JP2009302963A - Magnetic wave communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic wave communication device making use of a technical aspect in which a magnetic wave signal propagated by variation of magnetic field emitted from a magnetic field antenna has a lower loss compared to an electromagnetic wave signal propagated by variation of an electric field emitted from an electric field antenna and has long-distance propagation characteristics in a material having a relatively lower propagation loss in the variation of the magnetic field than the propagation loss in the variation of the electric field with a relative dielectric constant being 10 or more and a relative permeability being 10 or less. <P>SOLUTION: A magnetic wave signal having a relatively large bandwidth in a frequency range of 100 kHz or more is emitted from a magnetic wave communication device 21 into seawater by means of a magnetic field antenna 213 and the magnetic wave signal is received by a magnetic field antenna 223 connected to a magnetic wave communication device 22. The magnetic wave signal is propagated in the seawater with low loss over a long distance and accordingly, the magnetic wave signal can be communicated efficiently with low loss between the magnetic field antennas 213 and 223. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention radiates from a magnetic field antenna and a magnetic current antenna in a material having a relative permittivity of 10 or more, a relative permeability of 10 or less, and a propagation loss of magnetic field fluctuation is relatively smaller than a propagation loss of electric field fluctuation. Magnetic field signals that propagate due to magnetic field fluctuations and magnetic current fluctuations are low loss compared to electromagnetic wave signals that propagate due to electric field fluctuations radiated from an electric field antenna, and have a long-distance propagation characteristic. The present invention relates to a wave communication device.

Conventionally, a system for communicating underwater or a technique using a loop antenna has been proposed. (For example, Patent Documents 1, 2, and 3 and Non-Patent Documents 1, 2, and 3)
JP2007-221756 JP 2001-326526 A JP-A-2005-217120 "Basic Engineering Electromagnetism" by WH Hate, translated by Yamanaka et al., Asakura Shoten, pages 275-280 "Antenna and radio wave propagation" by Keiji Taniguchi, Kyoritsu Shuppan 188-189

FIG. 8 shows an example of a conventional “signal transmission device” described in Patent Document 1.
In FIG. 8, 21 is a transmission means, 211 is a control unit, 212 is a 27 MHz band transmitter, 213 is a small loop antenna, 22 is a reception means, 221 is a control unit, 222 is a 27 MHz band, for example. A receiver 223 is a small loop antenna, 224 is an interface unit, 225 is a connection terminal, and 111 is a water surface or a liquid surface.
An electromagnetic wave signal modulated by a signal including an identification code or the like is transmitted from the transmitter 212 in the 27 MHz band controlled by the control unit 211, and the electromagnetic wave signal is transmitted by a small loop antenna 213 provided below the liquid surface 111. Is efficiently radiated.

Here, the inner diameter dimension and the number of turns of the loop antenna 213 are selected to be in a resonance state or a matching state in the liquid so as to efficiently radiate the electromagnetic wave signal.
In this case, since the dielectric constant of the liquid generally shows a higher value than the dielectric constant of air, the loop antenna 213 has good radiation efficiency in the liquid, whereas the radiation efficiency is extremely low in the air. It becomes.
When the loop antennas 213 and 223 are immersed in a liquid having a high relative dielectric constant (ε = 81) such as fresh water or seawater, a resonance phenomenon or a matching phenomenon occurs as shown in FIG. Alternatively, the resonance phenomenon or the matching phenomenon appears most significantly at the matching frequency 314, and the coupling loss between the small loop antennas 213 and 223 decreases.

Therefore, by using the frequency band in which the resonance phenomenon or the matching phenomenon occurs, a low-loss signal transmission apparatus can be realized in the fresh water.
On the other hand, the permittivity of seawater is higher than that of fresh water, and the loop antennas 213 and 223 can be further downsized compared to fresh water. In the case of the same shape, the resonance frequency or matching frequency is lower. Therefore, it is said that there are merits such as low transmission loss.
Since the conventional “signal transmission device” is configured as described above, the mechanism of the resonance state or matching state in fresh water or seawater is unclear, and the resonance frequency of the loop antenna changes in the air and seawater. There is a problem that measures against this are not shown.

  In addition to the above, according to the “shielded antenna coil” described in Patent Document 2, “resonance that is connected to the power feeding pattern coil 19 connected to the transmission circuit and the outside of the power feeding pattern coil by mutual induction” In order to reduce the electric field component radiated from the resonance pattern coil, the matching circuit composed of the pattern coil 20, the capacitor 21 for adjusting the resonance frequency connected to the resonance pattern coil and the resistor 22 for adjusting the impedance and the Q value. Electric field shield patterns 23a and 23b, and by arranging the electric field shield pattern so as to sandwich the resonance pattern coil, it is possible to secure a magnetic field component necessary for communication with the communication means and to prevent communication of other wireless devices. It is said that it is possible to obtain a shield antenna coil that can reduce the electric field component .

Further, according to “Electromagnetic wave shield and loop antenna device using the same” described in Patent Document 3, “Electromagnetic wave shield of the present invention includes a conductor and a ground contact for connecting the conductor to the ground. The electromagnetic wave shield is configured such that the conductor is electrically connected to the ground via a ground contact, and is arranged so that a path from any point of the conductor to the ground contact is uniquely determined. The conductor is wound around.
Further, the loop antenna device of the present invention is configured to include the electromagnetic wave shield on at least one surface, and a far electric field can be generated while suppressing the attenuation of the near magnetic field of the electromagnetic wave emitted from the electromagnetic field generator. An object of the present invention is to provide an electromagnetic wave shield that can be attenuated and a loop antenna device using the same. It is said that.

  However, the “shield antenna coil” or “electromagnetic wave shield and loop antenna device using the electromagnetic shield” described in Patent Documents 2 and 3 are both “feed pattern coil” or “loop antenna device” used for the RFID tag. "Electric field shield pattern" or "electromagnetic wave shield" is provided outside of the cable, "while securing the magnetic field component necessary for communication with the communication means" or "while suppressing the attenuation of the nearby magnetic field" "communication of other wireless devices It is said that the electric field component that becomes a disturbance can be reduced "or" the far electric field can be attenuated ", and the present invention suppresses fluctuations in the resonance frequency of the loop coil by providing an electric field shield, Communication using a magnetic field component propagating far away is different in purpose and effect. I think and shall.

On the other hand, according to “9.3 Plane wave in lossy dielectric” described on pages 275 to 280 of Non-Patent Document 1, “the amplitude of Ex or Hy” is shown in the fourth line from the top of page 277. Is attenuated by a factor of 0.368 for every 1 m / 520 (about 2 mm) in the water, and the term “propagating” is used so vaguely. That ’s why sonar is used instead of being used. ”
In addition, according to “Attenuation characteristics of radio waves propagating in water” shown on page 189 of Non-Patent Document 2 and FIG. 5.3, 1 MHz radio waves are attenuated at a rate of about 100 dB / m in seawater. ing.

However, when a propagation experiment was performed in seawater using the magnetic field antenna or the magnetic current antenna of the present invention, it was confirmed that the propagation loss as rapid as described in Non-Patent Document 1 or Non-Patent Document 2 did not occur. Confirmed by experiment.

The present invention relates to a magnetic field antenna or a magnetic current antenna installed in a material having a relative permittivity of 10 or more, a relative permeability of 10 or less, and a propagation loss of magnetic field fluctuations being relatively smaller than a propagation loss of electric field fluctuations. This is to realize a magnetic wave communication device using propagation of magnetic field fluctuation or magnetic current fluctuation (hereinafter referred to as magnetic field fluctuation) radiated from (hereinafter referred to as magnetic field antenna).

  The magnetic wave communication device according to the present invention is installed in a material having a relative permittivity of 10 or more, a relative permeability of 10 or less, and a propagation loss of magnetic field fluctuation is relatively smaller than a propagation loss of electric field fluctuation. The magnetic field antenna enables a relatively long-distance and wide-band magnetic wave communication by utilizing a characteristic that can efficiently transmit and receive magnetic field fluctuations.

  On the other hand, even when the magnetic field antenna is installed in the atmosphere, since the propagation characteristics hardly change, when using the magnetic field antenna, when either or both of the transmission antenna and the reception antenna are installed in the atmosphere, Even in the case where both or one of the transmission antenna and the reception antenna is installed in fresh water or seawater, a relatively long-distance and broadband magnetic wave communication is possible.

The magnetic field antenna used in the magnetic wave communication apparatus according to the present invention has a magnetic field absorber or structure for partially absorbing and attenuating magnetic field fluctuations, or for suppressing or attenuating the radiation or reception of magnetic field fluctuations. A magnetic field absorber or structure.
The magnetic field absorber has a relatively large magnetic resistance and a relatively large magnetic field loss, or a ring-shaped structure or a sandwich structure in order to partially cover the antenna means with the magnetic field absorber. Or that the magnetic field absorber is in the form of a powder with a relatively large magnetic field loss.

  Conventionally, sound waves or ultrasonic waves are exclusively used for communication in seawater, or an electromagnetic wave signal of an extremely low frequency band of, for example, 100 kHz or less is generally used, and an electromagnetic wave of a relatively high frequency band of 100 kHz or more is used. It has been theorized that the signal is difficult to use because, for example, the attenuation in seawater is as rapid as about 100 dB / m in the 27 MHz band.

In the magnetic wave communication apparatus of the present invention, a long-range communication is possible, for example, in fresh water or in seawater by using a magnetic wave signal having a wide bandwidth in a frequency band of 100 kHz or higher. A magnetic wave communication apparatus capable of low-loss propagation over a long distance instead of the sound wave communication can be realized at low cost.

According to the magnetic wave communication apparatus according to the present invention, it is connected to the magnetic wave communication apparatus 21 as shown in the first embodiment of the present invention in FIG. 1 and claims 1, 2, and 3. When the magnetic wave signal is efficiently radiated from the magnetic field antenna 213 in fresh water or seawater and the magnetic field signal is received by the magnetic field antenna 213 connected to the magnetic wave communication device 22, the magnetic field antenna 213 emits the magnetic wave signal. The magnetic wave signal thus transmitted is propagated to the magnetic field antenna 223 over a long distance with low loss.

According to the structure and operation principle of the magnetic field antenna shown in FIG. 2 and claims 4 to 10, the magnetic field antenna of the present invention is (1) partially absorbed and attenuated by magnetic field fluctuations. Or a magnetic field absorber or structure for partially absorbing, suppressing, or attenuating the susceptibility to magnetic field fluctuations, and (2) the magnetic field. The absorber has a relatively small magnetic resistance and a relatively large magnetic field loss; and (3) a ring cylindrical structure or a sandwich structure so that the magnetic field absorber partially covers the antenna means. (4) It is necessary that the magnetic field absorber has a relatively large magnetic field loss and is powdery particles.

In the second embodiment of the present invention shown in FIG. 3 and claims 1 and 2, the magnetic wave communication devices 21 and 22 and the magnetic field antennas 213 and 223 are all in fresh water or seawater. It shall be installed or moving.
When the magnetic wave signal is transmitted and received by the magnetic field antennas 213 and 223 connected to the magnetic wave communication devices 21 and 22, the magnetic wave signal radiated from the magnetic field antenna 213 is low loss due to direct wave propagation and the magnetic field antenna 223. Is propagated to.

In the third embodiment of the present invention shown in FIG. 4 and claims 1, 2, and 17, detection is performed from the magnetic field antenna 233 b connected to the transmitter 231 b of the magnetic wave detection device 23. The magnetic wave signal 113b is transmitted toward fresh water or seawater, and the magnetic wave signal 113a reflected from the seabed or the like is received by the magnetic field antenna 233a of the magnetic wave detector 23, thereby measuring the distance to the seabed. Or obstacles in seawater can be detected.

In the fifth embodiment of the present invention shown in FIG. 5 and claims 4 to 14, in order to absorb the magnetic field fluctuation and attenuate the central portion of the antenna element 400 so as to show the internal structure of the magnetic field antenna 213. The magnetic field absorber 401 has a sandwich structure, the outer periphery of the magnetic field antenna 213 is covered with an electric field shield 402, and further covered with a pressure-resistant filler 403 and a corrosion-resistant outer shell 404, so that the magnetic field shown in FIG. Satisfy the requirements for antennas.

  In the sixth embodiment of the present invention shown in FIG. 6 and claims 15 to 16, a plurality of radiating elements 400a are shown so as to show the internal structure of the magnetic field antenna 213 in which a plurality of radiating elements are arranged in an array. ˜400 n has a structure embedded in a magnetic field absorber 401 for absorbing and attenuating magnetic field fluctuations, and the magnetic field antenna 213 is covered with an electric field shield 402 and further has a pressure resistance. 2 is satisfied, and the condition required for the magnetic field antenna shown in FIG. 2 is satisfied.

From the magnetic field antenna 213, most of the plurality of radiating elements 400a to 400n are exposed in the surface direction of the magnetic field absorber 401. Therefore, the magnetic field fluctuation is radiated in the surface direction of the magnetic field absorber 401 with low loss. In the back side direction, the magnetic field fluctuation is attenuated and radiated.
In addition, a so-called active phased array antenna can be configured by controlling the phase and amplitude when power is supplied to the plurality of radiating elements 401a to 401n, and a directional beam antenna suitable for a magnetic wave radar device is realized. be able to.

In the sixth embodiment of the present invention shown in FIG. 7 and claims 4 to 14, in the magnetic field antenna 213, a magnetic field absorber 401 for absorbing and attenuating magnetic field fluctuations on the outer periphery of the coaxial cable 406 is used. By providing the ring so as to surround it, the magnetic field variation is efficiently radiated only from the radiating elements 400a and 400b, thereby satisfying the conditions required for the magnetic field antenna shown in FIG.

(Embodiment 1)
FIG. 1 is a system configuration diagram showing a first embodiment of the present invention. In FIG. 1, reference numerals 21 and 22 denote magnetic wave communication devices, 211 and 221 denote control units, 212 and 222 denote transceivers, and 213 and 223. Is a magnetic field antenna and 111 is the sea surface.
Magnetic field fluctuations are radiated from the magnetic field antenna 213 connected to the transceiver 212 controlled by the control unit 211, propagated over a long distance with low loss, and received by the magnetic field antenna 223.

In propagation experiments in seawater conducted by the inventors, the propagation loss due to electric field fluctuations radiated from an electric field antenna such as a dipole antenna is rapidly attenuated to about 100 dB / m in the 27 MHz band, whereas the magnetic field antenna It has been confirmed that the propagation loss based on the fluctuation of the magnetic field radiated from the antenna is much lower even in the 27 MHz band, and that long-distance propagation is possible.
Therefore, for the electromagnetic wave signal propagated based on the electric field fluctuation radiated from the electric field antenna, the signal propagated by the magnetic field fluctuation radiated from the magnetic field antenna is newly called a magnetic wave signal, and the propagation by the former is electromagnetic wave propagation. The latter propagation is referred to as magnetic wave propagation.

Here, it is necessary to clarify the mechanism of magnetic wave propagation using FIG.
In FIG. 2, 600 is a transmission antenna using a loop coil, 601a and 601b are directions of a conduction current flowing through the transmission antenna 600, 602 is a magnetic field absorber for absorbing and attenuating magnetic field fluctuations, and 603a and 603b are transmission antennas. The connection terminal, 611 is the center line of the transmission antenna 600, 611 is the reception antenna, 612 is the distance (D) between the loops of the transmission antenna, and 613 is the distance (R) between the loop outside the transmission antenna 600 and the reception antenna 611.

Assuming that the conductive current I flows through the transmitting antenna 600, the magnetic field fluctuation at the position of the receiving antenna 611 is expressed by the fluctuation in magnetic flux density (dBR / dt).
(DBR / dt) = μ [{1 / (2πR)} − γ {1 / (2πR + D)}] (dI / dt) − − − (1)
Is represented by
Here, μ is the permeability of seawater, and γ is the rate of absorption or attenuation by the magnetic field absorber 602.

From equation (1)
(DBR / dt) = μ {2πR (1−γ) + D} / {2πR (2πR + D)} (dI / dt)
≈μ {(1-γ) / (2πR)} (dI / dt) − − − (2)
It becomes. However, (1-γ) >> (D / 2πR).
For example, if γ = 1 / 3≈−10 dB, this degree can be easily realized.
(DBR / dt) = μ {0.67 / 2πR} (dI / dt) − − − (3)
It becomes.

The above equation (3) indicates that the fluctuation of the magnetic flux density at the point of the receiving antenna 611, and hence the magnetic field fluctuation is inversely proportional to the distance R, and that the propagation of the magnetic field fluctuation is due to a plane wave.
On the other hand, if the receiving antenna 611 is a loop antenna, the electromotive force ER induced at both ends of the receiving antenna 611 is caused by the fluctuation of magnetic flux at the point of the receiving antenna 611.
ER = − (dΦ / dt) = − ∫ (dBR / dt)
= −μ∫ {0.67 / 2πR} (dI / dt) − − − (4)
Thus, the electromotive force ER also decreases in inverse proportion to the distance R.

Since the above propagation equation does not include the term of permittivity ε, the relative permittivity is as high as about 81, and the relative permeability is not shortened even in fresh water or seawater close to 1, so that a long distance is obtained as a plane wave. It can be seen that it propagates.
Also, since the relative permeability is close to 1 even in the atmosphere, it propagates a long distance as a plane wave without causing wavelength shortening, so that a magnetic wave signal can be transmitted from the atmosphere to the seawater without being attenuated. Can be expected.

  In the above description, an example using magnetic wave propagation in seawater has been described, but generally, the dielectric constant is 10 or more, the relative permeability is 10 or less, and the propagation loss of magnetic field fluctuation is electric field fluctuation. Similar effects can be obtained even if magnetic wave propagation is used in a material that is relatively smaller than the propagation loss.

  In addition, a plurality of magnetic field antennas are connected to one or both of the magnetic wave communication devices 21 and 22, and a magnetic wave signal is transmitted and received while periodically switching using a switch. By measuring the phase difference of the received magnetic wave signal, the direction in which the magnetic wave communication device 21 or 22 is located can be detected with high accuracy.

  Also, a magnetic wave signal including a plurality of carrier signals, subcarrier signals, modulation signals, or baseband signals that are synchronized or orthogonally different from each other is transmitted / received from one or both of the magnetic wave communication devices 21 and 22. The distance between the magnetic wave communication devices 21 and 22 can be detected with high accuracy by measuring the phase difference of the carrier signal, subcarrier signal, modulation signal, or baseband signal.

In addition, magnetic field antennas 213 and 223 connected to the magnetic wave communication devices 21 and 22 are installed in a plurality of moving bodies that move on the sea, and by detecting a relative positional relationship between the plurality of moving objects, An optimal ubiquitous mobile network can be configured instantaneously according to the movement of the plurality of mobile objects.
In addition, by installing the magnetic field antennas 213 and 223 connected to the magnetic wave communication devices 21 and 22 on the hull or the like below the waterline such as a ship, the position of the surrounding ship, or the distance and direction can be detected at all times. It can also be applied to an automatic monitoring device for avoiding collisions between ships.
In addition, the magnetic field antennas 213 and 223 are installed in fresh water or seawater, and the magnetic wave communication devices 21 and 22 are installed in the atmosphere, utilizing surface wave propagation existing on the contact surface between the fresh water or seawater and the atmosphere. However, it has been confirmed through experiments that long-distance communication can be performed.

(Embodiment 2)
FIG. 3 is a system configuration diagram showing the second embodiment of the present invention. In FIG. 3, 21 and 22 are magnetic wave communication apparatuses, 211 and 221 are control units, 212 and 222 are transceivers, 213 and 223 are magnetic field antennas, and 111 is a sea surface.
The magnetic wave communication devices 21 and 22 and the magnetic field antennas 213 and 223 are integrated and operated in fresh water or seawater, and the magnetic wave communication devices 21 and 22 and the magnetic field antennas 213 and 223 are each waterproof in a pressure-resistant structure. By storing in a housing, it is possible to operate even in deep water or deep water.

The magnetic wave communication devices 21 and 22 can function as passive tags or active tags that can be operated in fresh water or seawater.
In addition, by attaching the active tag to a swimming human body, an arbitrary moving body in seawater, or a fixed object in seawater, even if a weak magnetic wave signal is transmitted, the active tag can be placed at a position of about 1 km. Location management is possible by identifying existing active tags and measuring distance and direction.

(Embodiment 3)
FIG. 4 is a system configuration diagram showing the third embodiment of the present invention. In FIG. 4, 25 is a magnetic wave detection device or magnetic wave radar device, 251a is a receiver, 251b is a transmitter, 252 is a control unit, 253a and 253b are array type magnetic field antennas, 254 is an interface unit, and 255 is a connection terminal. 111 is, for example, the sea surface.
The array type magnetic field antenna 253b is connected to the transmitter 251b, and the array type magnetic field antenna 253b is connected to the receiver 251a.

A magnetic wave signal is transmitted in burst form from the array type magnetic field antenna 253a, reflected on the seabed or the like via the propagation path 113a, and received by the array type magnetic field antenna 253b via the propagation path 113b.
A propagation time required until a magnetic wave signal is transmitted from the array type magnetic field antenna 253a and received by the array type magnetic field antenna 253a is measured, or a carrier wave signal, subcarrier signal, modulation signal, or base of the magnetic wave signal is measured. By measuring the phase of the band signal, the distance to the seabed, the distance to the obstacle in the seawater, or the three-dimensional position of the obstacle in the seawater can be measured.

In addition, a magnetic wave signal that is synchronized or orthogonal and has at least different frequencies or a chirp-modulated magnetic wave signal is transmitted from the array-type magnetic field antenna 253b and received by the array-type magnetic field antenna 253a. Or the distance to the obstacle in seawater can be measured.
When using a magnetic wave signal in seawater, the propagation loss and wavelength shortening rate are almost the same as when using an electromagnetic wave signal in the atmosphere, so that resolution and detection accuracy equivalent to those in the atmosphere can be obtained. Be expected.
Further, since the propagation speed of the magnetic wave signal is much faster than that of the ultrasonic wave, the detection time and resolution when detecting an obstacle in water are drastically improved.

(Embodiment 4)
FIG. 5 is a sectional view showing an example of the structure of the magnetic field antenna according to the fourth embodiment of the present invention, which can efficiently transmit and receive magnetic wave signals.
In FIG. 5, 213 is a magnetic field antenna, 400 is a loop coil, 401 is a magnetic field absorber that absorbs and attenuates a magnetic wave signal, 402 is an electric field shield, 403 is a filler, 404 is a waterproof case, and 405a and 405b are input terminals. is there.

The magnetic field absorber 401 that absorbs and attenuates the magnetic wave signal is disposed so as to cover a part of the loop coil 400, and has an effect of absorbing and attenuating the magnetic wave signal transmitted and received from the part.
In other words, the magnetic field absorber 401 for absorbing and attenuating the magnetic wave signal is a magnetic field absorber for absorbing and attenuating a part of the magnetic field fluctuation, or radiating the magnetic field fluctuation to thereby change the magnetic field fluctuation. It is a magnetic field absorber for partially absorbing and attenuating the sensitivity to.

Further, the magnetic field absorber 401 that absorbs and attenuates the magnetic wave signal effectively attenuates the magnetic wave signal by covering the loop coil 400 in a ring shape or partially covering the loop coil 400 in a sandwich shape. Can do.
Further, since the resonance characteristics of the loop coil 400 are damped for the magnetic field absorber 401 that absorbs and attenuates the magnetic wave signal, an effect of widening the band can be obtained.
If a toroidal flight core is used instead of the magnetic field absorber 401, there is a problem that the impedance of the loop coil 400 becomes high and current does not flow through the loop coil.

It has been confirmed from experimental results that when the loop coil 400 is directly immersed in seawater and covered with a waterproof membrane, the resonance frequency varies greatly because the relative permittivity differs between air and seawater. .
Therefore, by providing the electric field shield 402 outside the loop coil 400, there are effects such as reducing the change of the resonance frequency or suppressing the influence of the change of the seawater concentration or the temperature.

  The electric field shield 402 has a characteristic of allowing the magnetic field fluctuation radiated from the loop coil 400 to pass through but attenuating the electric field fluctuation or the electric lines of force, or according to another expression, is made of a metal material. , A material, structure, configuration or shape that does not generate eddy currents due to magnetic field fluctuation, a thin film shape of 10 microns or less, a lattice shape, a linear shape, a net shape, a punching metal shape, It is formed by sputtering, formed by plating, fine metal particles or ferrite powder mixed in the insulating material, or a combination thereof.

In addition, since the substance is conductive when the substance is seawater, if the loop coil 400 is immersed in seawater with the metal as it is, the resonance phenomenon of the antenna disappears and the antenna does not function as a waterproof case 404. And filling the inside with the filler 403 eliminates the problems, withstands water pressure, and prevents erosion by seawater.
Further, the loop coil 400 can take various forms, and the same effect can be obtained by using various other types of antennas.

In addition, by changing the tuning conditions and adjusting the matching conditions in response to changes in tuning frequency or matching conditions that occur in the atmosphere and seawater, it is possible to respond to changes in the surrounding environment by providing a control means for adaptive control. It is also possible to keep the characteristics stable.
Further, by connecting the loading impedance to the loop coil 400, it is possible to reduce the size and improve the radiation efficiency of the magnetic field fluctuation.

Further, although the loop coil 400 is partially covered with the magnetic field absorber 401, the loss resistance of the loop coil 400 is increased, so that the Q is lowered and an essentially wideband magnetic field antenna is realized. it can.
Further, by connecting to the input terminal of the loop coil 400 via a broadband impedance converter, or by matching with a matching circuit having a plurality of adjacent tuning frequencies, a broadband and highly efficient magnetic field antenna can be configured. it can.
Further, the loop coil 400 is composed of a plurality of antenna elements, and the plurality of antenna elements are arranged loosely, and the single antenna element is composed of a plurality of portions having different thicknesses or widths or both, Alternatively, a broadband magnetic field antenna can be realized by dividing into a plurality of portions and arranging them so as to intersect each other at an angle.

(Embodiment 5)
FIG. 6 is a cross-sectional view showing another example of the magnetic field antenna showing the fifth embodiment of the present invention. A plurality of loop coils 400a to 400n arranged in an array form, one part of which is a magnetic wave signal. Is formed through the inside of the magnetic field absorber 401 that absorbs and attenuates and is connected to the printed circuit board 405.
The magnetic field absorber 401 is a part of the loop coils 400a to 400n and absorbs and attenuates the magnetic wave signal radiated from the portion formed through the inside of the magnetic field absorber 401, and the magnetic wave signal is on the back surface. This has the effect of preventing radiation.
An electric field shield 402 is disposed outside the plurality of loop coils 400 a to 400 n, and a filler or buffer material 403 is injected between the electric field shield 402 and the waterproof case 404.

Here, the plurality of loop coils 400a to 400n are connected to the outside by a delay control circuit and / or a distribution / combination circuit (not shown) to constitute a so-called active phased array antenna, and a directional beam. A directional beam antenna that can scan in the vertical direction, the horizontal direction, or the vertical and horizontal directions is configured.
Further, each of the plurality of loop coils 400a to 400n is configured by two sets of loop coils that intersect each other by 90 degrees at the center thereof, and high-frequency currents having a phase difference of 90 degrees are supplied to the two sets of loop coils. Therefore, it can function as a circularly polarized directional antenna. However, the intersecting angle is arbitrary, and the phase can be adjusted according to the angle.

The magnetic field absorber 401 that absorbs and attenuates the magnetic wave signal is, for example, a material in which metal particles having a large magnetic field loss are kneaded into a rubber material below the UHF band, and a foamed resin instead of the rubber material above the UHF band. By using the material of the system, necessary characteristics can be realized in a wide band.
The magnetic field absorber 401 that absorbs and attenuates the magnetic wave signal has a structure and an arrangement that efficiently emits the magnetic wave signal in the forward direction and suppresses the emission of the magnetic wave signal in the back direction.
Further, although the electric field shield 402 covers the entire loop coils 400a to 400n, the same effect can be obtained by individually covering the loop coils 400a to 400n.

Further, by covering each of the plurality of loop coils 400a to 400n with the electric field shield 402, unnecessary electric field coupling between the plurality of loop coils 400a to 400n can be eliminated.
Further, in seawater, particularly when the depth increases, the pressure from the periphery increases. Therefore, the waterproof case 404 needs to have a pressure resistant structure, and the waterproof case 404, the filler 403, and the electric field shield 402 are integrated. A thin metal foil of 10 microns or less is attached to a reinforced plastic material such as polycarbonate, the metal is vapor-deposited, the metal is subjected to electroless plating, or the paint containing metal particles is coated. it can.

(Embodiment 6)
FIG. 7 is a cross-sectional view showing another example of the magnetic field antenna according to the sixth embodiment of the present invention. Reference numeral 213 denotes a magnetic field antenna, 400a and 400b denote radiating elements, and 402 denotes a magnetic field that absorbs and attenuates a magnetic wave signal. An absorber, 406 is a coaxial cable, 407 is a coaxial connector, and 408 is a ground plane.
The magnetic field antenna 213 shown in FIG. 7 is normally used in the atmosphere, but can be used in seawater by providing an electric field shield, a filler, and a waterproof case as a radome.

The coaxial cable 406 and the radiating elements 400a and 400b constitute a loop coil, and the coaxial cable 406 is provided with a magnetic field absorber 402 that absorbs and attenuates a magnetic wave signal.
In-phase currents flow through the radiating elements 400a and 400b, and reverse current flows through the outer sheath of the coaxial cable 406. Therefore, magnetic field absorption that absorbs and attenuates magnetic field fluctuations generated by the current flowing through the outer sheath of the coaxial cable 406. By providing the body 402 in a ring shape, the conditions shown in FIG. 2 are satisfied.

Here, an arbitrary number of the radiating elements 400a and 400b may be provided, and may be linear, spiral, helical, or any shape.
In addition, the magnetic field absorber 402 that absorbs and attenuates magnetic field fluctuations is provided in a ring shape on the outer cover of the coaxial cable 406. Instead, by providing the magnetic field absorber 402 on the ground plane, a magnetic wave signal is radiated upward from the ground plane. It is also possible.

  Although the case where a loop coil is used as the magnetic field antenna has been described above, a helical antenna, a crescent-shaped loop antenna, a spiral antenna, a loop spiral antenna, a microstrip antenna, or the like can be used.

Also, instead of using the loop coil, magnetic field fluctuations such as a ferrite bar antenna wound around a ferrite core, a magnetic sensor using a Hall element, a magnetic resonance antenna, a magnetic rod antenna, or a surface wave propagation magnetic field antenna can be used. Similar effects can be obtained by using an antenna suitable for direct transmission or direct reception of magnetic field fluctuations.
The same effect can be obtained even if the polarization characteristics of the antenna means are linearly polarized waves, circularly polarized waves, or a combination thereof.

Also, high-speed broadband communication such as analog communication, digital communication, voice communication, data communication, or image communication using a spread spectrum code is possible using magnetic wave propagation in the substance.
Further, in the propagation of the magnetic wave signal, since it is possible to occupy a frequency band of 100 kHz or higher and a relatively wide frequency band, the advanced technology related to wireless communication for use in the atmosphere is equipped with antenna means. It can be used as it is in seawater by simply replacing it with a magnetic antenna.

Examples of the substance include substances having a large relative dielectric constant such as ice, snow, or the ground, in addition to fresh water or salt water having a salinity concentration of about 0% to 10%.
Even in a low frequency band of 100 kHz or less, long-distance communication is possible using a relatively small loop antenna.

In addition, by setting the band of the antenna means to a wide band, an effect can be obtained that can be applied to spread spectrum communication and can constitute a magnetic wave communication line with high secrecy and reliability.
Further, it is possible to extend the communication distance by using a directional antenna having a plurality of antenna elements arranged in an array and increasing the antenna gain.

Further, an antenna with good noise resistance can be realized by providing a magnetic field absorber that absorbs and attenuates the magnetic wave signal in a part of the loop of the loop antenna or shield loop antenna.
Further, fluctuations in magnetic field strength due to fading or multipath occurring when the magnetic wave signal propagates are suppressed by diversity means, or propagation delay distortion is suppressed by delay equivalent means, or delay is equivalent, or By providing means for adaptive control, a highly reliable long-distance communication line can be configured.

Further, by using the antenna means covered by the electric field shield, the transmitting means or the receiving means can be used in all areas such as the seawater, freshwater, seawater, freshwater, or the atmosphere. Long distance communication can be performed without readjustment of the resonance frequency.
In addition, the transmitting means has a built-in battery, a built-in power generating means, a means for rectifying a magnetic wave signal from the outside, or a combination thereof, which can be used for a long time or repeatedly. Can do.

Besides being used for preventing collision of ships, it can be widely used for telemetry in seawater, such as being used for solid management in tuna ponds and the like.
In addition, by applying to a fish finder, a seafloor finder, a metal detector, or the like, where ultrasonic waves have been used exclusively, detection with high accuracy becomes possible.
Also, audio information, large-capacity digital information, image information, or multimedia information can be transmitted by the magnetic wave signal.

Further, although propagation due to magnetic field fluctuations in fresh water or seawater is referred to as magnetic wave propagation, it can also be referred to as magnetic wave propagation in correspondence with the propagation of electromagnetic waves as radio wave propagation.
In addition, a system for monitoring crustal movement of the seabed can be constructed by discretely installing a plurality of sets of transmitting / receiving means and antenna means on the seabed and configuring an ad hoc network.

Since the present invention is configured as described above, the permittivity is 10 or more, the relative permeability is 10 or less, such as in fresh water or seawater, and the propagation loss of the magnetic field fluctuation is compared with the propagation loss of the electric field fluctuation. By using a magnetic wave signal that propagates in a relatively small material with relatively low loss, a magnetic wave communication device that enables long-distance communication can be realized.
Therefore, in seawater, etc., broadband long-range communication systems, ship collision prevention systems, biotelemetry, position detection systems for divers, sensing networks, RFID tag devices, communication devices with submarines, search for water victims or victims, depth measurement It can be applied to a wide range of fields such as aircraft, fish finder, submarine explorer, metal detector, or radar device.

Further, in seawater or the like, it is possible to realize secret communication using a spread spectrum communication system, high-speed and large-capacity data communication, or multimedia communication including image communication.
Moreover, the use of the antenna means of the present invention provides the advantage that long-distance communication is possible even in the atmosphere. Therefore, according to the present invention, seamless and super communication between the ground and outer space in the field of wireless communication is possible. The broadband environment can be expanded to seawater, which has been impossible until now.

1 is a system configuration diagram showing a first embodiment of the present invention. Explanatory drawing for analyzing the propagation characteristic of the magnetic wave signal in the first embodiment of the present invention System configuration diagram showing a second embodiment of the present invention System configuration diagram showing a third embodiment of the present invention System configuration diagram showing a fourth embodiment of the present invention Sectional drawing which shows the 5th Embodiment of this invention Sectional drawing which shows the 6th Embodiment of this invention Configuration diagram showing a conventional example The figure which shows the characteristic of the loop antenna by the conventional Example

Explanation of symbols

21-24 Magnetic wave communication device 111 Sea surface 112 Sea bottom 113a, 113b Transmitted wave, reflected wave 211 Control unit 212 Transceiver 213 Magnetic field antenna 221 Transceiver 222 Control unit 223 Magnetic field antenna

231a, 231b Receiver and transmitter 232 Controllers 233a, 233b, 233c Magnetic field antenna 234 Interface unit 400 Loop coil 401 Magnetic field absorber 402 for absorbing and attenuating magnetic wave signals Electric field shield 403 Filler 404 Waterproof case

405 Printed circuit board 406 Coaxial cable 407 Coaxial connector 408 Ground plate 600 Transmitting antennas 601a and 601b Current direction 602 Magnetic field absorbers 603a and 603b for absorbing and attenuating magnetic wave signals Antenna terminal 610 Center line 611 Receiving antenna 612 Loop coil spacing (D)
613 Distance between transmitting antenna and receiving antenna (R)

Claims (26)

An antenna means installed in a material having a relative permittivity of 10 or more, a relative permeability of 10 or less, and a propagation loss of magnetic field fluctuations relatively smaller than a propagation loss of electric field fluctuations, and connected to the antenna means A magnetic wave communication apparatus comprising: a transmitting means, a receiving means, or a transmitting / receiving means, wherein the antenna means is mainly sensitive to magnetic field fluctuations or magnetic current fluctuations and emits magnetic field fluctuations or magnetic current fluctuations.
A substance having a relative permittivity of 10 or more, a relative permeability of 10 or less, and a propagation loss of a magnetic field fluctuation that is relatively smaller than a propagation loss of an electric field fluctuation is fresh water or seawater having a salt concentration of 0% to 10%. A magnetic wave communication device corresponding to claim 1, wherein:
3. The magnetic wave communication device according to claim 1, wherein the magnetic field fluctuation or magnetic current fluctuation occupies a relatively wide bandwidth in a frequency band of 100 kHz or higher.
4. The magnetic wave communication device according to claim 1, wherein the antenna means is a magnetic field antenna or a magnetic current antenna.
The antenna means has a magnetic absorber or structure for partially absorbing and attenuating magnetic field fluctuations or magnetic current fluctuations, or radiates magnetic field fluctuations or magnetic current fluctuations and is sensitive to magnetic field fluctuations or magnetic current fluctuations. 5. A magnetic wave communication device corresponding to any one of claims 1 to 4, further comprising a magnetic field absorber or structure for partially absorbing and attenuating the light.
6. The magnetic wave communication device according to claim 5, wherein the magnetic resistance of the magnetic field absorber is relatively large, and a magnetic field loss or a magnetic current loss is relatively large.
The magnetic wave communication according to any one of claims 5 to 6, wherein the magnetic field absorber has a structure covering the antenna means in a ring shape or a structure covering the antenna means in a sandwich shape. apparatus.
8. The magnetic wave communication device according to claim 5, wherein the magnetic field absorber includes powdery metal particles having a relatively large magnetic field loss.
9. The antenna means according to any one of claims 4 to 8, wherein the antenna means is a loop antenna, a helical antenna, a crescent-shaped loop antenna, a spiral antenna, a loop spiral antenna, or a microstrip antenna. Magnetic wave communication device.
9. The magnetic wave communication device according to any one of claims 4 to 8, wherein the antenna means is a ferrite bar antenna wound on a ferrite core.
9. The magnetic wave communication device according to claim 4, wherein the antenna means is a magnetic sensor using a Hall element or a surface wave propagation magnetic field antenna.
5. The polarization characteristic of the magnetic wave signal radiated from the antenna means is vertical polarization, horizontal polarization, circular polarization, or a combination thereof. To a magnetic wave communication device corresponding to any one of items 11 to 11.
13. A part or all of the antenna means is covered with an electric field shield having a characteristic of allowing a magnetic field fluctuation or a magnetic current fluctuation to pass therethrough and attenuating electric field fluctuations or electric lines of force. The magnetic wave communication apparatus corresponding to any one of the items.
The electric field shield has a thin film shape of 10 microns or less, a lattice shape, a linear shape, a net shape, a punching metal shape, formed by sputtering, formed by a plating process, and has a fine insulating material. 14. The magnetic wave communication device according to claim 13, wherein metal particles or ferrite particles are mixed, or a combination thereof.
5. The antenna device according to claim 4, wherein the antenna unit includes a switching unit for switching the matching condition, an adjusting unit for adjusting the matching condition, or a control unit for controlling the matching condition adaptively. Item 15. A magnetic wave communication device corresponding to any one of items 14 to 14.
16. The antenna device according to any one of claims 1 to 15, wherein the antenna means is covered with a pressure-resistant and corrosion-resistant material or structure capable of withstanding an applied pressure without being eroded by surrounding substances. Applicable magnetic wave communication device.
The antenna means is an array antenna having a plurality of antenna elements arranged in an array, and radiates magnetic field fluctuations or magnetic current fluctuations toward the surface of the directional beam formed by the plurality of antenna elements with low loss. And a magnetic field absorber or structure for absorbing and attenuating radiation of magnetic field fluctuations or magnetic current fluctuations in the back direction. Communication device.
The plurality of antenna elements constitute an active phased array antenna having amplitude control means, delay control means, combining / distributing means, or a combination thereof, and the direction of the directional beam of the active phased array antenna is changed up and down. 18. The magnetic wave communication device according to claim 14, wherein the magnetic wave communication device scans in a direction, a left-right direction, or an up-down left-right direction.
The antenna means transmits a magnetic wave signal in a specific direction and receives a magnetic wave signal reflected from a reflecting object, and constitutes a depth measurement device, a detection device, a search device, or a radar device. A magnetic wave communication device corresponding to any one of claims 1 to 18.
The antenna means is installed in fresh water or seawater, the transmission means, the receiving means, or the transmission / reception means is installed in the atmosphere, and a long distance is obtained by using surface wave propagation existing in the contact surface between the fresh water or seawater and the atmosphere. 20. A magnetic wave communication device corresponding to any one of claims 1 to 19, wherein communication is performed.
The transmitting means or the receiving means has a plurality of antenna means and antenna switching means, and the receiving means measures the phase difference of the magnetic wave signals corresponding to the plurality of antenna means, and the direction in which the transmitting means is located or the receiving means is 21. The magnetic wave communication device according to claim 1, wherein a direction in which the head is directed is detected.
A magnetic wave signal including a plurality of carrier signals, subcarrier signals, modulation signals, or baseband signals that are synchronized or orthogonal and have at least different frequencies is transmitted from the antenna means connected to the transmission means, and connected to the reception means By measuring the phase difference of the received plurality of carrier signals, subcarrier signals, modulation signals, or baseband signals by the antenna means, the distance between the transmission means and the reception means is measured with high accuracy. A magnetic wave communication device corresponding to any one of claims 1 to 21.
23. A magnetic wave communication apparatus according to any one of claims 21 to 22, wherein a plurality of transmission means are discretely installed on the seabed and monitor crustal movements of the seabed.
23. The apparatus according to claim 21, wherein the transmitting means or the receiving means is provided on a plurality of moving bodies that move on the sea or in the sea, and measures relative distances and directions between the plurality of moving objects. A magnetic wave communication device corresponding to any one of the items 22.
25. The antenna means connected to the transmitting means and the antenna means connected to the receiving means are both installed in the atmosphere to transmit and receive a magnetic wave signal. Magnetic wave communication device corresponding to either.
  One of the antenna means connected to the transmitting means and the antenna means connected to the receiving means is installed in the atmosphere, and the other is installed in fresh water or sea water, and transmits and receives magnetic wave signals. 25. A magnetic wave communication device corresponding to any one of claims 1 to 24.

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