JP2012105125A - Antenna for mobile terminal and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized antenna for a mobile terminal, capable of securing sufficient isolation, and a method of manufacturing the same.SOLUTION: An antenna 20 for a mobile terminal, which is one embodiment of the present invention, includes a ground plate 1 comprising a conductor and a passive element 4. A monopole antenna element 2a is connected with the ground plate 1 through a feeding point 3a. A monopole antenna element 2b is connected with the ground plate 1 through a feeding point 3b. Concentration constant elements 6a and 6b are connected with the ground plate 1 at one end and are connected with the passive element 4 at the other end. The concentration constant element 6a is connected with the ground plate 1 and the passive element 4 at a position closer to the monopole antenna element 2a than the concentration constant element 6b. The concentration constant element 6b is connected with the ground plate 1 and the passive element 4 at a position closer to the monopole antenna element 2b than the concentration constant element 6a.

Description

  The present invention relates to an antenna and a manufacturing method thereof, and more particularly to an antenna for a mobile terminal and a manufacturing method thereof.

  With the recent development of wireless communication technology, the number of wireless systems mounted on mobile terminals is increasing. Furthermore, in order to improve communication speed, it is required to support multi-antenna technologies such as diversity and MIMO (Multiple Input Multiple Output). For this reason, the number of antennas mounted on portable terminals is increasing.

  On the other hand, since the size of the portable terminal is limited, it is necessary to arrange the antennas at a narrow interval. As a result, it has become difficult to ensure isolation between antennas. If sufficient isolation cannot be secured, there arises a problem that characteristic deterioration or destruction occurs due to interference between wireless systems.

  In a normal antenna device, a method of connecting antenna elements with a conductor is used to ensure isolation (Patent Document 1 or 2). In addition, in order to improve isolation, a method of providing an isolation element is known (Patent Documents 3 to 6). Furthermore, in order to improve isolation, a method of connecting a reactance element to a parasitic antenna element is known (Patent Document 7).

JP 2009-206847 A Special table 2010-525680 JP 2007-97167 A JP 2009-246560 A JP 2009-33548 A JP 2008-17047 A JP 2008-211586 A

  However, the inventor has found that the above method has the following problems. In the methods disclosed in Patent Documents 1 and 2, adjustment of characteristics is realized by changing the length, connection position, and the like of the bridge element. As a result, there is a problem that the distance between antennas and the antenna shape are limited.

  Further, the methods disclosed in Patent Documents 3 to 6 have a problem that the size of the isolation element is relatively large and the terminal size is increased. In the method disclosed in Patent Document 7, there is a problem that the arrangement of the antenna elements and the parasitic antenna elements is limited to a column.

  The present invention has been made in view of the above. An object of the present invention is to provide a small portable terminal antenna capable of ensuring sufficient isolation and a method for manufacturing the same.

  An antenna for a mobile terminal which is one embodiment of the present invention includes a ground plate made of a conductor, a parasitic element, a first antenna element connected to the ground plate through a first feeding point, and a second antenna A second antenna element connected to the outer edge of the ground plate via a feeding point, and first and second lumped constants having one end connected to the ground plate and the other end connected to the parasitic element. And the first lumped constant element is connected to the ground plate and the parasitic element at a position closer to the first antenna element than the second lumped constant element, The lumped constant element is connected to the ground plate and the parasitic element at a position closer to the second antenna element than the first lumped constant element.

  In a method for manufacturing an antenna for a portable terminal which is one embodiment of the present invention, a first antenna element is connected to a ground plate made of a conductor via a first feeding point, and a second antenna element is connected to a second antenna element. Connect to the ground plate via a feeding point, connect one end of the first lumped constant element to the ground plate at a position closer to the first antenna element than the second lumped constant element, and connect the other end to the ground plate One end of the second lumped constant element is connected to the ground plate at a position closer to the second antenna element than the first lumped constant element, and the other end is connected to the parasitic element. To connect with.

  ADVANTAGE OF THE INVENTION According to this invention, the small portable terminal antenna which can ensure sufficient isolation, and its manufacturing method can be provided.

1 is a top view showing a configuration of a mobile terminal antenna according to a first exemplary embodiment; 3 is a graph showing frequency dependence of S parameters in the portable terminal antenna according to the first exemplary embodiment; It is a graph which shows the frequency dependence of S parameter at the time of providing a capacitor | condenser and a parasitic element in the antenna for portable terminals (comparative example). FIG. 6 is a top view illustrating a configuration of a mobile terminal antenna according to a second exemplary embodiment. FIG. 6 is a top view showing a configuration of a mobile terminal antenna according to a third exemplary embodiment. FIG. 6 is a top view showing a configuration of a mobile terminal antenna according to a fourth exemplary embodiment. FIG. 10 is a top view illustrating a configuration of a mobile terminal antenna according to a fifth exemplary embodiment;

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings, similar constituent elements are denoted by the same reference numerals, and redundant description is omitted as appropriate.

Embodiment 1
First, the portable terminal antenna according to the first exemplary embodiment of the present invention will be described. FIG. 1 is a top view showing the configuration of the mobile terminal antenna 10 according to the first exemplary embodiment. As shown in FIG. 1, the mobile terminal antenna 10 includes a ground plate 1, monopole antenna elements 2a and 2b, feeding points 3a and 3b, parasitic elements 4, and capacitors 5a and 5b. FIG. 1 is a view when the main surface of the ground plate 1 is viewed from above.

  The ground plate 1 is composed of a conductor corresponding to the substrate of the mobile terminal. On the ground plate 1, monopole antenna elements 2a and 2b, feeding points 3a and 3b, parasitic element 4, and capacitors 5a and 5b are arranged. The monopole antenna elements 2a and 2b have a folded shape.

  Monopole antenna elements 2a and 2b are connected to the outer edge of ground plate 1 via feed points 3a and 3b, respectively. The parasitic element 4 is disposed between the monopole antenna elements 2a and 2b. In this case, the parasitic element 4 is arranged such that its longitudinal direction is parallel to a line connecting the monopole antenna elements 2a and 2b. The parasitic element 4 may be arranged on a line whose longitudinal direction connects the monopole antenna elements 2a and 2b.

  Both ends of the parasitic element 4 are connected to the ground plate 1 via capacitors 5a and 5b, respectively. That is, the capacitor 5a is connected to the ground plate 1 and the parasitic element 4 at a position closer to the monopole antenna element 2a than the capacitor 5b. Capacitor 5b is connected to ground plate 1 and parasitic element 4 at a position closer to monopole antenna element 2b than capacitor 5a.

  Next, the operation of the mobile terminal antenna 10 will be described. FIG. 2 is a graph showing the frequency dependence of the S parameter in the mobile terminal antenna 10. FIG. 3 is a graph showing the frequency dependence of the S parameter when the mobile terminal antenna is not provided with a capacitor and a parasitic element (comparative example). The S parameter S11 represents the reflection coefficient of the antenna of the monopole antenna element 2a or 2b. The S parameter S21 represents the mutual coupling between the monopole antenna elements 2a and 2b.

  In the comparative example, as shown in FIG. 3, the S parameter S21 tends to increase near the center frequency. Therefore, the interference between the monopole antenna elements 2a and 2b is increased, and it is difficult to ensure sufficient isolation.

  On the other hand, in the mobile terminal antenna 10, as shown in FIG. 2, the S parameter S11 is minimized and the S parameter S21 is minimized near the center frequency. That is, the mobile terminal antenna 10 can ensure isolation while realizing antenna matching near the center frequency.

  The frequency, bandwidth, or amount of improvement for improving isolation is to change the capacitance and spacing of the capacitors 5a and 5b, the length and thickness of the parasitic element 4, or the distance between the parasitic element 4 and the ground plate 1. Can be adjusted as appropriate. For example, the length of the parasitic element 4 is one tenth of the wavelength.

  Therefore, according to this configuration, the isolation between the monopole antenna elements can be easily improved only by adding a parasitic element and a capacitor. Therefore, according to this configuration, it is possible to provide a small portable terminal antenna capable of ensuring sufficient isolation and a manufacturing method thereof.

Embodiment 2
Next, an antenna according to the second embodiment of the present invention will be described. FIG. 4 is a top view of the configuration of the mobile terminal antenna 20 according to the second embodiment. As shown in FIG. 4, the portable terminal antenna 20 is obtained by replacing the capacitors 5a and 5b of the portable terminal antenna 10 according to the first embodiment with lumped constant elements 6a and 6b, respectively. The other configuration of the mobile terminal antenna 20 is the same as that of the mobile terminal antenna 10, and thus description thereof is omitted.

  The lumped constant elements 6a and 6b can be constituted by, for example, an inductor or a combination of an inductor and a capacitor. Further, the parasitic element 4 and the lumped constant elements 6a and 6b are not limited to the vicinity of the feeding points 3a and 3b but can be arranged at arbitrary positions.

  According to this configuration, the isolation between the monopole antenna elements can be easily improved just by adding a parasitic element and a lumped constant element, similarly to the mobile terminal antenna 10 according to the first embodiment. . Therefore, according to this configuration, it is possible to provide a small portable terminal antenna capable of ensuring sufficient isolation and a manufacturing method thereof.

Embodiment 3
Next, an antenna according to a third embodiment of the present invention will be described. FIG. 5 is a top view of the configuration of the mobile terminal antenna 30 according to the third embodiment. As shown in FIG. 5, the mobile terminal antenna 30 has a configuration in which a lumped constant element 6c is added to the mobile terminal antenna 20 according to the second embodiment. The lumped constant element 6c is connected in parallel to the lumped constant elements 6a and 6b. Since the other configuration of the mobile terminal antenna 30 is the same as that of the mobile terminal antenna 20, the description thereof is omitted.

  The number of lumped constant elements connected in parallel is not limited to three and can be any number. Further, the connection position between the lumped constant element and the parasitic element 4 is not limited to both ends of the parasitic element, and can be any position of the parasitic element.

  According to this configuration, even when a lumped element is added, isolation between monopole antenna elements can be easily improved as in the first and second embodiments. Therefore, according to this configuration, it is possible to provide a small portable terminal antenna capable of ensuring sufficient isolation and a manufacturing method thereof.

Embodiment 4
Next, an antenna according to a fourth embodiment of the present invention will be described. FIG. 6 is a top view of the configuration of the mobile terminal antenna 40 according to the fourth embodiment. As shown in FIG. 6, in the mobile terminal antenna 40, the parasitic element 4 of the mobile terminal antenna 20 according to the second embodiment is divided into parasitic elements 4a and 4b. A lumped element 6d is connected in series between the parasitic elements 4a and 4b. Since the other configuration of the mobile terminal antenna 40 is the same as that of the mobile terminal antenna 20, the description thereof is omitted.

  That is, the lumped constant element is not necessarily connected to the ground plate, and may be connected in series to the parasitic element. Further, the number of parasitic elements is not limited to two and can be three or more. For example, for n (n is an integer of 2 or more) parasitic elements, (n−1) lumped constant elements may be connected in series between adjacent parasitic elements.

  According to this configuration, the isolation between the monopole antenna elements can be easily improved just by adding a parasitic element and a lumped constant element as in the first to third embodiments. Therefore, according to this configuration, it is possible to provide a small portable terminal antenna capable of ensuring sufficient isolation and a manufacturing method thereof.

Embodiment 5
Next, an antenna according to Embodiment 5 of the present invention will be described. FIG. 7 is a top view of the configuration of the mobile terminal antenna 50 according to the fifth embodiment. As shown in FIG. 7, the mobile terminal antenna 50 is configured such that the parasitic element 4 of the mobile terminal antenna 20 according to the second embodiment is disposed in the ground plate 1. The mobile terminal antenna 50 is provided with a hollow portion 7 formed by hollowing out a part of the ground plate 1. The parasitic element 4 is disposed in the hollow portion 7 so as not to contact the ground plate 1. One end of the parasitic element 4 is connected to the ground plate 1 via the lumped constant element 6a. The other end of the parasitic element 4 is connected to the ground plate 1 via the lumped constant element 6b. The other configuration of the mobile terminal antenna 50 is the same as that of the mobile terminal antenna 20, and thus the description thereof is omitted.

  That is, the parasitic element 4 can be arranged not only outside the ground plate 1 but also inside the ground plate 1.

  According to this configuration, the isolation between the monopole antenna elements can be easily improved just by adding a parasitic element and a lumped constant element as in the first to fourth embodiments. Therefore, according to this configuration, it is possible to provide a small portable terminal antenna capable of ensuring sufficient isolation and a manufacturing method thereof.

Other Embodiments The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. In Embodiments 1 to 5, for example, the number of antenna elements is not limited to two, but can be any number of three or more. The antenna element is not limited to the position shown in FIGS. The feeding point is not limited to the outer edge of the ground plate, and may be arranged at an arbitrary position on the ground plate. The shape of the antenna element is not limited to a folded shape, and may be other shapes such as a straight shape, a helical shape, or a meander shape. The antenna system is not limited to a monopole, and other systems such as an inverted F antenna may be used.

  In the first to fifth embodiments, the antenna elements do not have to have the same shape, and antennas having different shapes can be mounted together. Moreover, the operating frequency of each antenna is not the same, and antennas having a plurality of operating frequencies can be mixedly mounted. Furthermore, a matching circuit may be provided between the antenna element and the feeding point.

  In the first to fifth embodiments, the parasitic element 4 can be an electric line such as a microstrip line or a coplanar line, or a coaxial cable.

  In the second to fifth embodiments, a capacitor may be used instead of the lumped constant element.

  The portable terminal antenna according to the first to fifth embodiments can be applied to an electronic device equipped with an antenna, such as a mobile phone, a PDA, a personal computer, and a data communication card.

  A part or all of the above embodiment can be described as in the following supplementary notes, but is not limited thereto.

  (Supplementary Note 1) A ground plate made of a conductor, a parasitic element, a first antenna element connected to the ground plate via a first feeding point, and the ground plate via a second feeding point A first lumped constant, comprising: a connected second antenna element; and first and second lumped constant elements having one end connected to the ground plate and the other end connected to the parasitic element. An element is connected to the ground plate and the parasitic element at a position closer to the first antenna element than the second lumped constant element, and the second lumped constant element is the first lumped constant element. A portable terminal antenna connected to the ground plate and the parasitic element at a position closer to the second antenna element than the second antenna element.

  (Supplementary Note 2) One end is connected to the ground plate at a position different from the first and second lumped constant elements, and the other end is not located at a position different from the first and second lumped constant elements. The mobile terminal antenna according to appendix 1, further comprising a lumped constant element of a third lumped constant element connected to the power feeding element.

  (Supplementary Note 3) The parasitic element includes a first parasitic element and a second parasitic element, and is connected in series between the first parasitic element and the second parasitic element. The mobile terminal antenna according to appendix 1 or 2, further comprising a fourth lumped constant element.

  (Supplementary note 4) The portable terminal according to any one of Supplementary notes 1 to 3, wherein the parasitic element is disposed between the first antenna element and the second antenna element. Antenna.

  (Additional remark 5) The said parasitic element is arrange | positioned inside the hollow part provided in the said ground plate, The antenna for portable terminals as described in any one of additional marks 1 thru | or 3 characterized by the above-mentioned.

  (Additional remark 6) The said 1st thru | or 4 lumped constant element is comprised by the combination of a capacitor | condenser, an inductor, or an inductor and a capacitor | condenser, The antenna for portable terminals of Additional remark 4 or 5 characterized by the above-mentioned.

  (Supplementary note 7) The portable terminal antenna according to any one of supplementary notes 1 to 6, wherein a longitudinal direction of the parasitic element is arranged in parallel to an outer edge of the ground plate.

  (Supplementary Note 8) The first lumped constant element is connected to an end of the parasitic element on the first antenna element side, and the second lumped constant element is the second lumped constant element of the parasitic element. The mobile terminal antenna according to appendix 7, wherein the mobile terminal antenna is connected to an end of the antenna element.

  (Additional remark 9) The said parasitic element is comprised with an electrical track | line, The antenna for portable terminals as described in any one of additional marks 1 thru | or 8 characterized by the above-mentioned.

  (Supplementary note 10) The portable terminal antenna according to supplementary note 9, wherein the electric line is configured by a coaxial cable, a microstrip line, or a coplanar line.

  (Supplementary note 11) The mobile terminal antenna according to any one of supplementary notes 1 to 10, wherein the shape of the first antenna element is different from the shape of the second antenna element.

  (Supplementary note 12) The mobile terminal antenna according to any one of Supplementary notes 1 to 11, wherein an operating frequency of the first antenna element is different from an operating frequency of the second antenna element.

  (Supplementary note 13) The portable terminal according to any one of Supplementary notes 1 to 12, further comprising a matching circuit provided between the first feeding point and the second feeding point. antenna.

  (Supplementary note 14) The first antenna element is connected to a ground plate made of a conductor via a first feeding point, the second antenna element is connected to the ground plate via a second feeding point, At a position closer to the first antenna element than the second lumped constant element, one end of the first lumped constant element is connected to the ground plate, the other end is connected to a parasitic element, and the first concentrated element A method for manufacturing an antenna for a portable terminal, wherein one end of the second lumped constant element is connected to the ground plate and the other end is connected to a parasitic element at a position closer to the second antenna element than a constant element.

DESCRIPTION OF SYMBOLS 1 Ground plate 2a, 2b Monopole antenna element 3a, 3b Feed point 4, 4a, 4b Parasitic element 5a, 5b Capacitors 6a, 6b, 6c, 6d Lumped constant element 7 Hollow part 10, 20, 30, 40, 50 Carrying Terminal antenna

Claims (10)

A ground plate made of a conductor;
A parasitic element;
A first antenna element connected to the ground plate via a first feeding point;
A second antenna element connected to the ground plate via a second feeding point;
A first and second lumped constant element having one end connected to the ground plate and the other end connected to the parasitic element;
The first lumped constant element is connected to the ground plate and the parasitic element at a position closer to the first antenna element than the second lumped constant element,
The second lumped constant element is connected to the ground plate and the parasitic element at a position closer to the second antenna element than the first lumped constant element;
Antenna for mobile terminals. One end is connected to the ground plate at a position different from the first and second lumped constant elements, and the other end is connected to the parasitic element at a position different from the first and second lumped constant elements. And further comprising a lumped constant element of the third lumped constant element,
The antenna for portable terminals of Claim 1. The parasitic element is composed of a first parasitic element and a second parasitic element,
Further comprising a fourth lumped constant element connected in series between the first parasitic element and the second parasitic element,
The antenna for portable terminals of Claim 1 or 2. The parasitic element is disposed between the first antenna element and the second antenna element,
The antenna for portable terminals as described in any one of Claims 1 thru | or 3. The parasitic element is arranged inside a hollow portion provided in the ground plate,
The antenna for portable terminals as described in any one of Claims 1 thru | or 3. The first to fourth lumped constant elements are constituted by a capacitor, an inductor, or a combination of an inductor and a capacitor,
The antenna for portable terminals of Claim 4 or 5. The longitudinal direction of the parasitic element is arranged in parallel to the outer edge of the ground plate,
The portable terminal antenna according to any one of claims 1 to 6. The first lumped constant element is connected to an end of the parasitic element on the first antenna element side,
The second lumped constant element is connected to an end of the parasitic element on the second antenna element side,
The mobile terminal antenna according to claim 7. The parasitic element is constituted by an electric line,
The antenna for portable terminals as described in any one of Claims 1 thru | or 8. Connecting the first antenna element to a ground plate made of a conductor via a first feeding point;
The second antenna element is connected to the ground plate via the second feeding point,
At a position closer to the first antenna element than the second lumped constant element, one end of the first lumped constant element is connected to the ground plate, and the other end is connected to the parasitic element,
At a position closer to the second antenna element than the first lumped constant element, one end of the second lumped constant element is connected to the ground plate, and the other end is connected to a parasitic element.
Manufacturing method of antenna for portable terminal.

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