JP2009033294A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an antenna device for broadening input impedance bandwidth without providing a resonance element or a coupling element other than a feeding element and without mounting a matching circuit on a circuit board other than an antenna mounting space. <P>SOLUTION: The antenna device includes: a first conductor 1; a second conductor 2 sufficiently thinner than wavelength and arranged with an optional interval with the first conductor; a third conductor 3 connected at least partially to the second conductor and arranged in the almost the same plane as that of the second conductor at an interval sufficiently smaller than the wavelength with respect to the second conductor; a fourth conductor 4 arranged in almost the same plane as that of the second conductor and the third conductor at an interval sufficiently smaller than the wavelength with the respect to the third conductor; a fifth conductor 5 connected at least partially to the fourth conductor and at least partially adjacently to the first conductor; and a sixth conductor 7 for connecting the first conductor and the second conductor, wherein a feed point 6 for applying ac voltage is provided between a part of the fifth conductor adjacent to the first conductor and a part of the first conductor facing the fifth conductor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wide impedance band of an inverted F antenna or a short patch antenna, and more particularly to an antenna device applied to a mobile communication terminal such as a mobile phone or a PDA.

  Inverted F-type antennas or short patch antennas have good electrical characteristics in spite of their small size, and are therefore widely used in wireless communication devices such as mobile communication terminals that require miniaturization of antenna elements.

  On the other hand, in recent mobile phone wireless communication systems, the frequency band used and the bandwidth of each frequency band are increasing year by year from the viewpoint of securing line capacity and line quality. Therefore, antennas for transmitting and receiving radio waves are also required to be multiband (multifrequency sharing) and wideband.

  In addition, wireless terminal devices such as mobile phones in recent years are required to be small and thin from the viewpoint of user convenience, etc., and widen the bandwidth while maintaining a small and low-profile physical shape. The development of methods is highly desired.

  As a method of widening the inverse F-type antenna or the short patch antenna or sharing the multi-frequency, there is known a method of arranging a parasitic element around the feeding element, but this method increases the volume of the antenna element. There is a problem of doing.

  As another method, there is a method of providing a distributed constant type matching circuit on a circuit board on which a feeder line is mounted to achieve a wide band (for example, see Non-Patent Document 1). In addition, since a relatively large area for mounting the distributed constant matching circuit is required, it is difficult to realize the wireless communication terminal whose mounting area is extremely limited, such as a mobile phone.

  If the matching circuit is composed of lumped constant circuit elements such as a chip inductor and a chip capacitor, this problem is almost solved, but a problem that the loss due to the matching circuit increases occurs. Furthermore, since the element values of the lumped constant circuit elements cannot be selected continuously and can only be selected discretely, it may be difficult to achieve optimum matching.

H. F. Pues et al., “An Impedance-Matching Technique for Increasing the Bandwidth of Microstrip Antennas,” IEEE Trans. Antennas Propagat., Vol.37, no.11, pp.1345-1354, Nov. 1989.

  The present invention has been made in view of the above points, and without providing a resonance element or a coupling element other than the feeding element, and without mounting a matching circuit on a circuit board other than the antenna mounting space, The input impedance bandwidth (operating frequency bandwidth) of the inverted F-type antenna, the short patch antenna, or the patch antenna can be widened in a form that can be easily mounted on a mobile radio terminal without almost increasing the volume. An object is to obtain an antenna device.

  The antenna device according to the present invention is at least one in the first conductor, the second conductor that is sufficiently thin compared to the wavelength, and is arranged at an arbitrary interval from the first conductor, and the second conductor. A third conductor disposed in a plane substantially equal to the second conductor and spaced apart from the second conductor by a sufficiently smaller distance than a wavelength; the second conductor; and A fourth conductor disposed substantially in the same plane as the third conductor and spaced apart from the third conductor by a sufficiently smaller distance than the wavelength, and at least a part of the fourth conductor is connected to the fourth conductor. And a fifth conductor at least partially adjacent to the first conductor, and a sixth conductor connecting the first conductor and the second conductor, the first conductor being An alternating voltage between the portion of the fifth conductor adjacent to the portion of the first conductor facing the portion of the fifth conductor Characterized in that the feeding point is applied to.

  In addition, the first conductor, the second conductor which is sufficiently thin compared to the wavelength, and is arranged at an arbitrary interval from the first conductor, and the second conductor are arranged in substantially the same plane as the second conductor. A fourth conductor disposed at a sufficiently small distance from the wavelength of the two conductors, and at least a part of the fourth conductor is connected to the fourth conductor, and the second conductor and the fourth conductor; A third conductor disposed in a substantially same plane with a sufficiently small interval relative to the wavelength with respect to the fourth conductor, at least a part of which is connected to the third conductor, and the first conductor A fifth conductor that is at least partially close to the first conductor, and a sixth conductor that connects the first conductor and the second conductor, wherein the fifth conductor is adjacent to the first conductor. A feeding point for applying an AC voltage is provided between the conductor part and the first conductor part facing the conductor part. And wherein the door.

  In addition, the first conductor, the second conductor which is sufficiently thin compared to the wavelength, and is arranged at an arbitrary interval from the first conductor, and the second conductor are arranged in substantially the same plane as the second conductor. A fourth conductor disposed at a sufficiently small distance relative to the wavelength of the two conductors, and at least partly connected to the fourth conductor and at least partly close to the first conductor A fifth conductor that connects the first conductor and the second conductor, and a portion of the fifth conductor that is close to the first conductor, and faces the fifth conductor. A feeding point for applying an AC voltage is provided between the first conductor portion and the first conductor portion.

  Further, the first conductor, a second conductor that is sufficiently thin compared to the wavelength, and is disposed at an arbitrary interval from the first conductor, and at least a part of the second conductor is connected to the second conductor, A third conductor disposed substantially in the same plane as the second conductor and spaced apart from the second conductor by a sufficiently smaller distance than the wavelength, and at least a part of the third conductor is connected to the third conductor. And a fifth conductor that is at least partially adjacent to the first conductor, a sixth conductor that connects the first conductor and the second conductor, and a wavelength of the fifth conductor compared to the wavelength. And a seventh conductor close to the first conductor with a sufficiently smaller distance than the wavelength, and the first conductor and the seventh conductor. A feeding point for applying an AC voltage is provided between them.

  According to this invention, without providing a resonant element or a coupling element other than the feeding element, and without mounting a matching circuit on a circuit board other than the antenna mounting space, the volume of the antenna is hardly increased. The input impedance bandwidth (operating frequency bandwidth) of the inverted F-type antenna, the short patch antenna, or the patch antenna can be widened in a form that can be easily mounted on a mobile radio terminal.

Embodiment 1 FIG.
Hereinafter, an antenna device according to Embodiment 1 of the present invention will be described. FIG. 1 is an explanatory view of the basic basic configuration and circuit model of an antenna device according to Embodiment 1 of the present invention. The antenna device shown in FIG. 1A is substantially the same as the conductor 1 and the conductor 2 which are arranged at an arbitrary interval from the conductor 1 exemplified by the rectangular conductor plate, and spaced apart from the conductor 1. Arranged at an arbitrary distance on the plane, the conductor 3 having an arbitrary shape that is electrically connected to the conductor 2 at one or a plurality of locations, and the conductor 2 and the conductor 3 on the side opposite to the conductor 2 when viewed from the conductor 3 On the same plane, the conductor 4 having an arbitrary shape arranged at an arbitrary distance from the conductor 3, at least a portion thereof is electrically connected to the conductor 4, and one end thereof is separated from the conductor 1 by an interval sufficiently smaller than the wavelength. An adjacent conductor 5 having an arbitrary shape, a feeding point 6 for supplying high-frequency power to the antenna apparatus, that is, between a portion of the conductor 5 adjacent to the conductor 1 and a portion of the conductor 1 opposed thereto, and a conductor 1 and a conductor 7 having an arbitrary shape for connecting the conductor 2. Here, it is assumed that the conductor 3 is connected to the conductor 2 at the tip in the + x-axis direction.

  Next, the operation will be described. Of the high-frequency current transmitted to the feeding point 6 through an arbitrary transmission line, a positive current flows into the conductor 5 and a negative current flows into the conductor 1. The positive current flowing into the conductor 5 reaches the conductor 4, and when the conductor 3 and the conductor 4 are arranged with a sufficiently small interval compared to the wavelength, the Coulomb attractive force of the (+) charge reaching the conductor 4 As a result, a (−) charge is induced in the conductor 3. Since the current flowing into the conductor 4 is a high-frequency current, the polarity of the charge changes periodically according to the AC frequency. Since charge transfer occurs in the conductor 3, a high-frequency current flows through the conductor 3. Thus, the conductor 4 and the conductor 3 are capacitively coupled in terms of high frequency. In this case, it is considered that the portion where the conductor 4 and the conductor 3 overlap mainly operates as a transmission line with an open end and does not contribute much to radiation.

Suppose the overlapping portions of the conductor 4 and the conductor 3 is operated as a transmission line of an ideal end open, when the length and L _a, impedance viewed + x-axis direction from the -x-axis direction end portion of the overlapping portion Z _a Is represented by the following equation (1).

Here, j is a unit imaginary number. Z _{o — a} is the width or diameter of the conductor 4 and the conductor 3, the distance t _a between the conductor 3 and the conductor 4, and the characteristic impedance of the transmission line determined by the relative permittivity ε _r1 around the conductor 3 and the conductor 4, λ Is the effective wavelength for the frequency used. Accordingly, the length _{L a} is, when satisfying the following formula (2), _{Z a} is a capacitive reactance.

Similarly to the high-frequency electromagnetic coupling between the conductor 3 and the conductor 4, when charge transfer occurs in the conductor 3, charge transfer also occurs in a portion adjacent to the conductor 3 on the conductor 2 and current flows. In this case, it is considered that the current flowing in the conductor 3 and the current flowing in the portion of the conductor 2 adjacent to the conductor 3 are in opposite phases, and furthermore, since the tip of the part is short-circuited by the conductor, the part is the main part. It is considered to operate as a transmission line whose tip is short-circuited. When the length of the portion where the conductor 2 and the conductor 3 are close to each other is L _b , the impedance Z _b seen from the −x-axis direction end of the portion in the + x-axis direction is expressed by the following equation (3).

Here, Z _{o — b} is the width W _{b of} the conductor 3, the distance t _b between the radiating conductor 2 and the conductor 3, the characteristic impedance determined by the relative dielectric constant ε _r2 between the radiating conductor 2 and the conductor 3, and λ is relative to the operating frequency. Effective wavelength. Accordingly, the length L _b of the sites, when satisfying the following expression (4), Z _b is the inductive reactance.

From the above consideration, the circuit model expressing the behavior of the input impedance Z _in of the antenna shown in FIG. 1A is given by assuming that the impedance of the resonator formed by the conductor 1, the conductor 2, and the conductor 7 is Z _r. First, it can be expressed as shown in FIG. Part A of FIG. 1B is formed by the conductor 3 and a part of the conductor 2 adjacent thereto, and is considered to be expressed by a series short stub from the viewpoint of the high frequency circuit. Similarly, the portion B in FIG. 1B is formed by a portion where the conductor 3 and the conductor 4 are close to each other, and can be expressed by a series open stub from the viewpoint of a high frequency circuit.

Furthermore, the use of the relationship of the formula (1) and (3), the circuit of FIG. 1 (b), can be written as in FIG. 1 (c), the length _L a, _{L b} are both lambda / When it is selected to be less than 4, it is approximately as shown in FIG. That is, it is considered that the LC series resonance circuit is configured by the conductor 2, the conductor 3, and the conductor 4. Inverted-F antenna, short patch antenna, the impedance Z _r of such a patch antenna, since it has an impedance characteristic of the parallel resonance becomes a form that the series resonance circuit is inserted in series between the parallel resonant circuit Z _r and the power supply line , the impedance matching band width of the feed line is considered to be a wide band from Z _r alone.

  In the first embodiment, the feed line may be any line that can provide a potential difference between the conductor 1 and the conductor 5, such as a coaxial line, a microstrip line, a triplate line, and a coplanar line. What is necessary is just to select an optimal track.

  Further, since the equations (1) and (3) are independent of each other, the equivalent inductance L and the equivalent capacitance C of the series resonance circuit can be selected independently of each other. The value of the equivalent capacitance C can be calculated from an equation in which the right side of the equation (1) is equal to 1 / (jωC). Further, the value of the equivalent inductance L can be calculated from a mathematical formula in which the right side of the formula (3) is equal to jωL.

Furthermore, as shown in FIG. 1A, the value of the equivalent inductance L can be adjusted by the width W _b and the length L _{b of the} conductor 3 while keeping the distance t _b between the conductor 2 and the conductor 3 constant. It is. The value of the equivalent capacitance C is also the interval t _a conductor 3 and conductor 4 remains constant, it is also possible to adjust the width W _a and the length L _a of the conductor 4.

In general, the lengths L _a and L _b are selected to be equal to or less than a quarter wavelength (when n = 0 in the formulas (2) and (4)), and the series inductive reactance L is set with the series short stub. The series capacitive reactance C is obtained with the series open stub, but the lengths L _a and L _b are selected out of the ranges of the equations (2) and (4), and the series capacitive reactance C is obtained with the series short stub. It is also possible in principle to obtain a series inductive reactance L with an open stub.

Moreover, when obtaining a desired series reactance, if L _a > L _b , the conductor 3 and the conductor 4 in FIG. 1 may be interchanged, and the configuration shown in FIG. Since the equivalent circuit in this case is a circuit in which L and C are interchanged in FIG. 1D, it is considered that an impedance broadening effect similar to the configuration of FIG. 1 can be obtained.

  If the length of the conductor 3 cannot be increased due to restrictions such as the required size and sufficient inductive reactance cannot be obtained, the shape of the conductor 5 is shown in FIGS. 3 (a) and 3 (b). May be formed in a meander shape or a spiral shape, and the inductive reactance deficiency may be supplemented by the conductor 5. Further, as shown in FIG. 3C, the conductor 3 may be removed, and inductive reactance may be obtained only by the conductor 5.

  Further, when the conductor 4 cannot be provided due to restrictions such as the required size and a series capacitive reactance cannot be obtained, the conductor 8 is extended from the feeding point 6 to be close to the conductor 5 as shown in FIG. The capacitive reactance may be obtained by electromagnetic coupling between the conductor 8 and the conductor 5. The value of the capacitive reactance is obtained according to the shape and area of the portion where the conductor 5 and the conductor 8 are close, the relative dielectric constant of the portion where the conductor 5 and the conductor 8 are close, and the distance between the conductor 5 and the conductor 8. It can be adjusted.

Embodiment 2. FIG.
FIG. 5 is an explanatory diagram showing the configuration of the antenna device according to Embodiment 2 of the present invention. Reference numeral 9 denotes a double-sided or multilayer dielectric substrate on which circuits necessary for wireless communication and electric / electronic components are mounted. Here, the double-sided substrate is exemplified. On the dielectric substrate 9, a conductor 1 and a conductor 8 serving as a feed line are formed by etching. 10a and 10b correspond to the conductor 5 and the conductor 7, respectively, and are conductive parts having elasticity. If one or both of the conductor 5 and the conductor 7 are made of a heat-resistant spring connector or a metal leaf spring, they can be mounted on the dielectric substrate 9 together with other electrical / electronic components in a solder reflow process. .

  Reference numeral 12 denotes an exterior housing of the wireless device, and a low dielectric constant resin is often used. 11 is a part including at least a part of the part 11 constituting the antenna device, for example, a part or all of the conductor 2, the conductor 3, and the conductor 4, and when the part 11 is manufactured only by sheet metal, the part 11 is What is necessary is just to fix in the exterior housing | casing 12 with a double-sided tape, an adhesive agent, etc., and when the component 11 is manufactured with the resin molding product in which conductor plating is possible, all conductor 2, conductor 3, and conductor 4 are conductor-plated on the surface. The conductor 2, the conductor 3, and the conductor 4 may be appropriately dispersed on the front and back surfaces of the resin molded product, or may be formed so as to straddle both sides. Regarding the installation, it may be fixed to the exterior housing 12 with a double-sided tape or an adhesive, or may be fixed so as to be fitted into the dielectric substrate 9 by providing a claw or the like on a resin molded product.

  Further, the component 11 may be manufactured using a rigid dielectric substrate or a flexible dielectric film substrate. When the component 11 is made of a flexible dielectric film substrate, the component 11 can be easily bent, so that the shape of the conductor 5 shown in FIGS. 3A and 3C is realized as shown in FIG. It becomes possible to do. As a method of electrically connecting the conductor 5 formed on the component 11 and the conductor 8 formed on the dielectric substrate 9, a method using soldering or a mating connector can be considered.

  Alternatively, the outer casing 12 may be a resin-made outer casing capable of conductor plating, and the conductor 2, the conductor 3, and the conductor 4 may be formed on the surface of the outer casing 12 by a conductor plating technique or the like.

  With the above configuration, the antenna configuration described in Embodiment 2 can be realized in a form that can be mounted on an actual wireless communication device.

It is explanatory drawing of the fundamental basic composition and circuit model of the antenna apparatus which concern on Embodiment 1 of this invention. It is a block diagram at the time of replacing the conductor 3 and the conductor 4 in Fig.1 (a). FIG. 6 is a diagram showing a modification of the shape of the conductor 5 that complements the shortage of inductive reactance by the conductor 5 when the length of the conductor 3 in FIG. 1A cannot be increased and sufficient inductive reactance cannot be obtained. is there. When the conductor 4 in FIG. 1A is not provided and a series capacitive reactance cannot be obtained, the conductor 8 is extended from the feeding point 6 to be close to the conductor 5, and the conductor 8 and the conductor 5 are electromagnetically coupled. It is a figure which shows the modification which obtains capacitive reactance. It is explanatory drawing which shows the structure of the antenna device which concerns on Embodiment 2 of this invention. It is explanatory drawing at the time of manufacturing the components 11 containing the conductor 2, the conductor 3, and the part or all of the conductor 4 in FIG. 5 with a flexible dielectric film board | substrate.

Explanation of symbols

  1 conductor (1st conductor), 2 conductor (2nd conductor), 3 conductor (3rd conductor), 4 conductor (4th conductor), 5 conductor (5th conductor), 6 feeding point, 7 Conductor (sixth conductor), 8 conductor (seventh conductor), 9 dielectric substrate, 10a and 10b Equivalent to conductor 5 and conductor 7, conductive parts having elasticity, 11 parts constituting antenna device, 12 Exterior housing.

Claims (10)

A first conductor;
A second conductor that is sufficiently thin compared to the wavelength and that is spaced from the first conductor by an arbitrary distance;
A third conductor that is at least partially connected to the second conductor and is disposed in substantially the same plane as the second conductor with a sufficiently small distance from the second conductor relative to the wavelength; When,
A fourth conductor disposed in substantially the same plane as the second conductor and the third conductor, with a sufficiently small distance from the third conductor compared to the wavelength;
A fifth conductor at least partially connected to the fourth conductor and at least partially adjacent to the first conductor;
A sixth conductor connecting the first conductor and the second conductor; and
An antenna device, wherein a feeding point for applying an AC voltage is provided between a portion of the fifth conductor adjacent to the first conductor and a portion of the first conductor facing the first conductor. A first conductor;
A second conductor that is sufficiently thin compared to the wavelength and that is spaced from the first conductor by an arbitrary distance;
A fourth conductor disposed in substantially the same plane as the second conductor, with a sufficiently small distance from the second conductor compared to the wavelength;
At least a portion is connected to the fourth conductor, and the second conductor and the fourth conductor are arranged in substantially the same plane with an interval sufficiently smaller than the wavelength with respect to the fourth conductor. A third conductor formed;
A fifth conductor that is at least partially connected to the third conductor and that is at least partially proximate to the first conductor;
A sixth conductor connecting the first conductor and the second conductor; and
An antenna device, wherein a feeding point for applying an AC voltage is provided between a portion of the fifth conductor adjacent to the first conductor and a portion of the first conductor facing the first conductor. A first conductor;
A second conductor that is sufficiently thin compared to the wavelength and that is spaced from the first conductor by an arbitrary distance;
A fourth conductor disposed in substantially the same plane as the second conductor, with a sufficiently small distance from the second conductor compared to the wavelength;
A fifth conductor at least partially connected to the fourth conductor and at least partially adjacent to the first conductor;
A sixth conductor connecting the first conductor and the second conductor; and
An antenna device, wherein a feeding point for applying an AC voltage is provided between a portion of the fifth conductor adjacent to the first conductor and a portion of the first conductor facing the first conductor. A first conductor;
A second conductor that is sufficiently thin compared to the wavelength and that is spaced from the first conductor by an arbitrary distance;
A third conductor that is at least partially connected to the second conductor and is disposed in substantially the same plane as the second conductor with a sufficiently small distance from the second conductor relative to the wavelength; When,
A fifth conductor that is at least partially connected to the third conductor and that is at least partially proximate to the first conductor;
A sixth conductor connecting the first conductor and the second conductor;
A seventh conductor that is close to the fifth conductor with a sufficiently small interval compared to the wavelength and that is close to the first conductor with a sufficiently small interval compared to the wavelength; and
An antenna device, wherein a feeding point for applying an AC voltage is provided between the first conductor and the seventh conductor. In the antenna device according to any one of claims 1 to 4,
The antenna device, wherein the fifth conductor has a zigzag shape or a spiral shape. In the antenna device according to any one of claims 1 to 4,
An antenna device, wherein at least one of the fifth conductor and the sixth conductor is formed of a conductive component having elasticity. In the antenna device according to any one of claims 1 to 6,
The antenna device, wherein the first conductor is formed on a dielectric substrate. The antenna device according to claim 7, wherein
At least a part of the components constituting the antenna device is made of a rigid dielectric substrate, a flexible dielectric film substrate, a sheet metal, or a molded resin capable of conductor plating. The antenna device according to claim 8, wherein
A wireless communication device characterized in that at least a part of components constituting the antenna device is housed in an outer casing of an arbitrary shape which is a dielectric. The antenna device according to claim 8, wherein
At least a part of the conductors other than the first conductor is formed on the surface of the resin-made outer casing.

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