JP4661547B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device used for transmission / reception of a digital television broadcast band, for example.

In recent years, terrestrial television broadcasting has begun to be digitized. This terrestrial digital broadcast can be a high-definition broadcast by digitizing a television broadcast, and can also add a data broadcast. And in this terrestrial digital broadcast, it broadcasts using the frequency of a 470 MHz-770 MHz band which is a UHF band.
On the other hand, in a portable terminal, a ¼ wavelength type antenna is used in a band of 470 MHz or higher. In the 1/4 wavelength type antenna, an electric length of an antenna element is 1/4 wavelength, and a whip antenna having a 1/4 wavelength physical length is used for a cellular phone. The built-in antenna can be built in a portable terminal by reducing the physical length to less than 1/4, and the bandwidth and antenna gain are deteriorated compared to the whip antenna due to the downsizing. Note that the specific bandwidth of the whip antenna is generally about a dozen percent.

By the way, when receiving terrestrial digital broadcasting with a portable terminal, even if the whip antenna is adjusted at 470 MHz to 770 MHz required in the broadcasting band of terrestrial digital broadcasting, the bandwidth of the whip antenna is 100 MHz or less. It is impossible to cover a bandwidth of 470 MHz to 770 MHz with one antenna. Therefore, one solution is to vary the resonance frequency.
Therefore, as a method for making the resonance frequency variable, an antenna device has been proposed in which the capacitance of the capacitor is controlled by voltage using a varicap and the resonance frequency of the antenna is made variable (see, for example, Patent Documents 1 and 2). .

Japanese Patent Laid-Open No. 10-209897 JP 2003-46315 A

  However, the following problems remain in the conventional antenna device. That is, in the conventional antenna device, since the physical length of the antenna element is ¼ of the antenna operating wavelength at the shortest, it is difficult to apply to a practical built-in antenna device in a frequency band of 470 MHz to 770 MHz, for example. is there.

  The present invention has been made in view of the above-described problems. For example, an object of the present invention is to provide a small antenna device having a variable resonance frequency and a high gain even in a wide frequency range such as 470 MHz to 770 MHz. To do.

  The present invention employs the following configuration in order to solve the above problems. That is, the antenna device of the present invention includes a substrate, a ground conductor formed on the surface of the substrate, and an element body made of a composite material disposed on the substrate and having both a dielectric and / or a magnetic material. A loading portion having a linear conductor pattern formed on the element body, an inductor portion connected between one end of the conductor pattern and the ground conductor, and a feeding point for feeding power to one end of the inductor portion The frequency adjustment unit is provided between one end of the conductor pattern and the inductor unit, and the frequency adjustment unit includes a variable capacitance element that connects the one end of the conductor pattern and the inductor unit. And capacitance adjusting means for adjusting the capacitance of the variable capacitance element.

According to the present invention, even if the electrical length of the antenna element alone is shorter than 1/4 of the antenna operating wavelength, by combining the loading unit and the inductor unit, 1/4 of the antenna operating wavelength is obtained as the overall electrical length. Satisfied. Thereby, for example, even in the frequency band of 470 MHz to 770 MHz, which is the broadcasting band of terrestrial digital broadcasting, the antenna device can be significantly shortened.
The resonance frequency of the antenna device is proportional to 1 / √ (L · C), where L is the inductance component due to the electrical length of the antenna element and C is the capacitance component due to the variable capacitance element. Therefore, the resonance frequency of the antenna device can be set by changing the capacitance of the variable capacitance element. Therefore, even if the bandwidth is wide, such as 470 MHz to 770 MHz, which is the broadcasting band of terrestrial digital broadcasting, the capacitance is adjusted according to the channel by using a capacitance variable element whose capacitance is variable within an appropriate range. This can be covered by shifting the resonance frequency.
Further, the impedance of the antenna device is adjusted by providing an inductor so as to connect one end of the frequency adjusting unit and the ground conductor. For example, in the frequency band of 470 MHz to 770 MHz, the voltage standing wave ratio (Voltage Standing Wave ratio) Ratio, hereinafter VSWR
To prevent deterioration of characteristics.

The antenna device according to the present invention includes a plurality of the loading units, and the frequency adjusting unit includes a plurality of the variable capacitance elements that respectively connect one end of the plurality of loading units and the inductor unit. preferable.
According to the present invention, one antenna unit is formed by one of the plurality of loading units, the variable capacitance element that connects the loading unit and the inductor unit, and the inductor unit. Therefore, the antenna device has a plurality of antenna units.
At this time, by configuring at least a part of the frequency band covered by at least one of the plurality of antenna units to be different from the frequency band covered by the other antenna device, the antenna unit is 1 Compared to a single case, a wider frequency band can be covered. On the other hand, even if the variable range of the capacitance of the capacitive variable element is small and the frequency band that can be covered by one antenna unit is narrow, a wide frequency band can be covered by sharing and covering each antenna unit.
Also, by selecting and receiving a high-frequency signal received by the antenna unit having the smallest VSWR from among a plurality of antenna units at the frequency to be received, the VSWR characteristics are less deteriorated and can be received in a good state. it can.

Further, in the antenna device according to the present invention, the variable capacitance element is configured by a variable capacitance diode, and the capacitance adjusting means applies a bias voltage to the variable capacitance diode to adjust the capacitance of the variable capacitance diode. Is preferred.
According to this invention, the width of the depletion layer of the variable capacitance diode is widened by inputting a bias voltage to the variable capacitance diode and increasing the voltage. This is the same effect as increasing the distance between the parallel plates in the parallel plate capacitor, and the capacitance of the variable capacitance diode is reduced by increasing the bias voltage. Therefore, as described above, by increasing the bias voltage to be applied, the resonance frequency of the antenna device is shifted to the high frequency side. As described above, the resonance frequency of the antenna device can be easily set by the bias voltage to be applied.

Moreover, the antenna device according to the present invention is preferably provided with a lumped constant element connected to one end of the conductor pattern.
According to the present invention, the electrical length can be adjusted by the lumped constant element without changing the length of the conductor pattern of the loading portion, so that the resonance frequency can be easily set. In addition, the impedance of the antenna device at the feeding point can be matched.

In the antenna device according to the present invention, it is preferable that the frequency adjustment unit is a frequency adjustment module that can be placed on the substrate and connects one end of the conductor pattern and the inductor unit.
According to the present invention, since the frequency adjustment unit is a frequency adjustment module, the circuit structure and the element value of the frequency adjustment unit can be black boxed for the user, and the antenna device can be further simplified. The degree of freedom of design increases.

Furthermore, in the antenna device according to the present invention, the frequency adjustment module includes a module substrate having a wiring pattern on a surface thereof, a frequency adjustment unit main body provided on the module substrate using the wiring pattern, and the module substrate. And an antenna terminal connected to the loading portion, wherein the wiring pattern has an adjustment pad portion for fine frequency adjustment that is connected to the antenna terminal and can be trimmed.
According to the present invention, the wiring pattern is provided with the trimming frequency adjustment pad portion that can be trimmed. Therefore, the variation in the shape accuracy of the wiring pattern and the discrete component itself such as the capacitance variable element to be mounted can be reduced. Fine adjustments can be made by trimming.

In the antenna device according to the present invention, it is preferable that the conductor pattern has a spiral shape wound in the longitudinal direction of the element body.
According to this invention, by making the conductor pattern into a spiral shape, the conductor pattern becomes longer and the gain of the antenna device can be increased.

In the antenna device according to the present invention, it is preferable that the conductor pattern has a meander shape formed on a surface of the element body.
According to this invention, by making the conductor pattern meander shape, the conductor pattern becomes longer and the gain of the antenna device is improved. Further, the conductor pattern is easily formed by forming the conductor pattern on the surface of the element body.

  According to the antenna device of the present invention, by combining the loading unit and the inductor unit, the electrical length can satisfy ¼ of the antenna operating wavelength, and the antenna device can be significantly shortened. In addition, the resonance frequency of the antenna device can be changed by adjusting the capacitance of the capacitance variable element by the capacitance adjusting means. Therefore, by using a capacitance variable element whose capacitance is variable within an appropriate range, even a wide bandwidth such as a broadcasting band of terrestrial digital broadcasting can be covered by adjusting the capacitance. Then, by providing the inductor portion, the impedance of the antenna device is adjusted and deterioration of the VSWR characteristic is suppressed.

Hereinafter, a first embodiment of an antenna device according to the present invention will be described with reference to FIGS. 1 to 3.
The antenna device 1 according to the present embodiment is an antenna device used for a mobile terminal capable of receiving terrestrial digital broadcasting, for example.

  The antenna device 1 includes a substantially inverted L-shaped substrate 2 made of an insulating material such as a resin, a ground conductor 3 formed on the surface of the substrate 2 and connected to the ground of a high-frequency circuit (not shown), A loading portion 4 disposed on the surface of the substrate 2 in a direction in which the distal end portion is separated from the ground conductor 3 from the base end portion, and one can be connected to the power feeding portion 7 and the other is connected to the ground conductor 3. Chip inductor (inductor unit) 5, frequency adjusting unit 6 disposed between one end of loading unit 4 and chip inductor 5, and power supply unit for supplying power to connection point P 1 between chip inductor 5 and frequency adjusting unit 6 7, and a power supply conductor 8 that connects the frequency adjustment unit 6, the chip inductor 5, and the power supply unit 7.

The loading unit 4 includes a loading element 11 and lands 12 </ b> A and 12 </ b> B that are formed on the surface of the substrate 2 and place the loading element 11 on the substrate 2. The land 12 </ b> A and the frequency adjusting unit 6 are connected by the connecting conductor 13.
As shown in FIG. 2, the loading element 11 is a rectangular parallelepiped element body 14 made of a dielectric material such as alumina, and is wound around the surface of the element body 14 in a spiral shape with respect to the longitudinal direction of the element body 14. And a linear conductor pattern 15.
Both ends of the conductor pattern 15 are connected to connection conductors 16A and 16B formed on the back surface of the element body 14 so as to be connected to the lands 12A and 12B.
The connecting conductor 13 is formed with a dividing portion (not shown) for dividing the connecting conductor 13, and the dividing portion is provided with a chip inductor 17 as a lumped constant element. The chip inductor 17 has a function of setting the resonance frequency of the antenna device 1.

  In addition, since the electrical length of the loading unit 4 alone is configured to be shorter than ¼ of the antenna operating wavelength of the antenna device 1, the self-resonant frequency of the loading unit 4 is higher than the resonance frequency that is the antenna operating frequency of the antenna device 1. Also on the high frequency side. Accordingly, when the resonance frequency of the antenna device 1 is considered as a reference, it cannot be said that the loading unit 4 is self-resonating, so that the property is different from the helical antenna that self-resonates at the antenna operating frequency. Yes.

  The chip inductor 5 has a function of adjusting the impedance of the antenna device 1 and is disposed so as to connect the ground conductor 3 and the power supply conductor 8.

The frequency adjustment unit 6 has a module structure, and includes a frequency adjustment unit main body 21 and six connection terminals 22A to 22F exposed to the outside from the frequency adjustment unit main body 21.
As shown in FIG. 3, the frequency adjustment unit main body 21 has a bias voltage applied to a variable point diode (capacitor variable element) 31A, 31B connected so that the cathode sides face each other, and a connection point P2 of the variable capacitance diodes 31A, 31B. RF block for preventing a high-frequency signal flowing in the variable capacitance diodes 31A and 31B from flowing to the ground by connecting the bias voltage input terminal (capacitance adjusting means) 32 for applying a voltage to the anode side of the variable capacitance diode 31A and the ground G Connected to the inductor 33A, the RF block inductor 33B that connects the anode side of the variable capacitance diode 31B and the ground G to prevent a high frequency signal flowing in the variable capacitance diodes 31A and 31B from flowing to the ground, and the bias voltage input terminal 32 The variable capacitance diode 31 is connected to the point P2. , 31B is connected to the RF block inductor 33C for preventing the high-frequency signal flowing to the bias voltage input terminal 32 from flowing to the bias voltage input terminal 32 and the anode side of the variable capacitance diode 31B and the feed conductor 8 to remove the DC current component in the received signal. And a DC block capacitor 34. In addition, RF shown in FIG. 3 has shown the high frequency circuit.

  Here, the bias voltage input terminal 32 is connected to the bias voltage input terminal connection conductor 35 formed on the substrate 2 via the connection terminal 22F shown in FIG. 1, and the ground G side of the RF block inductors 33A and 33B is connected to the connection shown in FIG. The connection point P3 of the variable diode 31A and the RF block inductor 33A is connected to the connection conductor 13 via the connection terminal 22B shown in FIG. 1, and the DC block capacitor 34 is the connection terminal shown in FIG. The power supply conductor 8 is connected to each other through 22E. The connection terminals 22A and 22C are terminals that are not electrically connected to other members, and are fixed on lands 36A and 36B formed on the substrate 2, respectively.

  FIG. 4 shows capacitance characteristics with respect to the reverse voltage applied to the variable capacitance diodes 31A and 31B. When the bias voltage to be applied to each of the variable capacitance diodes 31A and 31B is increased, the width of the depletion layer in each of the variable capacitance diodes 31A and 31B is increased, and the same effect as that of increasing the distance between the parallel plates of the capacitors occurs. . Thereby, as shown in FIG. 4, the capacitances of the variable capacitance diodes 31A and 31B are reduced. As described above, the capacitances of the variable capacitance diodes 31A and 31B are adjusted by the bias voltage applied to the bias voltage input terminal 32.

  The bias voltage input terminal connection conductor 35 is connected to a frequency setting circuit (not shown) that controls the bias voltage applied to the bias voltage input terminal 32. Here, the resonance frequency of the antenna device 1 is proportional to 1 / √ (L · C), where L is an inductance component due to the electrical length of the antenna element and C is a capacitance component due to the variable capacitance diodes 31A and 31B. . Therefore, the resonance frequency of the antenna device 1 can be set by changing the capacitances of the variable capacitance diodes 31A and 31B. Therefore, a bias voltage to be applied to the bias voltage input terminal 32 is set in accordance with the reception channel of terrestrial digital broadcasting.

  The power supply conductor 8 is a linear pattern that connects the frequency adjustment unit 6 and the power supply unit 7 connected to a high-frequency circuit (not shown). The power supply conductor 8 is connected to the above-described high-frequency circuit via the power supply unit 7.

  Here, the VSWR characteristic of the antenna device 1 is shown in FIG. The inductance of the chip inductor 5 is 6.8 nH, the inductance of the chip inductor 17 is 100 nH, the inductance of the RF block inductors 33A to 33C is 82 nH, and the capacitance of the DC block capacitor 34 is 100 pF. Curves C1 to C5 shown in FIG. 5 indicate the VSWR characteristics when the applied voltage to the bias voltage input terminal 32 is 0.0 V, 1.0 V, 2.0 V, 3.0 V, and 3.5 V, respectively. ing.

  As shown in FIG. 5, it is possible to cover a wide frequency range from 470 MHz to 700 MHz without deteriorating impedance characteristics. Therefore, in digital terrestrial broadcasting, a voltage is applied to the bias voltage input terminal 32 so that the resonance frequency of the antenna device 1 corresponds to the channel to be received, and the capacitances of the capacitance variable diodes 31A and 31B are set, so that a desired channel is obtained. Receive broadcasts.

  In the antenna device 1 configured as described above, even if the electric length of the antenna element alone is shorter than ¼ of the antenna operating wavelength, the antenna operation can be performed as the entire electric length by combining the loading unit 4 and the chip inductor 5. Satisfies ¼ of the wavelength. Thereby, for example, even if the frequency is 470 MHz to 770 MHz, which is a broadcasting band of terrestrial digital broadcasting, the antenna device can be significantly shortened.

Further, using the variable capacitance diodes 31A and 31B, the capacitance of the variable capacitance diodes 31A and 31B is adjusted by the bias voltage applied to the variable capacitance diodes 31A and 31B, and the resonance frequency of the antenna device 1 is changed. Here, the variable capacitance diodes 31A and 31B whose capacitance is variable within a predetermined range are used, and the chip inductor 5 is provided so as to connect the power supply conductor 8 and the ground conductor 3 without deteriorating impedance characteristics. 470 MHz to 770 MHz can be covered.
It is said that the 470 MHz to 710 MHz band will be used for terrestrial digital broadcasting from 2011 when full operation is performed, but this range is almost covered by changing the bias voltage applied in the range of 0 V to 3.5 V. To do.

  Next, a second embodiment will be described with reference to FIGS. In the following description of each embodiment, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that in the antenna device 40 according to the second embodiment, the loading unit 4 (hereinafter referred to as the first loading unit 4) and the second loading unit 42 are used. It is a point equipped with.

That is, the second loading part 42 is formed on the surface of the substrate 2 and the loading element 45 having the element body 43 and the conductor pattern 44 wound around the surface of the element body 43 in the same manner as the first loading part 4. Lands 46A and 46B for mounting the element 45 on the substrate 2 are provided. The land 46 </ b> A and the frequency adjusting unit 47 are connected by a connecting conductor 48. The loading element 45 is disposed so as to be antiparallel to the loading element 11 of the first loading unit 4.
The connecting conductor 48 is formed with a dividing portion (not shown) for dividing the connecting conductor 48, and the dividing portion is provided with a chip inductor 49 as a lumped constant element.

The frequency adjustment unit 47 includes a frequency adjustment unit main body 51 and six connection terminals 52A to 52F exposed from the frequency adjustment unit main body 51 to the outside.
As shown in FIG. 7, the frequency adjustment unit main body 51 includes two sets of variable capacitance diodes 31A, 31B and 31C, 31D arranged so that the cathode sides face each other, and a connection point P2 and variable capacitance diodes 31C, 31D. A bias voltage input terminal 32 for applying a bias voltage to the connection point P4, RF block inductors 33A to 33C, an RF block inductor 33D for preventing high-frequency signals flowing in the variable capacitance diodes 31C and 31D from flowing to the ground G, It has.

  Here, the bias voltage input terminal 32 is connected to the bias voltage input terminal connection conductor 35 via the connection terminal 52F, the ground G side of the RF blocks 33A, 33B, 33D is connected to the ground conductor 3 via the connection terminal 52D, and the connection point P3 is The connection conductor 52 is connected to the connection conductor 13 via the connection terminal 52B, the DC block capacitor 34 is connected to the power supply conductor 8 via the connection terminal 52E, and the connection point P5 of the variable capacitance diode 31C and the RF block inductor 33D is connected to the connection conductor 48 via the connection terminal 52C. Are connected to each other. The connection terminal 52 </ b> A is a terminal that is not electrically connected to other members, and is fixed on a land 53 formed on the substrate 2.

In the antenna device 40, a first antenna unit is formed by the first loading unit 4, the chip inductor 17, the variable capacitance diodes 31 </ b> A and 31 </ b> B, the chip inductor 5, and the feed conductor 8, and the second loading unit 42 and the chip inductor 49. The second antenna portion is formed by the variable capacitance diodes 31C and 31D, the chip inductor 5 and the feed conductor 8.
The second antenna unit adjusts the electrical length according to the length of the conductor pattern 44 and the inductance of the chip inductor 49 so that the resonance frequency of the second antenna unit does not apply to the variable capacitance diodes 31A to 31D. It is comprised so that it may become a high frequency side rather than the resonant frequency.

  The high-frequency circuit is configured to receive one high-frequency signal having a good reception state in the reception channel of terrestrial digital broadcasting among the high-frequency signals received by the first and second antenna units.

Here, the VSWR characteristic of the antenna device 40 is shown in FIG. The inductance of the chip inductor 5 is 15 nH, the inductance of the chip inductors 17 and 49 is 70 nH, the inductance of the RF block inductors 33A to 33D is 82 nH, and the capacitance of the DC block capacitor 34 is 100 pF. At this time, no bias voltage is applied to the bias voltage input terminal 32.
As shown in FIG. 8, when no bias voltage is applied, the first antenna unit has a resonance frequency of about 470 MHz, and the second antenna unit has a resonance frequency of about 650 MHz, which is higher than the resonance frequency of the first antenna unit. Has a frequency.

FIG. 9 shows the VSWR characteristics of the antenna device 40 in a state where the voltage applied to the bias voltage input terminal 32 is appropriately changed. Similarly, FIG. 9 shows the minimum value of VSWR when the resonance frequency is adjusted to each frequency.
As shown in FIG. 9, in the high frequency band such as 650 MHz or more, the low frequency band of 470 MHz to 770 MHz is received by the first antenna unit and the high frequency band is received by the second antenna unit. Can also cover the deterioration of impedance characteristics.

The antenna device 40 configured as described above has the same operations and effects as the antenna device 1 in the first embodiment described above, but the first and second antenna units share the low frequency band and the high frequency band. Thus, even in a wide frequency band, it is possible to cover with the deterioration of the impedance characteristics more suppressed.
In addition, since the frequency band covered by one antenna unit can be narrowed, the variable range of the capacitance of the variable capacitance diode that constitutes each antenna unit is reduced. Thereby, the range of the voltage applied to the bias voltage input terminal 32 can be reduced to 0 V to 3.0 V as compared with the antenna device 1 in the first embodiment.

Next, the communication apparatus according to the present invention will be specifically described with reference to examples.
As an example, the antenna device 1 in the first embodiment was manufactured as a sample 1 and the VSWR characteristics at 470 MHz to 770 MHz, which is a broadcasting band of digital terrestrial broadcasting, were measured. The result is as shown in FIG. Further, as a comparative example, as shown in FIG. 10, an antenna device without the chip inductor 5 is manufactured, and the applied voltage to the bias voltage input terminal 32 is similarly set to 0.0V, 1.0V, 2.0V. , VSWR characteristics at 3.0V and 3.5V were measured. The result is shown in FIG. Curves C6 to C10 shown in FIG. 11 indicate the VSWR characteristics when the applied voltage is 0.0 V, 1.0 V, 2.0 V, 3.0 V, and 3.5 V, respectively.

  From FIG. 5 and FIG. 11, it was confirmed that the deterioration of the impedance characteristics was suppressed by providing the chip inductor 5 so as to connect the power supply conductor 8 and the ground conductor 3. Therefore, even in a wide frequency range such as 470 MHz to 700 MHz, the resonant frequency is variable and a small antenna device with high gain can be obtained.

  Next, the antenna device of the sample 1 described above is mounted on a mobile phone, and the voltage applied to the bias voltage input terminal 32 is adjusted so that the resonance frequencies are 470 MHz, 500 MHz, 550 MHz, 600 MHz, 650 MHz, and 700 MHz. The VSWR characteristics were measured. The result is shown in FIG. Curves C11 to C16 shown in FIG. 12 indicate VSWR characteristics when the resonance frequencies are 470 MHz, 500 MHz, 550 MHz, 600 MHz, 650 MHz, and 700 MHz, respectively.

  As shown in FIG. 12, in the frequency band of 500 MHz to 650 MHz, it was confirmed that VSWR was 1.5 or less, and deterioration of impedance characteristics was suppressed.

  Further, the antenna device 40 in the second embodiment was manufactured as the sample 2, and the gain of horizontal polarization at 470 MHz to 770 MHz was measured. Further, the gain of horizontal polarization was measured in the same manner for the antenna device of Sample 1 described above. The result is shown in FIG.

  As shown in FIG. 13, by forming two antenna parts using two loading parts, an antenna whose resonance frequency is variable while maintaining a high gain even in a wide frequency range such as 470 MHz to 770 MHz. It was confirmed that the device can be used.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in this embodiment, the antenna device is used for a portable terminal capable of receiving terrestrial digital broadcasting, but may be used for other wireless communication devices such as a cellular phone.

In addition, each loading unit and the frequency adjustment unit are arranged on the same surface of the substrate, but each loading unit is arranged on the back surface of the substrate, and the frequency adjustment with each loading unit is made through a through hole formed in the substrate. The structure which connects a part may be sufficient.
Further, although the variable capacitance diode is used as the variable capacitance element, other variable capacitance elements such as a variable capacitance capacitor may be used. Further, although two capacitance variable diodes are used, one may be used or three or more may be used according to the variable range of the resonance frequency.

  Further, although the chip inductor having an inductance component is used as the lumped constant element, it is not limited to the inductance component, and a capacitor having a capacitance component may be used, or these may be combined. Further, since the lumped constant element has a function of adjusting the resonance frequency of the antenna device by the capacitance variable element, an element having an appropriate value according to the resonance frequency of the antenna device may be used. A configuration in which the dividing portion is not formed and the lumped constant element is not provided may be employed.

Further, although alumina as a dielectric material is used as the element body, a magnetic material or a composite material having both a dielectric material and a magnetic material may be used.
Further, the conductor pattern has a spiral shape wound on the surface of the element body, but may have a meander shape formed on the surface of the element body, or may have another shape.
Further, a dividing portion may be formed in the power supply conductor, and the dividing portion may be connected by a chip capacitor. Here, by appropriately setting the capacitance of the chip capacitor, it is possible to easily match the impedance in the power feeding unit. The impedance adjusting unit is not limited to the chip capacitor, and an inductor can be used.

Further, in the second embodiment described above, two antenna portions are formed by providing two loading portions. However, three or more antenna portions may be formed by providing three or more loading portions. Good.
Further, as shown in FIG. 14, an RF block inductor 33E is provided between the connection point P2 and the connection point P4 to prevent a high frequency signal from flowing between the connection point P2 and the connection point P4. There may be.

Further, as shown in FIG. 15, the variable capacitance diode 31 </ b> A may not be provided, and the variable capacitance diode 31 </ b> D may be shared by the first antenna unit and the second antenna unit.
In addition, as shown in FIG. 16, the connection point P2 and the connection point P4 are opened, and a voltage is applied from the bias voltage input terminal 32A to the capacitance variable diodes 31A and 31B of the first antenna section via the RF block inductor 33F. The voltage may be applied from the bias voltage input terminal 32B via the RF block inductor 33C to the variable capacitance diodes 31C and 31D of the second antenna unit.

Further, the frequency adjustment unit may be configured to be able to finely adjust the frequency.
As an example of this, a specific configuration and frequency fine adjustment method will be described with reference to FIGS.

  As shown in FIGS. 17 to 24, the frequency adjustment unit 106 that can finely adjust the frequency is a frequency adjustment module similar to the above-described embodiment, and the module substrate 108 having the wiring pattern 107 on the surface and wiring to the module substrate 108. A frequency adjusting unit main body 21 provided using the pattern 107, a connection terminal (antenna terminal) 22B provided on the module substrate 108 and connected to the loading unit 4, and a case member 109 are provided.

  The wiring pattern 107 is formed with a copper foil or the like as shown in FIG. On the wiring pattern 107, as shown in FIG. 19, six chip-shaped discrete components such as the variable capacitance diodes 31A and 31B, the RF block inductor 33A, the RF block inductor 33B, the RF block inductor 33C, and the DC block capacitor 34 described above. Is surface-mounted with a solder material or the like so as to have the connection relationship described above.

  The module substrate 108 is formed of a glass epoxy substrate, and three of the corner portions where the metal film is formed have a connection terminal 22B that is an antenna terminal, a connection terminal 22F that is connected to the bias voltage input terminal 32, A connection terminal 22E, which is an RF input / output terminal, is provided. In addition, a concave portion in which a metal film is formed is formed on each side of the module substrate 108, and the case member 109 is fitted into the concave portion to cover the frequency adjustment unit main body 21 with the case member 109. One of the recesses is a connection terminal 22D which is a GND terminal connected to the ground G side.

Further, the wiring pattern 107 has an adjustment pad portion 110 for fine frequency adjustment that is connected to the connection terminal 22B that is an antenna terminal and can be trimmed. The adjustment pad portion 110 is formed in a rectangular land shape and has a thickness capable of laser trimming.
As shown in FIG. 22, the frequency adjusting unit 106 as the frequency adjusting module is mounted on a substrate 102 which is a PCB substrate with a solder material or the like. As with the substrate 2 of the above embodiment, the substrate 102 is formed with the ground conductor 3, the power feeding unit 7, the connecting conductor 13, and the bias voltage input terminal connection conductor 35, and the chip inductor 17 and the chip inductor 5 are placed at predetermined positions. Has been implemented.

The fine adjustment of the frequency using the frequency adjustment unit 106 is performed as follows.
First, the frequency adjustment unit 106 is mounted on the substrate 102 before the case member 109 is attached, and the frequency characteristics are evaluated in an inspection process. At this time, if the frequency deviates from a desired frequency, a slit is formed in the adjustment pad portion 110 by a laser trimmer. For example, as shown in FIG. 23, the resonance frequency is corrected by forming only one or both of the slits S1 and S2 in accordance with the frequency adjustment degree. Thereafter, the case member 109 is attached on the substrate 102 to complete the fine adjustment of the frequency.

  FIG. 24 shows the results of examining the VSWR characteristics when one slit S1 is formed, when both the slit S1 and the slit S2 are formed, and when no slit is formed. As can be seen from this result, the adjustment pad portion 110 becomes narrower and longer as the number of slits increases, so that the inductance of the adjustment pad portion 110 increases and the frequency shifts to the lower frequency side.

As described above, the wiring pattern 107 is provided with the trimming adjustment pad portion 110 that can be trimmed, so that the shape accuracy of the wiring pattern 107 and the characteristic variations of the discrete components such as the variable capacitance diodes 31A and 31B to be mounted. Can be finely adjusted by trimming the adjustment pad portion 110.
In addition, by providing a process of correcting the resonance frequency using a laser trimmer after the process of evaluating the frequency, it becomes possible to correct the frequency simultaneously with the inspection.

  In the trimming shown in FIG. 23, the slits S1 and S2 are formed along the short side direction of the adjustment pad portion 110. However, the slits may be formed in other directions. For example, as shown in FIG. 25, slits S3 and S4 may be formed along the long side direction of the adjustment pad portion 110. In this case, the adjustment pad portion 110 can be made thinner and longer than when the slits S1 and S2 are formed, and the frequency adjustment range can be made larger.

1 is a plan view schematically showing an antenna device according to a first embodiment of the present invention. It is a perspective view of the loading element in FIG. It is the schematic which shows the antenna apparatus for demonstrating the frequency adjustment part in FIG. It is a graph which shows the capacitance with respect to the applied reverse voltage of the capacity variable diode of FIG. 2 is a graph showing VSWR characteristics at each bias voltage applied to a bias voltage input terminal of FIG. 1. It is a top view which shows typically the antenna device in the 2nd Embodiment of this invention. It is the schematic which shows the antenna apparatus for demonstrating the frequency adjustment part in FIG. It is a graph which shows the VSWR characteristic in the state which does not apply a voltage to the bias voltage input terminal of FIG. 2 is a graph showing VSWR characteristics at each bias voltage applied to a bias voltage input terminal of FIG. 1. It is a top view which shows typically the antenna apparatus in a comparative example. 11 is a graph showing VSWR characteristics at each bias voltage applied to the bias voltage input terminal of FIG. 10. It is a graph which shows the VSWR characteristic at the time of mounting an antenna apparatus in a mobile telephone. It is a graph which shows the gain in each resonance frequency. It is a top view which shows typically the other antenna apparatus which can apply this invention. Similarly, it is a top view which shows typically the other antenna apparatus which can apply this invention. Similarly, it is a top view which shows typically the other antenna apparatus which can apply this invention. Similarly, in another antenna device to which the present invention is applicable, it is an exploded perspective view in which a case member showing a frequency adjustment unit as a frequency adjustment module is removed. Similarly, in another antenna device to which the present invention is applicable, it is a perspective view showing a frequency adjustment unit as a frequency adjustment module. Similarly, in another antenna device to which the present invention is applicable, it is a plan view of a state in which a case member showing a frequency adjustment unit as a frequency adjustment module is removed. Similarly, in another antenna device to which the present invention can be applied, it is a rear view in a state in which a case member showing a frequency adjustment unit as a frequency adjustment module is removed. Similarly, it is a top view which shows the wiring pattern of the frequency adjustment part used as the frequency adjustment module in the other antenna apparatus which can apply this invention. Similarly, it is a top view which shows typically the mounting state of the frequency adjustment part used as the frequency adjustment module in the other antenna apparatus which can apply this invention. Similarly, in another antenna device to which the present invention is applicable, it is a plan view showing a state in which a slit is formed in an adjustment pad portion of a frequency adjustment portion that is a frequency adjustment module. Similarly, it is a graph which shows the frequency characteristic at the time of frequency evaluation according to the presence or absence of a slit in another antenna device to which the present invention is applicable. Similarly, in another antenna device to which the present invention can be applied, FIG. 24 is a plan view showing a state in which slits are formed in a direction different from that in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,40 ... Antenna apparatus 2,102 ... Board | substrate, 3 ... Ground conductor, 4 ... Loading part, 5 ... Chip inductor (inductor part), 6,106 ... Frequency adjustment part, 7 ... Feeding part, 8 ... Feeding conductor, 14, 43 ... Element body, 15, 44 ... Conductor pattern, 17, 49 ... Chip inductor (lumped constant element), 21 ... Frequency adjustment body, 31A to 31D ... Capacitance variable diode (capacitance variable element), 32, 32A, 32B ... Bias voltage input terminal (capacitance adjusting means), 42 ... second loading section, 107 ... wiring pattern, 108 ... module substrate 110 ... adjustment pad section, P1 ... connection point, S1, S2, S3, S4 ... slit

Claims (6)

A substrate, a ground conductor formed on the surface of the substrate, an element body made of a composite material disposed on the substrate and having a dielectric material or a magnetic material, or both, and a wire formed on the element body In an antenna device comprising a loading portion having a conductor pattern, an inductor portion connected between one end of the conductor pattern and the ground conductor, and a feeding point that feeds one end of the inductor portion,
A frequency adjustment unit is provided between one end of the conductor pattern and the inductor unit,
The frequency adjuster is, possess a variable capacitor which connects one end and the inductor portion of the conductor pattern, and a capacity adjustment means for adjusting the capacitance of the capacitive variable element,
The frequency adjustment unit is a frequency adjustment module that can be placed on the substrate and connects one end of the conductor pattern and the inductor unit,
The frequency adjustment module includes a module substrate having a wiring pattern on a surface thereof, a frequency adjustment unit body provided on the module substrate by using the wiring pattern, and the capacitance variable element and the capacitance adjusting unit, and the module substrate. And an antenna terminal connected to the loading unit.
The antenna device, wherein the wiring pattern has an adjustment pad portion for fine frequency adjustment that is connected to the antenna terminal and can be trimmed . A plurality of the loading portions;
The antenna device according to claim 1, wherein the frequency adjustment unit includes a plurality of the variable capacitance elements that respectively connect one end of the plurality of loading units and the inductor unit. The variable capacitance element is composed of a variable capacitance diode,
Said capacity adjusting means, said variable capacitance diode antenna device according to claim 1 or 2, characterized in that by applying a bias voltage to adjust the capacitance of the capacitive variable diode. Antenna device according to any one of claims 1 to 3, characterized in that the lumped constant element is connected to one end of the conductor pattern is provided. The conductor pattern, the antenna device according to any one of claims 1 4, characterized in that it comprises a longitudinally wound spiral shape of the body. The conductor pattern, the antenna device according to any one of claims 1 4, characterized in that it has a meander shape formed on the surface of the body.