JP5136289B2 - Antenna matching circuit and antenna device - Google Patents

Description

  The present invention relates to a two-frequency band or multi-frequency band antenna matching circuit and an antenna device including the same.

  Patent Document 1 discloses a multi-frequency antenna device built in a portable wireless device such as a cellular phone terminal that operates in a plurality of frequency bands.

FIG. 1 is a configuration diagram of the antenna device disclosed in Patent Document 1. In FIG. In this antenna device, a part of the inverted F antenna element composed of the plate-like element 2 and the plate-like element 1 in which the slit 5 is formed is electrically grounded to the ground plane 6 by the short-circuit portion 3. A series resonance circuit 9 in which an inductor 7 and a capacitor 8 are connected in series and a series resonance circuit 12 in which an inductor 10 and a capacitor 11 are connected in series are connected in parallel to the power supply unit 4. The other end of the parallel connection circuit of the series resonance circuit 9 and the series resonance circuit 12 is connected to the power supply terminal 13. A wireless circuit is connected to the power supply terminal 13.
JP 2003-179426 A

  In the antenna device shown in Patent Document 1, as shown in FIG. 1, an LC resonator is added to the feed line in order to make a double resonance by a circuit in a low frequency band.

  However, since such an LC resonator acts as a band-pass filter, it is difficult for frequency signals other than the resonance frequency to pass through, and the influence on other frequency bands is large. In addition, when the inductor, the capacitor, and the like are configured by discrete components, there is a concern that the loss as a resonator is large (Q value is low) and the frequency variation is also large.

  In the configuration of Patent Document 1, two LC resonators corresponding to high and low frequencies are provided. However, it is not possible to make a wide band by simultaneously double-resonating both frequency bands.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna matching circuit and an antenna apparatus including the antenna matching circuit that achieve a wide band for a plurality of frequency bands to be used while avoiding the disadvantages of using an LC resonator.

In order to solve the above problems, the present invention is configured as follows.
(1) An antenna matching circuit connected between an antenna connecting portion to which an antenna element is connected and a power feeding portion,
The antenna matching circuit includes a plurality of matching circuits having different utilization frequencies, and a switch that selects these matching circuits and connects between the antenna connection unit and the power feeding unit.
The plurality of matching circuits rotate the phase while converting impedance, and the return loss characteristics when the matching circuit is viewed from the power feeding unit in the direction of the antenna connection unit is a band of the use frequency for each band of the use frequency. It is characterized by being an impedance circuit having multiple resonances.

  With this configuration, the characteristic becomes double resonance at each of a plurality of use frequencies, and a wide band antenna characteristic can be obtained at each use frequency band.

(2) The impedance circuit includes an impedance conversion simultaneous phase rotation unit that simultaneously performs the impedance conversion and the phase rotation.

  Thereby, impedance conversion and phase rotation can be performed with a small number of circuit elements, and miniaturization and cost reduction can be achieved.

(3) The plurality of matching circuits are:
A π-type circuit comprising two parallel reactors connected to the shunt between the power supply unit and the ground, and a series reactor connected in series between the two parallel reactors, and the power supply unit and the antenna connection unit Are connected in series with each other and resonated at the use frequency.
As a result, it is possible to broaden the bandwidth optimally for each of a plurality of use frequency bands, and to reduce the size.

(4) In the matching circuit, part or all of the circuit elements constituting the matching circuit are packaged in a multilayer 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) An antenna device is configured by including the antenna matching circuit and an antenna element connected to the antenna connection portion.
Thereby, broadband antenna characteristics are obtained in a plurality of use frequency bands.

(6) The antenna matching circuit is configured on a circuit board, and the antenna element is mounted on the circuit board to configure an antenna device.
Thereby, the characteristics of the antenna matching circuit can be changed by selecting circuit elements according to the required antenna characteristics.

(7) The antenna element is formed by forming an electrode pattern on a dielectric or magnetic base, and a part or all of the antenna matching circuit is formed on the base.
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.

(8) The antenna element is an antenna element having a good radiation Q of the antenna element alone among a plurality of types of antenna elements connectable to the antenna connection portion of the antenna matching circuit.
With this configuration, an antenna device with high efficiency can be configured by connecting an antenna with good radiation Q to the antenna matching circuit.

(9) The selection condition for the plurality of types of antenna elements is any one of a position of a feeding point with respect to the antenna elements, a distance between the antenna element and the ground facing the antenna element, a size of the antenna element, or a combination thereof.
Thereby, an antenna element with good radiation Q can be selected easily and reliably, and a highly efficient antenna device can be configured.

  According to the present invention, the characteristic becomes double resonance at each of a plurality of use frequencies, and a broadband antenna characteristic can be obtained in each use frequency band. Further, by making each circuit element constituting the matching circuit indispensable, it is possible to configure a matching circuit that is optimal for widening the respective use frequency band, and miniaturization can be achieved.

<< First Embodiment >>
FIG. 2 is a perspective view showing a preliminary configuration for explaining the configuration of the antenna matching circuit 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 is formed on the substrate 31. The antenna device 100 is configured by mounting the antenna element 20 on the non-ground region NGA of the substrate 31.

  The antenna matching circuit 41 is configured between the antenna connecting portion 32 to which the antenna element 20 is connected and the power feeding portion 39. This antenna matching circuit 41 includes a high-band antenna matching circuit that is one of two use frequency bands, a low-band antenna matching circuit that is the other, and an antenna element side switch that selects the path of the two matching circuits. 33 and the power feeding unit side switch 38.

  The high-band antenna matching circuit and the low-band antenna matching circuit are obtained by adding various circuit elements on the paths as will be described later.

  In FIG. 2, the dimension indicated by the symbol W in the drawing of the non-ground region NGA of the substrate 31 is 40 mm, and the dimension indicated by the symbol L is 4 mm. The dimension indicated by the symbol T of the antenna element 20 is 3 mm, and its length is equal to W.

In FIG. 2, the configuration of each section P1 to P6 on the route is as follows.
P1-antenna element side switch part P2-reactance loading part P3-first matching part P4-phase shifting part P5-second matching part P6-feeding part side switch part The configuration of the antenna matching circuit 41 is divided into a low band side and a high band side. The change in characteristics when circuit elements are sequentially added from the antenna connection portion to the power feeding portion side will be described.

  3 to 7 are diagrams showing an antenna matching circuit on the low band side. In each figure, (A) is a perspective view of the antenna matching circuit, (B) is a return loss, and (C) is an antenna matching circuit from the power feeding unit 39. The impedance viewed from the side is represented on the Smith chart.

  First, as shown in FIG. 3, when the power feeding unit 39 and the antenna connection unit 32 are simply connected by a line, they do not resonate in the low band frequency band (900 MHz) and are not matched.

  In the example shown in FIG. 3, the return loss is slightly reduced in the vicinity of 2760 MHz, but this is merely unnecessary resonance.

  From such a state, as shown in FIG. 4, a series inductor 34a is connected as a series reactor in series with the line on the path.

  Thereby, in FIGS. 4B and 4C, resonance occurs in the low frequency band of 900 MHz as shown by the marker (1). Thus, the reactance component is added to the initial value of the antenna element 20 to determine the resonance frequency in a desired frequency band.

  Next, as shown in FIG. 5, a parallel inductor 35a is connected as a parallel reactor to a shunt between the line and the ground. As a result, the reference band 50Ω is matched in the low band (900 MHz), the return loss is reduced, and a small circle locus SCT is generated on the Smith chart as shown by the broken line in the figure. Markers (1) in FIGS. 5B and 5C correspond to frequencies. Thus, the impedance in the low band frequency band is close to the center of the Smith chart.

  Subsequently, as shown in FIG. 6, a phase shifter 36a is provided. As a result, the locus on the Smith chart shown in FIG. 5C rotates clockwise by the line length of the phase shifter 36a. The amount of phase shift by the phase shifter 36a is an amount until the small circle locus SCT moves to the third quadrant on the Smith chart in consideration of the addition of a subsequent parallel inductor.

  Since the phase shifter 36a shown in FIG. 6A is a 50Ω strip line, the locus shown in FIG. 5C should be rotated clockwise as it is. Tends to change the size of the small circle as shown in FIG. 6C due to other components. Markers (1) in FIGS. 6B and 6C correspond to frequencies.

  Finally, as shown in FIG. 7, a parallel inductor 37a is connected as an impedance element. As a result, as shown in FIG. 7C, the small circle locus SCT moves to a position surrounding the center on the Smith chart by turning in the direction of the arrow in the figure due to the connection of the parallel inductor 37a. Markers (1) and (2) in FIGS. 7B and 7C correspond to respective frequencies.

  In this way, the low-band matching circuit is constituted by an impedance circuit whose return loss characteristic seen from the power feeding part to the antenna connection part is double-resonated in the low-band frequency band, thereby returning the return of FIG. As shown in the loss characteristic, a double resonance occurs in the low-band frequency band, and a wide band can be achieved.

  By configuring the high-band matching circuit in the same manner as the low-band matching circuit, multiple resonances occur in the high-band frequency band, and the bandwidth can be increased.

  Here, when the actions of the first matching portion P3, the phase shifting portion P4, and the second matching portion P5 are summarized, “the impedance of the antenna deviating from 50Ω (including the reactance loading portion P2) is rotated on the Smith chart. However, it can be said that the impedance is directly converted to 50Ω which is the feeding point impedance, and the center of the Smith chart is aimed.

  This movement can be realized by a simpler circuit in which the first matching unit P3, the phase shifting unit P4, and the second matching unit P5 are represented by an F matrix (four-terminal matrix), and design based on this can be realized.

  FIG. 8 shows an antenna matching circuit designed by the above-described design method and its impedance on a Smith chart. In FIG. 8 (A), the structure of each section P1-P6 on the said path | route is as follows.

P1-antenna element side switch unit P2-reactance loading unit P345-impedance conversion + phase rotation unit P6-feeding unit side switch unit FIG. 8B shows the state shown in FIG. 4C (in series with the reactance loading unit P2. In the state where the inductor 34a is provided), while the impedance of the antenna including the reactance loading portion P2 is rotated on the Smith chart, the impedance is directly converted to 50Ω which is the impedance of the power feeding portion 39, and the center of the Smith chart is displayed. Represents the aim.

  FIG. 8C shows on the Smith chart the impedance of the antenna matching circuit viewed from the power feeding unit 39 in a state where the impedance conversion + phase rotation unit P345 is provided. This figure is equivalent to FIG.

  9A is a diagram showing the F matrix in a four-terminal network, FIG. 9B is a π-type circuit that realizes it, and FIG. 9C is four parameters that assume the π-type circuit. FIG. In this way, Z1, Z2, and Z3 of the π-type circuit are determined from the F matrix.

  The matching circuit shown in FIG. 2 has a configuration of “first matching portion P3” − “phase shift portion P4” − “second matching portion P5”. Considering this, the F matrix is set by configuring the phase shift part P4 with a general π type, and the π type first leg and first matching part, and the second leg and second matching. It can be regarded as equivalent to combining the reactance values of the parts (considering the same operation).

  FIG. 10 is a diagram showing this. 10A is a diagram showing the configuration of the first matching unit P3, the phase shift unit P4, and the second matching unit P5 shown in FIGS. 2 and 7A, and FIG. 10B is a circuit diagram of that part. It is. Since the phase shift unit P4 is represented by a π-type circuit having a parallel reactance and a series reactance, one parallel reactance of the phase shift unit P4 and the parallel reactance of the first matching unit P3 can be combined as one reactance element. Similarly, the other parallel reactance and the parallel reactance of the second matching unit P5 can be combined as one reactance element. FIG. 10C is a diagram showing the “impedance conversion + phase rotation unit” P345 in this way by a π-type circuit. The “impedance conversion + phase rotation unit” P345 corresponds to the “impedance conversion simultaneous phase rotation unit” according to the present invention.

  From the above, compared with the matching circuit shown in FIG. 2, the path can be simplified and the number of parts can be reduced. Further, at the time of designing, assuming that “first matching unit” − “phase shift unit” − “second matching unit” is set, or the second matching unit is omitted in the setting of the matrix Zout, the first matching unit is assumed. A part-phase shift part may be set and the reactance value may be synthesized.

  FIG. 11 is a perspective view illustrating a configuration of the antenna matching circuit and the antenna device according to the first embodiment. The antenna device 101 is obtained by replacing the first matching unit P3, the phase shift unit P4, and the second matching unit P5 with the “impedance conversion + phase rotation unit” P345 in the antenna device 100 shown in FIG. . In the example shown in FIG. 2, the first matching unit P3 is configured by the parallel reactors 35a and 35b, the phase shift unit P4 is configured by the phase shifters 36a and 36b, and the second matching unit P5 is configured by the parallel reactors 37a and 37b. However, in FIG. 11, the parallel reactors 45a and 45b, the serial reactors 46a and 46b, and the parallel reactors 47a and 47b constitute an “impedance conversion + phase rotation unit” P345. Other configurations are the same as those shown in FIG.

  FIG. 12 shows the return loss and efficiency characteristics of the antenna device 101 designed as described above. However, it is an experimental result in a state where the antenna element side switch 33 and the power feeding unit side switch 38 shown in FIG. 11 are not provided. Here, RL (L) is the return characteristic in the low band, η (L) is the efficiency in the low band, RL (H) is the return characteristic in the high band, and η (H) is the efficiency in the high band.

  As described above, both the low band centered on 900 MHz (GSM850 / 900) and the high band centered on 1900 MHz (DCS / PCS / UMTS) are in a double resonance state and can be widened. Moreover, high efficiency can be obtained in both low band and high band.

  In the example shown above, the “impedance conversion simultaneous phase rotation unit” is configured by a π-type circuit having three elements, but it may be configured by a T-type circuit or by two elements.

<< Second Embodiment >>
In the second embodiment, selection of an antenna with good radiation Q will be described.
In conclusion, when the antenna matching circuit of the present invention is applied, the efficiency is as follows. The antenna (the antenna element not including the matching circuit other than the loaded reactance that brings the resonance frequency to a desired frequency band) and the casing portion that contributes to radiation Depends on the radiation Q of the antenna itself. For this antenna, one having a radiation Q as good as possible (one with a small value) should be selected.

In the second embodiment, this effect is verified experimentally.
First, two types of antennas having different radiation Qs were prepared, an antenna matching circuit was applied to each, and the characteristics were measured.

  FIG. 13 is a perspective view of the two types of antennas. 13A and 13B, a series inductor 34 a is inserted between the antenna connection portion 32 and the power feeding circuit 40, and the power feeding position is changed with respect to the antenna element 20.

  In the example of FIG. 13A, the antenna connection portion 32 is disposed in the center portion of the substrate 31 and is configured to connect the center-fed antenna element 20. In the example of FIG. 13B, the antenna connection portion 32 is arranged at the end portion of the substrate 31B, and the end feeding antenna element 20B is connected.

  FIG. 14 shows measurement results of return loss and efficiency of the two types of antenna devices shown in FIG. Here, the meaning of each curve is as follows.

RLLC-Return loss of low-band side central feed antenna RLLE-Return loss of low-band side feed antenna ηLC-Efficiency of low-band side central feed antenna (after return loss correction)
ηLE-Low-band side feed antenna efficiency (after return loss correction)
RLHC-Return loss of high-band side central feed antenna RLHE-Return loss of high-band side feed antenna ηHC-Efficiency of high-band side central feed antenna (after return loss correction)
ηHE-Efficiency of high-band side feed antenna (after return loss correction)
The values of the radiation Q of the two types of antennas are as follows.

<Center feed antenna>
Low band 8.4
High band 25.4
<End feed antenna>
Low band 9.8
High band 35.8
In this way, a good (small value) antenna radiation Q can be obtained by using the central feeding.

  FIG. 15 shows an example in which the antenna matching circuit 30 shown in the first embodiment is applied to the antenna shown in FIG.

  FIG. 16 shows the return loss and efficiency for each antenna after the antenna matching circuit 30 is applied. However, it is an experimental result in a state where switches corresponding to the antenna element side switch 33 and the power feeding unit side switch 38 shown in FIG. 11 are not provided. Here, the low band is a GSM850 / 900 frequency band and the high band is a DCS / PCS / UMTS frequency band, and the average efficiency in each band is as follows.

<Center feed antenna>
Low band -2.6 (dB)
High band -2.3 (dB)
<End feed antenna>
Low band -2.4 (dB)
High band -3.9 (dB)
When the antenna matching circuit is loaded in this way, the ability of the antenna radiation Q is reflected, and the higher the radiation Q is, the higher the efficiency characteristic is obtained.

  In this example, in the low band frequency band, the ratio of the current flowing through the casing is large (the degree of dependence is high), so there is no difference in the radiation Q of the antenna including the casing, which is not suitable for this verification.

  FIG. 17 shows the result of simulating the intensity distribution of the surface current flowing through the housing for the two types of antennas. FIGS. 17A and 17C are examples of the central feeding antenna, and FIGS. 17B and 17D are current distributions in different frequency bands for the end (left end in the figure) feeding antenna. (A) shows the high band of the center feed antenna, (B) shows the high band of the end feed antenna, (C) shows the low band of the center feed antenna, and (D) shows the low band of the end feed antenna.

  As is clear from FIG. 17, (A) the central feeding antenna / high band flows well in the intensity distribution of current over the entire left and right, whereas (B) the end feeding antenna / high band has a current. The intensity distribution of the antenna has a left-right bias, the current intensity is particularly low on the left side, and the antenna (the antenna element that does not include a matching circuit other than the loaded reactance that brings the resonance frequency to the desired frequency band and the housing part that contributes to radiation It can be seen that the radiation Q of the antenna consisting of

  In the second embodiment, the central feeding antenna and the end feeding antenna are compared to indicate that an antenna with good radiation Q should be selected. However, in addition to the feeding type, the ground facing the antenna element is shown. Since the radiation Q varies depending on the distance between the antenna element and the size of the antenna element, an antenna element having a good radiation Q (small value) may be selected using any one or a combination of these as a selection condition.

<< Third Embodiment >>
In the third embodiment, several different examples of antenna elements and antenna element electrodes are shown.
FIG. 18 is an exploded perspective view of the antenna device according to the third embodiment. An antenna element 20C is used in which an antenna element electrode 21C extending in a funnel shape as shown in the figure is formed on the surface of a rectangular parallelepiped (rectangular prism) -shaped dielectric substrate. In this way, by forming the antenna element electrode 21C having a pattern in which the antenna element electrode 21C gradually spreads from the feeding portion of the antenna element 20C, the antenna element 20C resonates at a quarter wavelength over a wide frequency band, thereby increasing the bandwidth. Is promoted.

  Further, in the example shown in FIG. 18, since only the electrode for the antenna connection portion is formed on the bottom surface of the antenna element 20C, and since the antenna element 20C has a certain volume, it is directly connected to the ground region of the substrate 31C. Can be implemented.

  FIG. 19 is an exploded perspective view of another three antenna devices. In the example of FIG. 19A, an antenna element 20D obtained by bending a metal plate is used, and this is soldered to the antenna connection portion 32 formed on the substrate 31D, and the upper portion thereof is covered with the housing 50. . The ends of the antenna element 20 </ b> D and the substrate 31 </ b> D are shaped so as not to create a useless space in accordance with the shape of the housing 50.

  In the example of FIG. 19B, a (spring) pin-shaped antenna connection portion 32B is attached to the substrate 31D, the antenna element electrode 21E is provided on the inner surface of the housing 50, and the housing 50 is covered with the substrate 31D. In this state, the antenna connection portion 32B is connected to the antenna element electrode 21E. In this way, the present invention can also be applied to an antenna element provided in a part of a housing.

  In the example of FIG. 19C, the antenna element electrode 21F is directly formed in the non-ground region of the substrate 31E. In this way, the substrate pattern may also be used as an antenna element.

<< Fourth Embodiment >>
FIG. 20 is an exploded perspective view showing the configuration of the antenna device according to the fourth embodiment.
FIG. 20 shows an example in which the antenna matching circuit 30 shown in FIG. 11 in the first embodiment is configured as a packaged antenna matching circuit module 30 </ b> A and mounted on a substrate 31.

  The antenna matching circuit module 30A is configured by configuring the antenna matching circuit 30 shown in FIG. 11 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.

<< Fifth Embodiment >>
FIG. 21 is an exploded perspective view showing a configuration of two antenna devices according to the fifth embodiment.
The example of FIG. 21A is an example in which a series reactor 34 is provided for both the low band side and the high band side. This series reactor 34 selects an element such as an LC resonator so that it acts as a necessary inductor in the low band frequency band and as a necessary capacitor in the high band frequency band. As a result, the number of parts can be reduced and the area occupied by the antenna matching circuit can be reduced.

  In the example of FIG. 21B, not only the serial reactor 34 but also a parallel reactor 35 serving both as a low band and a high band is provided. For example, an intermediate value between the optimum reactance value for the low band and the optimum reactance value for the high band is selected.

  Further, portions other than the series reactor 34 and the parallel reactor 35 shown in FIG. 21 may be provided as the antenna matching circuit module 29 or 28. Further, the series reactor 34 and / or the parallel reactor 35 are switchable or tunable circuits including variable capacities, that is, the reactance values of the series reactor and / or the parallel reactor are adjusted according to the frequency band to be used. It may be applicable in the frequency band.

<< Sixth Embodiment >>
FIG. 22 is an exploded perspective view of two antenna devices according to the sixth embodiment.
In the example of FIG. 22A, the antenna element electrode 21G is formed on the antenna element 20E, and the antenna matching circuit 30B is configured inside the dielectric. Therefore, it is only necessary to provide a power feeding circuit on the substrate 31F on which the antenna element 20E is mounted.

  In the example of FIG. 22B, an antenna element electrode 21G is formed on the antenna element 20F, and a low-band series inductor 34a and a high-band series capacitor 34b are formed. The antenna matching circuit module 29 except for the series inductor 34a and the series capacitor 34b may be mounted on the substrate 31G side on which the antenna element 20F is mounted.

  In each of the embodiments described above, the antenna matching circuit is provided for the two frequency bands of the low band and the high band. However, in the case of adapting to three or more frequency bands, the antenna matching corresponding to each frequency band is provided. A circuit may be provided in the same manner.

  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.

  In each of the above embodiments, the phase shifter is conceptually represented by a stripline. However, for example, the phase shifter may be constituted by a π-type or T-type circuit using discrete parts, or the parts constituting the circuit may be structured. It may be replaced with a body.

1 is a configuration diagram of an antenna device shown in Patent Document 1. FIG. It is a perspective view which preliminarily shows the configuration of the antenna matching circuit according to the first embodiment. It is a figure explaining the characteristic change when a circuit element is sequentially added from the antenna connection part to the electric power feeding part side about the antenna matching circuit of a low band side, and is a figure which shows the state which comprised the track | line simply. It is a figure explaining the characteristic change when a circuit element is sequentially added from the antenna connection part to the electric power feeding part side about a low band side antenna matching circuit, and is a figure which shows the state which added the series inductor 34a. It is a figure explaining the characteristic change when a circuit element is sequentially added from the antenna connection part to the electric power feeding part side about the antenna matching circuit of a low band side, and is a figure which shows the state which added the parallel inductor 35a. It is a figure explaining the characteristic change when a circuit element is sequentially added from the antenna connection part to the electric power feeding part side about the antenna matching circuit of a low band side, and is a figure which shows the state which added the phase shifter 36a. It is a figure explaining the characteristic change when a circuit element is sequentially added from the antenna connection part to the electric power feeding part side about the antenna matching circuit of a low band side, and is a figure which shows the state which added the parallel inductor 37a. The antenna matching circuit designed by the above design method and its impedance are represented on a Smith chart. (A) is a diagram showing the F matrix in a four-terminal network, (B) is a π-type circuit for realizing it, and (C) is a diagram showing four parameters assuming the π-type circuit. (A) is a figure which shows the structure of the 1st matching part P3 shown in FIG.2 and FIG.7 (A), the phase shift part P4, and the 2nd matching part P5, (B) is the circuit diagram of the part. (C) is a diagram showing the impedance transformation + phase rotation unit P345 by a π-type circuit. It is a perspective view which shows the structure of the antenna matching circuit and antenna apparatus which concern on 1st Embodiment. This shows the return loss and efficiency characteristics of the antenna device 101 designed as described above. It is a perspective view of two types of antennas shown about selection of radiation Q of an antenna. It is a figure which shows the measurement result of the return loss and efficiency of two types of antenna apparatuses of FIG. It is the figure which applied the antenna matching circuit 30 shown in 1st Embodiment with respect to two types of antennas of FIG. It is a figure which shows about return loss and efficiency about each antenna after applying the antenna matching circuit 30 of FIG. FIG. 16 shows the result of simulating the intensity distribution of the surface current flowing through the housing for the two types of antennas in FIG. 15. It is a disassembled perspective view of the antenna device which concerns on 3rd Embodiment. It is a disassembled perspective view of another three antenna apparatus which concerns on 3rd Embodiment. It is a disassembled perspective view which shows the structure of the antenna apparatus which concerns on 4th Embodiment. It is a disassembled perspective view which shows the structure of the two antenna devices which concern on 5th Embodiment. It is a disassembled perspective view of the two antenna devices which concern on 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Antenna element 21 ... Antenna element electrode 28, 29, 30A ... Antenna matching circuit module 30 ... Antenna matching circuit 30A ... Antenna matching circuit module 30B ... Antenna matching circuit 31 ... Substrate 32 ... Antenna connection part 33 ... Antenna element side switch 34a ... Series inductor 34b ... Series capacitor 34 ... Series reactor 35a ... Parallel inductor 35b ... Parallel inductor 35 ... Parallel reactor 36 ... Phase shifter 37 ... Parallel reactor 38 ... Feeder side switch 39 ... Feeder 40 ... Feeder circuits 45a, 45b ... Parallel Reactors 46a, 46b ... series reactors 47a, 47b ... parallel reactor 50 ... casing 100, 101 ... antenna device GA ... ground region NGA ... non-ground region P1 ... antenna element side switch unit P2 ... reactance loading unit P3 ... first matching unit P4 ... Transfer Part P5 ... second matching portion P6 ... feeding unit-side switch unit P345 ... impedance conversion + phase rotation unit SCT ... small circle locus

Claims (9)

An antenna matching circuit connected between an antenna connecting portion to which an antenna element is connected and a power feeding portion,
The antenna matching circuit includes a plurality of matching circuits having different utilization frequencies, and a switch that selects these matching circuits and connects between the antenna connection unit and the power feeding unit.
The plurality of matching circuits rotate the phase while converting impedance, and the return loss characteristics when the matching circuit is viewed from the power feeding unit in the direction of the antenna connection unit is a band of the use frequency for each band of the use frequency. antenna matching circuit, wherein the inner an impedance circuit for multiple resonance in.   The antenna matching circuit according to claim 1, wherein the impedance circuit includes an impedance conversion simultaneous phase rotation unit that simultaneously converts the impedance and rotates the phase. The plurality of matching circuits are:
A π-type circuit comprising two parallel reactors connected to the shunt between the power supply unit and the ground, and a series reactor connected in series between the two parallel reactors, and the power supply unit and the antenna connection unit The antenna matching circuit according to claim 2, further comprising: a series reactor connected in series with each other to resonate at the use frequency.   The antenna matching circuit according to claim 1, 2 or 3, wherein a part or all of circuit elements constituting the matching circuit are packaged in a laminated substrate.   An antenna device comprising the antenna matching circuit according to claim 1 and an antenna element connected to the antenna connection unit.   An antenna device comprising the antenna matching circuit according to claim 1 on a circuit board, and the antenna element mounted on the circuit board.   5. The antenna device according to claim 1, wherein the antenna element is formed by forming an electrode pattern on a dielectric or magnetic substrate, and the substrate includes a part or all of the antenna matching circuit according to any one of claims 1 to 4.   The antenna element according to any one of claims 5 to 7, wherein the antenna element is an antenna element having a good radiation Q of the antenna element alone among a plurality of types of antenna elements connectable to an antenna connection portion of the antenna matching circuit. The antenna device described.   The selection condition for the plurality of types of antenna elements is any one of a position of a feeding point with respect to the antenna elements, a distance between the antenna elements and a ground facing the antenna elements, a size of the antenna elements, or a combination of these. Antenna device.

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