WO2001097323A1

WO2001097323A1 - Impedance matching circuit and antenna device

Info

Publication number: WO2001097323A1
Application number: PCT/JP2000/003866
Authority: WO
Inventors: Tetsu Ohwada; Moriyasu Miyazaki; Tsutomu Endo; Tamotsu Nishino
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2000-06-14
Filing date: 2000-06-14
Publication date: 2001-12-20
Also published as: JP3939649B2; KR20020019616A; CN1370340A

Abstract

An impedance matching circuit comprises a first matching circuit (8-1) adapted for impedance at a frequency (f2), a transmission line (6b) having a predetermined electrical length, and a second matching circuit (8-2) composed of an open stub (14) and a shorted stub (15) connected with the transmission line (6b) and adapted for impedance matching at a frequency (f1). The open stub (14) includes a portion (17) having discontinued characteristic impedance to associate the electrical length of the open stub (14) with that of the shorted stub (15) so that the sum of the susceptance values of the open stub (14) and the shorted stub (15) can be zero at the frequency (f2) and a predetermined value at the frequency (f1).

Description

Description Impedance matching circuit and antenna device

The present invention relates to an impedance matching circuit mainly applied to an antenna device for a VHF band, a UHF band, a microwave band, and a millimeter wave band, and an antenna device to which the impedance matching circuit is applied. . Background technology,

FIG. 1 is a perspective view showing an antenna device including a conventional impedance matching circuit disclosed in, for example, Japanese Patent Application Laid-Open Publication No. Hei 9-133733, and FIG. FIG. 3 is a circuit diagram of the antenna device shown in FIG. 3, and FIG. 3 is an enlarged view of an antenna 1 used in the antenna device. In Figs. 1 to 3, 1 is an antenna such as a chip antenna as shown in Fig. 3, 2 is the input terminal of antenna 1, 1-2 is the radiation conductor of antenna 1, and 1-2 is the radiation. Ceramic block that covers the outside of conductors 1-2.

3a is a variable capacitance capacitance element, 3b is a fixed capacitance capacitance element, 4a is an inductance element, and 7 is an impedance matching circuit formed by them. Note that an active element such as a parabolic diode is used as the variable capacitance capacity element 3a.

9 is an input terminal of the antenna device, and 10 is a power supply circuit or an external circuit such as an RF circuit connected to the input terminal 9. Reference numeral 12 denotes a dielectric substrate on which the antenna 1 and the impedance matching circuit 7 are mounted. Reference numerals 13a, 13b, and 13c denote ground conductors formed on the front and back surfaces of the dielectric substrate 12. . FIG. 4 is an equivalent circuit of the antenna 1 shown in FIG. In FIG. 4, 2 denotes an input terminal of the antenna 1, 3c denotes a capacitance element, 4-2 denotes a resistance element, and 4b denotes an inductance element. That is, the antenna 1 is a single-resonance antenna having a series resonance circuit operation composed of a capacitance element 3c, a resistance element 412, and an inductance element 4b connected in series.

Next, the operation will be described.

For example, it is assumed that at frequency f l, antenna 1 has a value of R l + j X l (both R l and X I are positive) as the input impedance at input terminal 2. At this time, in the impedance matching circuit 7 shown in FIG. 2, first, the capacitance value of the capacitance element 3a is changed by changing the bias voltage applied to the varactor diode constituting the capacitance element 3a. Adjust so that the reactance component X 1 becomes zero.

Then, utilizing the impedance transformation function obtained by an appropriate combination of the value of the inductance element 4a arranged in series and the value of the capacitance element 3b arranged in parallel, the resistance component of the input impedance is calculated. Match R 1 with the characteristic impedance of the external circuit 10. This makes it possible to reduce the generation of reflected waves at the frequency f 1, and to efficiently operate the antenna 1 from the external circuit 10.

Also, at a frequency f 2 different from the frequency f 1, the antenna 1 has a value of: R 2 + jX 2 (both R 2 and X 2 are positive) as the input impedance at the input terminal 2. However, if the value of the resistance component R2 does not greatly differ from the value of R1, the bias voltage applied to the capacitance element 3a is changed to change the capacitance value to an appropriate value, thereby changing the frequency 1 to the appropriate value. As in the case, the input impedance is changed to the characteristic impedance of the external circuit 10. They can be almost matched. Thus, the antenna apparatus shown in FIG. 1 can operate the antenna 1 efficiently at a plurality of frequencies.

Since the conventional antenna device is configured as described above, in order to perform impedance matching at a plurality of frequencies, the capacitance of the capacitance element 3a is made variable and this capacitance value is adjusted to an appropriate value. Like that. The adjustment of the capacitance value is performed by providing a bias circuit and adjusting the bias voltage applied to the varak diode, etc., when using an active element such as a varak diode.

For this reason, it is necessary to provide a control circuit in addition to the bias circuit, which complicates the circuit configuration. The complexity of the circuit configuration and the increase in the number of parts have led to an increase in manufacturing costs and a problem of increased power consumption. These issues are particularly important for portable wireless terminals such as mobile phones.

In addition, the conventional impedance matching circuit 7 has a problem that its application range is narrow because impedance matching can be performed only for the antenna 1 having a specific input impedance characteristic.

The present invention has been made in order to solve the above-described problems, and is intended to provide various types of single-resonant antennas in a wide range including two frequency bands or a band between the two frequency bands. An object of the present invention is to provide an impedance matching circuit and an antenna device that can operate efficiently in a frequency band of a low cost with a simple circuit configuration.

The "single-resonant antenna" referred to in this specification is used as a generic term for a wide variety of antennas, and is not limited to any particular antenna. Disclosure of the invention

The impedance matching circuit according to the present invention is configured to determine the input impedance of an antenna and the characteristic impedance of an external circuit that transmits and receives signals to and from the antenna, by using the frequency f1 and the frequency f1. A first matching circuit that performs impedance matching at the frequency f2, and a microstrip line that serves as a feed line to the antenna. And the like, and a first and second stub connected to this transmission line and formed by the microstrip line and the like. A second matching circuit that performs impedance matching at the frequency f1.If the first or second stub is provided with a discontinuous portion of the impedance such that the characteristic impedance is different. At the frequency f2, the sum of the susceptance values of the first and second stubs is 0, and at the frequency: f1, the sum of the susceptance values of the first and second stubs is The electrical lengths of the first and second sub-switches are set so that the predetermined value is obtained.

As a result, impedance matching can be performed in two different frequency bands, and the frequency characteristics of the input impedance of the antenna to be impedance-matched can be flexibly handled. However, in one of the bands close to the two frequencies, the return loss characteristics do not become narrower and the loss in the impedance matching circuit does not increase. This has the effect that the loss characteristics can be obtained.

In the impedance matching circuit according to the present invention, the first matching circuit includes a transmission line formed by a microstrip line or the like and having a predetermined electrical length, and a capacitance in series with the transmission line. It is composed of the given digital capacity. This eliminates the use of chip elements that require mounting work, making it easier to manufacture and lower cost, and easily and accurately producing a capacitance element with an arbitrary capacitance. It is possible to obtain an impedance matching circuit with good characteristics.

In the impedance matching circuit according to the present invention, the first matching circuit includes a one-to-four wavelength impedance transformer at a frequency f2.

This has the effect of making the circuit configuration simpler and enabling manufacture at low cost.

In the impedance matching circuit according to the present invention, the second matching circuit includes a first stub having an open stub having an impedance discontinuity and having one end opened, and a short stub having one end connected to a ground conductor. It consists of a second stub.

As a result, since chip elements requiring a mounting operation are not used, there is an effect that the manufacturing becomes easy and the impedance matching circuit can be manufactured at low cost.

In the impedance matching circuit according to the present invention, the second matching circuit includes a first stub having an open stub having one end opened, and a second stub having an impedance discontinuity portion having an open end. It is composed of the stubs.

This eliminates the need for chip elements or short-circuits that require mounting work, and thus has the effect of making fabrication easier and making it possible to manufacture an impedance matching circuit at low cost.

A plurality of impedance matching circuits according to the present invention are formed on a hollow cylindrical dielectric, and each of the input impedances of a plurality of antennas and a characteristic of an external circuit for transmitting and receiving signals between the plurality of antennas. The music dance A first matching circuit that performs impedance matching at the frequency f2 in the frequency band of the wave number f1 and the frequency f2 higher than the frequency f1; And a transmission line formed by a microstrip line having a predetermined electrical length and serving as a power supply line to the transmission line, and a first line formed by the microstrip line and connected to the transmission line. And a second matching circuit configured to perform impedance matching at the frequency f1. The first or second stub has a characteristic impedance different from that of the first or second stub. In addition to providing a discontinuity in the impedance, the sum of the susceptance values of the first and second stubs is 0 at the frequency f2, and the first and second stubs at the frequency f1. The sum of the susceptance values of So that, those were set boss an electrical length of said first and second scan evening drive.

As a result, impedance matching can be performed in two different frequency bands, and the frequency characteristics of the input impedance of the impedance matching impedance antenna can be flexibly accommodated. Good return loss in either band without the return loss characteristics becoming narrower in one of the bands near the two frequencies or the loss in the impedance matching circuit increasing There is an effect that characteristics can be obtained.

In the impedance matching circuit according to the present invention, a first matching circuit includes a transmission line formed by a microstrip line and having a predetermined electrical length, and an capacitance that gives a capacitance to the transmission line in series. It consists of a digital capacity and a digital capacity.

This eliminates the need for chip elements that require mounting work, making it easier to manufacture and lower cost, and also enables more easily and accurately manufacturing capacitance elements with arbitrary capacitance. Possible and characteristic There is an effect that a good impedance matching circuit can be easily obtained.

An impedance matching circuit according to the present invention includes a second matching circuit comprising: a first stub having an impedance discontinuity, an open stub having one open end; and a short stub having one end connected to a ground conductor. And a second stub.

In the impedance matching circuit according to the present invention, the second matching circuit includes a first stub having an open stub having one open end, and a second stub having an discontinuous portion of impedance having an open end. And a stub.

This eliminates the use of chip elements and short stubs that require mounting work, so that the production is easier and the impedance matching circuit can be produced at low cost.

An antenna device according to the present invention includes: a plurality of antennas formed on a hollow cylindrical dielectric; and a plurality of antennas formed on the hollow cylindrical dielectric and connected to the respective antennas. And a characteristic impedance of an external circuit for transmitting and receiving signals to and from each of the above-described antennas in a frequency band of frequency f1 and a frequency band f2 higher than the frequency f1. An impedance matching circuit; and a plurality of distribution circuits formed on the hollow cylindrical dielectric, connected to the impedance matching circuits, and providing a predetermined phase difference to a signal from the external circuit. Each of the impedance matching circuits described above includes a first matching circuit that performs impedance matching at the frequency f2 and a microstrip that serves as a feed line to each of the antennas. A transmission line having a predetermined electrical length formed by the line, the upper A second matching circuit formed by the microstrip line, configured by first and second stubs connected to the transmission line, and performing impedance matching at the frequency f1; In the first or second stub, a discontinuity of impedance is provided so that the characteristic impedance is different, and the first and second stubs are provided at the frequency f2. The first and second thresholds are set so that the sum of the susceptances of the first and second thresholds is 0 and the sum of the susceptances of the first and second thresholds at the frequency f1 is a predetermined value. The electric length of the loop is set.

As a result, impedance matching can be performed in two different frequency bands, and the frequency characteristics of the input impedance of the antenna to be impedance-matched can be flexibly accommodated. Good return loss characteristics can be obtained in any band without the return loss characteristics becoming narrower in one of the bands near the frequency or the loss in the impedance matching circuit increasing. There is an effect that can be.

In the antenna device according to the present invention, the first matching circuit includes a transmission line formed of a microstrip line and having a predetermined electric length, and an impedance providing capacitance in series with the transmission line. It consists of digital capacity.

This eliminates the need for chip elements that require mounting work, making it easier to manufacture and lower cost, and also enables more easily and accurately manufacturing capacitance elements with arbitrary capacitance. It is possible, and it is easy to obtain an antenna device having good characteristics.

In the antenna device according to the present invention, the second matching circuit includes a first stub having an open stub having one end provided with a discontinuous portion of impedance, and a second stub having a short stub having one end connected to a ground conductor. And by It is configured.

This eliminates the need for a chip element that requires a mounting operation, thereby facilitating the production and producing an antenna device at a low cost.

In the antenna device according to the present invention, the second matching circuit includes a first stub having an open stub having one open end, and a second stub having an open stub having an open end having an impedance discontinuity. It is composed of

This eliminates the use of chip elements or short stubs that require mounting work, and thus makes it easier to manufacture and has the effect that the antenna device can be manufactured at low cost. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing an antenna device including a conventional impedance matching circuit.

FIG. 2 is a circuit diagram of the antenna device shown in FIG.

FIG. 3 is an enlarged view of an antenna used in the antenna device shown in FIG.

FIG. 4 is an equivalent circuit of the antenna shown in FIG. FIG. 5 is a perspective view showing an antenna device according to Embodiment 1 of the present invention.

FIG. 6 is a top view of the antenna device shown in FIG.

FIG. 7 is a circuit diagram of the antenna device shown in FIG.

FIG. 8 is a Smith chart showing the input impedance characteristics of the antenna when the antenna side is viewed from the node A shown in the circuit diagram of FIG.

Fig. 9 shows the characteristics when the antenna side is viewed from node B shown in the circuit diagram of Fig. 7. It is a Smith chart which shows sex.

FIG. 10 is a Smith chart showing characteristics when the antenna side is viewed from the node C shown in the circuit diagram of FIG.

FIG. 11 is a Smith chart showing characteristics when the antenna side is viewed from the node D shown in the circuit diagram of FIG.

FIG. 12 is a diagram showing a frequency characteristic of a sum of susceptance values of two sub-bands.

FIG. 13 is a Smith chart showing characteristics when the antenna side is viewed from the node E shown in the circuit diagram of FIG.

FIG. 14 is a diagram showing a frequency characteristic of a return loss when the antenna side is viewed from the node E shown in the circuit diagram of FIG.

FIG. 15 is a diagram showing a comparison of the frequency characteristics of the sum of the susceptance values of two stubs with and without a discontinuity in the open stub. FIG. 16 is a diagram showing a comparison of the return loss frequency characteristics of the antenna device at the input terminal when there is a discontinuity in the open stub and when there is no discontinuity.

FIG. 17 is a diagram showing frequency characteristics of return loss when the antenna side is viewed from the node E shown in the circuit diagram of FIG.

FIG. 18 is a perspective view showing an antenna device according to Embodiment 2 of the present invention.

FIG. 19 is a top view of the antenna device shown in FIG.

FIG. 20 is a circuit diagram of the antenna device shown in FIG.

FIG. 21 is a perspective view showing an antenna device according to Embodiment 3 of the present invention.

FIG. 22 is a top view of the antenna device shown in FIG.

FIG. 23 is a circuit diagram of the antenna device shown in FIG. FIG. 24 is a Smith chart showing the input impedance characteristics of the antenna when the antenna side is viewed from the node A shown in the circuit diagram of FIG. FIG. 25 is a Smith chart showing characteristics when the antenna side is viewed from the node C shown in the circuit diagram of FIG.

FIG. 26 is a perspective view showing an antenna device according to Embodiment 4 of the present invention.

FIG. 27 is a developed view showing the outer surface of the cylindrical dielectric of the antenna device shown in FIG.

FIG. 28 is a developed view showing the inner side surface of the cylindrical dielectric of the antenna device shown in FIG.

FIG. 29 is an enlarged view of a strip conductor pattern for the impedance matching circuit portion of the antenna device shown in FIG.

FIG. 30 is a circuit diagram of the antenna device shown in FIG.

FIG. 31 is a perspective view showing an antenna device according to Embodiment 4 of the present invention.

FIG. 32 is a developed view showing the outer side surface of the cylindrical dielectric of the antenna device shown in FIG.

FIG. 33 is a developed view showing the inner side surface of the cylindrical dielectric of the antenna device shown in FIG.

FIG. 34 is an enlarged view of a strip conductor pattern corresponding to the impedance matching circuit portion of the antenna device shown in FIG. 32.

FIG. 35 is a circuit diagram of the antenna device shown in FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, in order to explain this invention in greater detail, the preferred embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment 1

FIG. 5 is a perspective view showing an antenna device according to Embodiment 1 of the present invention, FIG. 6 is a top view of the antenna device shown in FIG. 5, and FIG. 7 is a circuit diagram of the antenna device shown in FIG. It is. This antenna device consists of a small helical antenna used in a small wireless terminal such as a mobile phone, and an impedance matching circuit formed by microstrip lines so as to operate in two frequency bands. Are combined.

In FIGS. 5 to 7, 1 is an antenna using a small helical antenna, 2 is an input terminal of antenna 1, 12 is a dielectric substrate on which antenna 1 and impedance matching circuit 7 described later are mounted, 1 Reference numeral 3 denotes a ground conductor formed on the back surface of the dielectric substrate 12, and reference numeral 18 denotes a strip that forms a microstrip line serving as a feed line of the antenna 1 together with the dielectric substrate 12 and the ground conductor 13. The trip conductor, 10 is an external circuit such as a power supply circuit or an RF circuit for transmitting and receiving signals to and from the antenna 1, and 9 is an input terminal of the antenna device to which the external circuit 10 is connected.

6a is formed by a microstrip line, a transmission line having an electrical length 6> a at a frequency f2, 6b is formed by a microstrip line, and a frequency f1 Is a transmission line having an electrical length of 0b, and 22 is an digital capacity inserted between these transmission lines 6a and 6b to provide capacitance in series.

Numeral 14 is an open square formed by a microstrip line. In this open stub 14, the characteristic impedance of the line forming the stub is not constant within the stub, and there is one discontinuous position 17 of the characteristic impedance. An impedance line is used, and a low impedance line is used on the transmission line 6b side. Electrical length of high impedance line is 0 o 1, low impedance The electrical length of the transmission line is 0 2.

Reference numeral 15 denotes a short stub formed by a microstrip line and having an electrical length of 0 s. Reference numeral 16 denotes a through hole provided at the tip of the short stub 15. The open stub 14 and the short stub 15 are connected to the same location of the strip conductor 18 so as to face each other.

Here, the sum of electrical lengths 0 ol and 6> o 2 and 0 s is almost 7ΓΖ2 or slightly larger than 7ΓΖ 2, and the sum of the susceptance values of the two stubs at frequency 2 is 0 It is set to be. That is, in the frequency band near the frequency f2, the circuit operates as the quarter-wave resonance circuit 5-2 shown in FIG.

Also, the electrical lengths 0 o 1, Θ 0 2, 0 s are set so that the sum of the susceptances of the open stub 14 and the short stub 15 shows a predetermined susceptance value at the frequency f 1. Distribution has been decided. In addition, a required value is also selected for the electrical length 0b of the transmission line 6b. In FIG. 7, reference numeral 8-1 denotes a transmission line 6a and a capacitance element 3 corresponding to an input / output digital capacity 22 and a first element for performing impedance matching of the antenna 1 at the frequency 2. 8-2 is composed of transmission line 6 b, open stub 14, and short stub 15, and is the second matching that performs impedance matching of antenna 1 at frequency 1 Circuit. Reference numeral 7 denotes an impedance matching circuit composed of a first matching circuit 8-1 and a second matching circuit 8-2 and performing impedance matching in two frequency bands.

In FIG. 7, the nodes A, B, C, D, and 回路 of the circuit are shown for explanation of the operation described later.

Next, the operation will be described.

Here, the impedance matching circuit 7 of this antenna device is shown in FIG. It is assumed that they are designed to have impedance matching at the two frequencies shown in f1 and f2. Note that the relationship between the frequency 1 and f 2 is f 1 and f 2, and for simplicity, the matching impedance, that is, the characteristic impedance of the external circuit 10 side is the transmission line 6a, 6 Let it be equal to the characteristic impedance Z o of b.

The impedance locus A shown in FIG. 8 shows the locus when the antenna 1 is viewed from the node A shown in the circuit diagram of FIG. The transmission line 6a connected to node A rotates the trajectory clockwise until the resistance of the impedance at frequency f2 at node B matches the characteristic impedance Zo. Have. Therefore, the locus of the antenna 1 when viewed from the node B is the impedance locus B shown in FIG.

Next, at the node B, like the capacitance element 3, at the frequency: f2, the magnitude is the same as the reactance of the impedance at the frequency f2 in FIG. The one with the given capacitance value is connected. As a result, the locus of the antenna 1 when viewed from the node C is the impedance locus C shown in FIG. Here, the impedance at the frequency f 2 coincides with the characteristic impedance Z o, which means that the impedance has been matched. Thus, the impedance matching at the frequency f2 is performed by the first matching circuit 8-1 shown in FIG.

Next, in the second matching circuit 8-2 connected to the node C, the transmission line 6b further rotates the impedance locus C shown in FIG. 10 clockwise. Here, the electrical length (9b) of the transmission line 6b at frequency 1 is selected so that the conductance at the frequency fl is equal to 1 / Zo and the susceptance is a positive value. As a result, the trajectory of the antenna 1 viewed from the node D becomes the impedance trajectory D shown in FIG. At this time, the susceptance value at frequency 1 is a standardized value jb '. Note that j is an imaginary unit.

FIG. 12 is a diagram showing a frequency characteristic of a sum of susceptance values of two stubs. Since the 1/4 wavelength resonance circuit 5-2 is a parallel resonance circuit, the sum of the susceptance values of the two stubs at frequency 2 is 0 as shown in Fig. 12, and at frequencies lower than frequency 2, It has a negative susceptibility value. Therefore, since f l <f 2, a negative susceptance value is given at f 1. Here, the ratio of the lengths of the sweep lengths Θ s, Θ o 1, 6> o 2 is selected so as to exhibit a value of 1 j b ′ at the frequency f 1 ο

As a result, the trajectory of the antenna 1 viewed from the contact E becomes the impedance trajectory E shown in FIG. 13 and impedance matching at the frequency 1 is performed. At this time, at the frequency f 2, the quarter-wave resonance circuit 5-2 is in an open state because it is in a resonance state, and the impedance matching state by the first matching circuit 8-1 is the open stub 14, It is maintained even if shortsnap 15 is connected. In this way, impedance matching at frequency 1 is performed by the second matching circuit 8-2 shown in FIG.

As a result, as shown in FIG. 14, the frequency characteristic of the return port of the antenna device at the input terminal 9 in FIG. 7 has a valley at the frequencies f 1 and f 2.

The electrical lengths 0 o 1, Θ o 2, Θ s of the open stub 14 and the short stub 15, and the electrical length 0 b of the transmission line 6 b are represented by the following equations (1) and (2). From the simultaneous equations derived from

At frequency 2

ί Open stub 1 4 susceptance) + (short stub 1 5 Sep.) = 0 (1) At frequency 1,

Ζ ο- ¹ · (Y l + j Z o- an S b) / (Z o ^ + j Y ltan ^ b) + (opens 14 14 susceptance) + (shortstub 15 suscepte) Evening) = Z 0 (2)

Here, Y 1 in equation (2) is admittance at frequency f 1 when antenna 1 is viewed from node C in FIG. 7, that is, admittance at frequency f 1 in FIG. 10. . Also, since equation (2) is a complex number equation, it is separated into two equations by a real part and an imaginary part, and the above simultaneous equations become three equations. On the other hand, there are four unknowns. For example, by adding conditions such as 6> 0 1 = 6 »o 2, the electrical lengths of the open stub 14 and the short stub 15 Θ ο 1, θ ο 2, Θ s , And the electrical length 0b of the transmission line 6b can be obtained.

In this embodiment, the characteristic impedance is configured to be different in a part of the open stub 14, and the discontinuous portion 17 of the impedance is located in one place in the open stub 14. Existing. When the dimensions of the aperture 14 having the discontinuity 17 are determined by the above method, the total length of the aperture 14 is different from that without the discontinuity 17, and However, the frequency characteristics of the susceptance value of the open stub 14 are also different. However, the susceptance values at frequency 1 and f 2 are the same. FIG. 15 is a diagram showing a comparison of the frequency characteristics of the susceptance value of the quarter-wave resonance circuit 5-2 with and without the discontinuity 1 mm in the open stub 14. Thus, by providing the discontinuous portion 17 in the open stub 14, the frequency characteristics of the susceptance value of the resonance circuit at the frequencies f1 and f2 at which impedance matching is to be performed can be changed.

Therefore, the frequency characteristic of the initial loss obtained at input terminal 9 Also varies depending on the presence or absence of the discontinuous portion 17 of the open stub 14. FIG. 16 is a diagram showing a comparison of the frequency characteristics of the return loss of the antenna device at the input terminal 9 with and without the discontinuous portion 17 in the open stub 14. As shown in Fig. 16, by providing a discontinuous portion 17 in the open stub 14, in the band near the frequency f2, the width of the band with good return loss is slightly narrower, but on the other hand, In the band near the frequency f1, the width of the band with good return loss is widened.

In this way, by providing the characteristic impedance in a part of the open stub 14 and providing the discontinuity 17 of the characteristic impedance, the rejection in the two frequency bands near the frequency f1 and f2 is achieved. The frequency characteristics of the evening loss can be adjusted. Depending on the frequency characteristic of the input impedance of the antenna 1 to be impedance-matched, as shown in FIG. 16, when the discontinuous portion 17 is not provided in the open stub 14, the frequency: near f 2 However, the unbalanced return loss characteristic of a relatively narrow band near frequency 1 results in an unbalanced return loss characteristic. Thus, it is possible to obtain a return port characteristic in which the bandwidths near the frequencies f1 and f2 are almost the same.

That is, by providing the discontinuous portion 17 in the open stub 14, it is possible to prevent narrowing of the band in one frequency band, and to obtain a better re-transmission loss characteristic. In the narrow frequency band, the loss in the matching circuit increases.Therefore, providing the discontinuous portion 17 in the open stub 14 reduces the loss in the matching circuit in the narrow frequency band. It also leads to

Here, the frequency characteristic of the return loss depends on whether the frequency characteristic of the input impedance of the antenna 1 is steep or gradual, and the characteristic impedance of the external circuit 10. It depends on the ratio of the impedance to the resistance of the input impedance of antenna 1.

For example, when the frequency characteristic of the input impedance of antenna 1 is steep and the resistance of the input impedance of antenna 1 is smaller than the characteristic impedance of external circuit 10, as shown in FIG. ,: The frequency bands of e 1 and f 2 become narrower, and the return loss level in the frequency band between the frequency bands of f 1 and f 2 becomes larger.

On the other hand, when the frequency characteristic of the input impedance of antenna 1 is moderate and the resistance of the input impedance of antenna 1 is close to the characteristic impedance of external circuit 10, as shown in FIG. , F 1 and f 2 become wider, the level of return loss in the f 1 and f 2 frequency bands becomes lower, and the frequency band between the f 1 and f 2 frequency bands becomes smaller. Impedance matching can be efficiently performed in a wide frequency band including the above.

The position where the discontinuity of the characteristic impedance is provided, the number of discontinuities, and the ratio of the characteristic impedance of the line constituting the discontinuity depend on the frequency characteristic of the input impedance of the antenna 1 to be impedance-matched. It is only necessary to take this into consideration. In other words, it is needless to say that the partial impedance of the characteristic impedance of the open stub 14 is not necessarily different from that of the antenna device.

In the first embodiment, the transmission lines 6 a and 6 b, the open stub 14, and the shortstop 15 are formed by microstrip lines. Instead of a line, a strip line, a coaxial line, a coplanar line, or the like may be used.

As described above; according to the impedance matching circuit of the first embodiment, the frequency in two different frequency bands or the frequency between two frequency bands is different. In addition to being able to perform impedance matching in a wide frequency band including the band, it is possible to flexibly cope with the frequency characteristics of the input impedance of the antenna 1 to be impedance-matched, and Good return loss characteristics can be obtained in any of the bands, without narrowing the return loss characteristics in one of the bands near the number or increasing the loss in the impedance matching circuit. The effect that it can be obtained is obtained.

According to the first embodiment, the transmission line 6a and the digital capacity 22 are used as the first matching circuit 8-1, but the circuit of the first matching circuit 8-1 is used. By changing the configuration, it is possible to flexibly cope with impedance matching of various types of antennas. For example, if an inductance element is used instead of the input / output capacity 22, it is possible to support an antenna whose input impedance is high.

Further, according to the first embodiment, since the resonance circuit is configured using the open stubs 14 and the short stubs 15 and the digital capacity 22 is used, the mounting work is performed. Since there is no need for a chip element that requires a strip conductor, it can be manufactured only by forming a strip conductor pattern on the dielectric substrate 12, so that it is easy to manufacture and an impedance matching circuit can be manufactured at low cost. The effect is obtained.

Further, according to the first embodiment, the use of the in-line digital capacitance 22 makes it possible to easily and accurately manufacture a capacitance element having an arbitrary capacitance. This makes it easier to obtain an impedance matching circuit having good characteristics as compared to the case of using such a method. Embodiment 2

FIG. 18 is a perspective view showing an antenna device according to Embodiment 2 of the present invention. FIG. 19 is a top view of the antenna device shown in FIG. 18, and FIG. 20 is a view shown in FIG. It is a circuit diagram of an antenna device.

In Figs. 18 to 20, 14a is a first open stub having an electrical length of 0o formed by a microstrip line, and 14b is a microstrip line. It is a second open stub formed by the line. The second open stub 14 b is formed by using a line having a different characteristic impedance in a part of the stub. As a result, the discontinuity of the characteristic impedance at two places is formed in the stub. a, 17b, and the electrical length of each part is 6> sol, Θ so 2, 6> so 3 from the open end side. These two open stubs 14 a and 14 b are connected to the same location of the strip conductor 18 so as to face each other.

Reference numeral 8-2 denotes a second matching circuit, which includes the transmission line 6b and the open stubs 14a and 14b, and performs impedance matching of the antenna 1 at the frequency 1. Others are the same as those of Embodiment 1 having the same reference numerals shown in FIGS. 5 to 7.

Here, the sum of the electrical lengths of the two open stubs 14 a and 14 b is 7Γ or slightly larger than 7Γ at the frequency f 2, and the two stubs at the frequency 2 The sum of the susceptance values becomes 0 and resonates as a 1Z2 wavelength resonance circuit 5-3, and at frequency: fl, the sum of the susceptance values of the two stubs is set so as to exhibit a predetermined susceptance value. Length distribution is determined. In addition, a required value is also selected for the electrical length 0b of the transmission line 6b.

Next, the operation will be described.

In FIG. 20, the resonance circuit in the impedance matching circuit 7 is Embodiment 1 has a quarter-wavelength resonance circuit formed by a combination of open stubs 14 and short stubs 15, whereas Embodiment 2 has a combination of two open stubs 14 a and 14 b This is a 1 Z 2 wavelength resonance circuit.

Since these two open stubs 14a and 14b are connected in parallel at the same point with respect to the transmission line 6b, the 1- and 2-wavelength resonant circuit 5-3 should be considered as a kind of parallel resonant circuit. Can be. Therefore, the principle of operation is almost the same as that of the first embodiment.If the impedance locus of antenna 1 is given as shown in FIG. 8, when antenna 1 is viewed at nodes B to E The impedance is similar to the trajectories shown in FIGS. 9 to 13.

The electrical lengths of the two open stubs 14a and 14b and the electrical length of the transmission line 6 can be obtained by the following equations (3) and (4).

At frequency 2,

(The susceptance of the open tab 14a) + (the susceptance of the open tab 14b) = 0 (3)

Z o ^-CY l + j Z o ^ tan ^ b) / (Z o ^ + j Y lt an ^ b) + (susceptance of open stub 14 a) + (susceptance of open stub 14 b) ) = Z o— ¹ (4)

Here, Y 1 in equation (4) is the admittance at frequency f 1 when the antenna 1 side is viewed from the node C in FIG. That is, Y 1 corresponds to the admittance at f 1 in FIG. (4) Since the equation is a complex equation, the real and imaginary parts are separated into two equations, and the above simultaneous equations become three equations. Therefore, for example, if Θ s 03 is a constant and a condition such as 6> sol = 0 so 2 is added, the solution will be Can be requested.

In the second embodiment, the first open stub 14a and the second open stub 14b are formed by micro-strip lines. Instead of the line, it may be formed by a strip line, a coaxial line, a coplanar line, or the like.

As described above, according to the second embodiment, the same features and effects as those of the antenna device of the first embodiment are obtained. Furthermore, according to the second embodiment, since only the open stub is used for the stub and the short stub is not used, no through-hole is required, making the manufacturing easier and at a lower cost. The effect that it can be obtained is obtained. Embodiment 3.

FIG. 21 is a perspective view showing an antenna device according to Embodiment 3 of the present invention, FIG. 22 is a top view of the antenna device shown in FIG. 21, and FIG. It is a circuit diagram of the antenna device shown. This antenna device combines a circular microstrip antenna with an impedance matching circuit formed by a microstrip line so as to operate in two frequency bands.

In Figs. 21 to 23, 1 is an antenna with a circular microstrip antenna, 2 is a quarter-wave impedance transformer at frequency: 2, and 8-1 is a quarter-wave impedance. This is the first matching circuit using the transformer 24, and performs the impedance matching of the antenna 1 at the frequency 2. Others are the same as those of Embodiment 2 having the same reference numerals shown in FIGS. 18 to 20.

Next, the operation will be described.

Figure 24 shows the input of antenna 1 using a circular microstrip antenna. 7 is a Smith chart showing impedance characteristics, which corresponds to the characteristics when the antenna 1 is viewed from the node A in FIG. In general, in such a circular microstrip antenna, when a microstrip line is connected to the end of the microstrip antenna as shown in the figure to feed power, a high height as shown in FIG. 24 is used. Shows impedance characteristics.

Here, assuming that the reactance component is 0 at the frequency; f 2, and the impedance transformer 24 is connected for impedance matching at the frequency f 2, the characteristic becomes as shown in FIG. The resistance of the input impedance at the frequency f2 in the figure is converted to a characteristic impedance Zo (standardized impedance or characteristic impedance of the external circuit 10). With respect to the characteristics shown in FIG. 25, the operation of impedance matching at frequency 1 while maintaining the impedance matching state at frequency f2 is the same as that of the second embodiment.

As described above, according to the third embodiment, the same features as those of the antenna device of the second embodiment are obtained, and the same effects are obtained. In the third embodiment, the impedance transformer 24 is used in the first matching circuit 8-1 in consideration of the characteristics of the microstrip antenna, so that the circuit configuration becomes simpler. The advantage is that it can be manufactured at low cost. Embodiment 4.

FIG. 26 is a perspective view showing an antenna device according to Embodiment 4 of the present invention. Since this antenna device is used in small wireless terminals such as mobile phones, a four-wire (N-wire) helical antenna consisting of four (N) helical elements, and each of these four helical elements Four (N) impedance matching circuits that are connected and perform impedance matching in two frequency bands, and connected to the four impedance matching circuits described above. A four-partitioning circuit (N-partitioning circuit) that distributes or combines microwaves while giving a predetermined phase difference to it is formed on a hollow cylindrical dielectric. That is, in this antenna device, the antenna and the feed circuit are integrally formed using a hollow cylindrical dielectric.

In addition, the impedance matching circuit and the four-distribution circuit are composed of a strip conductor composed of a strip conductor formed on the outer surface of the hollow cylindrical dielectric and a ground conductor formed on the inner surface. ing.

FIG. 27 is a developed view of the outer surface of the cylinder of the antenna device shown in FIG. 26, and FIG. 28 is a developed view of the inner surface of the cylinder of the antenna device shown in FIG. As shown in Fig. 28, the ground conductor formed on the inner surface of the hollow cylindrical dielectric is the presence of the strip conductor of the microstrip line that constitutes the impedance matching circuit and the four distribution circuit. It is formed in the lower part of the inner surface of the cylinder corresponding to the area of the cylinder. FIG. 29 is an enlarged view of the strip conductor pattern of the impedance matching circuit portion, and FIG. 30 is a circuit diagram of the antenna device shown in FIGS. 26 to 29.

In FIGS. 26 to 30, 21 is a hollow cylindrical dielectric, 1 is an antenna composed of four spiral elements formed by forming a conductor pattern on the outer surface of the hollow cylindrical dielectric 21. , 2 are the four input terminals of antenna 1, 13 is a ground conductor formed on the inner surface of hollow cylindrical dielectric 21, 18 is a microstory with hollow cylindrical dielectric 21 and ground conductor 13 It is a strip conductor that constitutes a topping line.

6a is a transmission line formed by a microstrip line and having an electrical length of 0a at a frequency of 2, and 22 is a digital cable connected in series to the transmission line 6a. The capacity 22 is shown as a capacity 3 connected in series in the circuit diagram of FIG. 6b is formed by a microstrip line and has a frequency of 1 , A transmission line having an electrical length of 0 b, 14 is an open stub having an electrical length of 6> o formed by a microstrip line, and 15 is a microstrip line. A short stub having an electrical length of 6 s. Reference numeral 16 denotes a through hole provided at the end of the short stub 15 and connecting the strip conductor 18 to the ground conductor 13.

In the open stub 14, the characteristic impedance of the line forming the stub is not constant within the stub, and a low impedance There are discontinuous locations 17 and 17 b at two places. The electrical length of each part of the open stub 14 is 6> ο1, Θo2, 0o3 from the open end side. The open stub 14 and the short stub 15 are connected so as to face each other at the same location of the strip conductor 18.

Here, the sum of the electrical lengths Sol and 6 »o 2 and 0 o 3 and 6> s is almost slightly larger than ほぼ 2 or 7Γ / 2, and the susceptance of the two stubs at frequency 2 The sum of the values is set to 0. That is, in a frequency band near the frequency f2, the circuit operates as a quarter-wave resonance circuit 5_2. The distribution of the electric lengths Θ ο 1, Θ 0 2, θ ο 3, s s is set such that the sum of the susceptances of the open stub 14 and the short stub 15 exhibits a predetermined susceptance value at frequency 1. It is decided. In addition, a predetermined value is also selected for the electrical length 0b of the transmission line 6b.

Reference numeral 8-1 denotes a first matching circuit, which includes the transmission line 6 a and the capacitive element 3 and performs impedance matching of the antenna 1 at the frequency f 2. 8-2 is composed of a transmission line 6b and a one-to-four-wavelength resonance circuit 5-2 composed of an open stub 14 and a short stub 15, and the impedance matching of the antenna 1 at a frequency of 1 is performed. 2 is a matching circuit. Ί is composed of a first matching circuit 8-1 and a second matching circuit 8-2. Is an impedance matching circuit that performs impedance matching at f 1 and f 2, and four impedance matching circuits 7 (N) corresponding to each helical element of the antenna 1 It is prepared. 9 is an input terminal of the impedance matching circuit 7.

Reference numeral 23 denotes a four-distribution circuit (N-distribution circuit), which is composed of a microstrip line composed of a hollow cylindrical dielectric 21, a ground conductor 13, and a strip conductor 18. It has four (N) distribution terminals each exhibiting the required distribution amplitude characteristics and distribution phase characteristics, and each distribution terminal is connected to each input terminal 9 of the four impedance matching circuits 7 respectively. . The four distribution circuit 23 is configured so that a phase difference of about 90 degrees occurs between the four input terminals 9.

25 is an input terminal of the four distribution circuit 23, which is an input terminal of this antenna device. Reference numeral 10 denotes an external circuit including a power supply circuit or an RF circuit, which is connected to the input terminal 25. Also, in FIG. 29, the nodes A, B, C, D, E, and F of the circuit are shown for explanation of the operation described later.

Next, the operation will be described.

The four-wire wound helical antenna used in this antenna device generates circularly polarized radio waves by supplying power to the four helical elements with a phase difference of 90 degrees between the four helical elements. Radiate. Since the radiation directivity is centered on the axial direction of the hollow cylindrical dielectric 21 and the coverage area is wide, the 4-wire wound helical antenna is used in satellite portable terminals and the like. The antenna device according to the fourth embodiment enables such a four-wire wound helical antenna to be used in two frequency bands.

Since the four helical elements are connected to each other and operate integrally, the active impedance when the antenna 1 is viewed from the four input terminals 2 can be regarded as the load impedance to be impedance-matched. . Therefore, impedance matching circuit 7 is designed based on the active impedance when antenna 1 is viewed from each input terminal 2 (node A). Here, the active impedance when the antenna 1 side is viewed from the input terminal 2 is similar to the locus shown by the Smith chart in FIG. 8, so that the four impedance matching circuits 7 The operation is almost the same as that of the impedance matching circuit of the antenna device according to the first embodiment.

Therefore, when the antenna 1 is viewed at the nodes B to E, the impedance trajectory is similar to the trajectories shown in the Smith charts of FIGS. 9 to 11 and 13. Here, since impedance matching has already been performed in the two frequency bands at the node E, the impedance matching at the two frequencies fl and f2 is also seen in the characteristics when the antenna 1 is viewed from the node F. Is maintained. As a result, the reflection characteristics at the node F are as shown in FIG.

As described above, according to the fourth embodiment, the same features as those of the antenna device of the first embodiment are obtained, and similar effects are obtained.

Also, according to the second embodiment, the parallel resonance circuit 5-2 of the second matching circuit 8-2 is formed using a stub instead of a chip element, and the digital capacitance is used as a series capacitance element. Since evening was used, it was a chip press, and the production was easy and the effect of being able to produce at low cost was obtained. This is very important in terms of feasibility because the antenna device is formed using the hollow cylindrical dielectric 21.

Further, according to the fourth embodiment, four spiral elements that emit radio waves, four impedance matching circuits 7 operable at two frequencies: fl and f2, and a four-distribution circuit 2 Since 3 is integrally formed on the hollow cylindrical dielectric 21, an effect is obtained that the wireless terminal device including the antenna device can be compactly configured. Further, according to the fourth embodiment, the antenna 1 has four helical elements, and the antenna 1 also has four input terminals 2. However, since the four distribution circuits are integrally formed, the external circuit 1 Only one input terminal 25 is required to connect to the antenna device 0, which simplifies the structure of the interface between the antenna device and the external circuit 10 and is not only easy to assemble, lower in cost, but also significantly more reliable. The effect of leading to improvement is obtained. Embodiment 5.

FIG. 31 is a perspective view showing an antenna device according to Embodiment 5 of the present invention. FIG. 32 is a developed view of the outer cylindrical surface of the antenna device shown in FIG. 31, and FIG. 33 is a developed view of the inner cylindrical surface of the antenna device shown in FIG. FIG. 34 is an enlarged view of the strip conductor pattern of the impedance matching circuit, and FIG. 35 is a circuit diagram of the antenna device shown in FIGS. 31 to 34.

In FIGS. 31 to 35, 14a is formed by a microstrip line, a first open stub having an electrical length of 00, and 14b is formed by a microstrip line. This is the second open stub created. The second open stub 1 4 b is formed by using a line having a different characteristic impedance in a part of the stub, and as a result, there is a discontinuity in the stub between the two characteristic places of the characteristic impedance. a, 17b, and the electrical length of each part is 0 sol, 0 so 2, and 0 so 3 from the open end side. The two open stubs 14a and 14b are connected so as to face each other at the same location of the strip conductor 18.

Here, the sum of the electrical lengths of the two open stubs 14 a and 14 b is slightly larger than 7Γ or Γ at the frequency f 2, and the two open stubs at the frequency f 2 The sum of the susceptance values for 14a and 14b is It becomes 0 and resonates as a 1/2 wavelength resonance circuit 5-3, and at the frequency f1, the sum of the susceptance values of the two open stubs 14a and 14b exhibits a predetermined susceptance value. As such, the distribution of the length is determined. In addition, a predetermined value is also selected for the electrical length 0b of the transmission line 6b.

Reference numeral 8-1 denotes a first matching circuit comprising the transmission line 6 a and the capacitance element 3 and performing impedance matching of the antenna 1 at the frequency 2. 8-2 is composed of a transmission line 6b and a half-wavelength resonance circuit 5-3 consisting of open stubs 14a and 14 1), and performs impedance matching of the antenna 1 at a frequency: f1. This is the second matching circuit. Reference numeral 7 denotes an impedance matching circuit composed of a first matching circuit 8-1 and a second matching circuit 8-2, which performs impedance matching at two frequencies f1 and f2. Others are the same as those of Embodiment 4 having the same reference numerals shown in FIGS. 26 to 30.

The 4-wire wound helical antenna used in this antenna device operates in the same manner as the antenna device shown in the fourth embodiment.

As described above, according to the fifth embodiment, the same features as those of the antenna device of the fourth embodiment are obtained, and similar effects are obtained.

Also, according to the fifth embodiment, since the resonance circuit in the second matching circuit is constituted by the two open-air pumps 14a and 14b, no through-hole is required, and The advantage is that the fabrication is relatively easy and the antenna device can be fabricated at lower cost. Industrial applicability

As described above, the impedance matching circuit and the antenna device according to the present invention are capable of connecting various types of single-resonant antennas to two frequency bands. Or in a wide frequency band including the frequency band between the two frequency bands, and is suitable for a device that operates efficiently.

Claims

The scope of the claims

1. Match the input impedance of the antenna with the characteristic impedance of the external circuit that transmits and receives signals to and from the antenna in the frequency band of frequency f1 and frequency f2 higher than this frequency f1. In the impedance matching circuit

A first matching circuit that performs impedance matching at the frequency f2, and a transmission line having a predetermined electrical length formed by a microstrip line or the like serving as a feed line to the antenna. And a second stub connected to the transmission line and formed by the microstrip line and the like. And a matching circuit of

The first or second stub is provided with an impedance discontinuity so that the characteristic impedance is different,

At the frequency f2, the sum of the susceptance values of the first and second stubs is 0, and at the frequency: 1, the sum of the susceptance values of the first and second stubs becomes a predetermined value. An impedance matching circuit characterized in that the electrical lengths of the first and second switches are set as described above.

2. The first matching circuit is composed of a transmission line formed by a microstrip line or the like and having a predetermined electrical length, and an in-line digital capacity for providing capacitance in series to the transmission line. Composed by

2. The impedance matching circuit according to claim 1, wherein:

3. The first matching circuit is composed of a 1Z4 wavelength impedance transformer at frequency f2 The impedance matching circuit according to claim 1, characterized in that:

4. The second matching circuit

An impedance discontinuity was provided, and the first stub was formed by an open stub with one end open, and the second stub was formed by a short stub with one end connected to a ground conductor.

3. The impedance matching circuit according to claim 1, wherein:

5. The second matching circuit is

It consists of a first stub with an open stub with one end open and a second stub with an open stub with one end open, with a discontinuity in the impedance.

3. The impedance matching circuit according to claim 1, wherein:

6. The input impedance of each of the plurality of antennas formed on the hollow cylindrical dielectric and the characteristic impedance of the external circuit for transmitting and receiving signals to and from the plurality of antennas are represented by the following frequency:? 1 and this frequency: a first matching circuit that performs impedance matching at the frequency f2 in the impedance matching circuit that matches in a frequency band of a frequency f2 higher than e1, and the plurality of antennas A transmission line having a predetermined electrical length formed by a microstrip line serving as a power supply line to the power transmission line, and a transmission line formed by the microstrip line and connected to the transmission line. And a second matching circuit configured by the first and second stubs to perform impedance matching at the frequency f1.

The first and second stubs have different characteristic impedances. In addition to providing a discontinuity in the impedance,

At the frequency f2, the sum of the susceptance values of the first and second stubs is 0, and at the frequency: f1, the sum of the susceptance values of the first and second stubs is a predetermined value. An impedance matching circuit, wherein the electrical length of the first and second stubs is set so as to be as follows.

7. The first matching circuit is composed of a transmission line formed by a microstrip line and having a predetermined electric length, and an digital capacity for providing capacitance in series to the transmission line. did

7. The impedance matching circuit according to claim 6, wherein:

8. The second matching circuit

A discontinuous portion of the impedance was provided, consisting of a first stub with an open stub with one end open and a second stub with a short stub with one end connected to a ground conductor.

7. The impedance matching circuit according to claim 6, wherein:

9. Second matching circuit

It consists of a first stub with an open stub with one open end, and a second stub with an open stub with an open end with an impedance discontinuity.

7. The impedance matching circuit according to claim 6, wherein:

10. A plurality of antennas formed in a hollow cylindrical dielectric,

The antenna is formed on the hollow cylindrical dielectric and connected to each of the antennas, between the input impedance of each of the antennas and each of the antennas And a plurality of impedance matching circuits for matching the characteristic impedance of an external circuit for transmitting and receiving signals in a frequency band of a frequency f1 and a frequency higher than the frequency f1: f2.

A plurality of distribution circuits formed on the hollow cylindrical dielectric, connected to the impedance matching circuits, and providing a predetermined phase difference to a signal from the external circuit;

Each of the above impedance matching circuits is

A first matching circuit that performs impedance matching at the frequency: f2, and a transmission line having a predetermined electrical length formed by a microstrip line serving as a feed line to each of the antennas. A second matching circuit formed by the microstrip line and configured by first and second stubs connected to the transmission line and performing impedance matching at the frequency f1. With

The frequency: the sum of the susceptance values of the first and second stubs at f2 is 0, and the sum of the susceptance values of the first and second stubs at the frequency f1 is a predetermined value. An antenna device wherein the electrical lengths of the first and second stubs are set so as to be as follows.

11. The first matching circuit is composed of a transmission line formed by a microstrip line and having a predetermined electrical length, and an internal digital capacitor for providing capacitance in series to the transmission line. And

The antenna device according to claim 10, wherein:

1 2. The second matching circuit A discontinuous portion of impedance was provided, consisting of a first stub with an open stub with one end open, and a second stub with a short stub with one end connected to a ground conductor.

The antenna device according to claim 10, wherein:

1 3. The second matching circuit

It consisted of a first sub-opening with an open ends, and a second sub-open-seven with an open end with an impedance discontinuity.

The antenna device according to claim 10, wherein: