JP2010034740A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To configure an antenna having a high degree of freedom in design of a case of an apparatus, allowed to be more miniaturized and capable of obtaining stable characteristics. <P>SOLUTION: The antenna 201 includes a radiation electrode 51 and a feeding electrode 71. A root of the radiation electrode 51 is a ground connection part 61. The feeding electrode 51 includes an external connection part 81 and is close to a tip portion of the radiation electrode 51. Portions other than the ground connection part 61 of the radiation electrode 51 and the external connection part 81 of the feeding electrode 71 are sealed with sealing resin 91. Consequently, the radiation electrode 51 is sandwiched by the sealing resin 91 having a predetermined dielectric constant, a capacity value necessary for excitation of the antenna is obtained, an inter-electrode distance between the tip portion of the radiation electrode 51 and the feeding electrode 71 is also stabilized, the variance of capacity is reduced, and the stable capacity-feeding type antenna can be configured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a capacitively fed antenna applied to mobile communication devices and the like.

  Conventionally, Patent Documents 1 and 2 are disclosed as small antennas in which antenna elements are arranged in a synthetic resin (hereinafter simply referred to as “resin”).

  For example, as an antenna of a mobile phone terminal, a sheet metal is attached to a resin base for fixing an antenna, and a part of the terminal is bent. These antennas are monopole or inverted F type antennas, and are configured such that an RF circuit is directly connected to excite the antennas.

  On the other hand, Patent Document 1 discloses that an inverted F-type antenna is built in an IC chip and sealed with resin. FIG. 1 is a diagram showing an example of the configuration.

  In FIG. 1, a grounding portion 11b on the bottom side of the inverted F antenna 11 is connected to a chip base 12 on which an IC chip 20 is mounted so that a fixed potential is applied. The tip (open end) 11d of the resonating portion 11a of the inverted F antenna 11 is connected to the chip base 12 with a gap G at a predetermined interval so that a constant capacitance Cg is formed with the ground electrode 13. The tip portion 13a of the ground electrode 13 is disposed so as to face each other.

  An IC chip 20 having a high frequency power circuit is mounted on the surface of the chip base 12. A high-frequency input / output pad 21 on the IC chip 20 mounted on the chip pedestal 12 and the power feeding portion 11 c of the inverted F antenna 11 are connected by a gold wire 31. The high frequency input / output pad 21 is used as an input terminal for a high frequency signal when the inverted F antenna 11 is used for reception purposes. The other input / output pads 22 of the IC chip 20 mounted on the chip base 12 are connected to the corresponding input / output leads 14 via gold wires 32, respectively.

The lead frame 10 thus connected to the IC chip 20 is sealed except for the open end 11d of the inverted F antenna 11, the front end portion 13a of the ground electrode 13 opposed to the open end 11d, and the gap G therebetween. Molded with resin 40.
JP 2005-142627 A

  An antenna of a type configured by sticking a sheet metal to a fixing resin base is usually attached to a casing of a device, but it can only take a direct power supply and cannot use capacity effectively. Further, since the pasting area is large, there is a problem that the degree of freedom in designing the housing is low. A board-mounted antenna that is miniaturized using a dielectric base material is easy to design a housing, but has a problem that the area occupied on the substrate is larger than that of an antenna attached to the inside of the housing.

  On the other hand, although the antenna shown in Patent Document 1 is embedded in resin, it is not a capacitive power feed and does not effectively use the dielectric constant of the resin.

  Accordingly, an object of the present invention is to provide an antenna that solves the above-described problems, has a high degree of freedom in designing the housing of the device, can be reduced in size, and can obtain stable characteristics.

In order to solve the above problems, the present invention is configured as follows.
(1) A radiation electrode made of a metal plate and having a root portion as a ground connection portion;
It is made of a metal plate and includes an external connection part, and a power feeding electrode that generates a capacitance between the radiation electrode and the tip of the radiation electrode in the vicinity of the tip of the radiation electrode,
At least a portion where the tip of the radiation electrode and the power feeding electrode are close to each other is sealed with resin.

  With this configuration, the radiation electrode is sandwiched between resins having a predetermined dielectric constant, and a capacitance value necessary for exciting the antenna is obtained, and the electrode distance between the tip of the radiation electrode and the feeding electrode is also stabilized. Therefore, the variation in capacitance is reduced, and a capacitively fed antenna can be configured.

  In addition, since it is a capacitive power supply type, the side opposite to the power supply side of the radiation electrode is connected to the ground and does not have an open end, making it less susceptible to electromagnetic interference from members close to the antenna, and fluctuations in antenna characteristics Factors can be reduced.

(2) The ground connection portion of the radiation electrode is a ground connection terminal protruding outside from the sealing portion by the resin, and the external connection portion of the power feeding electrode is a power supply terminal protruding outside from the sealing portion by the resin. To do.
With this structure, an antenna with a terminal in which a power feeding terminal and a ground terminal are projected can be configured, and the degree of freedom in mounting an electronic device on a circuit board is increased.

(3) The ground connection portion of the radiation electrode is a portion exposed through a hole provided in a part of the sealing portion made of the resin, and a probe from the ground contacts, and the external connection portion of the power supply electrode is It is exposed through a hole provided in a part of the sealing portion made of resin, and is a portion where the probe from the power feeding circuit comes into contact.
With this structure, an antenna having a simple configuration connected by a probe can be obtained.

(4) There are a plurality of radiating electrodes, and each radiating electrode is arranged such that a capacitance is generated between the tip of the radiating electrode and the feeding electrode.
With this configuration, an antenna corresponding to a plurality of frequencies can be configured, which can contribute to downsizing of a multiband electronic device.

(5) The surface of the main part of the radiation electrode and the feeding electrode is exposed from the resin, and the radiation electrode and the feeding electrode are positioned between the tip of the radiation electrode and the feeding electrode so as to face each other. A capacity forming resin for sandwiching the power supply electrode is disposed.
With this configuration, the amount of resin used can be reduced, and the weight and thickness can be reduced.

  According to the present invention, it is possible to configure a capacity-feeding antenna with little variation in capacity. In addition, since the side opposite to the feeding side of the radiation electrode is connected to the ground and does not have an open end, it is less likely to receive electromagnetic interference from members close to the antenna, and the characteristic variation factor of the antenna can be reduced. .

<< First Embodiment >>
FIG. 2 is a perspective view of the antenna according to the first embodiment. The antenna 201 includes a radiation electrode 51 and a feeding electrode 71. The radiation electrode 51 has a ground portion 61 at the root and an open end. The power supply electrode 71 includes an external connection portion 81 and is close to the distal end portion of the radiation electrode 51.

  The radiation electrode 51 and the feeding electrode 71 are each formed by sheet metal processing of a metal plate, and portions other than the ground connection portion 61 and the external connection portion 81 are sealed with a sealing resin 91. The gap between the tip of the radiation electrode 51 and the feeding electrode 71 is set to a predetermined distance, and a predetermined capacity C is generated therebetween.

  In FIG. 2, in order to represent the structure inside the sealing resin 91, the sealing resin 91 is represented as if it was transparent. Actually, however, the sealing resin 91 is, for example, an epoxy in which a predetermined filler is dispersed. It is a resin or ABS resin and does not need to be transparent. The same applies to other embodiments described below.

  The ground connection portion 61 protruding from the sealing resin 91 is used as a ground connection terminal, and the external connection portion 81 is used as a power supply terminal. Therefore, the ground connection portion 61 and the external connection portion 81 are formed so that they are arranged at predetermined positions in the casing of the device.

  The metal plate is obtained by, for example, providing phosphor bronze with copper as an intermediate layer and silver plating. However, not limited to this, SUS (stainless steel) may be used, and plating may be Ni plating depending on circumstances.

  A power feeding circuit is connected to the external connection portion 81. As a result, capacitive power is supplied through the capacitance C generated between the feeding electrode 71 and the tip of the radiation electrode 51, and the radiation electrode 51 is excited. In this way, the antenna 201 functions as a capacitive feeding type antenna.

The resin sealing with the sealing resin 91 as shown in FIG. 2 is performed as follows.
First, the radiation electrode 51 and the feeding electrode 71 are insert-molded so that only the upper surfaces of the radiation electrode 51 and the feeding electrode 71 are exposed on the surface of the rectangular plate-shaped resin, and then the radiation electrode 51 and the feeding electrode are formed. By applying resin molding to the surface side of the electrode 71, the radiation electrode 51 and the feeding electrode 71 are sandwiched between two upper and lower resin portions (sandwich structure).

With the configuration described above, the following operational effects are obtained.
(1) Compared to conventional antennas made only of sheet metal and antennas made by attaching sheet metal to a dielectric, it is possible to reduce the size and improve the degree of freedom of arrangement in the built-in device, Enclosure design becomes easy.

(2) Even if an antenna composed only of a sheet metal or an antenna composed of a sheet metal attached to a dielectric material is used to construct a capacity-fed antenna, the coupling portion capacity is not sufficient, and the capacity It is not realistic because the variation becomes large. On the other hand, according to the first embodiment, the radiation electrode can obtain a capacitance value necessary for the excitation of the antenna, and is sealed with a resin so that the tip of the radiation electrode, the feeding electrode, Since the distance between them is also stable, the variation in capacitance is reduced, and a capacitively fed antenna with stable characteristics can be configured.

(3) Since it is a capacitive power supply type, the opposite side of the radiation electrode to the power supply side is connected to the ground, and the radiation electrode does not have an open end. Therefore, it becomes difficult to be influenced by members other than the antenna close to the antenna, and the characteristic variation factor of the antenna is small.
In addition, these effects are the same also about other embodiment shown below.

<< Second Embodiment >>
FIG. 3 is a perspective view of the antenna 202 according to the second embodiment. The antenna 202 includes a radiation electrode 52 and a feeding electrode 72. Unlike the antenna 201 illustrated in FIG. 2, the antenna 202 does not project the ground connection portion and the external connection portion from the sealing resin 92. The gap between the tip of the radiation electrode 52 and the power supply electrode 72 is set to a predetermined distance, and a predetermined capacity C is generated therebetween.

  The ground connection portion 62 of the radiation electrode 52 and the external connection portion 82 of the power feeding electrode 72 are exposed through holes provided in a part of the sealing resin forming surface (lower surface in the drawing) of the sealing resin 92. The feeding probe 111 and the ground probe 112 are inserted into the holes, and the feeding probe 111 and the ground probe 112 are brought into contact with the external connection portion 82 of the feeding electrode 72 and the ground connection portion 62 of the radiation electrode 52. Thus, the power supply electrode 72 and the radiation electrode 52 are directly connected to each other.

  The radiation electrode 52 and the feeding electrode 72 are formed by sheet metal processing of the same metal plate as that shown in the first embodiment, and are resin-sealed in the same manner as in the first embodiment.

  According to such a configuration, it can be handled as an antenna without a lead terminal, and the handling property as a part is high.

<< Third Embodiment >>
FIG. 4 is a perspective view of an antenna 203 according to the third embodiment. The difference from the antenna 202 shown in FIG. 3 is that two radiation electrodes are provided. That is, the antenna 203 includes radiation electrodes 53 and 54 and a feeding electrode 72. The gaps between the distal ends of the radiation electrodes 53 and 54 and the power supply electrode 73 are set to predetermined distances, respectively, and predetermined capacitances C3 and C4 are generated therebetween.

  Since the lengths of the radiation electrodes 53 and 54 and the values of the capacitances C3 and C4 generated between the tips of the radiation electrodes 53 and the feeding electrode 73 can be determined independently, the radiation electrodes 53 and 54 have two different frequencies. Each band has a gain.

Similarly, it is also possible to configure an antenna that can be applied to three or more frequency bands by arranging three or more radiation electrodes.
In the example shown in FIG. 4, the power supply probe 111 and the ground probes 112 and 113 are used. However, as shown in FIG. 2, the antenna having a structure in which the power supply terminal and the ground connection terminal are drawn out of the sealing resin. The same applies to the above.

<< Fourth Embodiment >>
FIG. 5 is a perspective view of an antenna 204 according to the fourth embodiment. Unlike the antenna 203 shown in FIG. 4, the surfaces of the radiation electrodes 53 and 54 and the feeding electrode 73 are exposed so as to be flush with the surface of the sealing resin 93. Further, the capacitor forming portion resin 101 is disposed at a position where the tip portions of the two radiation electrodes 53 and 54 and the power supply electrode 73 are opposed to each other. Therefore, the distal end portions of the radiation electrodes 53 and 54 and the feeding electrode 73 are sandwiched between the lower sealing resin 93 and the upper capacitance forming portion resin 101.

  The radiation electrodes 53 and 54 and the feeding electrode 73 are integrated with the sealing resin 93 by insert molding, and the capacity forming portion resin 101 is bonded to the integrated member with an insulating adhesive.

In this way, by sandwiching only the capacity forming portion with the resin, the amount of resin used can be reduced, and the weight and thickness can be reduced.
Such a capacitance forming portion resin 101 can be similarly applied to an antenna having a single radiation electrode as shown in FIG.

  In the first to fourth embodiments, the radiation electrodes 51 to 54 are all formed in a U-shape, but the shape of the radiation electrode is not limited to such a shape and is arbitrary. However, by using a U-shape, a radiation electrode having a predetermined electrical length and a predetermined reactance component necessary for antenna characteristics can be arranged within a limited area.

  Moreover, in each embodiment, although the ground connection part (ground connection terminal) and the external connection part (feeding terminal) were arranged in parallel on the same side of the sealing resin which forms a rectangular plate shape, the sealing which forms a rectangular plate shape You may arrange | position a ground connection part (ground connection terminal) and an external connection part (power feeding terminal) to the edge | side which the resin opposes, or an adjacent edge | side, respectively.

10 is a diagram illustrating a configuration example of a semiconductor device with a built-in antenna disclosed in Patent Document 1. FIG. 1 is a perspective view of an antenna according to a first embodiment. It is a perspective view of the antenna which concerns on 2nd Embodiment. It is a perspective view of the antenna which concerns on 3rd Embodiment. It is a perspective view of the antenna which concerns on 4th Embodiment.

Explanation of symbols

51-54 ... Radiation electrodes 61, 62 ... Ground connection parts 71-73 ... Feed electrodes 81, 82 ... External connection parts 91-93 ... Sealing resin 101 ... Capacitor formation part resin 111 ... Feed probe 112, 113 ... For ground Probes 201-204 ... Antenna C ... Capacitance C3, C4 ... Capacitance

Claims (5)

A radiation electrode made of a metal plate and having a root portion as a ground connection portion,
It is made of a metal plate and includes an external connection part, and a power feeding electrode that generates a capacitance between the radiation electrode and the tip of the radiation electrode in the vicinity of the tip of the radiation electrode,
At least the portion where the tip of the radiation electrode and the feeding electrode are close to each other is sealed with resin.   The ground connection portion of the radiation electrode is a ground connection terminal protruding outside from the sealing portion by the resin, and the external connection portion of the power feeding electrode is a power feeding terminal protruding outside from the sealing portion by the resin. Item 10. The antenna according to Item 1.   The ground connection portion of the radiation electrode is exposed through a hole provided in a part of the sealing portion made of the resin, and a probe from the ground contacts, and the external connection portion of the feeding electrode is sealed with the resin. The antenna according to claim 1, wherein the antenna is exposed through a hole provided in a part of the stop portion, and is a portion on which a probe from the power feeding circuit comes into contact.   The antenna according to any one of claims 1 to 3, wherein there are a plurality of the radiation electrodes, and each radiation electrode is disposed so that a capacitance is generated between a tip portion of the radiation electrode and the feeding electrode.   Surfaces of main portions of the radiation electrode and the feeding electrode are exposed from the resin, and the radiation electrode and the feeding electrode are disposed between the resin and a position where a tip portion of the radiation electrode and the feeding electrode face each other. The antenna in any one of Claims 1-4 which has arrange | positioned the capacity | capacitance formation part resin which pinches | interposes.

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