JP2010258815A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device which obtains higher-efficiency characteristics in accordance with the switching of frequency bands. <P>SOLUTION: On a substrate 31, an antenna matching circuit 30 and an antenna connecting section 32 are configured. Furthermore, on the substrate 31, a radiation Q termination circuit 60 and a radiation Q switching line 61 are configured. An antenna element 20, with which an antenna element electrode 21 is formed, is then mounted in a non-ground area NGA on the substrate 31, thereby configuring an antenna device 101. The antenna matching circuit 30 is configured between the antenna connecting part 32, to which the antenna element 20 is connected, and a power feeding section 39 and switched for low band and for high band. The radiation Q termination circuit 60 is a circuit for connecting the radiation Q switching line 61 to a ground under a predetermined connection condition and is switched for low band and for high band. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antenna device provided in, for example, a mobile phone terminal.

As a performance of an antenna device for a mobile radio terminal such as a mobile phone terminal, it is always required to be compatible with multiband and downsized.
Patent Documents 1 and 2 are disclosed as antennas corresponding to multiband.
The antenna device of Patent Document 1 covers a plurality of frequency bands by changing an equivalent electrical length of the antenna element by changing a reactance value of a reactance circuit connected to the base of the antenna element.

  FIG. 1 is a circuit diagram of the antenna device disclosed in Patent Document 1. In FIG. The antenna device of FIG. 1 includes a radiating element 1 and a tuning circuit 10. The tuning circuit 10 is provided between the radiating element 1 and the feeding point 2 and has a configuration in which a first inductive element 11 and a variable reactance circuit 12 are connected in series. The variable reactance circuit 12 is composed of a parallel circuit of a second inductive element 13 and a variable capacitive element 14.

The antenna device of Patent Document 2 changes the resonance frequency by switching the electrical length of an antenna element with a switch.
Although the physical volume of the antenna element itself does not change in the configuration of Patent Document 1, it can be said that Patent Document 2 changes the volume of the antenna element itself.

JP 2008-113233 A International Publication No. 2004/047223 Pamphlet

  In the antenna device of Patent Document 1, an antenna element (including a reactance circuit connected to the base) and a casing constitute a radiator that can be regarded as a pseudo dipole system, and casing radiation is used. However, in the antenna device of Patent Document 1, an emphasis is placed on controlling the resonance frequency of the antenna element. In other words, it does not control the radiation Q of the antenna including the housing.

  In the antenna device of Patent Document 1, the antenna element is fixed, whereas in Patent Document 2, it can be considered that the relationship between the antenna element and the housing is changed, but the volume of the antenna element is reduced, It does not optimize the relationship between the connection point between the element and the housing.

  An object of the present invention is to provide an antenna device that can obtain more efficient characteristics in accordance with switching of frequency bands.

In order to solve the above problems, the present invention is configured as follows.
(1) In an antenna device including an antenna element and an antenna matching circuit that is connected between the antenna element and a power feeding unit and switches a matching state according to a frequency band, the antenna element is opposed to the antenna element. The antenna matching line is provided between the radiation Q switching line extending to the housing ground and the antenna element and the radiation Q switching line, or between the radiation Q switching line and the housing ground. An impedance variable element that switches a connection state between the antenna element and the radiation Q switching line together with switching of a frequency band of the circuit.

  With this configuration, the radiation Q is switched according to the switching of the frequency band of the antenna matching circuit, and the antenna device is obtained with high efficiency in any frequency band that is determined and optimally switched to the radiation Q.

(2) The antenna matching circuit includes a plurality of matching circuits having different utilization frequencies, and a switch that selects the matching circuits and is connected between the antenna element and the power feeding unit. The matching circuit may be configured by an impedance circuit in which return loss characteristics when the matching circuit is viewed from the feeding unit toward the antenna element have double resonance characteristics in the band of the use frequency.
With this configuration, each frequency band can be widened.

(3) The antenna matching circuit includes a reactance loading unit that adjusts a resonance frequency, and a return loss characteristic when the matching circuit is viewed in the direction from the power feeding unit to the antenna connection unit. The variable reactance circuit may be configured such that the reactance value of the variable reactance circuit is controlled in accordance with the use frequency.

  With this configuration, it is possible to widen each frequency band.

(4) A part or all of the circuit elements constituting the antenna matching circuit may be packaged in a laminated substrate.
Thereby, it can be handled as a component that can be mounted on the circuit board of the mounting destination, and the occupied area on the circuit board can be reduced.

(5) The antenna element may be composed of a dielectric or magnetic substrate and an antenna element electrode disposed on the surface of the substrate or inside the substrate.
With this configuration, it is unnecessary or less necessary to mount the antenna matching circuit component on the circuit board of the mounting destination, and the overall size can be reduced accordingly.

(6) The antenna matching circuit may be included in the base body.
With this configuration, it is unnecessary or less necessary to mount the antenna matching circuit component on the circuit board of the mounting destination, and the overall size can be reduced accordingly.

  According to the present invention, the radiation Q is switched according to the switching of the frequency band of the antenna matching circuit, and the antenna device is obtained with high efficiency in any frequency band that is determined and optimally switched to the radiation Q.

10 is a circuit diagram of the antenna device disclosed in Patent Document 1. FIG. FIG. 2A is a perspective view showing the configuration of the antenna matching circuit and the antenna device according to the first embodiment. FIG. 2B is a frequency characteristic diagram of return loss when the antenna matching circuit 30 side is viewed from the power feeding unit 39. As a comparative example of the antenna device 101 shown in FIG. 2 (A), the standing wave of the antenna device 100 as a pseudo dipole composed of an antenna element and a substrate, standing on the housing ground in the low band when there is no radiation Q switching line. FIG. It is a figure which shows how the standing wave to the housing ground in a high band when there is no radiation Q switching line of the antenna apparatus 100 as a pseudo dipole comprising an antenna element and a substrate. It is a figure which shows how a standing wave stands to the housing | casing ground in a high band when there exists a radiation | emission Q switching line as a pseudo dipole which consists of an antenna element and a board | substrate of the antenna apparatus 101 shown to FIG. . FIG. 6A is an exploded perspective view of the antenna device when there is the radiation Q switching line 61 in the high band, and FIG. 6B is an exploded perspective view of the antenna device when there is no radiation Q switching line 61. FIG. 6C is a frequency characteristic diagram of return loss and antenna efficiency of the two antenna devices. FIG. 7A is an exploded perspective view of the antenna device when there is the radiation Q switching line 61 in the low band, and FIG. 7B is an exploded perspective view of the antenna device when there is no radiation Q switching line 61. FIG. 7C is a frequency characteristic diagram of return loss and antenna efficiency of the two antenna devices. It is a block diagram which shows the basic composition of an antenna matching circuit. It is a Smith chart of the impedance which looked at the antenna matching circuit side from the electric power feeding part. FIG. 10 is a circuit in which two antenna matching circuits shown in FIG. 9 are provided for high band and low band and are switched by a switch. It is a perspective view of the antenna matching circuit corresponding to two bands, a low band and a high band. It is a figure which shows the procedure of a deformation | transformation of the antenna matching circuit shown in FIG. FIG. 13 is a circuit diagram obtained by modifying the antenna matching circuit shown in FIG. 5 is a diagram illustrating an example of a switching circuit of a radiation Q termination circuit 60. FIG. It is a disassembled perspective view which shows the structure of the antenna matching circuit and antenna apparatus which concern on 2nd Embodiment. FIGS. 16A and 16B are exploded perspective views of two antenna devices according to the third embodiment. It is a disassembled perspective view of the three antenna devices which concern on 4th Embodiment. It is a disassembled perspective view of the antenna device which concerns on 5th Embodiment. It is a disassembled perspective view of the antenna device which concerns on 6th Embodiment. It is a disassembled perspective view of the antenna device which concerns on 7th Embodiment.

<< First Embodiment >>
FIG. 2A is a perspective view showing the configuration of the antenna matching circuit and the antenna device according to the first embodiment. A circuit board (hereinafter simply referred to as “substrate”) 31 is provided with a ground region GA and a non-ground region NGA, and an antenna matching circuit 30 and an antenna connection portion 32 are formed on the substrate 31. A radiation Q termination circuit 60 and a radiation Q switching line 61 are formed on the substrate 31. The antenna device 101 is configured by mounting the antenna element 20 on which the antenna element electrode 21 is formed in the non-ground region NGA of the substrate 31.

  The antenna matching circuit 30 is configured between an antenna connection portion 32 to which the antenna element 20 is connected and a power feeding portion 39, and is switched between a low band and a high band. Details of the antenna matching circuit 30 will be described later. A power feeding circuit 40 is connected to the power feeding unit 39. The radiation Q termination circuit 60 is a circuit for connecting the radiation Q switching line 61 to a substrate (housing) ground in a predetermined connection state, and can be switched between a low band and a high band. Details of the radiation Q termination circuit 60 will be described later.

  FIG. 2B is a frequency characteristic diagram of return loss when the antenna matching circuit 30 side is viewed from the power feeding unit 39. In FIG. 2B, a curve RL (L) indicates a return characteristic when the antenna matching circuit 30 and the radiation Q termination circuit 60 are switched to the low band, and a curve RL (H) indicates the antenna matching circuit 30 and the radiation Q. This is a return loss characteristic when the termination circuit 60 is switched to the high band.

  The antenna device 101 according to the first embodiment corresponds to a low band and a high band by including an antenna matching circuit that changes a matching state according to a band (band of a use frequency). The antenna device of the present invention can control the radiation Q of the antenna, and can obtain a good radiation Q in both the low band and the high band according to the band switching of the antenna matching circuit 30.

  An antenna device 101 illustrated in FIG. 2A includes an antenna element 20, an antenna matching circuit 30, and a substrate 31 (further, a housing that houses the antenna element 20 and the substrate 31). The antenna element electrode 21 of the antenna element 20 has a length of λ / 4 (an integral multiple of λ / 4), but also uses radiation due to the casing current (as an image or as a half crack of the dipole), so the antenna element and the substrate (and the casing) It can be regarded as a pseudo dipole antenna consisting of

  If the radiation Q of such a pseudo-dipole antenna is poor, the matching with the 50Ω RF circuit is not radiated efficiently. Although it is generally well known that the radiation Q of the antenna device depends on the size, the standing wave to the housing ground also occupies an important factor.

  The reason for picking up the standing wave of the case ground, which is one half of the pseudo dipole, is derived from the fact that the case ground is not linear but rectangular, and the standing wave is along the circumference. There is room for controllability in the way of standing waves with respect to the housing ground, but there is no room for the antenna element 20.

  The standing wave that matches the peripheral length and wavelength of the substrate (housing) means that the housing excitation becomes active, which improves the radiating ability of the housing. That is, the radiation Q of the antenna device is improved.

  “Control” of the radiation Q of the antenna means that the best standing wave state is drawn from the housing ground having a fixed size in each of the low band and the high band. Of course, the size of the housing ground is not sacrificed during this “control”, that is, the antenna element electrode 21 and the housing ground, which are given structures, are shared by both bands and are fully utilized as radiators.

  FIG. 3 is a diagram showing a standing wave standing on a housing ground in a low band of the antenna device 100 as a pseudo dipole including an antenna element and a substrate as a comparative example of the antenna device 101 shown in FIG. It is. This antenna device 100 does not have the radiation Q termination circuit 60 and the radiation Q switching line 61 of the antenna device 101 shown in FIG.

  In FIG. 3A, the reactance circuit 30X is a simple inductor in order to bring resonance to the low band. (The matching function is not added.) In addition, the dimension indicated by the symbol W in the drawing of the non-ground region NGA of the substrate 31 is 40 mm, the dimension indicated by the symbol L is 4 mm, and the dimension indicated by the symbol D is 100 mm. The dimension indicated by the symbol T of the antenna element 20 is 3 mm, and its length is equal to W.

FIG. 3B shows a current distribution (instantaneous value) of the housing ground, and FIG. 3C shows a voltage distribution (time average value) of the housing ground.
In the antenna device 101 shown in FIG. 2A, the antenna element 20 that determines the electrical length together with the reactance circuit 30X is a simple λ / 4 long element. In the low band, the housing ground is close to λ / 4 wavelength. Therefore, there is little room for standing wave control. At this time, the radiation Q (= Qr) of the antenna is 10.5.

FIG. 4 is a diagram showing a standing wave standing on the housing ground in the high band of the antenna device 100 as a pseudo dipole composed of the antenna element and the substrate. Also here, the radiation Q termination circuit 60 and the radiation Q switching line 61 of the antenna device 101 shown in FIG. In FIG. 4A, the reactance circuit 30X is a simple capacitor because resonance is brought to a high band. (No matching function is added.)
FIG. 4B shows the current distribution (instantaneous value) of the housing ground, and FIG. 4C shows the voltage distribution (time average value) of the housing ground.
In the antenna device 100 having such a structure, if the reactance of the reactance circuit 30 connected to the base of the antenna element 20 is simply applied to the high band as it is, the standing wave around the housing ground has a length of λ / 4 ( (Integer multiple of) and the radiation Q deteriorates. (The broken line arrow in FIG. 4B is an area that does not match the λ / 4 length.) The antenna element 20 has an effective electrical length longer than λ / 4 due to the influence of the opposing housing ground. Thus, the starting point A of the standing wave is generated in the middle, and if the λ / 4 length is applied from this base point, the standing wave of λ / 4 length does not fit well around the housing ground. That is, the feeling of fitting (= feeling of standing waves) is not the best. Therefore, the radiation Q of the antenna becomes a large value of 35.5.

  FIG. 5 is a diagram illustrating a standing wave standing on the housing ground in a high band as a pseudo dipole including the antenna element and the substrate of the antenna device 101 illustrated in FIG. When matching with the high band, the radiation Q termination circuit 60 in the antenna device 101 shown in FIG. 2A has a reactance of 0H. That is, it is short-circuited.

  In order to bring the resonance to the high band in FIG. 5A, a very small reactance value is sufficient, and the reactance circuit 30X can be omitted. The distance S between the antenna connection portion 32 of the antenna device 101 and the radiation Q switching line 61 is 15 mm.

FIG. 5B shows a current distribution (instantaneous value) of the housing ground, and FIG. 5C shows a voltage distribution (time average value) of the housing ground.
Here, when the starting point A and the antenna element 20 are connected by the radiation Q switching line 61, the starting point A disappears, and it is as if a constant length like a λ / 4 long element in which the radiation Q switching line 61 and the antenna connection portion 32 are integrated. It becomes a standing wave state. As a result, the “wave feeling” of the standing wave with respect to the periphery of the housing ground is improved, and the radiation Q of the antenna becomes a small value of 14.3 and the radiation Q is improved.

  Here, in addition to the standing wave of the housing ground, the size of the antenna element 20 with the width W = 40 mm is utilized, and the open end position remains at the short side edge of the substrate that easily radiates an electric field. This is also an important factor. In order to switch the frequency, as shown in Patent Document 2, a method of electronically cutting the size of the antenna element is known, but there are disadvantages such as changing the open end position where the antenna size is reduced. It will accompany. According to the present invention, this problem does not occur.

  Using the above phenomenon, the characteristics were compared with and without the radiation Q switching line to verify the effect. 6 and 7 show the results. Here, multiple resonance matching is performed using the antenna matching circuit 30 having the same circuit configuration (architecture).

  FIG. 6 is a diagram showing the high band. 6A is an exploded perspective view of the antenna device when the radiation Q switching line 61 is present, and FIG. 6B is a radiation Q termination circuit when the radiation Q switching line 61 is not present (FIG. 6A). FIG. 60 is an exploded perspective view of the antenna device 60 (corresponding to an open state). FIG. 6C is a frequency characteristic diagram of return loss and antenna efficiency of the two antenna devices.

  In FIGS. 6A and 6B, the antenna matching circuit 30 is a matching circuit that performs double resonance in a high band. Since the antenna element to be matched is different from the pseudo dipole consisting of the substrate, the element constants that make up the matching circuit are different, but the multi-resonance matching circuit design of the same architecture was applied. The reactance of the radiation Q termination circuit 60 in FIG. 6A is 1.5 nH, which is sufficiently close to a short circuit (FIG. 5). The configuration and operation of the antenna matching circuit 30 will be described later.

  In FIG. 6C, a curve RLs is a return loss of the antenna device shown in FIG. 6A, and a curve RLn is a return loss of the antenna device shown in FIG. 6B. A curve ηs is the antenna efficiency of the antenna apparatus shown in FIG. 6A, and a curve ηn is the antenna efficiency of the antenna apparatus shown in FIG.

  When the radiation Q switching line 61 is not provided, the radiation Q value is 35.5, and the average value of the antenna efficiency in the high band is -4.8 dB. When the radiation Q switching line 61 is provided, the radiation Q value is 14.3, and the average value of the antenna efficiency in the high band is −2.7 dB.

  In this way, by providing the radiation Q switching line 61 and connecting the radiation Q switching line 61 and the ground electrode with a predetermined reactor, the radiation Q of the antenna is improved, and the broadband return loss and high antenna efficiency are improved. Characteristics are obtained. Also in the bandwidth, the case where the radiation Q switching line 61 is provided covers a wider band than the case where the radiation Q switching line 61 is not provided, and the difference in the radiation Q (= f0 / BW) is reflected.

  FIG. 7 is a diagram showing the low band. 7A is an exploded perspective view of the antenna device when the radiation Q switching line 61 is present, and FIG. 7B is a radiation Q termination circuit when there is no radiation Q switching line 61 (FIG. 7A). FIG. 60 is an exploded perspective view of the antenna device 60 (corresponding to an open state). FIG. 7C is a frequency characteristic diagram of return loss and antenna efficiency of the two antenna devices.

  In FIGS. 7A and 7B, the antenna matching circuit 30 is a low-band single-resonance matching circuit. Since the antenna element to be matched and the pseudo dipole consisting of the substrate are different, the single-resonance matching circuit design of the same architecture was applied although the element constants constituting the matching circuit were different. The reactance of the radiation Q termination circuit 60 in FIG. 7A is set to a sufficiently large reactance value of 51 nH so that it appears to be cut off at a high frequency. The configuration and operation of the antenna matching circuit 30 will be described later.

  In FIG. 7C, the curve RLs is the return loss of the antenna device shown in FIG. 7A, and the curve RLn is the return loss of the antenna device shown in FIG. 7B. A curve ηs is the antenna efficiency of the antenna apparatus shown in FIG. 7A, and a curve ηn is the antenna efficiency of the antenna apparatus shown in FIG.

  When the radiation Q switching line 61 is not provided, the average value of the antenna efficiency in the low band is −2.0 dB. When the radiation Q switching line 61 is provided, the average value of the antenna efficiency in the low band is −2.1 dB. Also, in terms of bandwidth, when the radiation Q switching line 61 is terminated with a sufficiently large impedance, the bandwidth is equivalent to that when the radiation Q switching line 61 is not provided.

  Thus, it can be seen that there is a large difference in characteristics due to the difference in the radiation Q in the high band. It can also be seen that the presence of the switching line does not adversely affect the low-band characteristics depending on the connection conditions by the radiation Q termination circuit 60. That is, in the low band, if the termination condition of the radiation Q switching line is switched with a sufficiently large impedance, the antenna characteristics are not adversely affected.

  Note that single resonance matching is performed in the low band for the purpose of confirming whether or not there is an influence on the characteristics of the radiation Q switching line. However, in practice, multiple resonance matching may be performed as in the case of the high band. .

Here, the configuration and operation of the antenna matching circuit will be described with reference to FIGS.
FIG. 8 is a block diagram showing a basic configuration of the antenna matching circuit. This antenna matching circuit includes a reactance loading unit AA, a first matching unit M1, a phase shifter PS, and a second matching unit M2.

  The high-band antenna matching circuit 30 is shown in FIGS. 6A and 6B. The series inductor 34 of the antenna matching circuit 30 is the reactance loading portion AA, and the parallel inductor 35 is the first matching portion M1. The phase shifter PS corresponds to the phase shifter 36, and the parallel inductor 37 corresponds to the second matching unit M2.

  The reactance loading portion AA is a reactance loaded on the antenna element 20, and the resonance frequency of the antenna is set to a predetermined frequency by the loaded reactance. In FIG. 9, a locus T0 is an impedance locus on the Smith chart in a state where only the reactance loading portion AA is provided.

  By providing the first matching unit M1, the reference loss of 50Ω is matched in the predetermined frequency band, the return loss is reduced, and the loop is reduced while the locus T0 moves in the arrow (a) direction on the Smith chart. As shown by a trajectory T1 in FIG.

  By providing the phase shifter PS, the locus T1 rotates in the direction of the arrow (b) from the first quadrant to the third quadrant, and becomes a locus T2. The amount of rotation by the phase shifter is determined in anticipation of the movement of the locus by the second matching unit M2.

Finally, by providing the matching portion M2, the trajectory T2 moves as indicated by the arrow (c), and a loop is drawn around the center of the Smith chart as shown by the trajectory T3.
The antenna element 20 and the feeding circuit are matched by the above series of actions.

  FIG. 10 is a circuit in which two antenna matching circuits shown in FIG. 9 are provided for high band and low band, and are switched by a switch. The high-band antenna matching circuit includes a reactance loading unit AAH, a first matching unit M1H, a phase shifter PSH, and a second matching unit M2H. The low-band antenna matching circuit includes a reactance loading unit AAL, a first matching unit M1L, a phase shifter PSL, and a second matching unit M2L.

  FIG. 11 is a perspective view showing a more specific configuration example of the antenna matching circuit shown in FIG. In this antenna matching circuit, a series inductor 34a, a parallel inductor 35a, a phase shifter 36a, and a parallel inductor 37a constitute a low band side matching circuit. The matching circuit is configured.

  Since the phase shifters PSH and PSL in the circuit shown in FIG. 10 and the phase shifters 36a and 36b in the circuit shown in FIG. 11 are lines, the high-band antenna matching circuit and the low-band antenna matching circuit are switched and used. It will be. FIG. 12 is a diagram showing a modification of the circuit for configuring the phase shifter with lumped constant elements instead of lines and switching the state of the antenna matching circuit in accordance with switching between high band and low band.

  FIG. 12A is the same as the antenna matching circuit shown in FIG. When the phase shifter PS in this antenna matching circuit is replaced with a π-type circuit including reactance elements PS0, PS1, and PS2, the result is as shown in FIG. When the first matching unit M1 and the reactance element PS1 are integrated into the element MP1, and the second matching unit M2 and the reactance element PS2 are integrated into the element MP2, only the lumped constant circuit element as shown in FIG. An antenna matching circuit can be configured.

  Then, if the constants of the circuit elements shown in FIG. 12C can be switched between the high band and the low band, the high band and the low band respectively can be switched as shown in FIGS. Both bands can be selectively supported without selecting the entire antenna matching circuit.

  FIG. 13 is a circuit diagram obtained by modifying the antenna matching circuit shown in FIG. Since the phase shifter PS is a circuit for rotating to a desired quadrant in consideration of the movement of the locus by the second matching unit M2 as shown in the Smith chart of FIG. 9, the locus of the locus by the second matching unit M2 is Depending on the movement, there may be no phaser. That is, when the small circular locus generated by the first matching unit M1 can be moved to the center of the Smith chart by the second matching unit M2, the phase shifter PS is not necessary as shown in FIG. .

In this way, matching can be performed according to the two bands. In conjunction with the switching of the matching circuit, the reactance of the radiation Q termination circuit 60 may be switched.
FIG. 14 is a diagram illustrating an example of a switching circuit of the radiation Q termination circuit 60. In the example of FIG. 14A, a switch 62 is provided between the radiation Q switching line 61 and the ground, and the switch 62 is turned on / off according to band switching.

  In the example of FIG. 14B, termination reactors 63 and 64 and a switch 62 are provided between the radiation Q switching line 61 and the ground, and the switch 62 is switched according to band switching. The termination reactor 63 is a low-band reactor and the termination reactor 64 is a high-band reactor, and the connection state between the housing ground and the antenna element is determined by switching the switch 62. The switch 62 is selected in accordance with the switching between the low band and the high band, and acts so that the radiation Q becomes smaller in accordance with each of the low band and the high band.

  In the example of FIG. 14C, termination reactors 66 and 67 and a switch 65 are provided between the radiation Q switching line 61 and the ground, and the switch 65 is switched according to band switching. The termination reactor 66 is for the low band and the termination reactor 67 is for the high band. By switching the switch 65, the off-capacitance of the switch 65 (capacity on the non-selected terminal side) and the entire reactance including the termination reactors 66 and 67 are obtained. By switching, the connection state between the housing ground and the antenna element is determined. The switch 65 is selected in accordance with switching between the low band and the high band, and operates so that the radiation Q becomes smaller in accordance with each of the low band and the high band.

<< Second Embodiment >>
FIG. 15 is an exploded perspective view showing configurations of the antenna matching circuit and the antenna device according to the second embodiment.
The substrate 31A has no special non-ground region, and the antenna matching circuit 30, the antenna connection portion 32, the radiation Q termination circuit 60, and the radiation Q switching line connection portion 62 are formed.

  The antenna element electrode 21A as shown in the figure is formed on the upper surface (surface far from the ground electrode of the substrate) of the rectangular parallelepiped (rectangular prism) -shaped dielectric base, and the antenna element 20A is formed on the side surface, and the radiation Q is switched on the side surface. Line 61 is constructed. Only the electrodes connected to the antenna connection portion 32 and the radiation Q switching line connection portion 62 are formed on the lower surface of the antenna element 20A.

  Thus, the antenna element 20A is mounted on the ground electrode of the substrate 31A. In this example, since only the electrode for the antenna connection portion is formed on the bottom surface of the antenna element 20A, and the antenna element 20A has a certain volume, it can be directly mounted on the ground region of the substrate 31A.

<< Third Embodiment >>
FIGS. 16A and 16B are exploded perspective views of two antenna devices according to the third embodiment. In any antenna device, antenna element electrodes 21 and 22 are provided on the antenna element 20. Here, the antenna element electrode 21 acts as a feed radiation electrode, and the antenna element electrode 22 acts as a parasitic radiation electrode.

In the example of FIG. 16A, a parasitic element connecting portion 71, an antenna matching circuit 30, an antenna connecting portion 32, a radiation Q termination circuit 60, and a radiation Q switching line 61 are formed on the substrate 31.
As described above, by providing the antenna element with the feeding radiation electrode and the non-feeding radiation electrode, the antenna element can be double-resonated, and the bandwidth can be increased.

  In the example of FIG. 16B, the radiation matching Q switching line 71A, the short-circuit connection portion 71B, the radiation Q termination circuit 30A, the short-circuit termination circuit 30B, and the antenna matching circuit on the feeder element side are provided on the substrate 31. 30, an antenna connection portion 32, a radiation Q termination circuit 60, and a radiation Q switching line 61 are formed.

  The short-circuit termination circuit 30B and the antenna matching circuit 30 on the parasitic element side switch the target band depending on their reactance. In addition to obtaining the double resonance characteristics in the switching destination band by the antenna matching circuit 30, another resonance is added by the short-circuit connection portion 71 </ b> B, and a wider band is obtained. Further, the radiation element Q side circuit 30A on the parasitic element side and the radiation element Q termination circuit 60 on the feeder element side, due to their reactance, the antenna element electrode 21 that is a feeding radiation electrode and the antenna element electrode 22 that acts as a parasitic radiation electrode. The radiation Q is switched according to the band switching.

  In this way, the radiation Q may be switched for the antenna element having multiple resonances by switching the radiation Q of the parasitic radiation electrode and the ground position.

<< Fourth Embodiment >>
FIG. 17 is an exploded perspective view of three antenna devices according to the fourth embodiment. In the example of FIG. 17A, an antenna element 20B obtained by bending a metal plate is used, and this is soldered or spring-contacted to the antenna connection portion 32 formed on the substrate 31B. I try to cover it. The ends of the antenna element 20 </ b> B and the substrate 31 </ b> B are shaped so as not to create a useless space in accordance with the shape of the housing 50. Here, the connection of the antenna element 20 </ b> B to the radiation Q switching line 61 is the same as that of the antenna connection unit 32.

  In the example of FIG. 17B, a (spring) pin-shaped antenna connection portion 32B is attached to the substrate 31B, the antenna element electrode 21B is provided on the inner surface of the housing 50, and the housing 50 is covered with the substrate 31B. In this state, the antenna connecting portion 32B is connected to the antenna element electrode 21B. In this way, the antenna element can be applied to the case side. The connection to the antenna element electrode portion 21B by the (spring) pin-shaped connection portion 61B of the radiation Q switching line is the same as that of the antenna connection portion 32B.

  In the example of FIG. 17C, the antenna element electrode 21C is directly formed in the non-ground region of the substrate 31C. In this way, the substrate pattern may also be used as an antenna element.

<< Fifth Embodiment >>
FIG. 18 is an exploded perspective view of the antenna device according to the fifth embodiment. In this example, the upper casing 21D that can freely open and close the electronic device is regarded as an antenna element electrode.

  An antenna matching circuit 30, an antenna connection portion 32D, a radiation Q termination circuit 60, and a radiation Q switching line 61D are formed on the substrate 31D. The antenna connection portion 32D and the radiation Q switching line 61D are electrically connected to the antenna element electrode 21D of the antenna element 20D by spring contact, soldering, or the like.

<< Sixth Embodiment >>
FIG. 19 is an exploded perspective view of the antenna device according to the sixth embodiment. In this example, the antenna matching circuit 30 and the radiation Q termination circuit 60 shown in FIG. 2 in the first embodiment are configured as a packaged module and mounted on the substrate 31.

  These modules are configured using, for example, an LTCC multilayer substrate. Thereby, the number of parts can be reduced and the space of the board 31 can be used efficiently.

<< Sixth Embodiment >>
FIG. 20 is an exploded perspective view of the antenna device according to the seventh embodiment. In this example, an antenna element electrode 21E is formed on the antenna element 20E, and an antenna matching circuit 30E and a radiation Q termination circuit 60E are formed inside the dielectric. Therefore, the power supply circuit and the radiation Q termination circuit connecting portion 68 may be simply provided on the substrate 31A on which the antenna element 20E is mounted.

  Further, the antenna element is not limited to the one in which the electrode pattern is formed on the dielectric substrate, and may be configured by forming the electrode pattern on the magnetic substrate.

  The configuration of the antenna element electrode and the interface between the antenna element electrode and the conductor pattern on the substrate are not limited to the above-described embodiments, and other known configurations may be adopted.

  The target is not limited to switching between low band [GSM 800/900] / high band [DCS / PCS / UMTS]. Other systems may be applied or added (WLAN / Bluetooth / Wimax, etc.), and Pentaband may be covered with fine frequency band division. At that time, the values of the elements constituting the matching circuit and the value of the radiation Q termination circuit are prepared / set in detail.

The antenna element may be one to which a fundamental wave / harmonic wave is assigned, or one having a resonance point in a plurality of bands by inserting a reactance element in the element.
In addition, the inductor and capacitor components in the antenna matching circuit and the radiation Q termination circuit are not limited to discrete elements, and may be replaced with line patterns, for example.

  Further, the connection condition of the radiation Q switching line may be On / Off of the switch, or a circuit that causes a reactance suitable for the band (= frequency band) to be switched to appear. For example, an aspect such as an LC resonator that simultaneously realizes desired low-band / high-band reactance values may be employed.

GA ... ground area NGA ... non-ground area 20 ... antenna elements 20A, 20B, 20D, 20E ... antenna elements 21, 22 ... antenna element electrodes 21A, 21B, 21C, 21D, 21E ... antenna element electrodes 30 ... antenna matching circuit 30A, 30B, 30E ... Antenna matching circuit 31 ... Substrate 31A, 31B, 31C, 31D ... Substrate 32 ... Antenna connection 32B, 32D ... Antenna connection 33 ... Switch 34 ... Series reactor 34a ... Series inductor 34b ... Series capacitor 35 ... Parallel reactor 35a, 35b ... Parallel inductor 36 ... Phaser 36a, 36b ... Phaser 37 ... Parallel reactor 37a, 37b ... Parallel inductor 39 ... Power feeding unit 50 ... Housing 60 ... Termination circuit 60E ... Termination circuit 61 ... Radiation Q switching line 61D ... Radiation Q switching line 62 ... switches 63, 64 ... End reactor 65 ... Switch 66 ... terminating reactor 68 ... radiation Q termination circuit connector 71 ... passive element connection portions 71A, 71B ... passive element connection portions 100, 101 ... antenna device

Claims (6)

In an antenna device including an antenna element and an antenna matching circuit that is connected between the antenna element and the power feeding unit and changes a matching frequency band,
A radiation Q control connecting portion for connecting predetermined positions of the housing ground and the antenna element facing the antenna element;
The radiation Q control connection unit includes an impedance variable element that changes a connection state between the housing ground and the antenna element according to a frequency band matched by the antenna matching circuit. The antenna matching circuit comprises a plurality of matching circuits having different utilization frequencies, and a switch connected between the antenna element and the power feeding unit by selecting the matching circuits.
2. The plurality of matching circuits are configured by an impedance circuit in which return loss characteristics when the matching circuit is viewed from the power feeding unit in the direction of the antenna element each have a double resonance characteristic in the band of the use frequency. Antenna device.   The antenna matching circuit includes a reactance loading unit that adjusts a resonance frequency, and a variable reactance circuit in which a return loss characteristic when the matching circuit is viewed in the direction from the feeding unit to the antenna connection unit is double-resonated in the band of the use frequency. The antenna device according to claim 1, wherein the reactance value of the variable reactance circuit is controlled according to a use frequency.   4. The antenna device according to claim 1, wherein some or all of the circuit elements constituting the antenna matching circuit are packaged in a laminated substrate.   The antenna device according to claim 1, 2 or 3, wherein the antenna element comprises a dielectric or magnetic substrate and an antenna element electrode disposed on the surface of the substrate or inside the substrate.   The antenna device according to claim 5, wherein the antenna matching circuit is included in the base.