JP2010130100A - Multiband antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a built-in multiband antenna apparatus for a portable terminal device. <P>SOLUTION: The multiband antenna apparatus 110 includes: a ground plate 30; and an antenna unit. The ground plate 30 includes a feed point. The antenna unit is disposed adjacent to an end of the ground plate 30. The antenna unit includes: a dielectric resin piece 60; a first reverse L-shaped antenna element 210 which has one end connected to the feed point and the other end formed in a helical shape; a second antenna element 220 which is a non-fed parasitic element and which has one end short-circuited to be capacitively coupled to the first antenna element 210; a magnetic piece 40; and a dielectric piece 50. The first antenna element 210 and second antenna element 220 are formed on a surface of the dielectric resin piece 60, the magnetic piece 40 is loaded to a portion where current distribution of the first antenna element 210 is high, and the dielectric piece 50 is loaded to a portion where current distribution of the first antenna element 210 is low. The antenna element 110 can achieve a small-sized and excellent electric performance by using wavelength shortening effect of the magnetic piece 40 and dielectric piece 50. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multiband antenna device, and more particularly to a built-in multiband antenna device for a terminal that can easily adjust electrical characteristics, has a small mounting volume, and can realize high electrical performance.

  In recent years, with the increase in the number of functions and the need for international roaming, mobile terminals have a plurality of cellular systems as shown in Table 1 and other wireless systems (GPS, Bluetooth (registered trademark), RFID, etc.) ) Is becoming necessary.

  In view of such a situation, development of an antenna device that can be applied to a plurality of systems is underway. Such antenna devices are roughly classified into the following two types.

  The first type is an antenna devised to generate a multi-resonance mode by branching, capacitively coupling, or short-circuiting a plurality of antenna elements. As an example of this type of antenna, there is a multi-frequency band antenna described in Patent Document 1. The antenna described in Patent Document 1 is configured by connecting the first and second antenna elements to the same feeding point, and operates independently in different frequency bands without causing mutual interference. .

The second type is designed from the terminal side by designing a control circuit using a switch in the vicinity of the feeding part, or by attaching an active element such as a varicap diode or PIN diode in the middle of the feeding part circuit or antenna element. It is a tunable antenna that can obtain a wide-band performance by varying the resonance frequency by voltage control. Examples of this type of antenna include an antenna device described in Patent Document 2 and an antenna structure described in Patent Document 3. All of these realize multiband by using circuit elements.
JP 2007-288649 A JP 2007-143063 A JP 2005-150937 A

  According to the above-described conventional two types of multiband antenna devices, it is possible to make a terminal compatible with a plurality of systems. However, the antenna device formed of the first type, that is, a plurality of antenna elements, requires a certain installation space. From the viewpoint of portability and design, the interior of a terminal that tends to be miniaturized. It is often difficult to install.

In addition, the second type antenna that realizes a wide band by varying the resonance frequency by voltage control from the circuit side also has a problem of low efficiency due to occurrence of insertion loss. In the case of this type of antenna, the design difficulty of the antenna and the control circuit becomes high in order to make many resonance frequencies variable, and the number of parts increases because many circuit elements are required. Increase in process and cost.
Under such circumstances, there is a need for a built-in multiband antenna device for a terminal that can easily adjust electrical characteristics, has a small mounting volume, and can realize high performance.

  In order to solve the above-described problems, the present invention provides a built-in multiband antenna device for a portable terminal, which includes a ground plane provided with a feeding point, and an antenna portion disposed adjacent to an end of the ground plane. The antenna unit includes a dielectric resin piece, a first antenna element having an inverted L shape in which one end is connected to a feeding point and the other end is formed in a helical shape, and a parasitic element that is parasitic and has one end A second antenna element that is short-circuited and capacitively coupled to the first antenna element; a magnetic piece; and a dielectric piece; the first antenna element and the second antenna element are formed on the surface of the dielectric resin piece; The magnetic piece is loaded at a location where the current distribution of the first antenna element is high, and the dielectric piece is loaded at a location where the current distribution of the first antenna element is low. By having such a configuration, the multiband antenna device of the present invention can realize a wide band electrical performance corresponding to the frequency bands described in Table 1 above.

  In the multiband antenna device of the present invention, the other end of the first antenna element is wound on the surface of the dielectric piece to form a helical shape. By having such a configuration, the multiband antenna device of the present invention can achieve both miniaturization and good electrical performance.

  The present invention further provides a built-in multiband antenna device for a portable terminal, comprising: a ground plane provided with a feeding point; and an antenna section arranged adjacent to an end of the ground plane, Includes a printed circuit board piece, a first antenna element, and a second antenna element capacitively coupled to the first antenna element. The first antenna element is formed on the printed circuit board piece with one end connected to a feeding point. The other end of the first antenna line and one end of the first conductive line wound on the surface of the first dielectric piece are joined to each other to form an inverted L shape. Is formed by joining the other end of the second antenna line formed on the printed circuit board and the one end of the second conductive line formed on the surface of the second dielectric piece. Magnetic piece is loaded near the feeding pointBy having such a configuration, the multiband antenna device of the present invention can contribute to facilitating the manufacturing process and reducing the manufacturing cost.

  According to the present invention, a small multiband antenna device can be realized without using circuit elements with a small number of antenna elements. This multiband antenna device can secure all cellular frequency bands of GSM850 / 900, DCS / PCS and UMTS, and both VSWR and radiation efficiency are wideband and high performance. Therefore, it is possible to contribute to the realization of a small portable terminal that can support a plurality of systems.

Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a first embodiment of a multiband antenna device according to the present invention. 1A shows the front side of the antenna device 110, and FIG. 1B shows the back side of the antenna device 110. FIG. As shown in the figure, the antenna device 110 includes an antenna unit having an inverted L-shaped first antenna element 210, a second antenna element 220, a dielectric resin piece 60, a magnetic piece 40, and a dielectric piece 50. And the ground plane 30, and the antenna portion is disposed adjacent to one of the relatively short ends of the ground plane 30.

  2 and 3 show only the antenna portion in an enlarged manner. One end of the first antenna element 210 is connected to a feeding point, and the other end is formed in a helical shape. On the other hand, one end of the second antenna element 220 is short-circuited. The second antenna element 220 is a parasitic element (parasite element) with no power supply, and the first antenna element 210 and the second antenna element 220 are capacitively coupled to each other at the positions L1 and L2 shown in FIG.

  As for the overall size of the antenna unit, the symbol L × W × H in FIG. 2 is, for example, 10 mm × 45 mm × 2 mm (0.9 cc). Moreover, the ground plane 30 shall have a magnitude | size of 100 mm x 45 mm, for example. Ferrite can be used as the magnetic piece 40 and ceramic can be used as the dielectric piece 50. For the dielectric resin piece 60, ABS (acrylonitrile butadiene styrene) can be used.

  The tip portion of the first antenna element 210 is wound on the surface of the dielectric piece 50 to form a helical shape. The spacing and the number of turns of the helical-shaped winding are arbitrarily designed in relation to the resonance frequency of 0.8 GHz. In addition, the magnetic piece 40 is loaded on the base portion of the first antenna element 210 in the vicinity of the feeding point.

  In this antenna device 110, the ferrite piece 40 having a size of 5 mm × 6 mm × 2 mm (0.06 cc) and material characteristics of εr = 13 tan δ = 0.01 and μr = 3 tan δ = 0.05 is used. is doing. As the ceramic piece 50, a ceramic piece having a size of 10 mm × 5 mm × 2 mm (0.1 cc) and a material characteristic of εr = 60 tan δ = 0.06 is used. However, these material characteristics and dimensions can be arbitrarily designed according to the operating frequency and band of the antenna to be manufactured.

  In developing the multiband antenna device 110, the inventor first developed a single band antenna device in which a magnetic piece and a dielectric piece are effectively loaded. FIGS. 4A and 4B show the single band antenna device 10. The antenna device 10 is configured by disposing an antenna portion having an antenna element 20, a magnetic piece 40, and a dielectric piece 50 adjacent to one of relatively short ends of the ground plane 30. As shown in the enlarged view of the antenna portion in FIG. 4B, a magnetic piece 40 is loaded at the base portion near the feeding point of the antenna element 20, and the tip portion is wound around the dielectric piece 50 to form a helical shape. Form.

  FIG. 5 shows the current distribution in the antenna portion. The dark portion indicates that the current distribution is low, and the thin portion indicates that the current distribution is high. It can be confirmed that the current distribution is low at the tip portion of the antenna element 20 and the current distribution is high at the root portion. In consideration of the wavelength shortening effect of the magnetic material and the dielectric material, the loading of the dielectric material is effective at a location where the current distribution is low, and the loading of the magnetic material is effective at the location where the current distribution is high. The dielectric pieces 50 are loaded on the root portion and the tip portion of the antenna element, respectively.

  FIG. 6 shows the VSWR performance obtained with the single-band antenna device 10 together with the VSWR performance of the inverted L antenna and the inverted F antenna. According to FIG. 6, it can be seen that the VSWR value is improved by about 3 in the antenna device 10 as compared with the inverted L antenna. Further, the frequency ratio bandwidth in which the VSWR value is smaller than 3 is also improved by about 15% as compared with the inverted F antenna.

  The multiband antenna device 110 of the present invention has been developed based on such a single band antenna device 10. That is, by loading the magnetic piece 40 and the dielectric piece 50 at appropriate positions in accordance with the case of the single-band antenna device 10 and making the design efficient, the Q value can be increased or decreased by downsizing the antenna device. Impedance can be prevented, and increase in capacitive coupling between elements and the ground plane 30 can be prevented.

  Here, FIG. 7A shows the VSWR characteristics of the multiband antenna device 110. The resonance characteristics of the 2 GHz band are newly maintained while maintaining the VSWR characteristics of the single band antenna device 10 in the 0.8 GHz band. Have been gained. For the 2 GHz band, the second antenna element 220, which is a parasitic element, is disposed close to the first antenna element 210, and resonance characteristics are obtained by capacitive coupling. As shown in the figure, in the antenna device 110, the frequency band of 0.824 to 0.96 GHz used in GSM850 / 900 and the frequency band of 1.71 to 2.17 GHz used in DCS / PCS and UMTS are 3 Smaller than VSWR can be satisfied.

  FIG. 7B shows the radiation efficiency of the antenna device 110 as a relative ratio with the radiation efficiency of the standard dipole antenna as 100. As shown in the figure, as a result of measuring 6 points in the 0.8 GHz band and 10 points in the 2 GHz band at equal intervals, a value of 45% or more was obtained in the entire measured band. This can be said to be a good performance considering that the antenna is a small antenna for incorporating a terminal with a very small volume.

Next, a second embodiment of the multiband antenna device according to the present invention will be described.
As described above, the antenna device 110 according to the first embodiment has good performance and can be suitably used as a built-in antenna device for a portable terminal. However, the antenna device 110 is a material composite type antenna using an ABS resin, a ferrite material, and a ceramic material, and problems remain in terms of manufacturing method and manufacturing cost when commercialized.
The multiband antenna device according to the second embodiment can solve this problem and has a structure as shown in FIG. FIG. 8A is an overall view of the multiband antenna device 120, and FIGS. 8B and 8C are enlarged views of the antenna unit.

  In antenna device 120, a section of FR-4 material (glass epoxy substrate), which is a printed circuit board (PWB) material, is disposed adjacent to one of the relatively short ends of ground plane 30. A first antenna line 210a and a second antenna line 220a are formed in a copper foil pattern on the material surface of the FR-4 material. A helical first conductive line 210 b is formed on the surface of the ceramic material piece 50, and a second conductive line 220 b is formed on the surface of another ceramic material piece 70.

  The ground plane 30 has a size of, for example, 100 mm × 50 mm, and the mounting size of the antenna unit configured by surface-mounting the above-described components on the FR-4 material is, for example, 10 mm × 5 mm × 2 mm (FR-4 Do not take into account the volume of the material part). The ceramic piece 50 has a size of, for example, 5 mm × 13 mm × 2 mm (0.13 cc) and a material constant of εr = 60 tan δ = 0.06, and the ceramic piece 70 has a size of, for example, 1.5 mm × 16 mm × 2 mm. (0.05 cc), the material constant is εr = 60 tan δ = 0.06, the ferrite piece 40 is, for example, 5 mm × 5 mm × 1 mm (0.025 cc) in size, and the material constant is εr = 13 tan δ = 0.01. , Μr = 60 tan δ = 0.05.

  The ceramic pieces 50 and 70 are surface-mounted on the FR-4 material 60 so that the first conductive line 210b and the second conductive line 220b can be electrically connected to the first antenna line 210a and the second antenna line 210b, respectively. And the ferrite piece 40 is mounted in the vicinity of the feeding of the first antenna line 210a. The mounting position of each component is a portion surrounded by a broken line in FIG.

  When the ceramic piece 50 is mounted on the FR-4 material 60, an antenna element corresponding to the first antenna element 210 of the antenna device 110 is formed by the first antenna line 210a and the first conductive line 210b. When the ceramic piece 70 is mounted, an antenna element corresponding to the second antenna element 220 of the antenna device 110 is formed by the second antenna line 220a and the second conductive line 220b. The antenna element composed of the second antenna line 220a and the second conductive line 220b is a parasitic element as in the antenna device 110, and capacitively coupled to the antenna element composed of the first antenna line 210a and the first conductive line 210b. Is done.

  As described above, the ceramic parts 50 and 70 having the conductive lines formed on the surface and the ferrite part 40 can be chipped and mounted on the FR-4 material by using the mounting technique. Therefore, the multiband of the second embodiment is used. The antenna device 120 has good productivity and can bring great merit in terms of cost.

  FIG. 9A shows the VSWR characteristics of the multiband antenna device 120, and FIG. 9B shows the relative radiation efficiency (the standard dipole antenna is 100). As shown in the figure, similarly to the antenna device 110 according to the first embodiment, the antenna device 120 also uses the frequency band of 0.824 to 0.96 GHz used in GSM850 / 900, and is used in DCS / PCS and UMTS. VSWR smaller than 3 is satisfied in the frequency band of 71 to 2.17 GHz. Further, the radiation efficiency is 50% or more in the 0.8 GHz band and 40% or more in the 2 GHz band, and can provide good performance as a small antenna.

  The preferred embodiment of the present invention has been described above, but the characteristics of the terminal built-in antenna change depending on various conditions such as the size of the ground plane and the arrangement of components inside the portable terminal, and the material constant is arbitrarily changed and designed. Is possible.

  In the future, mobile terminal devices will be required to be global terminals, and a multiband satisfying performance in the cellular frequency band of GSM / DCS / PCS / UMTS (IMT2000) will be required. In addition, a plurality of wireless systems, including those for RF-ID, GPS, Bluetooth (registered trademark), TV-FM reception, etc., tend to increase and become multifunctional. By using the antenna device according to the present invention, a small antenna satisfying a plurality of cellular frequency bands can be realized with one antenna device.

The whole figure of the front side and back side of the multiband antenna device by a first embodiment of the present invention. The enlarged view which shows an antenna part. The enlarged view which shows an antenna part. (A) is a general view of a single band antenna device, (b) is an enlarged view showing an antenna section. The figure which shows the electric current distribution in the antenna element of a single band antenna apparatus. The figure which shows the electrical performance of a single band antenna apparatus. (A) is a figure which shows the VSWR characteristic of the multiband antenna device by 1st embodiment of this invention, (b) is a figure which shows relative radiation efficiency. (A) is a general view of a multiband antenna device according to a second embodiment of the present invention, and (b) and (c) are enlarged views showing an antenna section. (A) is a figure which shows the VSWR characteristic of the multiband antenna device by 2nd embodiment of this invention, (b) is a figure which shows relative radiation efficiency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Antenna apparatus 210 1st antenna element 220 2nd antenna element 30 Ground plane 40 Magnetic body piece 50 Dielectric piece 60 Dielectric resin piece

Claims (3)

A ground plane provided with a feeding point, and an antenna portion disposed adjacent to an end of the ground plane,
The antenna unit is
A dielectric resin piece;
An inverted L-shaped first antenna element having one end connected to the feeding point and the other end formed in a helical shape;
A parasitic element that is parasitic, and is short-circuited at one end and capacitively coupled to the first antenna element;
A magnetic piece,
A dielectric piece;
The first antenna element and the second antenna element are formed on a surface of the dielectric resin piece,
The magnetic piece is loaded at a location where the current distribution of the first antenna element is high,
The built-in multiband antenna device for a portable terminal, wherein the dielectric piece is loaded at a location where the current distribution of the first antenna element is low. The multiband antenna device according to claim 1,
The multi-band antenna device according to claim 1, wherein the first antenna element has the other end wound on the surface of the dielectric piece to form the helical shape. A ground plane provided with a feeding point, and an antenna portion disposed adjacent to an end of the ground plane,
The antenna unit includes a printed board piece, a first antenna element, and a second antenna element capacitively coupled to the first antenna element,
The first antenna element has one end connected to the feed point and the other end of the first antenna line formed on the printed board piece, and the first conductive element having one end wound on the surface of the first dielectric piece. Joined to the other end of the line, formed in an inverted L shape,
The second antenna element has one end short-circuited to join the other end of the second antenna line formed on the printed board piece and one end of the second conductive line formed on the surface of the second dielectric piece. Formed,
A built-in multiband antenna device for a portable terminal, wherein a magnetic piece is loaded in the vicinity of the feeding point of the first antenna line.

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