JP4790684B2 - Antenna device - Google Patents

Abstract

Provided is a dipole or monopole antenna device capable of realizing great miniaturization. In a dipole antenna device 1, a plurality of flat coils 3a and 3b, and 4a and 4b are connected in which conductors forms closed areas in the plan view in a magnetic field area in the vicinity of a power supply portion 2. Capacitors 5 and 6 as radiation conductors are connected to both ends of the antenna device 1, respectively. Resonant current radiation is performed from the capacitors 5 and 6 at the antenna ends, and magnetic field radiation is performed from flat foils 3a and 3b, and 4a and 4b in the vicinity of the power supply portion 2.

Description

  The present invention relates to a dipole or monopole antenna device that can be used in a small wireless communication device or the like.

  In general, the longer the antenna length, the higher the reception sensitivity compared to the wavelength. However, when the antenna is used as an antenna device for a mobile phone or the like, it is too large if the antenna length is the same as the wavelength length. Since it is not excellent, it is desirable to shorten the antenna length.

  FIG. 10A is a schematic diagram of a ½ wavelength dipole antenna. When a high frequency current is supplied to the antenna, current and voltage are distributed on the antenna line. When the length of the antenna is an integral multiple of ½ wavelength, the antenna resonates to efficiently radiate radio waves (resonant current radiation). In a half-wave dipole antenna, the length of the antenna needs to be about half a wavelength.

  In order to reduce the size of the antenna without changing the electrical length of the dipole or monopole antenna, it is conceivable to increase the equivalent capacitance C or the equivalent inductor L to reduce the resonance frequency. However, increasing the equivalent capacitance C is not preferable because the antenna area increases. Although the inductor L can be increased without increasing the size by inserting a chip inductor, the chip inductor does not radiate, so the efficiency of the entire antenna is deteriorated.

  FIG.10 (b) is a schematic diagram of the dipole antenna which comprised the antenna line by the meander line. By configuring the antenna line with a meander line, the length of the antenna can be reduced to about 1/8 wavelength without changing the electrical length of the antenna. However, the antenna length can be shortened as the interval between the meander lines is reduced. However, when the interval between the meander lines is reduced to a certain extent, there is a limit to miniaturization by the meander line due to the influence of the interstage coupling capacitance.

In addition, an antenna device that further shortens the antenna length from 1/8 wavelength in a dipole antenna configured with meander lines has been proposed (see, for example, Patent Document 1). The antenna device disclosed in Patent Document 1 is such that a radiating element is provided separately from a printed board, and a conductive pattern of the radiating element is formed on a dielectric member having a dielectric constant larger than that of the printed board. As a result, the amount of shortening of the received signal wavelength due to the relative permittivity of the dielectric member increases, and the antenna can be downsized.
JP 2006-319437 A

  However, like the antenna device described in Patent Document 1, there is a limit only by the amount of shortening of the received signal wavelength due to the relative permittivity of the dielectric member, and further downsizing of the antenna device is desired.

  The present invention has been made in view of this point, and an object of the present invention is to provide a dipole or monopole antenna device capable of realizing a significant reduction in size.

Monopole or dipole antenna device of the present invention includes a planar coil conductor in a plan view are connected to the feeding point to the magnetic field region near the feed point to form a closed region having an opening in a central portion, said The planar coil is formed by overlapping conductors formed in the first and second areas facing each other across the boundary line on the same surface of the film substrate so that the film substrate is folded around the boundary line and closed in plan view. A region is formed, and a magnetic field radiation by the planar coil is used as a radiation source.

  According to this configuration, although the antenna device is of a monopole or dipole type, radiation using magnetic field radiation by a planar coil as a radiation source is performed. Moreover, since the inductor (planar coil) in the magnetic field region is large, the antenna resonance frequency is lowered, and the antenna device can be downsized.

  In the monopole or dipole antenna device, a plurality of planar coils can be connected, and an inductor (planar coil) can be enlarged to lower the antenna resonance frequency.

  According to the present invention, in the above monopole or dipole antenna device, another radiation conductor connected to the planar coil is provided, and resonance current radiation by the other radiation conductor and magnetic field radiation by the planar coil are performed. It is characterized by.

  According to this configuration, as a monopole or dipole type antenna device, it is possible to radiate resonance current from other radiation conductors, and it is possible to radiate magnetic field lines from a planar coil in the vicinity of the power feeding unit.

  In the monopole or dipole antenna device according to the present invention, a variable capacitance element is connected in series to the planar coil, and a tuning voltage is applied to the variable capacitance element to make the antenna resonance frequency variable. And

  According to this configuration, the tuning voltage can be applied to the variable capacitance element to change the antenna resonance frequency, so that the reception band can be widened.

  According to the present invention, the antenna device can be significantly reduced in size.

Embodiments of an antenna device according to the present invention will be described below in detail with reference to the drawings.
FIGS. 1A and 1B are schematic views of the antenna device according to the present embodiment. FIG. 1A is a plan view of the antenna device as viewed from the opening direction of the high aperture planar coil, and FIG. FIG. 3 is a side view of the antenna device viewed from the side surface direction of the high aperture planar coil.

  In the antenna device 1 according to the present embodiment, a plurality of high aperture planar coils 3a and 3b are connected in series on one side (right side in the figure) of a power feeding unit 2 arranged at the center of the antenna. A plurality of high aperture planar coils 4a and 4b are connected in series on the other side (left side in the figure) to form a dipole antenna. In the antenna device 1, radiation conductors 5 and 6 for electric field radiation due to a resonance current are connected to both ends of the antenna that hit the electric field region. FIGS. 1A and 1B schematically show a state in which two high-aperture planar coils 3a, 3b and 4a, 4b are connected to both sides of the power supply unit 2, respectively. Is set to the number of connections that can achieve the required antenna sensitivity.

  The high aperture planar coils 3a, 3b and 4a, 4b are arranged in the vicinity of the power feeding unit 2 that is a magnetic field region. As shown in FIG. 1A, the high opening planar coil 3a has an opening 7 having a large opening at the center of the coil, and the conductor forms a closed region (7) in plan view from the coil opening direction. As shown in FIG. 1B, the high-aperture planar coil 3a is arranged so that a part of the conductors overlap in the vertical direction so that the conductors form a closed region (7) in plan view. The other high opening planar coils 3b and 4a, 4b have the same structure.

  FIG. 2 is a perspective view of the antenna device 1 extracted from the feeding portion 2 and the high-aperture planar coils 3a, 3b and 4a, 4b. In the present embodiment, the conductor is rotated four times in a rectangular shape so that the conductor forms a closed region in plan view. One end portion 12 of the high opening planar coil 3 a is connected to the power feeding portion 2 via the connection portion 11. In the high-aperture planar coil 3a, the one end portion 12 on the power feeding unit 2 side is the highest position in the vertical direction, and the conductor 13 goes around in a rectangular shape at the same height from the one end portion 12 (the first turn) Rectangular conductor 13). The other end portion of the first round rectangular conductor 13 that goes round in a rectangle starting from the one end portion 12 is lowered by one step slightly before the one end portion 12, and then the second round rectangular conductor 14 becomes the first round rectangular conductor. The lower side of 13 is rotated around substantially the same position in a rectangular shape in plan view. The second rectangular conductor 14 has a side opposite to the first rectangular conductor 13 as viewed from the one end portion 12 side, and passes through the inner side by one line, and the next-stage high opening planar coil 3b. In a place overlapping with the connection conductor 15, the structure is higher by one step to avoid interference. Further, the second rectangular conductor 14 is turned around one end 12 and passes through the inner side by one line from the first rectangular conductor 13. The third conductor 16 returns to the same height as the first rectangular conductor 13 and passes one line inside the first and second rectangular conductors 13 and 14 and goes around in a rectangular shape. ing. The fourth half-rectangular conductor 17 falls below the position where the second round rectangular conductor 14 is formed at a location close to the next-stage high-aperture planar coil 3b, and the connecting conductor 15 extending there Connected to the end.

  In this way, by arranging the continuous rectangular conductors 13, 14, 16 and the semi-rectangular conductor 17 so as to partially overlap in the vertical direction, a large opening 7 is formed at the center of the high opening planar coil 3 a. Yes. The other high opening planar coil 3b is similarly configured.

  In the antenna device 1 configured as described above, radiation is performed in different radiation modes of resonance current radiation and magnetic field radiation as shown in FIG. When a high-frequency current is supplied to the power feeding unit 2, it operates as a dipole antenna, and current and voltage are distributed on an antenna line composed of a plurality of high aperture planar coils 3 a and the like and a high aperture planar coil 4 a and the like. Is maximized and the voltage is minimized, and the current is minimized and the electric field is maximized at the end of the antenna farthest from the feeding unit 2. When the high-frequency current supplied to the power feeding unit 2 matches the resonance frequency of the antenna device 1, as shown in FIG. 3, the radiation conductors 5 and 6 at the end of the antenna are separated from the power feeding unit 2 and have a weak magnetic field. Resonance current radiation (radiation by resonance current) in the high-aperture planar coil arranged at the maximum is the strongest. The direction of resonance current radiation is the longitudinal direction of the antenna device 1.

  On the other hand, a strong magnetic field region is formed by the high aperture planar coils 3a and 3b and the high aperture planar coils 4a and 4b in the vicinity of the power feeding unit 2, and the high aperture planar coil 3a and the high aperture planar coil 4a and the like are generated. As shown in FIG. 3, magnetic field radiation is performed by the magnetic field. Since the maximum resonance current flows when the high-frequency current supplied to the power feeding unit 2 matches the resonance frequency of the antenna device 1, the magnetic field line radiation at that time becomes maximum.

  Further, in the present embodiment, an inductance (L) having a low Q that is easy to radiate is constituted by the high aperture planar coil 3a and the like and the high aperture planar coil 4a and the like. The vicinity of the power feeding unit 2 is a magnetic field region, and a large inductance (L) is disposed there, which has an effect of reducing the resonance frequency of the antenna device 1.

  FIG. 4 is a diagram showing a simulation result of the antenna resonance frequency that verifies the miniaturization effect of the antenna device 1 according to the present embodiment. The antenna length L is set to L = 150 mm. As shown in the present embodiment, when the antenna wire is composed of the high aperture planar coil 3a and the like and the high aperture planar coil 4a and the like, the antenna resonance frequency is around 200 MHz. On the other hand, the antenna resonance frequency in the case of a linear half-wave conductor as shown in FIG. 10A is around 1000 MHz, and the antenna resonance in the case of a meander line as shown in FIG. 10B. The frequency is around 500 MHz.

  As described above, since the resonance frequency of the antenna device 1 according to the present embodiment is ½ or less of that of the meander line, the antenna length is reduced to ½ or less of that of the meander line. Will be able to. Therefore, compared with the case of using the shortening effect of the received signal wavelength due to the relative permittivity of the dielectric member as in Patent Document 1, it is possible to achieve a significant downsizing effect.

Next, a modification of the antenna device in which the antenna resonance frequency is made variable will be described.
FIG. 5 is a schematic diagram of an antenna device with a variable resonance frequency. The antenna device 20 shown in the figure has the same basic configuration as the antenna device 1 shown in FIGS. 1A and 1B described above, and the same parts are denoted by the same reference numerals. Avoid duplication.

  In the antenna device 20, varactor diodes 21a and 22a are connected in series as variable capacitance elements between the high aperture planar coil 3a (4a) and the high aperture planar coil 3b (4b), respectively. Each cathode of the varactor diodes 21a and 22a is connected to the ground via resistors R3 and R4, and a tuning voltage VT is applied to each anode via resistors R1 and R2. Other configurations are the same as those of the antenna device 1.

In the antenna device 20 configured as described above, a resonant circuit is formed by the high aperture planar coil 3a and the like, the high aperture planar coil 4a and the like, and the varactor diodes 21a and 22a. High opening flat coil 3a, the inductor value of 4a L1, high opening flat coils 3b, 4b of the inductor value and L2, to the varactor diode 21a, a capacity 22a and _{C T.} The resonance frequency Fo of the antenna device 20 is as follows.
Fo = 1 / 2π ((C _TTL · (L1 + L2))) ^1/2
_{Incidentally, C TTL} is Total equivalent capacitance of the saddle, it is directly linked to the value of _{C T.}
Accordingly, the varactor diode 21a, the resonant frequency Fo by varying the capacitance _{C T} of 22a shifts.

  According to the antenna device 20 as described above, it can be miniaturized as a radiation source for resonance current radiation and magnetic field radiation, and the resonance frequency Fo can be varied, so that the reception frequency can be widened. A wideband signal can be received.

  FIG. 6 is a view showing a modification of the antenna device in which the shape of the planar coil is changed, and is an enlarged view showing the power feeding unit and the planar coil connected thereto. The planar coils 3a and 4a are conductors in which a linear conductor 18 having a predetermined thickness is rotated three times in a rectangular shape from the outside to the inside in a plane, and the central end of the conductor 18 is wound in a rectangular shape. It is connected to one end of the next planar coils 3b and 4b through the bottom. Varactor diodes 21a and 22a are connected in series between the planar coils 3a and 4a and the subsequent planar coils 3b and 4b.

Even when an antenna device is configured using such a planar coil, since the conductor 18 forms a closed region in plan view, radiation is performed in different radiation modes of resonance current radiation and magnetic field radiation. Since the inductance (L) having a low Q that is easy to radiate is formed by a planar coil, a large inductance (L) is arranged in the magnetic field region, and the resonance frequency of the antenna device is lowered to reduce the antenna length. be able to.
In the antenna device, a manufacturing method and a coil shape of a high-aperture planar coil that forms a closed region in a plan view and serves as a radiation source for magnetic field radiation will be described.

  As shown in FIG. 7A, rectangular conductor patterns 34a to 34d with one side on the folding line opened are formed at predetermined intervals in the upper half region 32 of the film substrate 31 made of an insulating flexible film. . In addition, rectangular conductor patterns 35a to 35d having an intermediate portion on one side of the folding line opened in the lower half region 33 of the film substrate 31 are formed at predetermined intervals with a substantially half cycle shift with respect to the upper conductor patterns 34a to 34d. To do.

  Next, by bending the film substrate 31 around the fold line, a plurality of planar coils in which closed regions 36a to 36g of rectangular conductors continue at a predetermined interval as shown in FIG. 7B are formed. The

  8A and 8B illustrate a method for manufacturing a planar coil in which a perfect circular closed region is formed by a conductor. As shown in FIG. 8A, oval conductor patterns 37 a to 37 c in which straight portions on the folding line are opened are formed at predetermined intervals in the upper half region 32 of the film substrate 31. Further, in the lower half region 33 of the film substrate 31, the ellipsoidal conductor patterns 38a and 38b whose straight lines on the folding line are opened are formed at predetermined intervals with a substantially half cycle shift with respect to the upper conductor patterns 37a to 37c. .

  Next, by bending the film substrate 31 around the fold line, the curved portions of the ellipsoidal conductor patterns 37a to 37c and the conductor patterns 38a and 38b overlap with each other as shown in FIG. A plurality of planar coils in which 39a to 39d are continuous at a predetermined interval are formed.

  9A and 9B illustrate a method for manufacturing a planar coil in which a semicircular closed region is formed by a conductor. As shown in FIG. 9A, rectangular conductor patterns 34a to 34d having one side on the folding line opened in the upper half region 32 of the film substrate 31 are formed at predetermined intervals. In addition, in the lower half region 33 of the film substrate 31, the oval conductor patterns 41a to 41d whose straight lines on the folding line are opened are formed at predetermined intervals with a substantially half cycle shift with respect to the upper conductor patterns 34a to 34d. .

  Next, by bending the film substrate 31 around the bend line, the curved portions of the rectangular conductor patterns 34a to 34d and the oval conductor patterns 41a to 41d overlap each other as shown in FIG. 9B. A plurality of planar coils in which semicircular closed regions 42a to 42g are continuous at a predetermined interval are formed.

  In the above description, a dipole antenna has been described as an example, but a monopole antenna can be similarly applied.

  The present invention is applicable to a dipole or monopole antenna device.

(A) It is the schematic diagram of the antenna apparatus which concerns on this Embodiment, and the top view seen from the opening direction of the high opening planar coil, (b) The side view which looked at the antenna apparatus from the side direction of the high opening planar coil The perspective view which extracted the electric power feeding part and high opening planar coil of the antenna device which concerns on this Embodiment The figure which shows the resonance current radiation | emission and magnetic field radiation | emission of the antenna apparatus which concerns on this Embodiment The figure which shows the simulation result of the resonant frequency which verified the miniaturization effect of the antenna device which concerns on this Embodiment Schematic diagram of antenna device with variable resonance frequency The figure which shows the modification of the antenna device which changed the shape of the plane coil (A) The top view which shows the state before bending in the manufacturing method of a rectangular high opening planar coil, (b) The top view which shows the state after bending (A) The top view which shows the state before bending in the manufacturing method of a circular high opening planar coil, (b) The top view which shows the state after bending (A) The top view which shows the state before bending in the manufacturing method of a semicircle high opening planar coil, (b) The top view which shows the state after bending (A) Schematic diagram of dipole antenna, (b) Schematic diagram of meander-type dipole antenna

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Antenna apparatus, 2 ... Feeding part, 3a, 3b, 4a, 4b ... High opening planar coil, 5, 6 ... Capacitor, 11 ... Connection part, 12 ... One end part of high opening planar coil, 13 ... Rectangular conductor (one round 14) Rectangular conductor (second turn), 15 ... Connection conductor, 16 ... Rectangular conductor (third turn), 17 ... Semi-rectangular conductor (fourth turn), 21a, 22a ... Varactor diode, 31 ... Film substrate 32 ... Upper half region, 33 ... Lower half region, 34a-34d ... Conductor pattern (upper side), 35a-35d ... Conductor pattern (lower side)

Claims (4)

The planar coil includes a planar coil connected to the feeding point in the vicinity of the feeding point and forming a closed region in which the conductor has an opening in the center in plan view, and the planar coil has a boundary line on the same surface of the film substrate. The conductors formed respectively in the first and second areas facing each other are formed by folding the film substrate around the boundary line to form a closed region in plan view, and the magnetic field lines generated by the planar coil A monopole or dipole antenna device characterized in that radiation is used as a radiation source.   The monopole or dipole antenna device according to claim 1, wherein a plurality of the planar coils are connected. Providing another radiation conductor connected to the planar coil;
3. The monopole or dipole antenna device according to claim 1 , wherein resonance current radiation by the other radiation conductor and magnetic field radiation by the planar coil are performed. The monolithic capacitor according to any one of claims 1 to 3 , wherein a variable capacitance element is connected in series to the planar coil, and a tuning voltage is applied to the variable capacitance element to change an antenna resonance frequency. Pole or dipole antenna device.

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