JP2001136019A - Inverted-f antenna and radio unit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverted-F antenna that is applicable to a plurality of frequency bands or a broad frequency band. SOLUTION: An antenna sections 1 has a feeding terminal connected to a radiation element 2 and frequency changeover terminals 5, 6. The frequency changeover terminals 5, 6 are respectively connected to switches 7, 9 controlled by a control circuit 13, and the frequency changeover terminals 6 is connected directly or via an inductor 8 to a ground plate 3. Thus, the resonance frequency is selected. Furthermore, the switch 9 allows the frequency changeover terminal 7 to be connected with or to be opened from the ground plate 3 so as to switch the resonance frequency of the inverted-F antenna. Since the inductor or the like can change the resonance frequency, the frequency can be changed by a small frequency step and adjacent frequencies can be selected optionally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverted F antenna and a radio apparatus using the inverted F antenna, and more particularly to an inverted F antenna capable of using a plurality of frequency bands and a wide band.
And a wireless device such as a digital mobile phone which needs to switch the reception frequency.

[0002]

2. Description of the Related Art Conventionally, an inverted-F antenna has been widely used as a receiving antenna of a portable telephone because it can be formed in a small size. Hereinafter, a general inverted-F antenna will be described with reference to the drawings.

As shown in FIG. 16, an inverted-F antenna 110 includes a radiating element 100 formed of a rectangular conductor plate,
The radiating element 100 has a circuit board 106 that is a ground conductive plate facing the plate surface, and a ground terminal 103 is provided on a short side around the plate surface of the radiating element 100. The ground terminal 103 is bent from the periphery of the plate surface of the radiating element 100 toward the circuit board 106, and the tip of the bent ground terminal 103 is further bent so as to be parallel to the surface of the circuit board 106. Are fixedly connected to the circuit board 106 by soldering or the like.

[0004] Such an inverted-F antenna 110 is used as a receiving antenna that receives a radio wave received by the radiating element 100 and supplies the signal to a receiving circuit of a portable wireless device such as a cellular phone.

[0005] Portable radios usually make calls using a certain fixed band. However, due to the explosive spread of portable telephones in recent years, the communication capacity has become insufficient, so that a plurality of distant bands, Alternatively, there is a case where communication is performed using a wide band. However, the inverted F antenna has a relatively narrow band of use, and when the built-in inverted F antenna is used in a portable wireless device as described above, there is a problem that the operating frequency of the portable wireless device becomes narrow.

Accordingly, Japanese Patent Application Laid-Open No.
No. 5437 (Title of Invention: Inverted-F antenna and wireless device) is provided with a frequency switching terminal 104 as shown in FIGS. 16 and 17, and the frequency switching terminal 104 is connected to ground or opened by a switch 105. Discloses a technique of switching the resonance frequency of an antenna and covering two bands separated from each other as shown in FIG. 18 and performing communication using a plurality of bands or a wide band.

Japanese Patent Application Laid-Open No. Sho 62-188504 (title of the invention: patch antenna) is designed to connect two radiating elements or adjust the degree of overlap so as to obtain a desired antenna gain over a wide band. Is disclosed. Thus, by providing a plurality of radiating elements, a plurality of bands can be covered.

On the other hand, in recent years, the demand for communication has further increased, and a problem has arisen in that the allocated frequencies are insufficient, and a new frequency band is further allocated in addition to the conventionally allocated frequencies, thereby expanding the frequency band used. It is considered to alleviate congestion of calls.

[0009]

However, the inverted-F antenna described in Japanese Patent Application Laid-Open No. 10-65437 adjusts the resonance frequency to be switched by changing the frequency switching terminal, that is, the distance between the ground terminal and the power supply terminal. Therefore, in order to provide a new use frequency band, a separate new ground terminal must be provided for the radiating element.

In particular, when the frequency bands used are in the 820 MHz band and the 880 MHz band, for example, and a frequency band near 830 MHz is newly allocated thereto, for example, a newly usable frequency band is assigned to the conventional frequency band. In the case of a frequency that is close to one of the frequency bands in the middle of the frequency that has been set, it is necessary to provide another ground terminal close to the conventional ground terminal, and the interval between the two bands switched in this way is narrow. And the frequency switching terminal and the ground terminal must be formed close to each other. However, since a certain distance between the terminals is physically required for manufacturing the ground terminal, it is difficult to perform fine frequency switching by changing the distance between the terminals. In recent years, mobile phones have been reduced in size and weight, and increasing the length of the side of the inverted F antenna to newly provide a ground terminal increases the size of the entire device. There was a problem that could not be secured.

When a ground terminal is newly formed on the inverted-F antenna, a new land for connecting the ground terminal to the substrate to which the inverted-F antenna is attached must be provided, which is troublesome. Since the circuit conductors are densely arranged, it is difficult to form a new land on the substrate.

Further, when a plurality of radiating elements are provided to correspond to a new frequency as in the invention described in Japanese Patent Application Laid-Open No. 62-188504, the volume of the antenna cannot be effectively used. was there.

[0013]

According to the present invention, an inverted-F antenna is constructed as follows to solve the above-mentioned problems.

That is, a radiating element, a ground conductor disposed to face the plate surface of the radiating element, and a ground terminal provided at a predetermined position of the radiating element and connecting the radiating element to the ground conductor. In an inverted-F antenna including a feed element that receives a high-frequency signal between the radiating element and a feeding element, a switch is provided on the ground terminal, and the switch is switched to connect the ground terminal directly to the ground conductor. The inverted-F antenna is configured such that switching between the case where the ground terminal is connected to the ground conductor via the impedance for determining the resonance frequency is possible, and the resonance frequency can be changed by the connection of the impedance. Thereby, the resonance frequency can be switched between two types.

Further, the switch connected to the ground terminal is connected to the ground conductor, the switch is connected to the ground conductor via an inductance, or the switch is connected to the ground conductor via a reactance. An inverted-F antenna was configured as a switch for switching. Thereby, the resonance frequency can be switched to three types.

A radiating element, a ground conductor disposed to face the plate surface of the radiating element, and a ground terminal provided at a predetermined position of the radiating element and connecting the radiating element to the ground conductor. And a feed element for receiving a high frequency signal between the radiating element and the feed element, wherein two ground terminals are provided at predetermined positions of the radiating element, and a first ground terminal is provided on the feed terminal side. The ground terminal is provided with a first switch that switches between a case where the ground conductor is directly connected to the ground conductor and a case where the ground terminal is connected to the ground conductor via an impedance for determining a resonance frequency. And a second switch for switching between opening and connection to the ground conductor to provide an inverted-F antenna. Thereby, in addition to the two frequency bands, it is possible to switch to a frequency approximate to one of the frequencies between the two frequency bands.

Also, the first switch connected to the first ground terminal is connected to the ground conductor, the first switch is connected to the ground conductor via an inductance, and the first switch is connected to the ground conductor via a reactance. An inverted-F antenna was configured as a switch for switching to either of the above cases. Thereby, the resonance frequency can be switched to three types.

The impedance is a reactance.

The impedance is an inductance.

An inverted-F antenna is constructed by interposing a dielectric having a predetermined permittivity between the radiating element and the ground conductor.

In the switch, a diode is provided between the ground terminal and a ground conductor, and the drive circuit opens and closes the diode.

The switch is directly driven to open and close using a GaAs switch.

The inverted-F antenna is configured such that the frequency in the state where the power consumption of the inverted-F antenna is the smallest is a frequency band in a standby state in a portable telephone system having the inverted-F antenna. As a result, the power consumption in the standby state can be minimized, and the talk time of the mobile phone can be extended.

When a diode is used for the switch, the frequency set when the first ground terminal is grounded via an impedance is defined as a standby frequency band in the portable telephone system. Thus, the current flowing through the diode can be reduced, and the power consumption can be reduced.

The length of the connecting portion connecting the power supply terminal and the ground terminal from the connection position of the radiating element is determined by the inverse F
The input impedance of the antenna was adjusted to a desired value. As a result, it is possible to eliminate a deviation in impedance that occurs when grounding via an inductance or the like, and it is possible to improve efficiency and the like.

The length of the connecting portion from the connection position of the radiating element can be changed to an arbitrary value. Thereby, the deviation of the impedance can be arbitrarily corrected.

14. A frequency selecting means for selecting a frequency band to be used, and a switch driving means for driving the switch according to the frequency selected by the frequency selecting means.
A wireless device includes the inverted F antenna according to any one of the above items and a receiving antenna.

The radio apparatus includes a main antenna and the inverted F antenna, and the inverted F antenna is used as one of the diversity antennas.

The ground terminal is made of a metal piece extending from the radiating element, and the tip of the ground terminal is bent in parallel with the ground conductor, and the tip of the ground terminal is fixed on the ground conductor.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an inverted-F antenna according to the present invention will be described below with reference to the drawings. Inverted F antenna 1
As shown in FIG. 1, a radiating element 2, a ground conductor plate (ground) 3 disposed to face the plate surface of the radiating element 2,
It comprises a power supply terminal 4, frequency switching terminals (ground terminals) 5, 6 and the like.

The power supply terminal 4 and the frequency switching terminals (ground terminals) 5 and 6 are metal pieces extending from the radiating element 2, and the power supply terminal 4 is connected to the control circuit 13 via the receiving circuit 12.

A switch 7 is connected to the frequency switching terminal 5, and by switching the switch 7, the frequency switching terminal 5 is selectively connected to either the ground 3 of the circuit board or the inductance 8.

A switch 9 is connected to the frequency switching terminal 6, and the switching of the switch 9 causes the frequency switching terminal 6 to be connected to the ground 3 of the circuit board or to be opened.

The switches 7 and 9 are controlled by switch driving circuits 10 and 11 controlled by a control circuit 12, and are thereby operated.
The receiving circuit 12 includes a high-frequency amplifier, a frequency converter,
The demodulator is configured by a demodulator and the like, and demodulates a received wave received by the inverted F antenna 1.

Next, the operation of the embodiment of the present invention will be described in detail with reference to FIGS. FIGS. 2 and 3 are diagrams showing return loss as viewed from the power supply terminal 4 of the antenna unit 1.

First, when the reception frequency is in the band 2, the control circuit 13 transmits the channel data of the reception frequency to the reception circuit 1.
2 and operates as a band 2 receiving circuit. At this time, a predetermined band switching signal A (for example, HIGH level) synchronized with the channel data from the control circuit 13
Is sent to the switch drive circuit 10, and the switch drive circuit 1
By 0, the switch 7 is connected to the ground 3 of the circuit board. At the same time, the band switching signal B (for example, LOW level) is transmitted to the switch drive circuit 11, and the switch 9 is opened by the switch drive circuit 11. FIG. 11 shows the switching state of the switches 7 and 9.

The state of the inverted F antenna 1 at this time is such that the frequency switching terminal 5 functions as a ground terminal, operates as a normal inverted F antenna including a ground terminal and a power supply terminal, and receives a reception wave in band 2. Become like For this reason,
The received wave of band 2 received by the inverted F antenna 1 passes through the feed terminal 4 and is sent to the receiving circuit 12 where it is demodulated.

Next, when the reception frequency is in the band 1, the channel data from the control circuit 13 is transmitted to the reception circuit 12, and operates as the band 1 reception circuit. At this time, a band switching signal A (for example, LOW level) that is opposite to band 2 and is synchronized with the channel data from the control circuit 13 is transmitted to the switch driving circuit 10, and the switch driving circuit 10
The switch 7 is switched to the inductance 8 side, and the frequency switching terminal 5 is connected to the inductance 8. Also,
At the same time, the band switching signal B (for example, LOW level) is transmitted to the switch drive circuit 11, and the switch 9 is opened by the switch drive circuit 11. FIG. 12 shows such a state.

Then, the inverted F antenna 1 operates as a band 1 antenna. For this reason, the reception wave of band 1 received by the inverted F antenna 1 passes through the feed terminal 4 and
The signal is demodulated at 2. Further, the state of the inverted F antenna at this time is the same as when the antenna is operating as the antenna of the above-mentioned band 2, in which the frequency switching terminal 5 operates as the ground terminal connected to the ground via the inductance 8, and It operates as an inverted F antenna composed of a terminal and a power supply terminal. However, since the frequency switching terminal 5 is connected to the ground via the inductance 8, the resonance frequency of the antenna is reduced, and the antenna operates as the inverted F antenna of the band 1.

Here, a change in the resonance frequency of the inverted-F antenna when the frequency switching terminal 5 is connected to the ground via the inductance 8 will be described with reference to FIG. FIG.
In the graph, the vertical axis represents the frequency, and the horizontal axis represents the inductance value. It can be seen that the resonance frequency of the antenna decreases as the inductance value of the frequency switching terminal 5 increases.

On the other hand, by increasing the inductance value, the input impedance of the antenna changes and becomes larger than the characteristic impedance (50Ω). It is known that the inverted-F antenna can change the input impedance by changing the distance between the feeding terminal and the ground terminal. Therefore, the power supply terminal 4 and the frequency switching terminal 5
However, as shown in FIG. 6, changing the distance Lc between the terminals is equivalent to changing the width Lc ′ connecting the terminals, so that the distance between the terminals Was changed and the alignment was adjusted. The right vertical axis of FIG. 5 shows the relationship between the connection width Lc ′ and the inductance value. When the impedance of the inverted-F antenna is shifted by increasing the inductance value,
By changing the connection width Lc ′ between the terminals, impedance matching can be achieved.

Note that a reactance may be used instead of the inductance 8. In this case, the resonance frequency shifts in the opposite direction to the case of the inductance.

Next, when the reception frequency is in the band 3, the channel data from the control circuit 13 is transmitted to the reception circuit 12 and operates as the band 3 reception circuit. At this time, a band switching signal A (for example, LOW level) synchronized with the channel data from the control circuit 13 is transmitted to the switch drive circuit 10, and the switch 7 is switched to the inductance 8 side by the switch drive circuit 10. At the same time, a band switching signal B (for example, HIGH level) opposite to the bands 1 and 2 is transmitted to the switch drive circuit 11, and the switch 9 is connected to the ground by the switch drive circuit 11.
(See FIG. 13) For this reason, the inverted F antenna 1 operates as a band 3 antenna. Therefore, the reception wave of the band 3 received by the inverted F antenna 1 passes through the feed terminal 4 and is demodulated by the reception circuit 12. The state of the inverted F antenna 1 at this time is the same as when the antenna is operating as the above-mentioned band 1 antenna, in which the frequency switching terminal 5 is connected to the ground conductor plate 3 via the inductance 8 as the ground terminal. It operates as an inverted F antenna composed of the ground terminal and the feed terminal 4. Further, since the frequency switching terminal 6 is also connected to the ground plate 3, this is equivalent to an increase in the width of the short terminal. In general, it is known that the resonance frequency of an inverted-F antenna is increased by increasing the short width to the ground. Therefore, the resonance frequency of the inverted-F antenna is higher than band 2 and Act as an antenna.

Next, a method of adjusting the inverted F antenna 1 will be described. First, the length L = (2La + 2Lb) around the plate surface of the radiating element as an antenna of band 2 is L ／ λ / 2,
(Λ is the free-space propagation wavelength of the reception frequency). Next, for adjusting the resonance frequency of the band 1, an inductance value to be connected to the frequency switching terminal 5 is determined from FIG. Further, the band 3 can be adjusted by changing the distance between the frequency switching terminal 5 and the frequency switching terminal 6.

At this time, if the horizontal axis represents the frequency and the vertical axis represents the return loss, the return loss characteristic of the inverted-F antenna 1 of the present invention is as shown in FIG. 2 so that three bands can be covered. Become. In addition, by overlapping the bands 1, 2, and 3, it is possible to operate as a wideband inverted-F antenna as shown in FIG.

FIG. 4 is a specific circuit diagram of the switch portion of the inverted F antenna 1. Here, a diode is used for the switch section of the inverted-F antenna 1. In this figure, the capacitors C1 and C2 are selected such that their impedance is sufficiently low in the reception frequency band, and the choke coils L2 and L3 are selected such that their impedance is sufficiently high.

The operation of the above example will be described. First, the band switching signal A output from the control circuit 13 is set to HIGH.
When the level is at the level, SW1 is turned on, current flows through diode D1, and diode D1 is turned on. At this time, the capacitor C
Since 1 is selected so as to exhibit a sufficiently low impedance at the reception frequency, the frequency switching terminal 3 is connected to the ground 3 at a high frequency, and the frequency switching terminal 5 operates as a ground terminal. At the same time, a LOW level is output from the control circuit as the band switching signal B, SW2 is turned off, and no current flows through the diode D2. Therefore, the diode D2 exhibits a high impedance, and the frequency switching terminal 6 is opened. For this reason, the inverted F antenna 1 has a feed terminal,
It operates as a normal inverted-F antenna having a ground terminal, and operates as a band 2 antenna. L2 and L3 are:
Since the impedance is sufficiently high in the reception frequency band, the influence of the impedance of the circuit on the power supply side can be almost ignored.

Next, when the band switching signal A is at the LOW level, SW1 is turned off and no current flows, so that the diode D1 has a high impedance and the frequency switching terminal 5
Is connected to the ground via the inductance L1. Also, a LOW level is output from the control circuit to the band switching signal B, so that SW2 is turned off and no current flows through the diode, so that the diode D2 exhibits a high impedance and the frequency switching terminal 6 is opened. For this reason,
Since the antenna operates as an inverted-F antenna in which the inductance L1 is connected to the ground terminal, the resonance frequency is lower than the band 2;
It operates as a band 1 antenna.

Further, when the band switching signal A is at the LOW level, SW1 is turned off, the diode D1 exhibits a high impedance, and the frequency switching terminal 5 is connected to the inductance L.
1 is connected to the ground 3. A HIGH level is output from the control circuit to the band switching signal B, and S
W2 turns on, current flows through diode D2, and diode D2 turns on. At this time, since the capacitor C2 is selected so as to exhibit a sufficiently low impedance at the reception frequency, the frequency switching terminal 6 is connected to the ground 3 in a high frequency, and the frequency switching terminal 6 operates as a ground terminal.
For this reason, since the frequency switching terminal 5 operates as a ground terminal via an inductance, and the frequency switching terminal 6 also operates as a ground terminal, the width of the ground terminal is equivalently widened. For this reason,
The resonance frequency of this inverted-F antenna is higher than band 2 and operates as a band 3 antenna.

The diodes D1 and D2 have such a characteristic that the larger the flowing current, the lower the impedance at the time of ON. For this reason, the values of the resistors R1 and R2 are determined so that a current flows so that the impedance when the diode is ON becomes a desired value. Further, in the case of the present embodiment, in a standby mode, a portable wireless device used in a communication system that receives a signal in a low frequency band 1 and uses a frequency having characteristics of the bands 1, 2, and 3 only when a call is made, Since current flows through the frequency switching circuit only when bands 2 and 3 are selected during a call, there is a great effect that current consumption can be reduced during standby in band 1.

The values of the capacitors C1 and C2 and the inductances L2 and L3 are appropriately selected depending on the frequency band to be used. However, in radio communication in a frequency band of about 800 MHz, these capacitors C1 and C2 are used.
Is about 100 picofarads, and the choke coil L
2, L3 is desirably about 100 nanohenries.

In the above embodiment, since a diode is used for the frequency changeover switch, a switch driving circuit is necessary. However, when an element which can be directly controlled by the control circuit, for example, a GaAs switch, is used. Is
The switch drive circuit can be omitted.

FIG. 8 shows another embodiment of the present invention. The inverted F antenna 1 is formed on a double-sided copper-clad dielectric substrate. That is, the dielectric substrate 15 such as a Teflon substrate (or a glass epoxy substrate or the like) having copper on both surfaces is etched to form the radiating element 2 and the ground plate 3 on each of both plate surfaces. The radiating element 1 is a rectangular plate surface, and the size of the plate surface is a long side La1 and a short side Lb1. A feed terminal 4 and a distance Lc1 are set from one of the short sides around the plate surface of the radiating element 2,
It has a frequency switching terminal 5 and a frequency switching terminal 6 at a distance Ld1, and a receiving circuit 12, a switch 7,
9 is connected.

In this antenna, since the dielectric substrate 15 is interposed between the radiating element 2 and the ground substrate 3, the radiating element 2
Can be reduced by the relative permittivity of the dielectric substrate 15. Let the relative permittivity of the dielectric substrate 15 be ε
r, the antenna resonance frequency fy of the antenna unit 1 in a state where the frequency switching terminal 5 is connected to the ground plate and the frequency switching terminal 6 is not connected to the ground plate 3 is Ly = (2
(La1 + 2Lb1) is a frequency satisfying (≒ λ / 2 (εr) 1/2). Therefore, the antenna unit 1 has a size of the plate surface of the radiating element 2 larger than that of the antenna 1 of FIG.
There is an effect that can be reduced by two. In addition, there is also an effect of stabilizing antenna radiation characteristics without using a spacer.

FIGS. 9 and 10 show another embodiment of the inverted F antenna. In the inverted F antenna 1 of FIG. 9, a cut 2a is formed in the radiating element 2 to reduce the size of the antenna, the current path length of the high-frequency current is increased, and the resonance frequency of the inverted F antenna 1 is reduced. FIG. 10 shows a configuration in which a capacitance is loaded in the open portion to lower the resonance frequency. For such antennas, the frequency switching terminals 5, 6
, The resonance frequency of the inverted-F antenna 1 can be switched.

In the above embodiment, the switches 7 and 9 are provided to select three frequency bands. However, the present invention is not limited to this, and the switches 7 and 9 are connected to the frequency switching terminal 5 as shown in FIG. Only the switch 7 may be provided, and the frequency switching terminal 5 may be grounded via the inductance 8, or may be directly grounded to the grounding conductor plate 3. In this case, it is possible to switch to two frequency bands between adjacent frequency bands.

Further, as shown in FIG. 15, the switch 7 connected to the frequency switching terminal 5 may be switched in three directions. Each of the switching directions is directly connected to the ground, via the inductance 8,
This is the case through the reactance 30. In this case,
By switching the switch 9, the frequency band can be switched to four.

[0058]

The first effect of the inverted-F antenna according to the present invention is that the frequency can be finely switched.

The reason is that the resonance frequency to be switched is adjusted by the inductance value or the like connected to the switching terminal, so that the resonance frequency can be finely switched.

The second effect is that the antenna can be operated as a wideband inverted-F antenna.

The reason is that the resonance frequency of the inverted-F antenna can be switched according to the reception frequency, so that it is possible to cover three separate bands or a band wider than the band originally possessed by the inverted-F antenna. .

The third effect is that the volume of the antenna can be effectively used.

The reason is that, in order to switch the resonance frequency and to make the inverted F antenna have a wide band, the radiating element is set to two.
This is because there is no need to arrange or overlap each other, and the volume of the antenna can be effectively used at each frequency.

[Brief description of the drawings]

FIG. 1 is a diagram showing an inverted-F antenna according to the present invention.

FIG. 2 is a diagram showing frequency bands.

FIG. 3 is a diagram showing frequency bands.

FIG. 4 is a circuit configuration diagram of the inverted-F antenna shown in FIG. 1;

FIG. 5 is a diagram showing a relationship between an inductance value and a resonance frequency.

FIG. 6 is a diagram illustrating a ground terminal and the like.

FIG. 7 is a diagram showing a ground terminal and the like.

FIG. 8 is a diagram showing another embodiment of the inverted-F antenna according to the present invention.

FIG. 9 is a diagram showing another embodiment of the inverted-F antenna according to the present invention.

FIG. 10 is a diagram showing another embodiment of the inverted-F antenna according to the present invention.

FIG. 11 is a diagram showing an open / closed state of a switch.

FIG. 12 is a diagram showing an open / closed state of a switch.

FIG. 13 is a diagram showing an open / closed state of a switch.

FIG. 14 is a diagram showing another embodiment of the inverted-F antenna according to the present invention.

FIG. 15 is a diagram showing another embodiment of the inverted-F antenna according to the present invention.

FIG. 16 is a diagram showing a conventional inverted-F antenna.

FIG. 17 is a diagram showing a conventional inverted-F antenna.

FIG. 18 is a diagram showing a conventional inverted-F antenna.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inverted F antenna 2 radiating element 3 ground conductor plate 4 feeding terminal 5, 6 frequency switching terminal 7, 9 switch 9 inductance 10, 11 switch driving circuit 12 receiving circuit 13 control circuit 14 spacer 15 dielectric substrate

Claims (16)

[Claims] 1. A radiating element, a ground conductor disposed to face a plate surface of the radiating element, and a ground terminal provided at a predetermined position of the radiating element and connecting the radiating element to the ground conductor. An inverted-F antenna comprising a feeding element for receiving a high-frequency signal between the radiating element and a feeding element, wherein a switch is provided on the ground terminal, and the ground terminal is directly connected to the ground conductor by switching the switch. An inverted-F antenna, wherein switching can be made between a case where the ground terminal is connected to the ground conductor via an impedance for determining a resonance frequency, and a resonance frequency is changed by the connection of the impedance. A switch connected to the ground terminal; a switch connected to the ground conductor via an inductance for determining a resonance frequency; and a reactance for determining a resonance frequency. 2. The inverted-F antenna according to claim 1, wherein the switch is configured to switch to any one of a case where the antenna is connected to the ground conductor through a switch. 3. A radiating element, a ground conductor disposed to face a plate surface of the radiating element, and a ground terminal provided at a predetermined position of the radiating element and connecting the radiating element to the ground conductor. An inverted-F antenna comprising: a feeding element that receives a high-frequency signal between the radiating element and a feeding element that receives a high-frequency signal. The ground terminal is provided with a first switch that switches between a case where the ground conductor is directly connected to the ground conductor and a case where the ground terminal is connected to the ground conductor via an impedance for determining a resonance frequency. And a second switch for switching between open and connection to the ground conductor. 4. A method in which a first switch connected to the first ground terminal is connected to the ground conductor, a case where the first switch is connected to the ground conductor via an inductance for determining a resonance frequency, and The inverted-F antenna according to claim 3, wherein the switch is configured to switch to one of a case where the switch is connected to the ground conductor via a reactance for determination. 5. The inverted-F antenna according to claim 1, wherein the impedance is a reactance. 6. The inverted F antenna according to claim 1, wherein the impedance is an inductance. 7. The inverted-F antenna according to claim 1, wherein a dielectric having a predetermined dielectric constant is interposed between the radiation element and a ground conductor. 8. The reverse F according to claim 1, wherein the switch has a diode provided between the ground terminal and a ground conductor, and the drive circuit opens and closes the diode. antenna. 9. The switch according to claim 1, wherein said switch is directly opened and closed using a GaAs switch.
The inverted F antenna according to any one of claims 1 to 7. 10. A frequency in a state where power consumption of the inverted F antenna is the smallest is defined as a frequency band in a standby state in a mobile phone system including the inverted F antenna according to any one of claims 1 to 9. An inverted-F antenna, characterized in that: 11. A frequency set when the first ground terminal is grounded via an impedance,
The inverted-F antenna according to claim 8, wherein the frequency band is a standby frequency band in a mobile phone system provided with the antenna. 12. A length of a connecting portion connecting between a power supply terminal and a ground terminal from a connection position of the radiating element is adjusted such that an input impedance of the inverted-F antenna is set to a desired value. The inverted-F antenna according to any one of claims 1 to 11, wherein: 13. The inverted-F antenna according to claim 12, wherein the length of the connecting portion from the connection position of the radiating element can be changed to an arbitrary value. 14. A frequency selecting means for selecting a frequency band to be used, a switch driving means for driving said switch according to the frequency selected by said frequency selecting means,
14. A wireless device comprising: the inverted F antenna according to claim 13; and a receiving antenna. 15. The wireless device according to claim 14, wherein the wireless device includes a main antenna and the inverted F antenna, and the inverted F antenna is used as one of the diversity antennas. 16. The ground terminal is made of a metal piece extending from the radiating element, a tip of the ground terminal is bent in parallel with the ground conductor, and a tip of the ground terminal is fixed on the ground conductor. 16. The method according to claim 14, wherein:
A wireless device according to claim 1.