JP2001053528A - Frequency-switching structure for surface mounted type antenna and communications equipment provided with the structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the degradation of antenna characteristics due to electric field concentration on a radiation electrode. SOLUTION: A dielectric substrate 5 for constituting a surface mounted type antenna 2 is turned to the laminate of substrates 11 and 12, and a radiation electrode 7 is provided on the peak surface of the dielectric substrate 5, that is the upper surface 12a of the substrate 12. On the upper surface of the substrate 11 inside the dielectric substrate 5, an electrode 3 for frequency changeover is formed. By switching the potential of the electrode 3 for the frequency changeover by a switching circuit 4, capacitance between the radiation electrode 7 and a ground electrode 15 is switched, and the transmission/reception frequency band of the radio waves of the surface mounted type antenna 2 is switched. The electrode 3 for the frequency changeover faces the almost entire area electrode surface of the radiation electrode 7, and the radiation electrode 7 is provided with the capacitance with the electrode 3 for the frequency changeover over the almost entire area. Thus, electric field is dispersedly generated between the electrode 3 for the frequency changeover and the radiation electrode 7, and deterioration of the antenna characteristics due to the electric field concentration on the radiation electrode 7 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency switching structure for switching a transmission / reception frequency band of a radio wave of a surface mount antenna and a communication device having the structure.

[0002]

2. Description of the Related Art FIG. 13 shows an example of a frequency switching structure of a surface mount antenna proposed by the present inventor. The frequency switching structure 1 of the surface mount antenna shown in FIG. 13 includes a surface mount antenna 2, a frequency switching electrode 3, and a switching circuit 4.

The surface mount antenna 2 includes a dielectric substrate 5, and a feed electrode 6 and a radiation electrode 7 formed on the surface of the dielectric substrate 5. The power supply electrode 6 is conductively connected to a power source 8. When AC power is supplied from the power source 8 to the power supply electrode 6, the power is transmitted from the power supply electrode 6 to the radiation electrode 7 by capacitive coupling and radiated. The electrode 7 resonates, and a part of the resonance energy is transmitted as a radio wave.

The above-mentioned frequency switching electrode 3 is formed on the surface of the dielectric substrate 5 of the above-mentioned surface-mount type antenna 2 at an interval from the end of the radiation electrode 7, and has a capacitance between itself and the radiation electrode 7. Things. A switching circuit 4 for switching the potential of the frequency switching electrode 3 is connected to the frequency switching electrode 3.

When the potential of the frequency switching electrode 3 is switched by the switching circuit 4, the capacitance between the radiation electrode 7 and the ground changes.
The transmission / reception frequency band of the radio wave of the surface mount antenna 2 is switched.

[0006]

In the frequency switching structure 1 of the surface-mounted antenna 2 having the above-described structure, a local portion where the frequency switching electrode 3 and the radiation electrode 7 face each other as shown in FIG. A generates a capacitance. For this reason, in the radiation electrode 7, the electric field concentrates on a local portion facing the frequency switching electrode 3, and the frequency band of the surface mount antenna 2 becomes narrow due to the concentration of the electric field, There is a problem that the antenna characteristics are deteriorated such as the gain is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a surface capable of preventing deterioration of antenna characteristics due to electric field concentration generated between a frequency switching electrode and a radiation electrode. An object of the present invention is to provide a frequency switching structure of a mounting antenna and a communication device having the structure.

[0008]

In order to achieve the above-mentioned object, the present invention provides means for solving the above-mentioned problems with the following configuration. That is, the frequency switching structure of the surface-mounted antenna according to the first aspect of the present invention is characterized in that the surface-mounted antenna in which the radiation electrode is formed on the dielectric substrate is disposed between the radiation electrode and the radiation electrode. A frequency switching electrode having a capacitance, and a switching circuit for switching the potential of the frequency switching electrode to switch the capacitance between the radiation electrode and the ground. A frequency switching structure of the surface-mounted antenna for switching a transmission / reception frequency band of a radio wave of the surface-mounted antenna by switching a capacitance of the surface-mounted antenna, wherein the frequency switching electrode is at least a short-side area electrode of the radiation electrode. Capacitance sufficient to disperse the electric field generated between the radiation electrode and the frequency switching electrode And a means for solving the problem with a configuration having a function as a field dispersion electrode with.

According to a second aspect of the present invention, there is provided a frequency switching structure for a surface mount antenna having the configuration of the first aspect,
The dielectric substrate of the surface-mounted antenna is a laminate in which a plurality of substrates are laminated from the mounting substrate side on which the surface-mounted antenna is mounted, and the radiation electrode is formed on the top surface of the dielectric substrate. The frequency switching electrode is arranged on the substrate surface of the substrate inside the dielectric substrate, facing the radiation electrode with a space therebetween.

[0010] A frequency switching structure for a surface mount antenna according to a third aspect of the present invention has the configuration of the second aspect of the present invention.
The plurality of substrates constituting the dielectric substrate are characterized in that at least one of the dielectric constant and the thickness is different from each other.

A fourth aspect of the present invention provides a frequency switching structure for a surface-mounted antenna, comprising: a surface-mounted antenna in which a radiation electrode is formed on a dielectric substrate; and a radiation electrode disposed at a distance from the radiation electrode. A frequency switching electrode having a capacitance therebetween, and a switching circuit for switching the potential of the frequency switching electrode to switch the capacitance between the radiation electrode and the ground. By switching the capacitance between, the frequency switching structure of the surface-mounted antenna that switches the transmission and reception frequency band of radio waves of the surface-mounted antenna, wherein the frequency switching electrode is at least the Formed along the electrode surface on the short side of the radiating electrode and occurs between the radiating electrode and the frequency switching electrode. With a configuration having a function as a field dispersion electrode having a capacitance sufficient to disperse an electric field is a means to solve the problem.

According to a fifth aspect of the present invention, there is provided a frequency switching structure for a surface mounted antenna having the configuration of the first or fourth aspect, wherein the frequency switching electrode is formed on a mounting substrate on which the surface mounted antenna is mounted. It is characterized by having.

According to a sixth aspect of the present invention, there is provided a frequency switching structure for a surface-mounted antenna having the configuration of any one of the first to fifth aspects, wherein the frequency switching electrode is provided in substantially the entire area of the radiation electrode. It has a characteristic that it has a capacitance between.

According to a seventh aspect of the present invention, there is provided the communication apparatus according to the first to sixth aspects.
The present invention provides a means for solving the above-mentioned problem with a configuration including a frequency switching structure of a surface mount antenna having the configuration of any one of the inventions.

In the invention having the above structure, the frequency switching electrode is disposed so as to face at least the short-side region electrode surface of the radiation electrode, or formed at least along the short-side region electrode surface of the radiation electrode. . For this reason, the radiation electrode has capacitance at least between the short-circuit-side region electrode surface and the frequency switching electrode. In other words, the radiation electrode has a capacitance between the frequency switching electrode and the frequency switching electrode, not in a linear shape as in the related art, but in a planar shape. Thereby, the electric field generated between the frequency switching electrode and the radiation electrode can be dispersed,
It is possible to avoid a problem of deterioration of characteristics of the surface mount antenna due to electric field concentration between the frequency switching electrode and the radiation electrode.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In the description of each embodiment described below, the same components as those of the frequency switching structure of the surface mount antenna shown in FIG. 13 are denoted by the same reference numerals, and redundant description of the common portions will be omitted.

FIG. 1 shows a frequency switching structure of a surface mount antenna characteristic of the first embodiment in an exploded state.

In the first embodiment, as shown in FIG. 1, the dielectric substrate 5 of the surface-mount type antenna 2 has two substrates 11 and 12, and these substrates 11, 1
2 are stacked and integrated in order from the mounting substrate 10 side on which the surface mount antenna 2 is mounted. Such substrates 11, 12
The meandering radiating electrode 7 is formed on the top surface of the dielectric substrate 5, that is, on the upper surface 12 a of the substrate 12. On the upper surface 11 a of the substrate 11, the frequency switching electrode 3 is formed so as to face almost the entire surface electrode surface of the radiation electrode 7 via the substrate 12.

The above point is a characteristic configuration of the first embodiment.

In the first embodiment, as shown in FIG. 1, the power supply electrode 6 and the ground electrode 13 are provided on the side surface of the dielectric substrate 5 (the side surface 11b of the substrate 11 and the side surface 12b of the substrate 12). 14 are formed. The ground electrode 13 is conductively connected to one end of the meandering radiation electrode 7, and a power supply electrode 6 is formed in a region near the other end of the radiation electrode 7 with an interval from the radiation electrode 7. I have. Thus, in the example shown in FIG.
Of the radiation electrode 7 is an open end.

Further, on the side surface 11b of the substrate 11, a connection electrode 1 electrically connected to the frequency switching electrode 3 is provided.
6 are formed.

The surface mount antenna 2 shown in FIG. 1 is configured as described above. This surface mount antenna 2
Is mounted on the mounting substrate 10 on which the ground electrode 15 is provided.
Are formed, and the non-ground regions 10b and 10c where no is provided. In the non-ground area 10b, there are formed a switching section 17 constituting the switching circuit 4 and a connection conductor pattern 18 electrically connected to the switching section 17. The non-ground area 10c has a power source 8
A power supply conductor pattern 20 that is electrically connected to the power supply conductor pattern 20 is formed.

The ground electrodes 13 and 14 of the surface-mounted antenna 2 are electrically connected to the ground electrodes 15 of the mounting substrate 10 by mounting the surface-mounted antenna 2 having the above configuration on the mounting board 10. The power supply electrode 6 is conductively connected to the power supply conductor pattern 20 of the mounting substrate 10, and is conductively connected to the power source 8 via the power supply conductor pattern 20. Further, the frequency switching electrode 3 is arranged to face the ground electrode 15 via the substrate 11. Further, the connection electrode 16 of the frequency switching electrode 3 is conductively connected to the connection conductor pattern 18 of the mounting substrate 10, whereby the frequency switching electrode 3 is connected to the switching circuit via the connection electrode 16 and the connection conductor pattern 18. 4 is electrically connected.

The switching circuit 4 has a circuit configuration for switching the potential of the frequency switching electrode 3.
There are various circuit configurations, and in this case, the switching circuit 4 may be formed by any of the circuit configurations. One example is shown in FIGS. 2B and 2C.
The switching circuit 4 shown in FIGS. 2B and 2C includes a diode 22 and a voltage source 23 for making the diode 22 conductive, in addition to the switching unit 17. Although not shown, a switching control circuit for controlling the switching operation of the switching unit 17 is provided on, for example, the mounting board 10.

By the control operation of the switching control circuit, as shown in FIG. 2B, when the switching section 17 is on, the diode 22 is turned on by the voltage source 23 and the frequency switching electrode 3 is turned on. Grounded through the diode 22 to the ground, the frequency switching electrode 3 has the same potential as the ground. FIG.
As shown in (c), when the switching unit 17 is in the off state, the diode 22 is turned off, and the frequency switching electrode 3 has a potential higher than the ground.

As described above, when the switching unit 17 is in the off state, the potential of the frequency switching electrode 3 is higher than the ground potential. It has a capacitance between itself and the ground electrode 15. Here, the capacitance between the frequency switching electrode 3 and the radiation electrode 7 when the switching unit 17 is off is C1 and the capacitance between the frequency switching electrode 3 and the ground electrode 15 is C2.

On the other hand, when the switching unit 17 is in the ON state, the frequency switching electrode 3 is at the ground potential, so there is no capacitance between the frequency switching electrode 3 and the ground electrode 15, and the frequency switching is not performed. Only the capacitance C1 is provided between the use electrode 3 and the radiation electrode 7.

That is, by the switching operation of the switching section 17 of the switching circuit 4, the potential of the frequency switching electrode 3 is switched, and the capacitance between the radiation electrode 7 and the ground electrode 15 is switched.

In the first embodiment, as described above, the frequency switching electrode 3 is opposed to the electrode surfaces of the radiation electrode 7 and the ground electrode 15 with a space therebetween. Therefore, the frequency switching electrode 3 and the radiation electrode 7
Alternatively, as shown in FIG. 2A, the capacitor has a distributed capacitance over the entire region opposed to the ground electrode 15, but in FIG. 2B and FIG. These capacitances are collectively represented by capacitances C1 and C2.

The frequency switching structure 1 of the surface mount antenna according to the first embodiment is configured as described above. When power is supplied from the power source 8 to the power supply electrode 6 through the power supply conductor pattern 20, the power is transmitted from the power supply electrode 6 to the radiation electrode 7 by capacitive coupling, and an antenna operation is performed.

When the switching section 17 of the switching circuit 4 is in the ON state during the operation of the antenna, the frequency switching electrode 3 is at the ground potential as described above, and the frequency between the radiation electrode 7 and the ground electrode 15 is changed. The capacitance becomes C1. At this time, assuming that the transmission / reception frequency band of the radio wave of the surface mount antenna 2 is f1, when the switching unit 17 switches from on to off, the capacitance between the radiation electrode 7 and the ground electrode 15 becomes static. As a result, the transmission / reception frequency band of radio waves of the surface mount antenna 2 becomes f2 higher than the above f1.

According to the first embodiment, since the frequency switching electrode 3 is arranged to face the electrode surface of the radiation electrode 7 with a space therebetween, the frequency switching electrode 3 is disposed at a distance from the radiation electrode 7. Has an electrostatic capacitance between the electrode surface and almost the entire area. As a result, the electric field between the frequency switching electrode 3 and the radiation electrode 7 can be dispersed in a plane to reduce the electric field concentration, and the electric field concentration between the frequency switching electrode 3 and the radiation electrode 7 can be reduced. It is possible to prevent the characteristic deterioration of the surface mount antenna 2 due to the deterioration.

Conventionally, a circuit has been proposed in which a circuit for switching the transmission / reception frequency band of the radio wave of the surface mount antenna 2 is provided on the mounting substrate 10 without using the frequency switching electrode 3. The circuit for switching the frequency is complicated, and there is a problem that a mounting space of the mounting substrate 10 is required to be wide. Furthermore, since power is supplied from the power source 8 to the surface mount antenna 2 through the frequency switching circuit, there is a problem that transmission loss of power is inevitable.

On the other hand, in the first embodiment, it is only necessary to form the frequency switching electrode 3 on the surface mount type antenna 2 and to provide the switching circuit 4 having a simple configuration on the mounting substrate 10. . That is, it is not necessary to provide a complicated circuit for frequency switching as in the above-described conventional case on the mounting board 10, and thus the mounting area of the mounting board 10 can be enlarged and the cost can be reduced. Also,
In the first embodiment, since the power from the power source 8 is supplied to the radiation electrode without passing through the frequency switching circuit, an effect that the transmission loss of the power can be reduced can be achieved. Can be.

Hereinafter, a second embodiment will be described. In the description of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description of the common portions will not be repeated.

FIG. 3 shows a frequency switching structure of a surface-mounted antenna characteristic of the second embodiment in an exploded state. In the second embodiment, the dielectric substrate 5 of the surface-mounted antenna 2 is formed of a single body, not a laminate, and the frequency switching electrode 3 is mounted on the mounting substrate 1.
The radiation electrode 7 of the dielectric substrate 5
Are formed so as to face the entire surface of the electrode surface. Other configurations are almost the same as those of the first embodiment.

In the second embodiment, the transmission / reception frequency band of the surface-mount antenna 2 can be switched between two different frequency bands, similarly to the first embodiment, by providing the above configuration. . That is, when the switching unit 17 of the switching circuit 4 is in the ON state, the capacitance between the radiation electrode 7 and the ground electrode 15 is substantially the same as the capacitance C1 between the radiation electrode 7 and the frequency switching electrode 3. When the switching unit 17 is in the OFF state, the radiation electrode 7 has a capacitance C1 between the frequency switching electrode 3 and the radiation electrode 7 and a capacitance C2 between the frequency switching electrode 3 and the ground electrode 15. The capacitance between the ground electrode 15 and the switching unit 1
7 is smaller than when ON. Thus, the radiation electrode 7
By switching the capacitance between the ground electrode 15 and the ground electrode 15, the transmission / reception frequency band of the radio wave used by the surface mount antenna 2 is switched.

According to the second embodiment, the first
Since the frequency switching electrode 3 is disposed so as to face almost the entire area of the electrode surface of the radiation electrode 7 as in the embodiment of FIG.
The concentration of the electric field generated between the frequency switching electrode 3 and the radiation electrode 7 can be reduced, and the characteristic deterioration of the surface mount antenna 2 due to the concentration of the electric field between the frequency switching electrode 3 and the radiation electrode 7 can be prevented. it can.

Hereinafter, a third embodiment will be described. In the description of the third embodiment, the same reference numerals are given to the same components as those in each of the above-described embodiments, and the overlapping description of the common portions will be omitted.

The third embodiment is different from the above embodiments in that the feed electrode 6 and the radiation electrode 7 of the surface mount antenna 2 are spaced apart from each other as shown in FIGS. Rather than being arranged via
The power of the power source 8 is transmitted directly from the power supply electrode 6 to the radiation electrode 7. In such a case, the power supply side of the radiation electrode 7 forms a short-circuit portion, and the ground side of the radiation electrode 7 forms an open end. Other configurations are almost the same as those of the above embodiments.

The frequency switching structure 1 of the surface mounted antenna shown in FIG. 4 corresponds to the first embodiment, and the frequency switching structure 1 of the surface mounted antenna shown in FIG. This corresponds to the second embodiment. Reference numeral 25 shown in FIGS. 4 and 5 indicates a matching circuit.

According to the third embodiment, in the surface mount antenna 2 of the direct power supply type in which power is transmitted directly from the power supply electrode 6 to the radiation electrode 7, as in each of the above embodiments, The configuration is such that the frequency switching electrode 3 is provided so as to face the almost entire area electrode surface of the radiation electrode 7. With this configuration, the frequency-switching electrode 3 and the radiation electrode 7 can be provided in the direct-feed type surface-mounted antenna 2 as in the case of the capacitive-feed type surface-mounted antenna 2 described in each of the above embodiments. The concentration of the electric field generated between the electrodes can be reduced, and the problem of the characteristic deterioration of the surface mount antenna 2 due to the concentration of the electric field between the frequency switching electrode 3 and the radiation electrode 7 can be avoided.

Hereinafter, a fourth embodiment will be described. In the description of the fourth embodiment, the same components as those of the above embodiments are denoted by the same reference numerals, and the description of the common portions will not be repeated.

In the fourth embodiment, FIG.
And a specific configuration example when the dielectric substrate 5 as shown in FIG. 4 is a laminate. The unique configuration is that the plurality of substrates constituting the dielectric substrate 5 differ from each other in at least one of the dielectric constant and the thickness. Other configurations are the same as the configurations shown in FIG. 1 and FIG.

According to the fourth embodiment, since the same configuration as that of each of the above-described embodiments is provided, it is generated between the frequency switching electrode 3 and the radiation electrode 7 as in each of the above-described embodiments. The electric field can be dispersed, and the problem of deterioration in characteristics of the surface mount antenna 2 due to the electric field concentration between the frequency switching electrode 3 and the radiation electrode 7 can be prevented. In addition, in the fourth embodiment, the plurality of substrates constituting the dielectric substrate 5 which is a laminate have a configuration in which at least one of the dielectric constant and the thickness is different from each other. With this configuration, the dielectric constant or the thickness of each substrate of the dielectric substrate 5 is appropriately set, and the capacitance between the frequency switching electrode 3 and the radiation electrode 7 and the capacitance between the frequency switching electrode 3 and the ground electrode 15 are set. It is easy to set both of the capacitances to desired values. From this, the surface mount antenna 2
It is easy to control the width between two different transmission / reception frequency bands that can be used, that is, the switching width to a desired width,
The degree of freedom in design can be increased.

Hereinafter, a fifth embodiment will be described. In the description of the fifth embodiment, the same reference numerals are given to the same components as those in each of the above embodiments, and the duplicated description of the common portions will be omitted.

A feature of the fifth embodiment is that, as shown in FIG. 6, the frequency switching electrode 3 is formed along almost the entire surface of the radiation electrode 7 of the surface mount antenna 2. That is.

That is, in the example shown in FIG.
0 has a ground area 10a and a non-ground area 10e. The non-ground area 10e is divided into an antenna mounting area 26 in which the surface mount antenna 2 is mounted and an area 27 other than the antenna mounting area 26. The frequency switching electrode 3 is formed in the area 27 other than the antenna mounting area. I have. As described above, the frequency switching electrode 3 is formed along almost the entire surface of the radiation electrode 7 of the surface mount antenna 2 and has a capacitance between itself and the radiation electrode 7.

According to the fifth embodiment, the frequency switching electrode 3 extends along almost the entire surface of the radiation electrode 7.
Is formed. By forming such a frequency switching electrode 3, the radiation electrode 7 is provided in the entire region from the short-circuit side (the power supply side in FIG. 6) to the open end side (the ground side in FIG. 6) of the radiation electrode 7. Has a capacitance between itself and the frequency switching electrode 3. For this purpose, the frequency switching electrode 3 and the radiation electrode 7
The electric field generated therebetween is dispersed, so that the problem of characteristic deterioration of the surface mount antenna 2 due to the electric field concentration between the frequency switching electrode 3 and the radiation electrode 7 can be avoided, as in the above-described embodiments.

Hereinafter, a sixth embodiment will be described. In the description of the sixth embodiment, the same reference numerals are given to the same components as those in each of the above-described embodiments, and the overlapping description of the common portions will be omitted.

The feature of the sixth embodiment is that the radiation electrode 7 is formed on the side surface of the dielectric substrate 5 as shown in FIG.

In the sixth embodiment, as shown in FIG. 7A, a non-ground area 10f is formed in the mounting substrate 10, and the surface-mount antenna 2 is formed in the non-ground area 10f. Implemented. The board surface opposite to the board surface on which the surface mount antenna 2 is mounted has a structure shown in FIG.
As shown in (b), a non-ground area 10g including an area 28 facing the mounting area of the surface mount antenna 2 is formed. In the non-ground area 10g, the frequency switching electrode 3 is formed along the almost entire area electrode surface of the radiation electrode 7 of the surface mount antenna 2.

The frequency switching electrode 3 is a radiation electrode 7
And has a capacitance between them. The frequency switching electrode 3 has a configuration in which a switching operation of the switching circuit 4 switches between a state in which the frequency becomes the ground potential and a state in which the frequency has a capacitance between the electrode and the ground electrode 15.

According to the sixth embodiment, in the surface mount antenna 2 in which the radiation electrode 7 is formed on the side surface of the dielectric substrate 5, the frequency can be switched along almost the entire surface of the radiation electrode 7 in the surface area. The electrode 3 was formed. With this configuration, the radiation electrode 7 has a capacitance between itself and the frequency switching electrode 3 over almost the entire area, and the frequency switching electrode 3 and the radiation electrode 3 The electric field generated between the electrodes 7 can be dispersed, and the problem of the characteristic deterioration of the surface mount antenna 2 due to the electric field concentration between the frequency switching electrode 3 and the radiation electrode 7 can be prevented.

Hereinafter, a seventh embodiment will be described. In the description of the seventh embodiment, the same components as those in the above embodiments are denoted by the same reference numerals, and redundant description of the common portions will be omitted.

By the way, as described above, the surface mount antenna 2 shown in each of the above embodiments has the switching circuit 4
, The potential of the frequency switching electrode 3 is switched. As a result, the state is switched between a state having the capacitance between the frequency switching electrode 3 and the ground electrode 15 and a state not having the capacitance, and the transmission / reception frequency band of the surface mount antenna 2 is switched by this switching.

The switching width of the transmission / reception frequency band of the surface mount antenna 2 can be increased as the capacitance between the frequency switching electrode 3 and the ground electrode 15 is increased. Based on the relationship between the switching width of the transmission / reception frequency band of the surface mounted antenna 2 and the capacitance between the frequency switching electrode 3 and the ground electrode 15, the switching width of the transmission / reception frequency band of the surface mounted antenna 2 is changed. The capacitance between the frequency switching electrode 3 and the ground electrode 15 is determined so as to have a desired value.

However, as shown in each of the above embodiments, when the frequency switching electrode 3 is formed so as to have a capacitance between the radiation electrode 7 and almost the entire surface of the electrode surface, the frequency switching electrode 3 is formed. In some cases, the capacitance between the ground electrode 15 and the ground electrode 15 becomes larger than the above determined value.

Therefore, in the seventh embodiment, as shown in FIGS. 8 to 11, the capacitance between the frequency switching electrode 3 and the ground electrode 15 becomes the above-mentioned determined value.
The electrode area of the frequency switching electrode 3 is reduced as compared with the embodiments described above.

The most characteristic feature of the seventh embodiment is that the reduced-type frequency switching electrode 3 is arranged so as to have a capacitance between the radiation electrode 7 and the short-side region electrode surface. It is established.

That is, the example shown in FIG. 8 is a modification of the above-mentioned FIG. 1, and the reduced type frequency switching electrode 3 is opposed to the ground side region electrode surface which is the short side region electrode surface of the radiation electrode 7. It is arranged. The example shown in FIG. 9 is a modified example of FIG. 4, in which the reduced-type frequency switching electrode 3 is disposed so as to face the power supply side region electrode surface which is the short-side region electrode surface of the radiation electrode 7. I have.

The example shown in FIG. 10 is a modification of the above-mentioned FIG. 6, and the reduced type frequency switching electrode 3 is arranged along the power supply side region electrode surface which is the short side region electrode surface of the radiation electrode 7. Is formed. The example shown in FIG. 11 is a modification of FIG. 7, in which the reduced type frequency switching electrode 3 is formed along the ground-side region electrode surface that is the short-side portion region electrode surface of the radiation electrode 7.

According to the seventh embodiment, when the electrode area of the frequency switching electrode 3 is smaller than that of each of the above embodiments, at least the short-side area electrode surface of the radiation electrode 7 is used. The reduced frequency switching electrode 3 is arranged so as to have a capacitance between the frequency switching electrodes 3. Normally, the radiation electrode 7 has a strong electric field on the open end side.
According to the above configuration, the electric field at the open end side of the radiation electrode 7 can be dispersed by providing a capacitance between the short-side area electrode surface of the radiation electrode 7 and the frequency switching electrode 3. Thus, similarly to the above-described embodiments, it is possible to prevent the characteristic deterioration of the surface mount antenna 2 due to the electric field concentration between the frequency switching electrode 3 and the radiation electrode 7.

Hereinafter, an eighth embodiment will be described. In the eighth embodiment, a configuration example of a communication device will be described. The communication device according to the eighth embodiment is a portable telephone as shown in FIG. A circuit board (mounting board) 32 is built in a case 31 of the portable telephone 30, and the surface mount antenna 2 as shown in each of the above-described embodiments is mounted on the circuit board 32. Although not shown, a frequency switching electrode 3 and a switching circuit 4 are formed on the dielectric substrate 5 or the circuit board 32 of the surface-mounted antenna 2 which are the same as those of the above-described embodiments. That is, the portable telephone 30 is provided with any one of the frequency switching structures 1 of the surface mount antenna 2 shown in the first to seventh embodiments.

The circuit board 3 of the portable telephone 30
2, a transmission circuit 33, a reception circuit 34, a transmission / reception switching circuit 35, and a lead pattern 36 are formed in the second circuit 2, as shown in FIG. The surface-mounted antenna 2 is electrically connected to the transmission circuit 33 and the reception circuit 34 via a lead pattern 36 and a transmission / reception switching circuit 35 by being mounted on a circuit board 32. This mobile phone 3
In the case of 0, the switching operation of the transmission / reception switching circuit 35 allows the transmission / reception operation to be performed smoothly.

According to the eighth embodiment, the portable telephone 30 is provided with the frequency switching structure 1 of the surface mount antenna 2 shown in each of the above embodiments. With this configuration, the portable telephone 30 can switch and use two different frequency bands, and furthermore, as described in the above embodiments, the frequency switching electrode 3 and the radiation electrode. The effect of preventing the problem of the characteristic deterioration of the surface mount antenna 2 due to the electric field concentration between 7 can be prevented. This allows
A mobile phone with high reliability of antenna characteristics can be provided.

It should be noted that the present invention is not limited to the above embodiments, but can take various embodiments. For example, in each of the above embodiments, the radiation electrode 7 formed on the top surface of the dielectric substrate 5 has a meandering shape, but the shape of the radiation electrode 7 is not limited to a meandering shape.
Various suitable shapes can be taken.

In each of the above embodiments, when the dielectric substrate 5 is a laminate, the frequency switching electrode 3 is formed on the upper surface of the substrate 11 different from the substrate 12 on which the radiation electrode 7 is formed. Although an example has been described, for example, the frequency switching electrode 3 may be formed on the bottom surface of the substrate 12 on which the radiation electrode 7 is formed. In each of the above embodiments, when the dielectric substrate 5 is a laminate, the dielectric substrate 5 is
Although the dielectric substrate 5 includes the substrates 11 and 12, the dielectric substrate 5 may be a laminate of three or more substrates.

Further, in each of the above embodiments, when the dielectric substrate 5 is a laminate, the dielectric substrate 5 has a configuration in which a plurality of substrates are laminated from the mounting substrate 10 side. For example, when the radiation electrode 7 is formed on the side surface of the dielectric substrate 5 as shown in the sixth embodiment, a plurality of substrates are arranged in a horizontal direction as shown in FIG. The body base 5 may be used. In such a case, the frequency switching electrode 3 may be formed on the substrate surface inside the dielectric substrate 5 so as to face the radiation electrode 7 on the side surface of the dielectric substrate 5.

Further, in each of the above embodiments, the configuration for switching between two different transmission / reception frequency bands of the surface mount type antenna 2 has been described.
And a switching circuit for switching the potential of each frequency switching electrode 3 may be used to switch three or more transmission and reception frequency bands.

In each of the above embodiments, when the frequency switching electrode 3 is formed on the mounting substrate 10,
Although the dielectric substrate 5 is composed of a single body, the dielectric substrate 5 may be a laminate of a plurality of substrates as necessary. Furthermore, in the examples shown in FIGS. 3, 5, 6, and 10, the frequency switching electrode 3 is formed on the surface of the substrate on which the surface-mounted antenna 2 is mounted. The frequency switching electrode 3 may be formed on the substrate surface opposite to the surface.

Further, in the eighth embodiment, the portable telephone 30 has been described as an example of the communication device. However, the present invention is not limited to the portable telephone, but is applicable to various communication devices. can do. By providing the communication device with the frequency switching structure of the surface mount antenna as shown in the first to seventh embodiments,
It is possible to obtain an excellent effect that a plurality of frequency bands can be switched and used, and the reliability of antenna characteristics can be improved.

[0073]

According to the present invention, the frequency switching electrode is provided so as to face at least the short-side portion region electrode surface of the radiation electrode, or the frequency is switched along at least the short-side portion region electrode surface of the radiation electrode. The configuration is such that a switching electrode is provided. With this configuration, at least a capacitance is dispersed between the short-side area electrode surface of the radiation electrode and the frequency switching electrode, thereby opening the radiation electrode where the electric field is more concentrated. The electric field at the end can be dispersed. Therefore, it is possible to prevent the antenna characteristics from deteriorating due to the electric field concentration between the frequency switching electrode and the radiation electrode.

The dielectric substrate of the surface-mount type antenna is composed of a laminate of a plurality of substrates, a radiation electrode is formed on the top surface of the dielectric substrate, and a frequency opposing the radiation electrode is formed inside the dielectric substrate. In the case where the switching electrode is formed, even when the surface mount antenna is mounted on the ground electrode of the mounting substrate, the frequency switching electrode facing the radiation electrode on the top surface of the dielectric substrate is used. Accordingly, the antenna characteristics can be prevented from deteriorating due to the electric field concentration between the frequency switching electrode and the radiation electrode as described above.

In the case where the dielectric substrate is composed of a laminate of a plurality of substrates, and the plurality of substrates differ from each other in at least one of the dielectric constant and the thickness, the switching width of the transmission / reception frequency of the surface mount antenna is different. Is a desired band, and it is possible to easily form a surface mount antenna capable of avoiding the problem of antenna characteristic deterioration caused by the electric field concentration between the frequency switching electrode and the radiation electrode as described above. Therefore, the degree of freedom in design can be improved.

In the case where the frequency switching electrode is formed on the mounting substrate of the surface mount antenna, the mounting substrate is much larger than the surface mount antenna. The frequency switching electrode can be formed more easily than in the case of forming.

When the frequency switching electrode has a capacitance between almost the entire area of the radiation electrode, the electric field between the frequency switching electrode and the frequency switching electrode is dispersed over the entire area of the radiation electrode. Thus, it is possible to more reliably avoid the problem of deterioration of antenna characteristics due to electric field concentration between the frequency switching electrode and the radiation electrode.

In the communication apparatus having the characteristic frequency switching structure of the surface mount antenna according to the present invention, the transmission and reception of radio waves can be performed by switching a plurality of different frequency bands, A problem of deterioration of antenna characteristics due to electric field concentration between the frequency switching electrode and the radiation electrode is prevented, and a communication device with high reliability of antenna characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an exploded state of a frequency switching structure of a surface-mounted antenna that is characteristic in the first embodiment.

FIG. 2 is an explanatory diagram showing a configuration for switching a transmission / reception frequency band of a radio wave of a surface mount antenna using a frequency switching electrode and a switching circuit.

FIG. 3 is an explanatory diagram showing an exploded state of a frequency switching structure of a surface-mounted antenna which is characteristic in the second embodiment.

FIG. 4 is an explanatory view showing, in an exploded state, an example of a frequency switching structure of a direct-feed type surface-mounted antenna according to the present invention.

FIG. 5 is an explanatory view showing another example of the frequency switching structure of the direct-feed type surface-mount antenna according to the present invention in an exploded state.

FIG. 6 is an explanatory diagram showing a fifth embodiment.

FIG. 7 is an explanatory diagram showing a sixth embodiment.

FIG. 8 is an explanatory diagram showing an example of disposition of reduced-type frequency switching electrodes.

FIG. 9 is an explanatory view showing another arrangement example of the reduced type frequency switching electrode.

FIG. 10 is an explanatory view showing another example of the arrangement of reduced-type frequency switching electrodes.

FIG. 11 is an explanatory view showing another example of the arrangement of the reduced type frequency switching electrodes.

FIG. 12 is an explanatory diagram illustrating an example of a communication device.

FIG. 13 is an explanatory diagram showing an example of a frequency switching structure of a conventional surface mount antenna.

[Description of Signs] 1 Frequency switching structure of surface mounted antenna 2 Surface mounted antenna 3 Frequency switching electrode 4 Switching circuit 5 Dielectric substrate 6 Feeding electrode 7 Radiating electrode 10 Mounting substrate 15 Ground electrode 30 Mobile phone

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuya Kawabata 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. 5J021 AA01 AB06 CA01 DB04 DB07 FA00 FA02 FA31 HA05 HA10 JA03 5J045 AA03 DA08 EA08 HA03 MA07 NA03 5J046 AA03 AB13 PA07

Claims (7)

[Claims] 1. A surface-mounted antenna having a radiation substrate formed on a dielectric substrate, a frequency switching electrode disposed at a distance from the radiation electrode and having a capacitance between the radiation electrode, A switching circuit for switching the capacitance between the radiation electrode and the ground by switching the potential of the frequency switching electrode, and switching the capacitance between the radiation electrode and the ground by the switching circuit. A frequency switching structure of a surface mount antenna for switching a transmission / reception frequency band of an antenna radio wave,
The frequency switching electrode is an electric field dispersing electrode having a capacitance sufficient to disperse an electric field generated between the radiation electrode and the frequency switching electrode by disposing at least on the short-side area electrode surface of the radiation electrode. A frequency switching structure for a surface-mounted antenna characterized by having a function as a function. 2. The dielectric substrate of a surface-mount antenna is a laminate in which a plurality of substrates are laminated from a mounting substrate on which the surface-mount antenna is mounted, and a radiation electrode is formed on the top of the dielectric substrate. 2. The surface mounting type antenna according to claim 1, wherein the frequency switching electrode is formed on the surface of the substrate, and the frequency switching electrode is disposed on the substrate surface of the substrate inside the dielectric substrate with an interval between the radiation electrode and the radiation electrode. Frequency switching structure. 3. The frequency switching structure for a surface-mounted antenna according to claim 2, wherein the plurality of substrates constituting the dielectric substrate are different from each other in at least one of a dielectric constant and a thickness. 4. A surface mount antenna having a radiation substrate formed on a dielectric substrate, a frequency switching electrode disposed at a distance from the radiation electrode and having a capacitance between the radiation electrode, A switching circuit for switching the capacitance between the radiation electrode and the ground by switching the potential of the frequency switching electrode, and switching the capacitance between the radiation electrode and the ground by the switching circuit. A frequency switching structure of a surface mount antenna for switching a transmission / reception frequency band of an antenna radio wave,
The frequency switching electrode is formed at least along the short-circuit-side region electrode surface of the radiation electrode with an interval from the radiation electrode, and is sufficiently static to disperse an electric field generated between the radiation electrode and the frequency switching electrode. A frequency switching structure of a surface mount antenna, having a function as an electric field dispersing electrode having a capacitance. 5. The frequency switching structure for a surface-mounted antenna according to claim 1, wherein the frequency switching electrode is formed on a mounting substrate on which the surface-mounted antenna is mounted. 6. The surface-mounted antenna according to claim 1, wherein the frequency switching electrode has a capacitance between almost all areas of the radiation electrode. Frequency switching structure. 7. A communication device comprising the frequency switching structure of the surface-mounted antenna according to claim 1. Description: