JP2005094360A - ANTENNA DEVICE AND WIRELESS COMMUNICATION DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-frequency antenna device capable of widening the respective bandwidths of two frequencies while dealing with the two frequencies with a simpler structure. <P>SOLUTION: A frequency selection plate member comprises: a ground conductor 1; a large number of patch conductors 2 arranged in first and second directions that are directed along the surface of the ground conductor 1 and are perpendicular to each other; and connection conductors 3 for electrically connecting the central parts of the patch conductors 2 to the ground conductor 1. First radiating electrodes 4a and 4b are arranged along the first direction and second radiating electrodes 5a and 5b are arranged along the second direction in close proximity to the side of patch conductors 2. The antenna device can be used as a surface mounted antenna which is compatible with small height, miniaturization and two frequencies. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a two-frequency antenna device used in a microwave band communication device and a wireless communication device using the antenna device.

  Mobile communication devices such as mobile phones have been rapidly reduced in size, and further miniaturization and height reduction have been demanded for antennas that are constituent parts thereof. Further, recent mobile phone terminals are compatible with two frequencies, that is, different two frequencies, such as GSM (Global System for Mobile Communication) and DCS (Digital Cellular System). In order to be able to cope with two frequencies, an antenna device corresponding to two frequencies is used. For example, a planar inverted F antenna (PIFA) corresponding to GSM 900 MHz and DCS 1800 MHz is adopted as a dual-frequency antenna for such a cellular phone terminal.

  Such a conventional dual-frequency antenna, PIFA, will be described with reference to FIG. FIG. 8 is a perspective view showing a schematic configuration of an example of a conventional PIFA. 8 is a radiation electrode, 9 is a substrate serving as a ground conductor, 10 is a power supply terminal, 11 is a ground terminal, and 12 is formed on the radiation electrode 8. It is a slit. As shown in FIG. 8, the PIFA is composed of a substrate 9 serving as a rectangular ground conductor, a rectangular radiation electrode 8 mounted at one end in the longitudinal direction, and a feeding terminal 10 and a ground terminal 11 connected thereto. In addition, an L-shaped slit 12 is formed in the rectangular radiation electrode 8. As a result, the electrical length is increased by the slit 12, and the resonance of the two frequencies of 900 MHz and 1800 MHz is caused by the change in the width of the radiation electrode 8 generated in the slit 12, and the antenna operates as a two-frequency antenna. The direction in which the intensity of the radiation electric field of PIFA is maximum is the longitudinal direction of the rectangular substrate 9 serving as the ground conductor for both two frequencies.

  A whip antenna will be described with reference to FIG. 9 as another example of a conventional two-frequency antenna. FIG. 9 is a perspective view showing a schematic configuration of an example of a conventional whip antenna, in which 18 is a radiation electrode, 19 is a substrate serving as a ground conductor, and 20 is a power supply terminal. The whip antenna is an antenna having a large protruding portion of the radiation electrode 18 from the substrate 19 and is known as a wide band antenna. As shown in FIG. 9, a rod-shaped radiation electrode 18 and a rectangular grounding are provided. A substrate 19 serving as a conductor is connected to a radiation electrode 18 via a power supply terminal 20 so as to extend in the longitudinal direction of the substrate 19. As a result, the whip antenna resonates at two frequencies of ¼ wavelength and ¾ wavelength, and operates as a two-frequency antenna. By using this whip antenna, a dual-frequency antenna can be easily realized, and the gain of the antenna is also high. The direction in which the intensity of the radiated electric field of the whip antenna is maximized is also the longitudinal direction of the rectangular substrate 19 serving as the ground conductor for both frequencies.

Recently, a technique for suppressing an induced current induced by a linear antenna has been reported. According to this technique, since the induced current is suppressed, the linear antenna can be arranged close to the substrate constituting the ground plane, and the ground conductor and connection conductor on the lower surface of the substrate and the patch on the upper surface are arranged. A resonance circuit composed of conductors is arranged on a ground conductor, and the frequency band in which the induced current can be suppressed is determined by the characteristics of the resonance circuit. By using this, the connection position of the connection conductor with respect to each patch conductor is changed, or the patch conductors constituting the resonance circuit having different resonance characteristics are arranged in two layers above and below to resonate at two frequencies. Has also been reported (see, for example, Patent Document 1).
US Patent 6,483,481

  However, in the conventional PIFA as a two-frequency antenna device, an induced current opposite to the current flowing through the radiation electrode 8 is generated in the ground conductor 9, so that the radiation efficiency of the antenna is significantly reduced and the bandwidth is narrowed. There was a problem.

  On the other hand, in order to alleviate the influence of the induced current, the distance between the radiation electrode 8 and the ground conductor 9 is increased (about 10 mm in a GSM mobile phone), so that GSM and DCS A PIFA having radiation efficiency and bandwidth that can be used in such a system has been realized.

  However, since this PIFA is increased in size, a mobile phone antenna is required to have a low profile, and thus a thinner and wider-band two-frequency antenna device is required.

  In addition, the whip antenna, which is another conventional antenna device that supports two frequencies, requires that the radiation electrode 18 be arranged so as to protrude greatly from the mobile phone, and this configuration significantly impairs the appearance. There is a point. On the other hand, if it is arranged close to the substrate 19 so that the projection of the radiation electrode 18 is eliminated, the radiation efficiency is remarkably reduced due to the induced current flowing through the ground conductor by the substrate 19, and the bandwidth becomes narrow and not practical. There was a problem.

  Furthermore, in the two-frequency antenna device having a structure in which a large number of resonance circuits are arranged in Patent Document 1, although it can support two frequencies, an anti-resonance occurs between the two resonance frequencies. There is a problem that the bandwidth of the frequency at which the current can be suppressed becomes narrow at a certain frequency.

  The present invention has been devised to solve the above-described problems in the prior art, and its purpose is a simpler structure capable of widening each bandwidth while supporting two frequencies. An object of the present invention is to provide a two-frequency antenna device that can handle two frequencies.

  Another object of the present invention is to provide a wireless communication apparatus capable of operating in good response to two frequencies, having the antenna apparatus of the present invention having good characteristics as an antenna apparatus compatible with two frequencies. It is in.

  An antenna device according to the present invention is an antenna device including a frequency selection plate that supports two frequencies with a wide band by configuring a two-frequency resonator structure that suppresses a current flowing in a ground conductor in two orthogonal directions. Thus, the antenna device is compatible with a wide band of two frequencies.

  That is, the antenna device of the present invention includes a ground conductor, a large number of patch conductors arranged in the first and second directions perpendicular to each other along the surface of the ground conductor, the central portion of the patch conductor, and the ground. A first radiation electrode extending in the first direction in the vicinity of the patch conductor side of the frequency selection plate member comprising a connection conductor for electrically connecting the conductor and the second direction; The second radiation electrode is arranged so as to extend along the line.

  Moreover, the antenna device of the present invention is characterized in that, in the above configuration, the patch conductor has a different length with respect to the first and second directions.

  The antenna device according to the present invention is characterized in that, in the above configuration, the patch conductor is rectangular.

  The antenna device according to the present invention is characterized in that the patch conductors have the same length in the first and second directions, and have different arrangement intervals in the first and second directions. To do.

  Moreover, the antenna device of the present invention is characterized in that, in the above configuration, the patch conductor is square.

  The antenna device according to the present invention is characterized in that, in the above configuration, at least one of the first and second radiation electrodes has a meander shape.

  Further, in the antenna device of the present invention, in the above configuration, the frequency selection plate member has the ground conductor formed on the back surface of the substrate made of a dielectric or magnetic material, and the patch conductor formed on the surface of the substrate. The connection conductor is formed so as to penetrate the substrate.

  The wireless communication apparatus of the present invention includes the antenna apparatus of the present invention having any one of the above-described configurations, and at least one of a transmission circuit and a reception circuit connected to wireless signals of two different frequency bands connected thereto. It is characterized by comprising.

  According to the antenna device of the present invention, a ground conductor, a large number of patch conductors arranged in the first and second directions perpendicular to each other along the surface of the ground conductor, the central portion of the patch conductor, and the ground conductor A frequency selection plate member comprising a connection conductor for electrically connecting the frequency selection plate member to the patch conductor side of the frequency selection plate member, the first radiation electrode extending along the first direction, and Since the second radiation electrodes are arranged along the second direction, a large number of patch conductors arranged in the first direction, and the central portion of the patch conductor and the ground conductor are electrically connected. The antenna in the first direction consisting of a set of a frequency selection plate member comprising a connection conductor connected to the first radiation electrode arranged along the first direction is similarly a frequency selection plate. Set of member and second radiation electrode Because the plane of polarization is orthogonal to the antenna in the second direction, the antenna can operate as two antennas that do not interfere with each other, and thus can be reduced in size and can be reduced in size. It can be used as a surface mount antenna.

  According to the antenna device of the present invention, when the patch conductor has a different length with respect to the first and second directions, the inductance component formed by the patch conductor is in the first and second directions. Therefore, it is possible to operate at two different frequencies while keeping the gap between the patch conductors the same.

  Further, according to the antenna device of the present invention, particularly when the patch conductor is rectangular, the effect of decreasing C in the LC resonance of the patch conductor portion occurs, so that the frequency band in which the impedance of the frequency selection plate member is high is widened. Thus, a broadband antenna can be configured.

  According to the antenna device of the present invention, when the patch conductors have the same length in the first and second directions and the arrangement intervals in the first and second directions are different, the patch conductors Since the capacitive components formed by the gaps are different in the first and second directions, it is possible to operate at two different frequencies.

  Also, according to the antenna device of the present invention, when the patch conductor is square in the configuration, the effect of reducing C in the LC resonance of the patch conductor portion occurs, so that the frequency band where the impedance of the frequency selection plate member is high is wide. Thus, a broadband antenna can be configured.

  Further, according to the antenna device of the present invention, when at least one of the first and second radiation electrodes has a meander shape, the antenna device can be configured by arranging the radiation electrodes in a narrow space. Can be reduced in size.

  Further, according to the antenna device of the present invention, the frequency selection plate member is formed such that the ground conductor is formed on the back surface of the substrate made of dielectric or magnetic material, the patch conductor is formed on the surface of the substrate, and penetrates the substrate. When the connection conductor is formed, the wavelength shortening effect by the substrate made of a dielectric or magnetic material can be utilized, so that the antenna can be downsized.

  As described above, according to the antenna device of the present invention, it is possible to realize a low-profile antenna having a wide band and corresponding to two frequencies by including a frequency selection plate having a simple configuration.

  The wireless communication apparatus of the present invention includes the antenna apparatus of the present invention having any one of the above-described configurations, and at least one of a transmission circuit and a reception circuit connected to wireless signals of two different frequency bands connected thereto. Therefore, both of the two frequencies have good antenna characteristics while reducing the height and size of the apparatus, and good radio communication corresponding to two frequencies can be performed.

  Hereinafter, embodiments of a surface-mounted antenna, an antenna device, and a wireless communication device according to the present invention will be described with reference to the drawings.

1A is a perspective view showing an example of an embodiment of an antenna device of the present invention, FIG. 1B is a sectional view in the first direction, and FIG. 1C is a second direction. FIG. In FIG. 1, 1 is a ground conductor, 2 is a plurality of patch conductors arranged in first and second directions perpendicular to each other along the surface of the ground conductor 1, and 3 is a central portion of the patch conductor 2 and the ground conductor 1 Connecting conductors for electrically connecting the ground conductor 1, the patch conductor 2 and the connecting conductor 3 to each other.
Thus, a frequency selection plate member is configured. 4 (4a and 4b) is a first radiation electrode disposed so as to be close to the patch conductor 2 and along the first direction, and 5 (5a and 5b) is also a second electrode close to the patch conductor 2. It is the 2nd radiation | emission electrode arrange | positioned so that it may follow along the direction. These frequency selection plate members and the first and second radiation electrodes 4a, 4b, 5a, 5b constitute the antenna device of the present invention. Reference numeral 6 denotes a first feed line for feeding power to the first radiation electrodes 4a and 4b, and reference numeral 7 denotes a second feed line for feeding power to the second radiation electrodes 5a and 5b.

  As shown in FIG. 1, in the antenna device of the present invention, as shown in FIGS. 1 (a) and 1 (b), a plurality of patch conductors 2 arranged in the frequency selection plate member interfere with each other. It has a periodic structure which is different in two directions orthogonal to each other, that is, in the first direction and the second direction. As a result, a frequency selection plate that resonates at the frequency F1 by the electric field in the first direction and a frequency selection plate that resonates at the frequency F2 by the electric field in the second direction are obtained.

  The first radiating electrodes 4a and 4b are arranged so as to be close to the surface of the patch conductor 2 and along the first direction, and the second radiating electrodes 5a and 5b are close to the surface of the patch conductor 2. The first radiation electrodes 4a and 4b are arranged in a direction orthogonal to the second direction. In this way, the first radiation electrodes 4a and 4b and the second radiation electrodes 5a and 5b are kept orthogonal to each other, so that the first radiation electrodes 4a and 4b and the second radiation electrodes 5a and 5b It is possible to effectively prevent deterioration of antenna characteristics due to interference between the two.

  Next, the operation of the frequency selection plate member in the antenna device of the present invention will be described using the equivalent circuit diagram shown in FIG. In the equivalent circuit diagram shown in FIG. 2, when compared with the antenna device of the present invention shown in FIG. 1, the connection conductor 3 connecting the common ground conductor 1 and each patch conductor 2 becomes an inductance L2, and the patch conductor 2 The conductor portion from the location where the connection conductor 3 is connected to the end of the patch conductor 2 becomes the inductance L1, and the capacitance generated in the gap between the adjacent patch conductors 2 becomes C. At this time, the operating frequency f of the frequency selection plate member is the product of 1 / (2π) and the inverse of the square root of 2 × (L1 + L2) × C (f = 1 / [2π × √ {2 × (L1 + L2) × C }])).

  In the frequency selection plate member in the antenna device of the present invention, as shown in a plan view in FIG. 3, a plurality of rectangular patch conductors 2 having different lengths in the first and second directions are arranged vertically and horizontally. In the case where the first direction and the second direction are different from each other, the frequency selection plate member that operates at different frequencies in the first direction and the second direction is obtained because L1 is different between the first direction and the second direction.

  Further, as shown in the plan view of FIG. 4, the patch conductor 2 is a square patch conductor 2 having the same length in the first and second directions, and the pitch P1 of the periodic structure in the first direction is When the pitch P2 of the periodic structure in the second direction is different, that is, when the gap between the adjacent patch conductors 2 is different between the first direction and the second direction, the first direction and the second direction And the capacitance C is different, and similarly, the frequency selection plate member operates at different frequencies in the first direction and the second direction.

  According to the antenna device of the present invention, for example, on the upper surface of a substrate made of a dielectric having a thickness of 2 mm and a relative dielectric constant of 4.7, 9.6 mm and 14.6 respectively in a first direction and a second direction orthogonal to each other. A rectangular patch conductor 2 having a length of mm is arranged with an interval of 0.4 mm in both the first and second directions, a ground conductor 1 is arranged on the lower surface of the dielectric substrate, and the center of each patch conductor 2 on the upper surface is arranged. A connection conductor 3 is formed so as to be electrically connected to the grounding conductor 1 to form a frequency selection plate member. The frequency selection plate member has a distance of 1 mm from the upper surface on which the patch conductor 2 is arranged in the first direction. A second dipole antenna having a length of 35 mm in the second direction at a distance of 1 mm from the upper surface where the first radiation electrodes 4a and 4b of the dipole antenna having a length of 30 mm and the patch conductor 2 of the frequency selection plate member are disposed. Radiation electrodes 5a and 5b When the configured antenna device in the first radiation electrode 4a of the first direction, 4b in the 5 GHz, the second radiation electrode 5a in the second direction, 5b is assumed to operate respectively at 4 GHz. At this time, the bandwidth is not different from the conventional dipole antenna, the frequency selection plate member functions as a reflector, and the radiation intensity above the frequency selection plate member is almost twice that of the conventional dipole antenna.

  In the antenna device of the present invention, the frequency selection plate member includes the ground conductor 1 formed on the back surface of the substrate made of a dielectric or magnetic material, the patch conductor 2 formed on the surface of the substrate, and the connection conductor passing through the substrate. 3 is preferably formed.

  The substrate at this time has a plate-like shape made of a dielectric or magnetic material, and a magnetic material is preferable to a dielectric material in order to increase the operating frequency of the frequency selection plate member. Care should be taken because reducing the antenna gain may be problematic due to the large loss at the antenna. As the dielectric material, for example, the dielectric material is produced using ceramics obtained by pressure-molding and firing a powder made of a dielectric material mainly composed of alumina (relative permittivity εr: 9.6). The substrate may be a composite material of ceramic and resin as a dielectric, or a magnetic material such as ferrite. Other examples of the magnetic material include YIG (yttria, iron, garnet), Ni-Zr compounds, Ni-Co-Fe compounds, and the like.

  When the substrate is made of a dielectric, when εr exceeds 30, although the size can be reduced, the bandwidth in which the frequency selection plate member operates becomes narrow, so the bandwidth as the antenna device becomes too small, and the antenna There is a tendency that it does not fulfill its characteristics. Therefore, when the substrate is made of a dielectric, it is desirable to use a dielectric material having a relative dielectric constant εr of 30 or less. Examples of such a dielectric material include ceramic materials such as alumina ceramics and zirconia ceramics, and resin materials such as tetrafluoroethylene and glass epoxy.

  When the substrate is made of a magnetic material, the magnetic material generally has a large tan δ, which tends to act as a radio wave absorber at the resonance frequency of the frequency selection plate member, thereby reducing the efficiency of the antenna. Therefore, when the substrate is made of a magnetic material, it is desirable to use a magnetic material having a small tan δ. Examples of such a magnetic material include YIG (yttria, iron, garnet), Ni—Zr compounds, Ni—Co—Fe compounds, and the like.

  The patch conductor 2, the first radiating electrode 4 (4a, 4b) and the second radiating electrode 5 (5a, 5b) and the first feeding line 6 and the second feeding line 7 are made of, for example, aluminum, copper, nickel, It is formed of a metal whose main component is silver, palladium, platinum, or gold. In order to form each pattern with these metals, conductors having a desired pattern shape can be formed by various printing methods, thin film forming methods such as vapor deposition methods and sputtering methods, metal foil bonding methods, and plating methods. The layer may be formed on a predetermined side surface of the substrate.

  The ground conductor 1 may be formed of a conductor used for a normal circuit board such as copper or silver, and the patch conductor 2, the first radiation electrode 4 (4a, 4b), and the second radiation electrode 5 (5a). , 5b) may be formed of the same metal.

  The wireless communication device (not shown) of the present invention includes at least one of the antenna device of the present invention as described above and a transmission circuit and a reception circuit connected to the wireless signals of two different frequency bands connected thereto. One. Further, in order to enable wireless communication as desired, the wireless signal processing circuit may be connected to the antenna device, the transmission circuit, or the reception circuit, and various other configurations may be adopted.

  According to such a radio communication apparatus of the present invention, the antenna apparatus of the present invention as described above and at least one of a transmission circuit and a reception circuit connected to the radio signals of two different frequency bands connected thereto are provided. Thus, the single antenna device that can be reduced in height and size can be used for a two-frequency wireless communication device that is compatible with two different frequencies and that is small and highly functional.

  Note that the antenna device and the wireless communication device of the present invention are not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the first and second radiation electrodes 4a, 4b, 5a, 5b in the antenna device of the present invention are not limited to a linear shape, and may be a meander shape or a helical shape as shown in a plan view in FIG. The direction of the radiated electric field only needs to coincide with the corresponding direction (first or second direction) of the frequency selection plate member.

  Further, the first radiation electrode 4 (4a, 4b) and the second radiation electrode 5 (5a, 5b) disposed above the frequency selection plate member do not need to intersect as shown in FIG. For example, the first radiation electrode 4 and the second radiation electrode 5 may be arranged in an L shape as shown in a perspective view in FIG. 6, and the first radiation electrode as shown in the perspective view in FIG. 4 and the second radiation electrode 5 may be arranged in a T-shape. In FIGS. 6 and 7, reference numeral 13 denotes a frequency selection plate member.

(A)-(c) is a perspective view showing an example of an embodiment of an antenna device of the present invention, a sectional view in the 1st direction, and a sectional view in the 2nd direction, respectively. It is an equivalent circuit diagram for demonstrating operation | movement of the frequency selection board member in the antenna apparatus of this invention. It is a top view which shows the example of the frequency selection board member in the antenna apparatus of this invention. It is a top view which shows the other example of the frequency selection board member in the antenna apparatus of this invention. It is a top view which shows the example of the 1st or 2nd radiation electrode in the antenna apparatus of this invention. It is a perspective view which shows the other example of embodiment of the antenna apparatus of this invention. It is a perspective view which shows the further another example of embodiment of the antenna apparatus of this invention. It is a perspective view which shows schematic structure of the example of the plate-shaped inverted-F antenna (PIFA) which is the conventional 2 frequency corresponding | compatible antenna. It is a perspective view which shows schematic structure of the example of the conventional whip antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ground conductor 2 ... Patch conductor 3 ... Connection conductor 4, 4a, 4b ... 1st radiation electrode 5, 5a, 5b ... 2nd radiation electrode 6 ... 1st Feed line 7 ... second feed line
13 Frequency selection plate

Claims (8)

A ground conductor, a plurality of patch conductors arranged in the first and second directions perpendicular to each other along the surface of the ground conductor, and a connection for electrically connecting the central portion of the patch conductor and the ground conductor A first radiation electrode extending along the first direction and a second radiation extending along the second direction adjacent to the patch conductor side of the frequency selection plate member made of a conductor; An antenna device comprising an electrode. The antenna device according to claim 1, wherein the patch conductors have different lengths with respect to the first and second directions. The antenna device according to claim 2, wherein the patch conductor is rectangular. The antenna device according to claim 1, wherein the patch conductors have the same length in the first and second directions and have different arrangement intervals in the first and second directions. The antenna device according to claim 4, wherein the patch conductor is a square. The antenna device according to claim 1, wherein at least one of the first and second radiation electrodes has a meander shape. In the frequency selection plate member, the ground conductor is formed on the back surface of a substrate made of a dielectric or magnetic material, the patch conductor is formed on the surface of the substrate, and the connection conductor is formed through the substrate. The antenna device according to claim 1, wherein: 8. An antenna device according to claim 1, and at least one of a transmission circuit and a reception circuit connected to radio signals in two different frequency bands connected thereto. Wireless communication device.

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