JP4661816B2 - 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.

  Patent Document 1 is disclosed as an antenna used in a plurality of frequency bands in a wireless communication device such as a terminal device (mobile phone) of a mobile phone system.

  FIG. 1 is a diagram showing a configuration of a surface mount antenna shown in Patent Document 1. In FIG. In the surface mount antenna 1, radiation electrodes 3a and 3b and a parasitic radiation electrode 12 are formed on a dielectric substrate 2. The parasitic radiation electrode 12 is formed on the upper surface 2e of the dielectric substrate 2 in a meander shape in the direction from the side surface 2d to the side surface 2b. An introduction pattern 12a is formed from the bottom surface 2f to the side surface 2d of the dielectric substrate 2, and one end side of the meandering parasitic radiation electrode 12 is electrically connected to the introduction pattern 12a, and the other end side is an open end. ing. In this way, in addition to the radiation electrodes 3a and 3b, the parasitic radiation electrode 12 coupled to the radiation electrode is arranged adjacent to each other, thereby achieving double resonance. The bandwidth can be expanded by this double resonance.

Further, when two antennas having different resonance frequencies are arranged to form a multiband antenna using a plurality of frequency bands, the first and second antennas are used to prevent deterioration of antenna efficiency due to coupling between the two antennas. Patent Document 2 discloses a metal plate provided between two antennas to reduce the coupling between both antennas.
JP 2001-68917 A JP-A-9-93031

  However, in the configuration shown in Patent Document 1, the overall antenna size is increased by adding the parasitic radiation electrode 12 as shown in FIG. In addition, when a plurality of antennas are arranged to support multiband, there is a problem that the antenna size increases, so that inter-antenna interference with other antennas increases and the characteristics deteriorate.

  Moreover, in the structure of patent document 2, since a metal will be brought close to an antenna, generally antenna characteristics deteriorate. In addition, the structure for arranging the metal plate is complicated and the number of parts is increased, which increases the cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna corresponding to a plurality of frequency bands which are small and low cost as a whole without deteriorating the antenna characteristics, and a radio communication apparatus including the antenna.

In order to solve the above problems, the present invention is configured as follows.
(1) a dielectric (dielectric substrate and the dielectric substrate), includes a first and second antenna unit including a radiating electrode fed from each feeding part, the first and second antenna portions each 1 It has the following and a secondary resonance mode, the first and second resonance modes of the antenna portion and is coupled to the second resonance mode of the second antenna portion, the first and second antenna portions It is characterized in that the secondary resonance mode is made double resonance.

  (2) At least some of the radiation electrodes of the first and second antenna portions may be formed on a mounting substrate (a circuit forming substrate other than the antenna).

  (3) One of the first and second antenna portions is a surface-mounted antenna element in which the radiation electrode is formed on a base, and the other antenna portion is mounted with the surface-mounted antenna element. The antenna element may be formed by forming the radiation electrode on a mounting substrate.

  (4) Further, the wireless communication device of the present invention is configured by including a wireless communication circuit that includes the antenna having any one of the above-described configurations and supplies power to the power supply unit.

According to the present invention, the following effects can be obtained.
(1) Since the secondary resonance mode of the first antenna unit and the secondary resonance mode of the second antenna unit are coupled to make the secondary resonance mode of the second antenna double resonant, the frequency band is expanded. can do. In addition, since there is no need to add a parasitic radiation electrode as in Patent Document 1, the antenna size can be reduced.

  In order to support multiband with the structure of Patent Document 1, first and second antenna portions each having a feeding electrode and a parasitic electrode are provided, and the feeding electrode and the parasitic electrode of the second antenna portion are provided. It is necessary to control both the coupling and the coupling of the feeding electrode or non-feeding electrode of the second antenna unit and the feeding electrode of the first antenna unit, and they cannot be controlled independently. Goes up. In addition, there is a problem that characteristic variation during mass production becomes large. On the other hand, according to the present invention, the frequency characteristic of the first antenna unit is determined by its primary resonance mode, the frequency characteristic of the second antenna unit is determined by its primary and secondary resonance modes, and Since the secondary resonance mode of the first antenna unit and the secondary resonance mode of the second antenna unit are coupled to make the secondary resonance mode of the second antenna unit double resonant, desired frequency characteristics can be easily obtained. be able to.

  Moreover, since it is not necessary to provide a metal plate for reducing the coupling as in Patent Document 2, the cost can be reduced without causing deterioration of characteristics.

  In addition, since the antenna size is reduced, layout and circuit arrangement with respect to the housing are facilitated.

  If the space for arranging the antennas is the same, the antenna electrode size can be made larger than that of the configurations of Patent Documents 1 and 2, so that good antenna characteristics can be obtained.

  In addition, since the secondary mode not used in the first antenna unit is used, the state of the double resonance of the secondary resonance mode of the second antenna unit (frequency, matching, Band) can be changed.

  (2) By forming at least a part of the radiation electrodes of the first and second antenna portions on the mounting substrate, the degree of freedom in design increases.

  (3) One of the first and second antenna portions is a surface-mounted antenna element, and the other antenna portion is formed on a mounting substrate on which the surface-mounted antenna is mounted. A plurality of types of antenna characteristics can be set according to the arrangement positional relationship of the antenna elements, and the degree of freedom in design increases.

<< First Embodiment >>
FIG. 2 is a perspective view of the antenna according to the first embodiment. FIG. 3 is a six-sided view thereof.

  As shown in FIGS. 2 and 3, a parallel resonant radiation electrode 23 having a gap G1 in part and a parallel resonant radiation electrode 27 having a gap G2 in part are formed on the upper surface of a rectangular parallelepiped dielectric base 21. is doing. Further, the meander electrode 26 is formed so that one end thereof is connected to the parallel resonance radiation electrode 27.

  A feed line 22 that feeds power to the parallel resonant radiation electrode 23 and a feed line 25 that feeds the meander electrode 26 from the top surface of the dielectric substrate 21 to a part of the bottom surface through the front side surface in the figure. Forming. In addition, mounting electrodes 28 and 29 are formed to wrap around from the other side surface to the lower surface of the dielectric substrate 21.

  The mounting substrate is provided with feeding means 31 and 32, and the feeding means 31 and 32 are connected to the parallel resonant radiation electrode 23 and the meander electrode 26 via the feeding lines 22 and 25 in a state where the antenna 100 is mounted on the mounting substrate. Power each.

  A distance D between the two parallel resonant radiation electrodes 23 and 27 is set in a range of 0.3 to 10 mm. The first antenna unit ANT1 by the parallel resonance radiation electrode 23 is used as an antenna for GPS 1575 MHz, and the second antenna unit ANT2 by the parallel resonance radiation electrode 27 and the meander electrode 26 is 843 to 890 MHz of CDMA800 and 2110 of CDMA2000. Acts as an antenna for 2130 MHz. That is, the first antenna unit ANT1 uses the primary resonance mode, and the second antenna unit ANT2 uses the primary resonance mode and the secondary resonance mode by the parallel resonance radiation electrode 27.

  In FIG. 2, a capacity is generated in the gap G2 of the parallel resonant radiation electrode 27. When considering a path Z1 from the feeding point Y of the parallel resonant radiation electrode 27 to one end of the capacity and a path Z2 to the other end, The primary resonance mode of the path Z1 portion contributes to the characteristics of the frequency band of CDMA800, and the secondary resonance mode of the path Z2 portion contributes to the characteristics of the frequency band of CDMA2000. Further, the inductance and capacitance properties of the meandering electrode 26 contribute to the frequency characteristics of the second antenna portion ANT2 and impedance matching with the power feeding means 32. Furthermore, an inductance component of an impedance matching circuit between the feeding point of the meandering electrode 26 and the feeding unit 32 also contributes to the frequency characteristics. Therefore, the frequency of the primary resonance mode and the secondary resonance mode by the parallel resonance radiation electrode 27 are respectively determined by the size of the parallel resonance radiation electrode 27, the position / gap size of the gap G2, the pattern of the meander electrode 26, and the matching circuit. Set to frequency.

  Then, the secondary resonance mode of the parallel resonance radiation electrode 23 and the secondary resonance mode of the parallel resonance radiation electrode 27 are combined, and the secondary resonance (by the parallel resonance radiation electrode 27) of the second antenna unit ANT2 is made into double resonance. The frequency band is expanded.

  Next, a comparison result between the antenna according to the first embodiment and the antenna having the structure shown in Patent Document 1 is shown.

  FIG. 4 is a perspective view of an antenna designed to be used in the same frequency band as the antenna shown in FIG. Here, the antenna 111 is a GPS antenna in which a parallel resonance radiation electrode 23 is provided on the upper surface of the dielectric substrate, and a power supply line 22 for supplying power from the power supply means 31 is formed on the side surface of the dielectric substrate.

  The antenna 112 has meandering radiation electrodes 3a and 3b and a meandering parasitic electrode 12 formed on the upper surface of a dielectric substrate, and the feeding line 5 and the end of the meandering parasitic electrode 12 feeding power from the feeding means 32 on the side surface. A ground connection conductor 12a for grounding the portion is formed.

  Here, the meandering radiation electrodes 3a and 3b act as an antenna for CDMA800 / 2000. The meandering parasitic electrode 12 is for extending the band of the CDMA2000 antenna.

  5A is a frequency characteristic of the return loss of the antenna 100 according to the first embodiment of the present invention shown in FIG. 2, and FIG. 5B is a return loss of the antenna as a comparative example shown in FIG. It is the frequency characteristic. FIG. 6 shows a comparison result of antenna efficiency in the three frequency bands used.

In FIG. 5, the characteristic indicated by R11 is the characteristic due to the primary resonance mode of the first antenna unit ANT1 shown in FIG. 2, and R12 is the characteristic due to the secondary resonance mode. R21 is a characteristic of the second antenna unit ANT2 shown in FIG. 2 according to the primary resonance mode, and R22 is a combination of the secondary resonance mode of the second antenna unit ANT2 and the secondary resonance mode of the first antenna unit ANT1. This is a characteristic obtained by the double resonance. In this way, two resonances are generated so as to be surrounded by a broken line due to the double resonance.

  On the other hand, in FIG. 5B, the characteristic indicated by R11 ′ is the characteristic due to the primary resonance mode of the antenna 111 shown in FIG. 4, and R12 ′ is the characteristic due to the secondary resonance mode. Further, R21 'is a characteristic due to the meandering radiation electrode 3b of the antenna 112 shown in FIG. 4, and R22' is a characteristic due to double resonance between the meandering radiation electrode 3a and the meandering parasitic electrode 12 of the antenna 112 shown in FIG. It is.

  6A shows the antenna efficiency of the two antennas in the frequency band of the CDMA 800 antenna, FIG. 6B shows the antenna efficiency of the two antennas in the frequency band of the GPS antenna, and FIG. The antenna efficiency of the two antennas in the frequency band of the CDMA2000 antenna.

  As is apparent from FIGS. 5 and 6, according to the configuration shown in Patent Document 1 shown in FIG. 4, the return loss is large for all three frequency bands to be used, and the antenna efficiency is reduced. In particular, when trying to widen the bandwidth, the return loss in the frequency band for CDMA2000 increases and the antenna efficiency decreases. On the other hand, according to the present invention, it is possible to maintain high antenna efficiency while expanding the bandwidth of the frequency band in which the resonance of the second resonance mode of the first antenna unit ANT1 is effectively used to make double resonance.

<< Second Embodiment >>
FIG. 7 is a perspective view of an antenna according to the second embodiment, and FIG.
In this example, parallel resonant radiation electrodes 23 and 27 and a meander electrode 26 are formed on a substrate 41. A chip antenna 51 is mounted on a portion of the parallel resonant radiation electrode 23 opened at a predetermined position. Similarly, a chip antenna 52 is mounted on a portion of the parallel resonant radiation electrode 27 that is opened at a predetermined position. Each of these chip antennas 51 and 52 is formed by forming two radiation electrodes facing each other with a predetermined gap on a dielectric substrate, and constitutes an inductor part and a capacitor part together with parallel resonant radiation electrodes 23 and 27.

  Similarly, when the radiation electrode is formed on the substrate 41 as well as when the chip antenna is further mounted, by arranging the two parallel resonance radiation electrodes at a predetermined interval, the secondary of the first antenna unit ANT1 is arranged. The resonance mode and the secondary resonance mode of the second antenna unit ANT2 can be coupled to achieve double resonance.

<< Third Embodiment >>
FIG. 9 is a perspective view of an antenna according to the third embodiment. In this example, the first antenna unit ANT1 is configured on the substrate 41, and the second antenna unit ANT2 is configured on the dielectric substrate 21. That is, the parallel resonant radiation electrode 23 is formed on the upper surface of the substrate 41 and the chip antenna 51 is mounted. In the second antenna portion ANT2, a parallel resonant radiation electrode 27 and a meander electrode 26 are formed on the upper surface of the dielectric substrate 21. Other configurations are the same as those in the first embodiment.

  Thus, even if the first antenna part ANT1 and the second antenna part ANT2 are formed on different base materials, the second resonance mode of the first antenna part ANT1 and the second resonance mode are determined by setting a predetermined gap between them. The second resonance mode of the second antenna unit ANT2 can be coupled to achieve double resonance.

  In the example shown in FIG. 9, the substrate 41 is shown separately from the second antenna unit ANT2, but the parallel resonant radiation electrode 23 is formed on the mounting substrate, and the second antenna unit ANT2 is formed on the mounting substrate. You may make it surface mount. Of course, the two antenna portions ANT1 and ANT2 shown in FIG. 9 may be surface-mounted on the mounting substrate.

<< 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.
For example, when the antenna 100 shown in FIG. 2 is used, a wireless communication circuit including the power feeding means 31 and 32 is provided on the mounting substrate, a non-ground region is provided at the end of the mounting substrate, and an antenna is provided in the non-ground region. 100 is surface mounted. As a result, a CDMA 800/2000 compatible mobile phone incorporating a GPS receiver can be configured.

  When the antenna 102 shown in FIG. 7 is used, the antenna 102 is surface-mounted on a non-ground region of the mounting substrate, or each pattern of the antenna 102 is formed on the mounting substrate, and the chip antennas 51 and 52 are surface-mounted. .

  When the antenna 103 shown in FIG. 9 is used, the antenna 103 is surface-mounted on the non-ground region of the mounting substrate, or the pattern of the first antenna portion ANT1 is formed on the mounting substrate, and the chip antenna 51 and the second antenna The antenna portion ANT2 is surface-mounted. At this time, the antenna characteristics may be set by determining the interval between the parallel resonant radiation electrodes 23-27 according to the arrangement positional relationship of the antenna unit ANT2 with respect to the mounting substrate.

It is a figure which shows the structure of the antenna shown by patent document 1. FIG. It is a perspective view which shows the structure of the antenna which concerns on 1st Embodiment. 6 is a six-sided view of the antenna. FIG. It is a perspective view which shows the structure of the antenna as a comparative example by a prior art. It is a figure which shows the frequency characteristic of the return loss of the antenna which concerns on 1st Embodiment, and the antenna as a comparative example. It is a figure which shows the antenna efficiency in the three frequency bands used. It is a perspective view of the antenna which concerns on 2nd Embodiment. 6 is a six-sided view of the antenna. FIG. It is a perspective view of the antenna which concerns on 3rd Embodiment.

Explanation of symbols

21-Substrate 22, 25-Feeding line 23, 27-Parallel resonant radiation electrode 26-Meander electrode 28,29-Mounting electrode 31,32-Feeding means 41-Substrate 51,52-Chip antenna 100,103-Antenna G1 , G2-Gap

Claims (4)

A dielectric, comprising a first and second antenna unit including a radiating electrode fed from each feeding part,
It said first and second antenna portions each have a primary and secondary resonance mode,
The secondary resonance mode of the first antenna unit and the secondary resonance mode of the second antenna unit are coupled to make the secondary resonance mode of the first and second antenna units double resonant. An antenna characterized by.   The antenna according to claim 1, wherein at least part of the radiation electrodes of the first and second antenna portions is formed on a mounting substrate.   One of the first and second antenna portions is a surface-mounted antenna element in which the radiation electrode is formed on a base, and the other antenna portion is a mounting substrate on which the surface-mounted antenna element is mounted. The antenna according to claim 1, wherein the antenna element is formed by forming the radiation electrode.   A wireless communication apparatus comprising the antenna according to claim 1, and a wireless communication circuit that supplies power to the power supply unit.

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