that high-frequency current flows into the sheath of the coaxial cable due to mismatch in characteristic impedance between the antenna and the coaxial cable, affecting the radiation characteristics of the antenna. Another problem is that if the connection to the ground of the connected device is not properly connected, such as with a pigtail, noise from the device flows into the sheath of the coaxial cable, and depending on the length of the coaxial cable, the sheath of the coaxial cable becomes an antenna and radiates radio waves. In addition, there is also a problem that common mode and normal mode noise jumps into the sheath or core of the coaxial cable due to the influence of noise radiated from the connected device.

[0003] In the past, to solve the former problem, a supertop was provided on the antenna to provide high impedance at the desired frequency, or a balun was used. To solve the latter problem, the connections around the connector were made perfectly all around to prevent this. If this still caused problems, a ferrite core was wrapped around the base of the coaxial cable on the connector side to prevent current from flowing through the shielded sheath of the coaxial cable. Also, when inserting the coaxial cable into a mobile device such as a smartphone, the sheath of the coaxial cable was stripped and connected to the device's ground to prevent current from flowing through the shielded sheath of the coaxial cable.

[0004] This technology aims to solve the problem of cable connections preventing performance from being achieved due to the effects of high-frequency currents flowing through the cable and noise emitted from the equipment. In other words, it makes it possible to prevent high-frequency currents from flowing through the cable sheath and suppress the effects of noise from the equipment.

[0005] Regarding noise suppression in cables, such as cables used in the USB standard (USB cables), a technology such as that described in Patent Document 1 is known. A USB cable has four electric wires: a pair of differential data lines, a power line, and a ground line. In general, a shielding layer made of woven copper wires is provided to suppress noise emitted from the cable to the outside and electromagnetic waves entering the cable from the outside. Both ends of this shielding layer are connected to ground potential parts.

[0006] However, if the ground potential is uncertain, there is a problem that the effectiveness of the electromagnetic shield is insufficient. Furthermore, if the ground potentials of the two connected devices are not equal, there is a problem that current flows through the shield layer and noise is transmitted to the devices. As a countermeasure to this problem, it has been proposed to suppress noise by using a resin mixed with a radio wave absorbing material such as ferrite as a coating material that covers the shield layer. Another countermeasure is to provide a noise suppressing material such as an inductance at the connection part of the cable that connects to the device.

[0007] For example, Patent Document 1 shows a cable having two signal lines and a shield covering the periphery thereof, and two power lines covered with a sheath layer. The sheath layer is made of a magnetic component-mixed resin layer and a protective sheath layer of resin covering the periphery thereof. It is said that the magnetic component-mixed resin layer can reliably prevent noise from the power lines from invading the signal lines, and that even if noise from the signal lines leaks from the shield, the magnetic component-mixed resin layer can reliably prevent it from invading the power lines 2. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4032898 Summary of the Invention [Problem to be solved by the invention]

[0009] The configuration of Patent Document 1 mentioned above is intended for a cable in which the power line and the signal line are arranged within a common sheath layer, and the measures against noise emission from the cable to the outside and against noise intrusion from the outside into the cable are insufficient.

[0010] Therefore, an object of the present technology is to suppress the effects of noise from devices and to suppress noise radiation from cables. Same With axial cable Television An object of the present invention is to provide an antenna device. [Means for solving the problem]

[0011] This technology is Two parallel wires in an insulator; a balanced antenna comprising a first antenna element and a second antenna element attached to an insulator and connected to one end of each of the two wires; a coaxial cable in which the other ends of the two wires are connected to the central conductor and the outer conductor; a connector connected to the coaxial cable, Coaxial cables are It is made of a metal that is placed on the outside of the central conductor through an insulator. A first shield portion; The first shield is covered with a protective layer that absorbs radio waves. resin A first layer consisting of On the outside of the first layer Made of metal A second shield portion; The second shield is covered with a layer of insulating material that absorbs radio waves. resin a second layer consisting of and an insulating resin that covers the outside of the second layer. Television antenna device with coaxial cable It is. Effect of the Invention

[0012] According to at least one embodiment, a first shielding portion, a first layer, a second shielding portion, and a second layer are arranged in this order, thereby making it possible to suppress noise caused by a large electromagnetic field in the near field. Note that the effects described herein are not necessarily limited to those described herein, and may be any of the effects described in the present technology or effects different thereto. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a graph used to explain near and far fields. [Diagram 2] FIG. 2 is a graph showing the magnitude of the near-field electromagnetic field. [Diagram 3] FIG. 3 is a schematic diagram for explaining a method for measuring noise in the vicinity of a television receiver. [Figure 4] 4A and 4B are graphs used to explain noise in the high band of the VHF band. [Diagram 5] Figure 5 is a graph used to explain noise in the UHF band. [Figure 6] FIG. 6 is a schematic diagram for explaining noise of a television receiver with respect to an indoor antenna. [Figure 7] 7A and 7B are cross-sectional and front views of one embodiment of the present technology. [Figure 8] FIG. 8 is a schematic diagram used to explain a noise suppression effect according to an embodiment of the present technology. [Figure 9] 9A and 9B are schematic diagrams for explaining the occurrence of noise. [Figure 10] FIG. 10 is a block diagram showing a system configuration for evaluating sensitivity. [Figure 11] FIG. 11 is a front view showing an example of the configuration of a receiving antenna. [Figure 12] FIG. 12 is a graph showing the results of sensitivity evaluation in the high VHF band. [Figure 13] FIG. 13 is a graph showing the results of sensitivity evaluation in the UHF band. [Figure 14]FIG. 14 is a cross-sectional view of a USB 2.0 cable to which the present technology can be applied. [Figure 15] FIG. 15 is a cross-sectional view of a USB 3.0 cable to which the present technology can be applied. [Figure 16] FIG. 16 is a cross-sectional view of an Ethernet cable to which the present technology can be applied. [Figure 17] FIG. 17 is a cross-sectional view of a variation of the present technology. [Figure 18] FIG. 18 is a partial perspective view showing a configuration of another example of the shielding member of the present technology. [Figure 19] FIG. 19 is a perspective view used to explain a winding method of another example of a shielding member of the present technology. [Figure 20] FIG. 20 is a cross-sectional view used to explain a winding method of another example of a shielding member of the present technology. [Figure 21] FIG. 21 is a perspective view used to explain a winding method of another example of a shielding member of the present technology. [Figure 22] FIG. 22 is a cross-sectional view used to explain a winding method of another example of the shielding member of the present technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present technology will be described with reference to the drawings. Note that the embodiments described below are preferred specific examples of the present technology, and various technically preferred limitations are attached, but the scope of the present technology is not limited to these embodiments unless otherwise specified in the following description to limit the present technology.

[0015] When an electromagnetic shield is used near an antenna, the effectiveness of the shield changes depending on the wave impedance. Wave impedance is the ratio (E / H) of the electric field (E) to the magnetic field (H) at a certain location. Figure 1 is a graph showing the change in wave impedance with distance, and shows the change in wave impedance of an infinitesimal dipole antenna and an infinitesimal loop antenna. Near the dipole antenna, the wave impedance is high because the electric field is strong. On the other hand, near the loop antenna, the wave impedance is low because the magnetic field is strong. When the distance exceeds λ (wavelength of the electromagnetic field) / (2π), both antennas converge to a certain value (376.7 Ω). Conventionally, the near field is up to this λ / (2π), and anything further than that is called the far field.

[0016] Figure 1 shows the distance r normalized by λ / (2π), with 1 on the horizontal axis corresponding to (r = λ / (2π), this distance being the boundary between the near field and the far field. For example, in the case of 100 MHz, the boundary distance r = 0.48 m, (0.1) is (r = 4.8 cm), and (10) is (r = 4.8 m). Similarly, in the case of 200 MHz, it is (1:r = 0.24 m), (0.1:r = 2.4 cm), and (10:r = 2.4 m). Furthermore, in the case of 500 MHz, it is (1:r = 0.095 m), (0.1:r = 0.95 cm), and (10:r = 0.95 m).

[0017] The graph in Figure 2 shows the strength of the electromagnetic field, induced electromagnetic field, and radiated wave against the horizontal axis (λ / (2π)). As can be seen from the graph in Figure 2, the electromagnetic field is quite large in the near field, so shielding is necessary as a noise countermeasure. To eliminate the effects of noise, it is necessary to reduce the effects of conducted noise transmitted through the cable and spatial noise that jumps into the cable. In particular, the magnetic field component has a low impedance, making it difficult to eliminate noise.

[0018] We measured noise components generated from an electronic device, for example a commercially available television receiver 1. As shown in Fig. 3, a dipole antenna 2 is installed close to the back of the television receiver 1, and the signal received by the dipole antenna 2 is supplied to a spectrum analyzer 4 via a cable 3. The noise components (spatial noise) received by the dipole antenna 2 can be analyzed by the spectrum analyzer 4.

[0019] 4A and 4B show the noise component level in the VHF high band (179 MHz to 228 MHz) obtained by the configuration shown in FIG. 3. When the power of the television receiver 1 is OFF, the noise component level is quite small, as shown in FIG. 4A. On the other hand, when the power of the television receiver 1 is ON, the noise signal level becomes high, as shown in FIG. 4B. FIG. 5 shows the frequency distribution of the noise signal in the UHF band (450 MHz to 850 MHz) when the power of the television receiver 1 is ON. The noise component becomes high in the UHF band as in the VHF band.

[0020] In particular, as shown in Fig. 6, when an indoor antenna, for example, a balanced antenna 7, is connected to a television receiver 1 via a coaxial cable 8, in order to reduce the influence of such noise components (space conduction noise), it is necessary to separate the balanced antenna 7 from the television receiver 1. The coaxial cable 8 is connected to the television receiver 1 by an IEC connector or an F connector. This technology is applied to, for example, the coaxial cable 8. This technology makes it possible to suppress noise entering the coaxial cable 8 as well as noise generated from the coaxial cable 8.

[0021] Hereinafter, an embodiment of a cable according to the present technology that can suppress the effects of the above-mentioned near-field magnetic and electric field noise will be described. Figures 7A and 7B are a cross-sectional view and a front view of a cable according to an embodiment of the present technology. The front view of Figure 7B shows the internal structure in an easy-to-understand manner by sequentially shifting and stripping off the coating from the center toward the outer periphery. The embodiment is an example in which the present technology is applied to a coaxial cable.

[0022] A signal transmission line (center conductor) 11 made of, for example, a annealed copper wire is located at the center of the cable. An insulator 12 made of, for example, foamed polyurethane, polyethylene, or foamed polyethylene is located outside the line 11. A first shield section S1 having an electric field shielding function is provided around the insulator 12 so as to cover the insulator 12. For example, the first shield section S1 is configured by an aluminum sheet 13 arranged on the outer surface of the insulator 12 and a braided wire 14 arranged on the outer surface of the aluminum sheet 13. The first shield section S1 is not limited to the above configuration, and may have a configuration made of a braided wire made by weaving annealed copper wires, a braided wire and a foil-like metal sheet (metal sheet of aluminum, copper, iron, etc.) arranged inside or outside the braided wire, a winding made by winding annealed copper wire, and a foil-like metal sheet (metal sheet of aluminum, copper, iron, etc.) arranged inside or outside the winding. The annealed copper wire may be tin-plated.

[0023] The braided wire 14 of the first shield part S1 is connected to a ground point of a circuit inside an electronic device through a connector, etc. The first shield part S1 is intended to prevent the line 11 from being affected by noise or to prevent noise from escaping from the line 11 to the outside.

[0024] A first layer F1 made of a resin that absorbs radio waves, for example, a resin mixed with magnetic powder, is disposed on the outer periphery of the braided wire 14 of the first shield section S1. The first layer F1 has a function of a magnetic shield. That is, the first layer F1 has a function of countering conductive noise. The resin mixed with magnetic powder is a synthetic resin mixed with magnetic powder. An example of the synthetic resin is a styrene-based elastomer. Other synthetic resins such as olefin-based elastomer and PVC may also be used. An example of the magnetic powder is Ni-Zn-based ferrite. The ratio of the iron powder and ferrite powder to the resin is 70% or more and 98% or less by weight. As the magnetic powder, magnetic powders such as Ni-Cu-Zn-based ferrite, Mn-Zn-based ferrite, soft magnetic metal-based, copper-based, magnesium-based, lithium-based, zinc-based, iron-based (for example, permalloy), and cobalt-based magnetic powders may also be used.

[0025] The second shield part S2 having an electric field shielding function is disposed so as to cover the outer periphery of the first layer F1. The second shield part S2 is, for example, an aluminum sheet. Other than an aluminum sheet, it may be only a braided wire or only a winding wire. It may also be a combination of a braided wire or a winding wire and a metal sheet such as aluminum. The second shield part S2 does not need to be grounded.

[0026] A second layer F2 made of a resin that absorbs radio waves, such as a resin mixed with magnetic powder, is disposed on the outer periphery of the second shield section S2. The second layer F2, which has a magnetic shielding function, is provided to counter spatial noise. The outer periphery of the second layer F2 is covered with a covering material 15. The covering material 15 can be made of an insulating material such as polyethylene, polypropylene, PVC (polyvinyl chloride), elastomer, etc.

[0027] Generally, complex permeability is expressed by the real part of the inductance component and the imaginary part corresponding to the resistance component (loss component), as shown in the following equation.

[0028]

number

[0029] When comparing the first layer F1 and the second layer F2, the first layer F1 has a function of converting noise into heat by the high-frequency resistance indicated by the imaginary part, and the second layer F2 has a function of magnetic shielding to prevent the influence of magnetic fields by the inductance component indicated by the real part. That is, the inner first layer F1 blocks noise that is carried on the outer sheath of the braided wire 14 of the first shield part S1 by the high-frequency impedance of the ferrite. In addition, the second layer F2 forms a magnetic shield, so that the influence of external noise (spatial conduction noise) can be prevented. Since the effect of ferrite depends on the volume, the high-frequency resistance of the cable is increased even if the thickness of the first layer F1 is not increased, and noise to the outer sheath of the braided wire 14 of the first shield part S1 can be suppressed.

[0030] The impact of noise from a noise source (emission side) on equipment such as electronic circuits (immunity side) and the noise suppression function of this technology are described with reference to Figure 8. There are several types of noise interference: conductor conduction, in which noise is conducted to the equipment side through a conductor; spatial conduction, in which noise is conducted to the equipment side through space; conductor-space conduction, in which noise changes from a conductor to space and is conducted to the equipment side; and space-conductor conduction, in which noise changes from space to a conductor and is conducted to the equipment side. If the equipment is an antenna, it is necessary to keep it a necessary distance away from the television receiver, which is the noise source (2.4m or more is desirable for 200MHz). If the equipment is not an antenna, it is necessary to shield the equipment.

[0031] In Fig. 8, the solid arrow indicates the electric field component of the noise, and the dashed arrow indicates the magnetic field component of the noise. The second shield part S2 reflects the electric field component of the noise, and the second layer F2 can suppress the magnetic field component of the noise. That is, the second shield part S2 and the second layer F2 can reduce the influence of noise due to spatial conduction in the near field. In addition, the first layer F1 can suppress noise (noise due to conductor conduction and noise due to conductor-spatial conduction) flowing through the first shield part S1 connected to the ground of the device.

[0032] Conventional measures against noise sources will be described with reference to Figures 9A and 9B. As shown in Figure 9A, even when a circuit board 22 is housed inside a shielding case 21, noise is generated due to conductor conduction through lines 23 that enter and exit the shielding case 21, and noise is also generated due to spatial conduction with the lines 23 acting as an antenna. Thus, even if an attempt is made to eliminate noise due to spatial conduction by the shielding case 21, noise is generated by the lines 23 that enter and exit the shielding case 21.

[0033] As a countermeasure to this, as shown in Fig. 9B, a shielded cable 24 (shown by a dotted line) is provided to cover the line 23, and the shielded cable 24 is connected to the circuit ground of the circuit board 22 and also to the housing shield ground of the shield case 21. If the circuit ground is sufficiently stable, it is sufficient to connect only to the circuit ground. If connecting only to the housing shield ground, it is necessary to provide a separate wiring as a signal wiring that connects the housing and the circuit ground. However, even with such a countermeasure, the noise suppression effect is insufficient.

[0034] The noise suppression performance of the present technology was evaluated using a system configured as shown in Fig. 10. A test signal (e.g., DVB-T2 mode) is generated by a signal generator 31, the signal level is varied by an attenuator 32, and the signal is transmitted by a transmitting antenna 33. A receiving antenna 34 configured as a balanced antenna is provided at a position separated by a predetermined distance from the transmitting antenna 33, and a signal received by the receiving antenna 34 is supplied to a television receiver 36 through a coaxial cable 35 having a length of, for example, 1.3 m and an F connector (or an IEC (International Electrotechnical Commission) connector). The length of the coaxial cable 35 is preferably 1 m or more in order to ensure the amount of magnetic powder contained in each of the first layer F1 and the second layer F2 required for noise suppression.

[0035] The receivable transmission signal level is measured when the transmission signal level is gradually lowered by the attenuator 32. For example, an audio signal is used as the measurement signal. A microphone 37 is used to detect the output audio of a television receiver 36, and the output signal of the microphone 37 is amplified by an amplifier 38 and monitored by an audio monitor (for example, a speaker) 39 outside a darkroom (shown enclosed by a dotted line) 40. It is not limited to audio, and an image monitor may be used instead of the microphone 37 to monitor an image.

[0036] An example of the receiving antenna 34 is shown in Fig. 11. Two lines 52 and 53 are provided in parallel as a balanced transmission line on an insulating substrate 51. One end of the line 52 is connected to the central conductor (core wire) of the coaxial cable 35, and one end of the line 53 is connected to the outer conductor (braided wire) of the coaxial cable 35. The coaxial cable 35 is connected to a tuner of a television receiver 36 via an F-type connector 41, for example.

[0037] Antenna elements 60 and 70 are provided on both sides of the balanced transmission line, respectively. The antenna elements 60 and 70 have a similar configuration. The antenna element 60 is connected to the other end of the line 52, and the antenna element 70 is connected to the other end of the line 53. The antenna element 60 is connected between the ends of the linear elements 61 and 62, between the ends of the linear elements 61 and 63, and between the ends of the linear elements 62 and 63. When connected together, they form a triangular antenna element.

[0038] Similarly, antenna element 70 is configured as a triangular antenna element by connecting ends of linear elements 71 and 72, ends of linear elements 71 and 73, and ends of linear elements 72 and 73. The apex formed by the ends of linear elements 72 and 73 is connected to the other end of line 53 of the balanced transmission line.

[0039] Furthermore, a linear element 74 is provided which is connected to the linear element 71 of the triangular antenna element and extends (or turns back) toward one end of the line 53 of the balanced transmission line. The extended end of the linear element 74 is fixed onto the insulating substrate 51. However, it is not connected to the line 53. Impedance matching is achieved by the balanced transmission line and the linear element 74.

[0040] The lengths (L1, L2, L3, and L4) of the linear elements 61, 62, 63, and 64 are set equal to the lengths of the linear elements 71, 72, 73, and 74. As described above, these lengths are set according to the reception frequency.

[0041] The linear elements 61-64 and 71-74 are made of metal wires made of a material such as copper, silver, iron, or aluminum that is conductive and can flexibly change the shape of the antenna elements 60 and 70. In order to ensure strength when repeatedly bent to change the shape, two or more metal wires may be bundled together. Furthermore, the insulating substrates 51, 65, and 75 are printed circuit boards made of glass epoxy or ceramic, or plastics such as FPC (Flexible Printed Circuit), glass, or molded resin. Furthermore, the insulating substrates 51, 65, and 75 may be entirely covered with a case made of resin or the like.

[0042] The antenna element 70 and the antenna element 60 form a dipole antenna. The feeding point 100 for the antenna device is the other end of the balanced transmission line (lines 52 and 53), and by appropriately setting the length of the balanced transmission line, it is possible to connect the unbalanced transmission line (coaxial cable 35) to the balanced load (antenna device) without using a balun. By passing through the balanced transmission line, it is possible to adjust the phase and achieve a wide bandwidth.

[0043] According to the above-mentioned antenna device, the length of each of the linear elements of the antenna elements 60 and 70 can be set to a value corresponding to the reception frequency, thereby realizing a wide band. Specifically, in order to receive the high band (200 MHz band) of the VHF band, the length of (L3+L1+L4) or (L2+L4) is set to about (1 / 4) the wavelength (λ1) of the frequency band, for example, about 38 cm. Also, in order to receive the band (470 Hz to 800 MHz) of terrestrial digital television in the UHF band, the length of L3 or L2 is set to about (1 / 4) the wavelength (λ2) of the frequency band, for example, about 16 cm. These lengths L1 to L4 are values ​​including the wavelength shortening rate.

[0044] The results of receiver sensitivity evaluation performed by the system shown in Fig. 10 are shown in Fig. 12 and Fig. 13. Fig. 12 is a graph showing receiver sensitivity evaluation in the VHF high band (179 MHz to 228 MHz), and Fig. 13 is a graph showing receiver sensitivity evaluation in the UHF band (450 MHz to 850 MHz). In these graphs, the horizontal axis is frequency and the vertical axis is sensitivity, with smaller values ​​on the vertical axis indicating better sensitivity.

[0045] The graphs in Figures 12 and 13 show the sensitivity when the type of coaxial cable 35 is changed. That is, the sensitivity is shown for a normal coaxial cable, a coaxial cable with a configuration of S+F, a coaxial cable with a configuration of S+F+S, and a coaxial cable with a configuration of S1+F1+S2+F2 (the configuration of the present technology). Note that S, S1, and S2 represent the shielding portion, and F, F1, and F2 represent the resin layer in which magnetic powder such as ferrite is mixed, and are listed in the order from the center of the cable to the outside.

[0046] From the graph in Figure 12, we can see that the coaxial cable to which this technology is applied has the best sensitivity characteristics. The coaxial cable with the second best sensitivity characteristics is S+F, the coaxial cable with the third best sensitivity characteristics is S+F+S, and the normal coaxial cable has the worst sensitivity characteristics. Since the influence of magnetic fields is large in the high VHF band, a configuration with a high magnetic field shielding effect shows better results.

[0047] From the graph in Figure 13, we can see that the coaxial cable to which this technology is applied has the best sensitivity characteristics. The coaxial cable with the second best sensitivity characteristics is S+F+S, the coaxial cable with the third best sensitivity characteristics is S+F, and the normal coaxial cable has the worst sensitivity characteristics. Since the influence of the electric field is large in the UHF frequency band, a configuration with a higher electric field shielding effect shows better results.

[0048] In the above description, the embodiment in which the present technology is applied to a coaxial cable has been described. The present technology can also be applied to cables other than a coaxial cable. A cable to which the present technology can be applied will be described.

[0049] 14 is a cross-sectional view of a USB 2.0 cable. The USB cable has five wires: a pair of signal cables 81a (D-) and 81b (D+) for differential transmission, power cables 82a and 82b, and a drain wire 83 as a ground wire. Each of these cables 81a, 81b, 82a, and 82b has an insulating coating covering the periphery of its core wire.

[0050] Copper is used as the core wire, and either a single wire consisting of a single conductor or a stranded wire consisting of thin conductors twisted together to form a single conductor may be used. The signal cables 81a and 81b are twisted pair cables. The signal cables 81a, 81b and the power cables 82a, 82b are covered with an aluminum foil shield 84 and a copper wire mesh shield 85. The drain wire 83 and the aluminum foil shield 84 are electrically connected.

[0051] When the present technology is applied to such a USB 2.0 cable, the aluminum foil shield 84 and the copper wire mesh shield 85 are the first shield section S1. Then, a first layer F1, a second shield section S2, and a second layer F2 are provided on the outer periphery in that order. A coating 86 is provided on the outermost periphery. A USB 2.0 cable to which the present technology is applied can suppress noise.

[0052] FIG. 15 is a cross-sectional view of a USB 3.0 cable. As with the USB 2.0 cable, the cable has four wires, namely, signal cables 91a and 91b for a pair of differential transmission and power cables 92a and 92b. The signal cables 91a and 91b are called UTP (Unshielded Twisted Pair). The cable further has USB 3.0 signal cables 93a and 93b and a drain wire 93c, and other USB 3.0 signal lines 94a and 94b and a drain wire 94c. The signal cables 93a and 93b are called SDP (Shielded Differential Pair). A filler 95 is used as an option. These wires and the filler are covered with a copper wire mesh shield 96.

[0053] When the present technology is applied to such a USB 3.0 cable, the copper wire mesh shield 96 is the first shield section S1. Then, a first layer F1, a second shield section S2, and a second layer F2 are provided on the outer periphery in that order. A coating 97 is provided on the outermost periphery. A USB 3.0 cable to which the present technology is applied can suppress noise.

[0054] 16 is a cross-sectional view of an Ethernet cable (LAN cable). Four pairs of signal lines 101a, 101b, 101c, and 101d in the twisted pair cable configuration are covered with a shield. The shield is made by layering an aluminum / PET shield part 102 and a braided wire 103 from the inside.

[0055] When the present technology is applied to such an Ethernet cable (LAN cable), the aluminum / PET shielding part 102 and the braided wire 103 form a first shielding part S1. A first layer F1, a second shielding part S2, and a second layer F2 are provided on the outer periphery in that order. A coating 104 is provided on the outermost periphery. An Ethernet cable (LAN cable) to which the present technology is applied can suppress noise.

[0056] FIG. 17 is a cross-sectional view of a modified example in which the present technology is applied to a cable having two wires 110a and 110b. The wires 110a and 110b are a power cable consisting of two wires, a signal transmission line or a hot line and a ground line. The cable has a shielding configuration similar to that of the embodiment shown in FIG. 7. That is, an insulator 12 made of, for example, polyurethane foam, polyethylene, or polyethylene foam is located outside the wires 110a and 110b. A first shield section S1 having an electric field shielding function is provided around the insulator 12 so as to cover the insulator 12. For example, the first shield section S1 is formed by an aluminum sheet 13 arranged on the outer surface of the insulator 12 and a braided wire 14 arranged on the outer surface of the aluminum sheet 13. The first shield portion S1 is not limited to the above configuration, but may have a configuration consisting of a braided wire made by weaving soft copper wire, a braided wire and a foil-like metal sheet (a metal sheet such as aluminum, copper, iron, etc.) arranged on the inside or outside of the braided wire, a winding made by winding soft copper wire, and a winding and a foil-like metal sheet (a metal sheet such as aluminum, copper, iron, etc.) arranged on the inside or outside of the winding.

[0057] A first layer F1 made of a resin that absorbs radio waves, for example, a resin mixed with magnetic powder, is disposed on the outer periphery of the braided wire 14 of the first shield section S1. The first layer F1 has a function of a magnetic shield. That is, the first layer F1 has a function of countering conductive noise. The resin mixed with magnetic powder is a synthetic resin mixed with magnetic powder. An example of the synthetic resin is a styrene-based elastomer. Other synthetic resins such as olefin-based elastomer and PVC may also be used. An example of the magnetic powder is Ni-Zn-based ferrite. The ratio of the iron powder and ferrite powder to the resin is 70% or more and 98% or less by weight. As the magnetic powder, magnetic powders such as Ni-Cu-Zn-based ferrite, Mn-Zn-based ferrite, soft magnetic metal-based, copper-based, magnesium-based, lithium-based, zinc-based, iron-based (for example, permalloy), and cobalt-based magnetic powders may also be used.

[0058] The second shield part S2 having an electric field shielding function is disposed so as to cover the outer periphery of the first layer F1. The second shield part S2 is, for example, an aluminum sheet. Other than an aluminum sheet, it may be only a braided wire or only a winding wire. It may also be a combination of a braided wire or a winding wire and a metal sheet such as aluminum. The second shield part S2 does not need to be grounded.

[0059] A second layer F2 made of a resin that absorbs radio waves, such as a resin mixed with magnetic powder, is disposed on the outer periphery of the second shield section S2. The second layer F2, which has a magnetic shielding function, is provided to counter spatial noise. The outer periphery of the second layer F2 is covered with a covering material 15. The covering material 15 can be made of an insulating material such as polyethylene, polypropylene, PVC (polyvinyl chloride), elastomer, etc.

[0060] A modified example of the present technology will be described below. As shown in FIG. 18, a member provided on the braided wire 14 of the first shield section S1 is configured as a sheet-like or tape-like shield member SP. For example, a double-sided adhesive tape 16 is provided on the innermost periphery, and a magnetic sheet F11 constituting the first layer F1 is laminated on the double-sided adhesive tape 16. A conductive layer S12 forming the second shield layer S2 is laminated on the magnetic sheet F11. A magnetic sheet F12 constituting the second layer F2 is laminated on the conductive layer S12. The double-sided adhesive tape 16 may not be provided.

[0061] The conductive layer S12 is made of a metal foil such as aluminum or copper, and a magnetic material such as iron powder, ferrite powder, or carbon powder is deposited or applied to both sides of the metal foil. As an example, the thickness of each of the magnetic sheets F11 and F12 is 0.05 mm, and the thickness of the conductive layer S12 is 0.03 mm.

[0062] As shown in Fig. 19, the above-mentioned shielding member SP is tightly wrapped around the outer surface of the braided wire 14 constituting the first shielding portion S1 (see, for example, Fig. 7A). In Fig. 19, gaps are provided at the ends of the shielding member SP for ease of understanding, but as shown in Fig. 20, the shielding member SP is wrapped around the braided wire 14 so that the ends overlap. The outer peripheral surface of the magnetic sheet F12 is covered with a covering material (not shown). The covering material is, for example, an insulating material such as polyethylene, polypropylene, PVC (polyvinyl chloride), elastomer, etc.

[0063] As shown in Fig. 21, a sheet-shaped shielding member SP' may be tightly wound around the braided wire 14. As shown in Figs. 21 and 22, the ends of the sheet-shaped shielding member SP' in the cable extension direction are arranged to overlap each other. As with the shielding member SP, the shielding member SP' is formed by depositing or applying a magnetic material on both sides of the conductive layer S12 to form magnetic sheets F11 and F12. The outer peripheral surface of the magnetic sheet F12 is covered with a covering material (not shown). The covering material is, for example, an insulating material such as polyethylene, polypropylene, PVC (polyvinyl chloride), elastomer, etc.

[0064] The magnetic sheet F11 of the shield member SP or the shield member SP' has a function of countering conductive noise like the first layer F1 made of the above-mentioned magnetic powder mixed resin, and the magnetic sheet F12 is provided for countering spatial noise like the second layer F2. The conductive layer S12 has the function of the second shield part S2 (electric field shielding function).

[0065] Compared with the first layer F1 and the second layer F2 in which magnetic powder is mixed into synthetic resin, the magnetic sheets F11 and F12 in which a magnetic material is vapor-deposited or applied can improve the magnetic permeability and can reduce the thickness of the layers. As a result, the cable can be made thinner and lighter. A small and lightweight cable is suitable for use in a vehicle, for example.

[0066] Although the embodiments of the present technology have been specifically described above, they are not limited to the above-mentioned embodiments, and various modifications based on the technical ideas of the present technology are possible. For example, the configurations, methods, steps, shapes, materials, and values ​​given in the above-mentioned embodiments are merely examples, and different configurations, methods, steps, shapes, materials, and values ​​may be used as necessary. For example, the present technology is not limited to the above-mentioned cables, and can also be applied to HDMI (registered trademark) cables, IEEE (Institute of Electrical and Electronics Engineers) 1394 cables, and the like.

[0067] 11...line, 12...insulator, 13...aluminum sheet, 14...braided wire, S1...first shielding portion, F1...first layer, S2...second shielding portion, F2: Second layer, SP, SP': Shielding material

Claims

1. Two parallel wires provided in an insulator; a balanced antenna comprising a first antenna element and a second antenna element attached to the insulator and connected to one end of each of the two wires; a coaxial cable in which the other ends of the two wires are connected to a central conductor and an outer conductor; a connector connected to the coaxial cable, The coaxial cable includes: a first shield portion made of metal and provided on an outer side of the central conductor via an insulator; a first layer made of a resin that absorbs radio waves and provided so as to cover an outer periphery of the first shield portion; a second shield portion made of metal provided on the outside of the first layer; a second layer made of a resin that absorbs radio waves and provided so as to cover an outer periphery of the second shield portion; and an insulating resin covering the outside of the second layer.

2. 2. A television antenna device with a coaxial cable as described in claim 1, wherein the first shield portion is a braided wire made by weaving soft copper wire, or a winding made by winding soft copper wire, or a metal sheet is formed on the upper or lower part of the braided wire or winding.

3. 2. A television antenna device with a coaxial cable according to claim 1, wherein the first layer and the second layer are made of a magnetic material which is evaporated or applied onto both sides of the second shield portion.

4. 2. A television antenna device with a coaxial cable as described in claim 1, wherein a tape or sheet on which the first layer of magnetic material and the second layer of magnetic material are vapor-deposited or coated on both sides of the second shield portion is wrapped around the outside of the first shield portion.

5. 2. A television antenna device with a coaxial cable according to claim 1, wherein the resin is made of a mixture of iron powder, ferrite powder, or carbon powder and a synthetic resin.

6. 6. A television antenna device with a coaxial cable according to claim 5, wherein the resin of said first layer and said second layer contains iron powder and ferrite powder in a ratio of 70% to 98% by weight based on the resin.

7. 2. A television antenna device with a coaxial cable according to claim 1, wherein said first layer has a high high frequency resistance and has a function of converting noise into heat.

8. 2. A television antenna device with a coaxial cable according to claim 1, wherein the second layer has a function of a magnetic shield to prevent the device from being affected by a magnetic field.

9. 2. A television antenna device with a coaxial cable according to claim 1, wherein the length of said coaxial cable is 1 m or more.

10. 2. A television antenna device with a coaxial cable according to claim 1, wherein the connector of said coaxial cable is an IEC connector or an F connector.

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