JP4798047B2 - Antenna and wireless communication device - Google Patents

Description

  The present invention relates to an antenna used in a wireless communication device such as a mobile communication device and a wireless communication device including the antenna.

  When configuring antennas to be used in multiple frequency bands in wireless communication devices such as mobile phone system terminal devices (cell phones), antennas applied to each frequency band are generally arranged in the form of a substrate or substrate, respectively. Has been.

  For example, FIG. 1 is a diagram showing a configuration of an antenna including two antenna units ANT1 and ANT2 according to the prior art. In FIG. 1, the first antenna portion ANT1 is formed of a loop electrode having a gap portion in part. The second antenna portion ANT2 is an antenna composed of a monopole electrode bent at a predetermined location. The two antenna units are fed by feeding means 51 and 52, respectively.

  Thus, when arranging two antenna parts, in order to reduce interference between antenna parts, it is provided so that the distance between two antenna parts ANT1-ANT2 may be separated as much as possible. When these two antennas are constituted by individual chip antennas, the two chip antennas are mounted with a distance as far as possible. When two antennas have to be mounted in a certain range due to the antenna mounting space, it is usual to arrange them with a predetermined distance in the same plane.

  However, the antenna characteristics often depend on the volume (volume, size) of the antenna. Generally, the larger the antenna volume, the better the characteristics.

  In addition, when two or more antennas are arranged, when there is interference between the antennas, there are many cases where the respective antenna characteristics deteriorate. In order to suppress the interference of the antennas, it is most effective to increase the distance between the antennas. Therefore, an arrangement that increases the distance between the antennas is required. However, when the distance between the antennas is increased, the volume of each antenna is reduced, and good antenna characteristics cannot be obtained. As described above, when a plurality of antennas are provided, the antenna volume of each antenna and the interference due to the distance between the antennas have a trade-off relationship, which is a design bottleneck.

  Accordingly, an object of the present invention is to effectively use a space in which an antenna is provided without reducing a substantial antenna volume and suppressing interference between antennas, and to provide a small and highly efficient (high gain) antenna. It is to provide a wireless communication device provided.

In order to solve the above problems, the present invention is configured as follows.
(1) A loop electrode having a gap in part is formed on the first main surface of the substrate, and the loop electrode is formed on the second main surface of the substrate facing the region where the loop electrode is formed . A monopole electrode having a portion along a part is formed, and the feed point for the loop electrode and the feed point for the monopole electrode are arranged at substantially opposite positions across the substrate, and the loop The gap portion of the electrode and the open end of the monopole electrode are arranged at positions opposite to each other.

  (2) The region where the loop electrode and the monopole electrode are formed is a non-ground region provided at the end of the substrate, and the loop electrode is arranged so that the gap is closer to the ground electrode. The monopole electrode may be arranged at a position away from the ground electrode.

(3) a wireless communication device is the antenna of the present invention, constructed by providing a wireless communication circuit for feeding respectively the loop electrode and the monopole-like electrode board.

  According to this invention, the direction of the current that is fed from the feeding point to the loop electrode formed on the first main surface of the substrate and the current flowing to the monopole electrode formed on the second main surface of the substrate. Since the direction of the flowing current is the same direction along the substrate, the antenna with the loop electrode and the antenna with the monopole electrode can maintain their original characteristics.

  In addition, by arranging the loop electrode so that the gap of the loop electrode is closer to the ground electrode, and disposing the monopole electrode away from the ground electrode, the monopole electrode is not affected by the ground electrode. Since it is difficult to receive, the original characteristics of the antenna by the monopole electrode can be maintained, and the gap portion of the loop electrode is located away from the open end of the monopole electrode, so the antenna and the monopole electrode by the loop electrode Interference with the antenna due to can also be prevented.

  Furthermore, since independent antennas can be arranged on the front and back of such a substrate, the area occupied by the antenna with respect to the mounting substrate is reduced, and a small wireless communication device can be configured as a whole.

<< First Embodiment >>
An antenna and a wireless communication device according to the first embodiment will be described with reference to FIGS.
FIG. 2 is a plan view of the antenna according to the first embodiment. Here, <s> is a plan view viewed from the first main surface side of the substrate, and <b> is a plan view (back surface) viewed from the second main surface side of the substrate. A ground electrode 41 is provided on the first main surface of the substrate 61, and a non-ground region 31 is provided at an end thereof. In this non-ground region 31, a loop electrode 10 having a gap 11 in part is formed.

  A ground electrode 42 is provided on the second main surface of the substrate 61, and a non-ground region 32 is provided at a position facing the non-ground region 31 on the first main surface. A monopole electrode 20 is formed in the non-ground region 32.

  The substrate 61 is provided with power supply means 51 for supplying power to a predetermined power supply point 12 of the loop electrode 10. In addition, power supply means 52 for supplying power to the power supply point 21 which is one end of the monopole electrode 20 is provided.

  Thus, the first antenna portion ANT1 is formed by the loop electrode 10 having the gap 11 in the non-ground region 31 on the first main surface of the substrate 61, and the non-ground region 32 on the second main surface of the substrate 61 is formed. In addition, a second antenna portion ANT2 is formed by the monopole electrode 20.

  As shown in FIG. 2, the feeding point 12 for the loop electrode 10 and the feeding point 21 for the monopole electrode 20 are arranged at substantially opposite positions across the substrate 61, and the gap portion 11 of the loop electrode 10. And the open end 22 of the monopole electrode 20 are arranged at positions opposite to each other.

3 and 4 show the relationship between the positional relationship between the loop electrode 10 and the monopole electrode 20 facing each other across the substrate 61 and the antenna characteristics.
FIG. 3A is a plan view of the antenna according to the first embodiment as shown in FIG. 2, and FIG. 3B is a plan view of the antenna as a comparison target. 3A and 3B, the feeding point 12 for the loop electrode 10 and the feeding point 21 for the monopole electrode 20 are arranged at substantially opposite positions with the substrate 62 interposed therebetween. In FIG. 3A, the gap 11 of the loop electrode 10 and the open end 22 of the monopole electrode 20 are arranged at the counter electrode positions. In FIG. 11 and the open end 22 of the monopole electrode 20 are not located at the counter electrode positions. That is, the gap 11 is arranged at a position facing the back side of the monopole electrode 20 on the side far from the ground electrode 41 of the substrate 62.

  FIG. 4 shows frequency characteristics of the antenna efficiency of the two antennas shown in FIGS. A black circle is a characteristic of the antenna according to the first embodiment shown in FIG. 3A, and a white circle is a characteristic of the antenna as a comparative example shown in FIG. The first antenna unit ANT1 functions as an antenna corresponding to CDMA2000 2110 to 2130 MHz and CDMA800 843 to 875 MHz, and the second antenna unit ANT2 functions as a GPS 1575 MHz antenna.

  The antenna efficiency of the first antenna unit ANT1 is about −6 dB in the CDMA 800 band and about −5 dB in the CDMA 2000 band, and there is no significant difference in the structures of FIGS. 3 (A) and 3 (B). .

  That is, it can be seen that the parallel resonance type antenna using the loop electrode 10 having the gap 11 in part is not significantly affected by the monopole electrode 20 provided on the back surface of the substrate.

  On the other hand, the antenna efficiency of the second antenna portion ANT2 by the monopole electrode 20 is −3 dB in the configuration of FIG. 3A and −8.5 dB in the configuration of FIG. Then, it turns out that the antenna by the monopole electrode 20 does not act as an original antenna.

  From this, as shown in FIG. 3A, out of the current 1-1 and the current 1-2 flowing from the feeding point 12 to the loop electrode 10, the current 1-1 and the monopole electrode 20 On the other hand, if the current 2-1 flowing from the feeding point 21 is in the same direction, it can be seen that the second antenna portion ANT2 by the monopole electrode 20 exhibits the original characteristics. In the configuration shown in FIG. 3B, as shown in FIG. 3, the current 1-1A that flows from the feeding point 12 to the loop electrode 10 and the current 2 that flows from the feeding point 21 to the monopole electrode 20 are shown. Since -1A is in the opposite direction, it is considered that the electromagnetic field generated in the second antenna portion ANT2 by the monopole electrode 20 is canceled and the antenna efficiency is lowered.

  Note that in FIG. 3B, the 800 MHz band radiation due to the current 1-1A is also generated from the substrate, so the efficiency is hardly lowered. Moreover, about 2000 MHz radiation | emission by the electric current 1-2A, since the electric current 2-1A and the electric current 1-2A which flow into the monopole electrode 20 are the same direction, rather efficiency increases. On the other hand, the efficiency of the second antenna portion ANT2 by the monopole electrode 20 is greatly affected by the cancellation by the current 1-1A. These are considered to be the reasons why the characteristic of the second antenna part ANT2 due to the monopole electrode 20 is significantly affected as compared with the characteristic of the first antenna part ANT1 due to the loop electrode 10.

  In the case where the L-shaped monopole electrode 20 is formed as shown in FIG. 2, it is inevitably possible to obtain a higher efficiency by disposing the main part as far away from the ground electrode 42 as possible. It will arrange | position in the position along an edge part. Further, since the efficiency of the antenna with the loop electrode 10 increases as the loop diameter (peripheral length) increases, the loop electrode 10 is arranged along the outer periphery of the non-ground region 31. For this reason, a part of the loop electrode 10 and the main part of the monopole electrode 20 are inevitably disposed at positions facing each other with the substrate 61 interposed therebetween. Even with such an electrode arrangement, the directions of the currents flowing from the feeding point are the same as described above, so that the original characteristics of both antennas can be maintained.

<< Second Embodiment >>
FIG. 5 is a plan view of an antenna according to the second embodiment. Here, <s> is a plan view viewed from the first main surface side of the substrate, and <b> is a plan view (back surface) viewed from the second main surface side of the substrate. A ground electrode 41 is provided on the first main surface of the substrate 63, and a non-ground region 31 is provided at an end thereof. In this non-ground region 31, a loop electrode 10 having a gap 11 in part is formed.

  A ground electrode 42 is provided on the second main surface of the substrate 63, and a non-ground region 32 is provided at a position facing the non-ground region 31 on the first main surface. A monopole electrode 70 is formed in the non-ground region 32.

  The substrate 63 is provided with power supply means 51 for supplying power to a predetermined power supply point 12 of the loop electrode 10. Further, a power feeding means 52 for feeding power to a power feeding point 71 which is one end of the monopole electrode 70 is provided.

  In this example, the monopole electrode 70 is disposed near the ground electrode 42 in the non-ground region 32. Accordingly, the gap 11 of the loop electrode 10 on the first main surface side is positioned opposite to the open end 72 of the monopole electrode 70 on the side far from the ground electrode 41 (near the end of the substrate 63). It is arranged.

  In such a configuration, since the monopole electrode 70 is close to the ground electrode 42, it is disadvantageous in terms of efficiency of the second antenna portion ANT2 compared to the configuration shown in FIG. Since it is hardly affected by the electrode 10, the original characteristics of the antenna by the monopole electrode 70 can be maintained.

<< Third Embodiment >>
FIG. 6 is a plan view of an antenna according to the third embodiment. Here, <s> is a plan view viewed from the first main surface side of the substrate, and <b> is a plan view (back surface) viewed from the second main surface side of the substrate. A ground electrode 41 is provided on the first main surface of the substrate 64 and a non-ground region 31 is provided at an end thereof. In this non-ground region 31, a loop electrode 10 having a gap 11 in part is formed.

  A ground electrode 42 is provided on the second main surface of the substrate 64, and a non-ground region 32 is provided at a position facing the non-ground region 31 on the first main surface. A monopole electrode 80 is formed in the non-ground region 32.

  The substrate 64 is provided with power supply means 51 for supplying power to a predetermined power supply point 12 of the loop electrode 10. Further, a power supply means 52 for supplying power to a power supply point 81 which is one end of the monopole electrode 80 is provided.

  In this example, the monopole electrode 80 is arranged so as to extend linearly in a direction away from the feeding point 81 and the ground electrode 42 (direction of the end portion of the substrate 64). Accordingly, the gap 11 of the loop electrode 10 on the first main surface side is disposed near the ground electrode 41 so as to be at the counter electrode position with respect to the open end 82 of the monopole electrode 80.

  Even in such a configuration, the current 1-1 flowing from the feeding point 12 to the loop electrode 10 and the current 2-1 flowing from the feeding point 81 to the monopole electrode 80 are in the same direction. The original characteristics of the antenna can be maintained.

<< Fourth Embodiment >>
A wireless communication device such as a cellular phone is configured as follows using the antenna shown in the first to third embodiments.
When the antenna shown in FIGS. 2, 5, and 6 is used, a wireless communication circuit including the power feeding means 51 and 52 is provided on the mounting board, and a non-ground region is provided at the end of the mounting board. The antenna shown in FIGS. 2, 5, and 6 is formed in the ground region. As a result, a CDMA 800/2000 compatible mobile phone incorporating a GPS receiver can be configured.

It is a figure which shows the structural example of the antenna by a prior art. It is a top view of the antenna which concerns on 1st Embodiment. It is a figure which shows the structure of the antenna as an antenna and a comparative example. It is a figure which shows the difference in efficiency of the antenna which concerns on 1st Embodiment, and the antenna as a comparative example. It is a top view of the antenna which concerns on 2nd Embodiment. It is a top view of the antenna which concerns on 3rd Embodiment.

Explanation of symbols

10-loop electrode 11-gap 12, 21, 71, 81-feeding point 20,70,80-monopole electrode 22,72,82-open end 31,32-non-ground region 41,42-ground electrode 51,52-feeding means 61-64-substrate ANT1-first antenna part ANT2-second antenna part

Claims (3)

The first major surface of the substrate, part forms a loop electrode having a gap, the second main surface of the substrate opposite the region formed the loop electrode, a portion of the loop electrode with a monopole-like electrodes are formed with along the part, arranging the feed point for the monopole-like electrode and the feeding point for the loop electrode substantially opposing positions across the substrate, the loop electrode An antenna characterized in that the gap and the open end of the monopole electrode are arranged at positions opposite to each other.   The region where the loop electrode and the monopole electrode are formed is a non-ground region provided at an end portion of the substrate, and the loop electrode is disposed so that the gap portion is closer to the ground electrode. The antenna according to claim 1, wherein the monopole electrode is disposed at a position away from the ground electrode.   A wireless communication device comprising the antenna according to claim 1 or 2 and comprising a wireless communication circuit that supplies power to the loop electrode and the monopole electrode on the substrate.

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