JP2013223073A - Composite antenna and composite antenna device - Google Patents

Abstract

Provided are a composite antenna that does not require a matching element, and a small composite antenna device that is equipped with the composite antenna and has high watertightness and airtightness.
First and second coupling coils (14, 15) arranged opposite to each other via an airtight container (11) that transmits radio signals in at least first and second frequency bands, and a first coupling A first antenna 16 that extends from the coil 14 and transmits a radio signal in the first frequency band is disposed on the same side as the second coupling coil 15 with respect to the hermetic container 11, and the first and second A second antenna 17 for receiving a radio signal in the second frequency band through the inner peripheral side of the coupling coils 14, 15, and at least the first of the first and second coupling coils 14, 15. One coupling coil 14 is a self-resonant coil, and a radio signal in the first frequency band fed to the second coupling coil 15 is transmitted to the first antenna 16 via the hermetic container 11.
[Selection] Figure 2

Description

  The present invention relates to a composite antenna and a composite antenna device, and more particularly to a composite antenna and a composite antenna device in which different types of antennas operating at different frequencies are integrated.

  Conventionally, a composite antenna in which different types of antennas operating at different frequencies are integrated has been proposed (see, for example, Patent Document 1). For example, a conventional composite antenna is a satellite that automatically rises to the sea surface when a ship is lost, determines its own position from the received GPS signal, and transmits a beacon signal carrying that position information to an artificial satellite It was installed in the system IPR (Emergency Position Indicate Radio Beacon).

  FIG. 10 is an explanatory diagram showing a configuration of a conventional composite antenna disclosed in Patent Document 1. In FIG. As shown in FIG. 10, the conventional composite antenna has a patch antenna 31 for GPS signals arranged in a housing 30 (only the upper part is shown in FIG. 10) and a housing 30. And a beacon signal monopole antenna 32 to be arranged. The watertightness of the housing 30 is realized by the watertight packing 33 in the through hole of the housing 30.

  A through-hole 34 for allowing the monopole antenna 32 to pass therethrough is formed at the center of the patch antenna 31. That is, the installation place of the antenna (patch antenna 31) responsible for the high frequency and the antenna (monopole antenna 32) responsible for the low frequency are shared. Furthermore, a matching element 36 for impedance matching between the monopole antenna 32 and the radio device (beacon transmitter 35) is disposed below the monopole antenna 32.

  A GPS signal from the GPS satellite is received by the patch antenna 31 and sent to the GPS receiver 37. The GPS receiver 37 calculates its position based on this signal. The calculated position information is sent to the beacon transmitter 35, is carried on a carrier wave having a predetermined frequency, and is radiated from the monopole antenna 32 to the space. Necessary power is supplied from a battery 38 to the beacon transmitter 35 and the GPS receiver 37.

Japanese Patent Laid-Open No. 10-247815

  In a situation where a conventional composite antenna as disclosed in Patent Document 1 is used in the sea or on the sea surface, it is essential to have a waterproof structure in order to protect the antenna element and the internal electronic circuit. . Since the patch antenna for GPS signals has a planar structure, it can be placed in a waterproof case made of a material that easily transmits radio waves. However, the monopole antenna needs to penetrate the waterproof case depending on its shape, and there is a problem that water is likely to be flooded from the waterproof structure portion of the penetrating portion.

  In addition, a matching element is often required below the monopole antenna, which complicates the structure of the composite antenna and increases the overall size of the apparatus on which the composite antenna is mounted.

  The present invention has been made to solve such a conventional problem, and includes a composite antenna that does not require a matching element, and a small composite antenna device that is equipped with the composite antenna and has high watertightness and airtightness. The purpose is to provide.

  In order to solve the above-described problems, the composite antenna of the present invention includes a first and a second that are disposed to face each other via a dielectric material that transmits radio signals in at least the first and second frequency bands. A coupling coil, a first antenna extending from the first coupling coil and transmitting a radio signal in a first frequency band; and on the same side as the second coupling coil with respect to the dielectric material And a second antenna for receiving a radio signal in the second frequency band through the inner peripheral side of the first and second coupling coils, the first and second coupling coils , At least the first coupling coil is a self-resonant coil, and the radio signal in the first frequency band fed to the second coupling coil is transmitted to the first antenna via the dielectric material. A structure characterized by The has.

  With this configuration, the composite antenna of the present invention transmits the radio signal in the first frequency band fed to the second coupling coil to the first antenna connected to the first coupling coil that is a self-resonant coil. can do.

  Furthermore, the composite antenna of the present invention has an advantage that it is not necessary to provide a separate matching element by performing impedance matching between the first antenna and the radio device using the first coupling coil and the second coupling coil. As a result, the reliability of the composite antenna is increased and the structure can be simplified as compared with the conventional case. Furthermore, it is possible to reduce the size, weight, and cost of the composite antenna and the apparatus including the composite antenna.

  In the composite antenna of the present invention, the first and second coupling coils are both self-resonant coils, and the second coupling coil is fed by the magnetic field resonance of the first and second coupling coils. A radio frequency signal in the first frequency band may be transmitted to the first antenna through the dielectric material.

The composite antenna of the present invention may have a configuration in which the first coupling coil is a spiral coil.
In addition, the composite antenna of the present invention may have a configuration in which an inner circumference shape of the first and second coupling coils is a circle or an ellipse.

  In the composite antenna of the present invention, the inner and outer diameters of the first and second coupling coils have a diameter or a minor axis, and a radio signal in the second frequency band is transmitted from the first and second coupling coils. You may have the structure which is the length which can pass the inner peripheral side.

  According to another aspect of the present invention, there is provided a composite antenna device comprising any one of the above composite antennas and an airtight container made of a dielectric material that transmits at least the radio signals in the first and second frequency bands. The first coupling coil and the first antenna are disposed outside the airtight container, and the second coupling coil and the second antenna are disposed inside the hermetic container. ing.

  With this configuration, the composite antenna device of the present invention does not need to be provided with a through hole for allowing the antenna to pass through the hermetic container.

  The present invention provides a composite antenna that does not require a matching element, and a small composite antenna device that is equipped with the composite antenna and has high watertightness and airtightness.

Explanatory diagram for explaining wireless power transmission technology using magnetic field resonance Explanatory drawing which shows schematic structure of the composite antenna apparatus provided with the composite antenna which concerns on this invention The perspective view which shows schematic structure of the composite antenna which concerns on this invention Explanatory drawing which shows the structural example of the 1st coupling coil installed in the outer side of an airtight container. Graph showing the relationship between the ratio of gap to wire diameter and Q value Sectional drawing which shows the structure of a 1st coupling coil typically Explanatory drawing which shows the structure which integrated the matching coil and the 1st antenna. Explanatory drawing which shows the structural example of the 2nd coupling coil installed inside an airtight container. First coupling coil, the graph showing the results of simulation of the reflection loss S ₁₁ of the second coupling coil and the first antenna Explanatory drawing showing the configuration of a conventional composite antenna

  The present invention applies a wireless power transmission technique using magnetic field resonance disclosed in US Pat. No. 7,825,543 and the like, without providing a through hole in the hermetic container, from a radio inside the hermetic container, A radio signal is transmitted to an antenna outside the hermetic container.

  Hereinafter, an outline of a wireless power transmission technique using magnetic field resonance will be described with reference to FIG. As shown in FIG. 1, the wireless power transmission technique disclosed in US Pat. No. 7,825,543 and the like includes an excitation coil 40 and a resonance coil 41 arranged on the power transmission side, and a resonance coil arranged on the power reception side. 42 and the excitation coil 43 are used.

  The resonance coils 41 and 42 are designed to have a high Q value by adjusting their inductance L and the line-to-line capacitance C of the windings, and to have a magnetic field resonance relationship in which both resonate at the same resonance frequency. Has been.

  When high frequency power is applied to the excitation coil 40 having one turn by the high frequency power supply 44, high frequency power is supplied from the excitation coil 40 having one turn to the resonance coil 41 by electromagnetic induction. The high-frequency power supplied to the resonance coil 41 is transmitted to the resonance coil 42 arranged away from the resonance coil 41 by a predetermined distance by magnetic field resonance. Further, the high frequency power from the resonance coil 42 is transmitted to the excitation coil 43 having the number of turns of 1 by electromagnetic induction, and is taken out by the load 45 connected to the excitation coil 43.

  In this way, by using magnetic field resonance, it is possible to perform power transmission with higher efficiency over a longer distance compared to power transmission by general electromagnetic induction.

  Hereinafter, embodiments of a composite antenna and a composite antenna device according to the present invention will be described with reference to the drawings. In addition, the dimensional ratio of each structure on each drawing does not necessarily correspond with the actual dimensional ratio.

  FIG. 2 is an explanatory diagram showing a schematic configuration of the composite antenna device 1 including the composite antenna 10 according to the present embodiment. FIG. 3 is a perspective view showing a schematic configuration of the composite antenna 10.

  That is, the composite antenna device 1 of the present embodiment transmits a radio signal in the first frequency band and receives a radio signal in the second frequency band, and at least the first and second frequencies. Radio communication that transmits a radio signal in the first frequency band and receives a radio signal in the second frequency band via the hermetic container 11 made of a dielectric material that transmits the radio signal in the band and the composite antenna 10 A device 12 and a power source 13 such as a battery for supplying power to the wireless communication device 12 are provided.

  As the airtight container 11, it is assumed that the watertightness and airtightness are high enough to withstand use on the seabed or outer space. The shape of the airtight container 11 is, for example, a sphere, and the diameter is about 30 cm.

  The wireless communication apparatus 12 receives a transmitter 18 that transmits a radio signal in the first frequency band through the first antenna 16 and a radio signal in the second frequency band through the second antenna 17. Machine 19.

  The composite antenna 10 includes a first coupling coil 14 and a second coupling coil 15 that are arranged to face each other through the wall of the hermetic container 11 that transmits at least radio signals in the first and second frequency bands. A first antenna 16 extending from the first coupling coil 14 and transmitting a radio signal in the first frequency band.

  The composite antenna 10 is disposed on the same side as the second coupling coil 15 with respect to the wall of the hermetic container 11 and has a second frequency band through the inner peripheral sides of the first and second coupling coils 14 and 15. And a second antenna 17 for receiving a radio signal.

  That is, the composite antenna device 1 includes the first coupling coil 14 and the first antenna 16 outside the hermetic container 11, and the second coupling coil 15, the second antenna 17, the wireless communication device 12, and the power source 13. Is provided inside the airtight container 11.

  As the first frequency band, a VHF band to a UHF band are assumed. In addition, the UHF band is assumed as the second frequency band, and for example, a 1.5 GHz band that is a frequency band of a GPS signal transmitted from a GPS satellite can be mentioned. The first and second frequency bands are not limited to the above example.

  As the first antenna 16, for example, a monopole antenna (whipped antenna) capable of transmitting a radio signal from the VHF band to the UHF band is assumed. As the second antenna 17, a patch antenna for receiving GPS signals is assumed. The types of the first and second antennas are not limited to the above example.

  The inner peripheral shape of the first and second coupling coils 14 and 15 may be a circle, an ellipse, or a polygon. In addition, the diameter or short diameter of the inner peripheral shape is such that the radio signal in the second frequency band passes through the inner peripheral side without being obstructed by the first and second coupling coils 14 and 15. The length must be received by the second antenna 17. For example, it is desirable that the above length is ½ or more of the wavelength of the radio signal in the second frequency band.

  FIG. 4 is an explanatory diagram showing a configuration example of the first coupling coil 14 installed outside the airtight container 11. As the first coupling coil 14, a spiral coil having no winding at the center is preferably used. The inner end portion 14 b of the first coupling coil 14 is open, and the outer end portion 14 a can be connected to the first antenna 16.

  The first coupling coil 14 is a self-resonant coil that self-resonates at a predetermined resonance frequency by the line capacitance C and the inductance L of the winding. Hereinafter, a design method of the first coupling coil 14 having a high Q value will be described.

The Q value of the first coupling coil 14 is expressed by [Equation 1] by the resistance value R, inductance L, and line capacitance C of the winding. The self-resonant frequency f ₀ of the first coupling coil 14 is expressed by [Equation 2].

  From [Equation 1], it can be seen that in order to realize a high Q value, the resistance value R of the winding and the capacitance C between the lines may be reduced. In order to reduce the resistance value R, a thick wire having high conductivity may be used. Furthermore, in order to reduce the line capacitance C, the average diameter (diameter) of the first coupling coil 14 may be increased to widen the line spacing of the windings.

Further, the inductance L [H] of the spiral coil can be obtained from the following equation. Here, r is the average radius [m] of the coil, N is the number of turns, and d is the thickness of the coil (difference between outer diameter and inner diameter) [m].

Further, the line capacity C per unit length generated between parallel lines is expressed by the following equation. Here, a is a spiral obtained by setting a as a radius [m] of the winding, b as a value [m] of ½ of the distance between adjacent windings, and ε as a dielectric constant [F / m] of vacuum. It is considered as the line capacitance C of the coil.

Further, the skin depth δ [m] of the winding can be obtained from the following equation. Here, f is the frequency [Hz] of the radio signal in the first frequency band, ω is the angular velocity [rad / s], μ is the magnetic permeability [H / m], and σ is the conductivity [S / m].

Furthermore, the resistance value Ra [Ω] of the winding in consideration of the skin effect can be obtained from the following equation. Here, l (el) is the length [m] of the winding, and c is the circumference [m] of the winding.

Therefore, first, the value of L × C is determined so that the self-resonant frequency f ₀ obtained by [Equation 2] is equal to the frequency f of the radio signal in the first frequency band. Then, by substituting Ra in [Equation 6], L in [Equation 3], and C in [Equation 4] into R, L, and C in [Equation 1], respectively, the first as a spiral coil is obtained. Q value of the coupling coil 14 can be obtained.

From the above [Equation 4], when the radius a of the winding is increased in order to reduce the resistance value R, the capacitance C between the lines is increased, and as a result, the Q value shown in [Equation 1] is lowered. I understand. Further, from Expression 2 and Equation 3, in order to obtain the desired self-resonant frequency f _0, it can be seen that constraints on the relationship of the average radius r and the number of turns N of the coil occurs. Therefore, it is presumed that the maximum Q value is obtained in consideration of the radius a of the winding, the average radius r (inner diameter and outer diameter) of the coil, and the number N of turns.

Here, as an example, based on [Equation 1] to [Equation 6], the first coupling coil having an inner diameter of 100 mm, a wire diameter of 1 mm, a conductivity σ of about half that of copper, and a self-resonant frequency f ₀ of 10 MHz. Consider the case of designing 14. That is, here, an example in which the winding radius a and the average radius r of the coil are constant and the number of turns N is adjusted will be described.

  FIG. 5 is a graph showing the results of calculating the Q value of the first coupling coil 14 designed with the above design values from [Equation 1] to [Equation 6]. FIG. 6 is a cross-sectional view schematically showing the configuration of the first coupling coil 14.

The graph of FIG. 5 shows a change in Q value with respect to the ratio between the gap between adjacent windings (= the distance 2b between adjacent windings−the wire diameter 2a of the windings) and the wire diameter. Here, since the average radius r and the wire diameter of the winding are constant, the number of turns N is adjusted in the range of 3.9 to 5.2 times so that the self-resonant frequency f ₀ is constant. Yes.

  As can be seen from the graph of FIG. 5, for the purpose of obtaining a high Q value, there is an optimum value (a value around 0.8 in the example shown in the graph) for the size of the gap between adjacent windings. Was confirmed. In the present embodiment, the first coupling coil 14 is designed according to a design guideline that maximizes a Q value that is a performance index of the coil.

  By the way, as shown in FIG. 3, the root of the first antenna 16 is connected to the outer end portion 14 a of the first coupling coil 14. Here, if the frequency of the radio signal in the first frequency band is the beacon signal frequency 43 MHz, the wavelength is about 7 m. This is a wavelength with a length of about 1.7 m in a general quarter-wave monopole antenna, which is too long for an airtight container 11 having a diameter of about 30 cm.

  Therefore, as shown in FIG. 7, the impedance matching with the transmitter 18 is performed between the first antenna 16 as a monopole antenna and the outer end portion 14 a of the first coupling coil 14. The structure which inserts the matching coil 20 for shortening the length of the antenna 16 can be considered. This is a technique that has been conventionally used to reduce the length of a monopole antenna.

  On the other hand, in the composite antenna 10 according to the present invention, the first coupling coil 14 and the second coupling coil 15 perform impedance matching between the first antenna 16 and the transmitter 18, thereby matching coils. 20 is omitted, and the length of the first antenna 16 can be reduced to 45 cm.

  FIG. 8 is an explanatory diagram showing a configuration example of the second coupling coil 15 installed inside the airtight container 11. As the second coupling coil 15, for example, a loop coil having one or more turns is employed. Ends 15 a and 15 b of the second coupling coil 15 can be connected to a terminal (not shown) of the transmitter 18.

The inventors simulate the reflection loss S ₁₁ of the first coupling coil 14, the second coupling coil 15, and the first antenna 16 in the configuration of the composite antenna 10 shown in FIGS. (FIG. 9). From the simulation results shown in FIG. 9, a desired resonance frequency is obtained in a configuration in which the matching coil 20 is omitted by the combination of the first coupling coil 14, the second coupling coil 15, and the first antenna 16 having a length of 45 cm. It was confirmed that a monopole antenna (43 MHz here) can be realized.

  The second coupling coil 15 excites the first coupling coil 14 installed outside the airtight container 11. The first and second coupling coils 14 and 15 transmit a first frequency band radio signal fed to the second coupling coil 15 to the first antenna 16 through the wall of the hermetic container 11. Is possible.

  That is, in the composite antenna 10 according to the present invention, the transmission side excitation coil 40 and the resonance coil 41 in the configuration of FIG. 1 are replaced with the second coupling coil 15, and the reception side resonance coil 42 and the excitation coil in the configuration of FIG. 43 is replaced with the first coupling coil 14 and the first antenna 16, respectively.

  When the second coupling coil 15 is a self-resonant coil having the same self-resonance frequency as the first coupling coil 14, the second coupling coil 15 causes the second resonance due to the magnetic field resonance of the first and second coupling coils 14 and 15. The radio signal of the first frequency band fed to the coupling coil 15 can be transmitted to the first antenna 16 with higher efficiency through the wall of the hermetic container 11.

  As described above, the composite antenna 10 and the composite antenna device 1 according to the present invention pass through the inside of the first and second coupling coils 14 and 15 and the second antenna 17 having a high frequency passes through the second from the space. A radio signal in the frequency band can be received and transmitted to the radio communication device 12.

  Further, the composite antenna 10 and the composite antenna device 1 transmit the wireless signal of the first frequency band transmitted from the wireless communication device 12 to the outside of the hermetic container 11 via the first and second coupling coils 14 and 15. By supplying the first antenna 16, a radio signal in the first frequency band can be sent out to space.

  The composite antenna and the composite antenna device according to the present invention are useful as a composite antenna and a composite antenna device for measurement / communication equipment such as a submarine seismometer and a satellite system probe that require a watertight structure. The composite antenna and the composite antenna device according to the present invention are also useful as a composite antenna and a composite antenna device for measurement / communication equipment such as a high-altitude flying device and an artificial satellite that require an airtight structure.

  Further, the present invention is not limited to the configuration in which the composite antenna is provided inside and outside the hermetic container, and may be a configuration in which the composite antenna is provided with a dielectric plate such as glass interposed therebetween. Application to is also possible.

DESCRIPTION OF SYMBOLS 1 Composite antenna apparatus 10 Composite antenna 11 Airtight container 12 Wireless communication apparatus 13 Power supply 14 1st coupling coil 14a Outer end part 14b Inner end part 15 2nd coupling coil 15a, 15b End part 16 1st antenna 17 2nd antenna Antenna 18 Transmitter 19 Receiver 20 Matching coil 40, 43 Excitation coil 41, 42 Resonance coil 44 High frequency power supply 45 Load

Claims (6)

First and second coupling coils disposed opposite to each other via a dielectric material that transmits radio signals of at least first and second frequency bands;
A first antenna extending from the first coupling coil and transmitting a radio signal in a first frequency band;
A second material is disposed on the same side as the second coupling coil with respect to the dielectric material, and receives a radio signal in a second frequency band through the inner circumferential side of the first and second coupling coils. An antenna, and
Of the first and second coupling coils, at least the first coupling coil is a self-resonant coil, and the radio signal in the first frequency band fed to the second coupling coil is converted into the dielectric. A composite antenna transmitting to the first antenna through a material.   The first and second coupling coils are both self-resonant coils, and the first frequency band radio signal is fed to the second coupling coil by magnetic field resonance of the first and second coupling coils. The composite antenna according to claim 1, wherein the signal is transmitted to the first antenna through the dielectric material.   The composite antenna according to claim 1, wherein the first coupling coil is a spiral coil.   The composite antenna according to any one of claims 1 to 3, wherein an inner circumference of each of the first and second coupling coils is a circle or an ellipse.   The diameter or short diameter of the inner circumference of the first and second coupling coils is such that the radio signal in the second frequency band can pass through the inner circumference of the first and second coupling coils. The composite antenna according to claim 4, wherein The composite antenna according to any one of claims 1 to 5,
An airtight container made of a dielectric material that transmits radio signals of at least the first and second frequency bands, and
The first coupling coil and the first antenna are arranged outside the hermetic container, and the second coupling coil and the second antenna are arranged inside the hermetic container. Antenna device.

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