JP4586998B2 - Chip antenna, antenna device using the same, and wireless communication device - Google Patents

Description

  The present invention relates to a chip antenna for a wireless communication device such as a mobile phone, and more particularly to a multiband chip antenna having a small electric field affecting a circuit in a miniaturized wireless communication device, an antenna device using the chip antenna, and a wireless communication device. .

  The spread of wireless communication devices such as mobile phones in recent years is remarkable, and the functions and services of mobile phones are being improved more and more. Taking mobile phones as an example, such systems include GSM (Global System for Mobile Communications), which is mainly popular in Europe, DCS1800 (Digital Cellular System 1800), PCS (Personal Communications Services), which is popular in the United States, There are various systems such as PDC (Personal Digital Cellular) system adopted in Japan. However, with the rapid spread of mobile phones nowadays, especially in major metropolitan areas in developed countries, the frequency band allocated to each system cannot cover the system users, making it difficult to connect, There is a problem such as disconnection. Therefore, by making it possible for a user to use a plurality of systems, an increase in the frequency that can be practically used is measured, and further expansion of service areas and effective use of communication infrastructure of each system are performed. In the case of a mobile phone equipped with a GPS function, it is necessary to support both the cellular transmission / reception band used for the mobile phone line and the GPS band. A mobile phone that supports a plurality of systems is called a multiband mobile phone, and is distinguished from a single-band mobile phone that supports only a single system.

  Conventionally, it is difficult to design an antenna having a plurality of resonance frequencies with a single radiation electrode in a multi-band mobile phone, and a plurality of radiation electrodes corresponding to different resonance frequencies have been used. However, there are problems such as an increase in the volume of the antenna and mutual interference between both radiation electrodes.

  Therefore, a dual antenna that supports two frequencies with one chip antenna has been proposed. For example, Japanese Patent Laid-Open No. 2004-247791 (Patent Document 1) discloses a built-in reverse type capable of transmitting and receiving signals in two different transmission / reception frequency bands by primary resonance and high-order resonance of a radiation conductor formed on a dielectric. An F antenna is disclosed. As shown in FIG. 23, the inverted F antenna has a slightly different shape from the radiation conductor 61 formed on the upper surface of the dielectric 60 and the radiation conductor 61 formed on the back surface of the dielectric 60 at substantially the same position. A radiation conductor 62, and at one end of the radiation conductors 61, 62, common feeding points 63a, 63b for supplying signals and ground points 64a, 64b electrically connected to the ground conductor 65 are provided. They are provided at close positions. The inverted F antenna is mounted on an insulating spacer 66 (for example, having a thickness of about 6 mm) installed on the upper surface of the ground conductor 65.

  However, in this inverted F antenna, the radiating conductors 61 and 62 are arranged in parallel to the surface of the dielectric 60, so that currents flowing through the antenna and the circuit board affect each other. For this reason, it is desirable that the antenna and the circuit board be separated as much as possible, but with the recent miniaturization and thinning of mobile phones, the decrease in gain (sensitivity) due to the image current induced from the antenna current to the circuit board is ignored. I can't do it.

  This problem is particularly serious in the case of a folding cellular phone or a sliding cellular phone. FIGS. 19A to 19D show a foldable mobile phone 40 in which the chip antenna 1 is built, and FIGS. 20A to 20D show the folded state. FIGS. 21 (a) to 21 (d) show a slide type mobile phone 50 in which the chip antenna 1 is built, and FIGS. 22 (a) to 22 (d) show the closed state. As shown in FIGS. 19 (b) to (d) and FIGS. 21 (b) to (d), the chip antenna 1 is arranged at various positions in both the folding cellular phone 40 and the sliding cellular phone 50. However, the chip antenna 1 can be placed in the folded state in any position as shown in FIGS. 20 (b) to (d) and FIGS. 22 (b) to (d). Proximity to 51 elements. For this reason, an image current flows in the circuit of the element due to an electric field induced between the chip antenna 1 and an element such as a liquid crystal panel, and the sensitivity of the chip antenna 1 is significantly reduced.

  Recently, it has become important to reduce the influence of electromagnetic waves radiated from mobile phones on the human body (head) from the health aspect, and antenna devices with low specific absorption rate (SAR) of electromagnetic waves. Is desired.

JP 2004-247791 A

  Accordingly, a first object of the present invention is to provide a chip antenna for a wireless communication apparatus such as a mobile phone having a small electric field affecting the circuit, particularly a chip antenna corresponding to multiband.

  A second object of the present invention is to provide an antenna device and a wireless communication device having the chip antenna.

  As a result of diligent research in view of the above object, the present inventor has (a) provided strip electrode portions on the opposite longitudinal side surfaces of a rectangular parallelepiped base, connected the two at the folded portion, and supplied to one strip electrode portion. When the feeding electrode connected to the electric wire is connected, a dual-band chip antenna with a small influence of the electric field from the circuit can be obtained, and (b) a multi-band antenna can be obtained if the laminated body is a multilayered band-like electrode. (C) It was discovered that by installing this chip antenna on a mounting substrate, a multiband antenna device and a wireless communication device that are small in size and have a small influence of an electric field from a circuit can be obtained. I came up with it.

That is, the present invention can be achieved by the following means.
(1) A multi-band chip antenna having a radiating electrode formed on a rectangular parallelepiped base, the radiating electrode extending from a bottom face of the base on a longitudinally opposite side surface at a predetermined interval . The first and second strip electrode portions, a folded portion connecting the two strip electrode portions, and a feed electrode coupled to the first strip electrode portion , wherein the feed electrode has a first capacitance. And the first strip electrode portion is grounded via a second capacitance, and thus includes the radiation electrode and the first capacitance. A chip antenna characterized by having multiple resonances by a first series resonance circuit, and a second series resonance circuit composed of the first strip electrode part and the second capacitance .
(2) In the chip antenna according to the above (1), the feeding electrode is formed on the bottom surface of the base body, and a strip-shaped extension portion extending to the bottom surface of the base body is connected to an end portion of the second strip-shaped electrode portion. A chip antenna that faces the feeding electrode .
(3) The chip antenna according to (1) or (2), wherein the folded portion extends to an end surface, an upper surface, or a bottom surface of the base.
(4) In the chip antenna according to any one of (1) to (3), a short-circuit portion that connects the first and second strip electrode portions is provided between the folded portion and the feeding electrode. The short-circuit portion is provided on the upper surface or the bottom surface of the base body.
(5) The chip antenna according to any one of (1) to (4), wherein the base is provided with a through hole, a groove, a notch, or a recess.
( 6 ) The chip antenna according to any one of (1) to ( 5 ), wherein a ground electrode is connected to the radiation electrode at a position in the vicinity of the feeding electrode.
( 7 ) In the chip antenna according to ( 6 ), the ground electrode is connected to an end of the radiation electrode, and the feeding electrode is connected to the radiation electrode in the vicinity of the ground electrode. And chip antenna.
( 8 ) In the chip antenna according to ( 6 ), the feeding electrode is connected to an end of the radiation electrode, and the ground electrode is connected to the radiation electrode in the vicinity of the feeding electrode. And chip antenna.
( 9 ) An antenna device in which the chip antenna according to any one of (1) to ( 8 ) is installed on a mounting board, and the mounting board has a ground conductor at a position separated from the chip antenna. An antenna device characterized by that.
( 10 ) An antenna device in which the chip antenna according to any one of (1) to ( 8 ) is installed on a sub-board provided on a mounting board, wherein the mounting board is separated from the sub-board. An antenna device having a ground conductor at the position.
( 11 ) A wireless communication device having the antenna device according to any one of ( 9 ) to ( 10 ).
( 12 ) In the wireless communication device according to ( 11 ), the wireless communication device is a foldable or slide type mobile phone, and when the antenna device is closed, the mounting substrate of the antenna device faces another circuit substrate. A wireless communication device.

  In the chip antenna of the present invention, since the radiation electrode is formed on the side surface of the base, the electric field between the radiation electrode and the circuit board is small (the image current flowing through the circuit board is small), and the sensitivity is reduced by the image current. Is suppressed. In addition, since the radiation electrode is formed on both side surfaces of the substrate, it can cope with multiband. Further, it is possible to provide an antenna device and a wireless communication device that have a wide band and a low specific absorption rate (SAR) of electromagnetic waves with respect to the human body.

  Hereinafter, the present invention will be specifically described with reference to the drawings, but the present invention is not limited thereto.

[1] First Embodiment FIGS. 1 to 3 show a chip antenna 1 and an antenna apparatus having the chip antenna 1 according to an embodiment of the present invention. The chip antenna 1 includes an elongated rectangular parallelepiped base 2 and a radiation electrode 3 formed on the base 2. The radiation electrode 3 is formed by connecting the first and second strip electrode portions 31 and 32 extending on the longitudinally opposite side surfaces (elongated side surfaces) 2a and 2b of the substrate 2 and the two strip electrode portions 31 and 32 to each other. 2 has a folded portion 33 extending to the bottom surface, and a power feeding electrode 34 connected to the end of the first strip electrode portion 31 and extending to the bottom surface of the base 2. The power supply electrode 34 has a bottom electrode part for fixing with solder or the like, and is connected to the signal source 5 via the power supply line 4. In this example, the folded portion 33 of the chip antenna 1 is formed on the bottom surface of the base 2. Therefore, the printed surface of the radiation electrode 3 in the base 2 is only three surfaces, and the productivity of the chip antenna 1 is high. The radiation electrode 3 is continuously formed and there is no structural difference.

Although it is desirable that the mounting space of the chip antenna 1 is as small as possible in response to the miniaturization of the mobile phone, the chip antenna 1 preferably has an elongated shape because it is necessary to maintain the same performance as the conventional one. When the length of the substrate 2 is P and the width is W, P / W is preferably 20 or less. More preferably, it is 3-15. Further, when the length of the first strip electrode portion 31 is Lg ₁ , the width is P ₁ , the length of the second strip electrode portion 32 is Lg ₂ , and the width is P ₂ , Lg ₁ / P ₁ and Lg ₂ / P ₂ is preferably 1 to 100 respectively. More preferably, it is 3-50.

The material of the substrate 2 is preferably ceramics having a relative dielectric constant of 2 to 30, but may be plastic, glass, or a mixed material of these and ceramics as long as the relative dielectric constant is within the above range. When the substrate 2 made of a dielectric is used, the chip antenna 1 can be downsized due to the wavelength shortening effect. The dielectric is preferably alumina, but is not limited thereto. An example of the alumina-based dielectric is 10 to 60% by mass (converted to Al ₂ O ₃ ) of Al as a main component, 25 to 60% by weight of Si (converted to SiO ₂ ), and 7.5 to 50% by weight (converted to SrO) of Sr. , And 20% by mass or less (in terms of TiO ₂ ), and 0.1 to 10% by mass (in terms of Bi ₂ O ₃ ) as Bi, 0.1 to 5% by mass (in terms of Na ₂ O), Na as subcomponents, It contains at least one of 0.1 to 5% by mass (converted to K ₂ O) of K and 0.1 to 5% by mass (converted to CoO) of Co. Further, when the substrate 2 is made of a magnetic material, the chip antenna 1 can be further downsized because the inductance is large. When the substrate 2 is made of a mixture of a dielectric and a magnetic material, it is possible to reduce the size of the antenna due to the wavelength shortening effect and to increase the bandwidth by reducing the Q value of the antenna. Further, a mixed material of a magnetic material and a resin material such as plastic, or a mixed material of a magnetic material and glass may be used.

  The radiation electrode 3 is preferably made of a metal mainly composed of Ag or Cu. The radiation electrode 3 is formed by screen-printing a metal paste on the surface of the substrate 2 and then drying and baking. The radiation electrode 3 can also be formed by a thin film method such as etching or sputtering. Further, the radiation electrode 3 may be formed of a thin metal plate or a conductive film and fixed to the base 2.

  As shown in FIGS. 2 and 3, the antenna device 10 includes a mounting substrate 8 having a ground conductor portion 9 and a feeder 4 extending so as not to contact the ground conductor portion 9 and a region 8a other than the ground conductor portion 9 of the mounting substrate 8. And a chip antenna 1 mounted thereon. As shown in FIG. 3B, a ground conductor portion 9 a is also provided on the back surface of the mounting substrate 8 at the same position as the ground conductor portion 9. The ground conductor portions 9 and 9a and the feeder line 4 on the mounting substrate 8 are formed by screen printing. The feed electrode 34 of the chip antenna 1 is connected to the feed line 4 by solder or the like.

Since the first strip electrode portion 31 of the chip antenna 1 is separated from the ground conductor portion 9 by the distance D, a capacitance Cg is generated between the first strip electrode portion 31 and the ground conductor portion 9. The capacitance between the second open end 32a and the feeding electrode 34 of the strip-shaped electrode portions 32 is C, the inductance of the first strip-shaped electrode portions 31 and L _1, the inductance of the second strip-shaped electrode portions 32 Assuming L ₂ and assuming that the radiation resistances of the first strip electrode portion 31 and the second strip electrode portion 32 are R ₁ and R ₂ , respectively, an equivalent circuit of the antenna device 10 is expressed as shown in FIG.

The antenna device 10 adjusts the lengths Lg ₁ and Lg ₂ and the capacitances C and Cg of the first and second strip electrode portions 31 and 32 to thereby adjust the first and second strip electrode portions 31 and 32. The dual-band antenna device has a series resonance circuit A composed of 32 and a capacitance C, and a series resonance circuit B composed of a first strip electrode portion 31 and a capacitance Cg. Since the radiation electrode 3 corresponding to the electrode portion of the series resonance circuit A is longer than the first strip electrode portion 31 corresponding to the electrode portion of the series resonance circuit B, the resonance frequency in the series resonance circuit A is lower than the resonance frequency in the series resonance circuit B. .

Assuming that the signal wavelength from the signal source 5 is λ [m] and the total length of the radiation electrode 3 is Lt [m], in the series resonance circuit A, the following formula (1):
Lt = (λ / 4) / √ (ε _r × μ _r ) (1)
Holds. ε _r is the relative permittivity of the substrate 2, and μ _r is the relative permeability of the substrate 2. As can be seen from the equation (1), when ε _r or μ _r is increased, the total length of the radiation electrode 3 can be shortened by the wavelength shortening effect, and the chip antenna 10 can be miniaturized.

  In this embodiment, for example, the resonance frequency on the low frequency side (series resonance circuit A) is 900 MHz corresponding to the GSM system, and the resonance frequency on the high frequency side (series resonance circuit B) is 1800 MHz corresponding to the DCS system. Can do. In this case, the external dimensions of the chip antenna 1 can be set to, for example, 30 mm × 3 mm × 3 mm.

The resonance frequencies of the series resonance circuits A and B can be adjusted by changing the length of the radiation electrode 3, the dielectric constant of the base 2, and the like. For example, FIG. 5 shows changes in the resonance frequency on the low frequency side and the high frequency side when the length Lg ₂ of the second strip electrode portion 32 is changed. When Lg ₂ is changed, the resonance frequency on the low frequency side changes greatly, but the resonance frequency on the high frequency side hardly changes. From this, it can be seen that the resonance frequency on the high frequency side does not depend on the length of the second strip electrode portion 32.

  The antenna device 10 needs to be impedance matched with respect to the two resonance frequencies on the low frequency side and the high frequency side. The degree of impedance matching can be represented by VSWR (voltage standing wave ratio) representing the magnitude of reflection between the chip antenna 1 and the feeder line 4. When VSWR = 1, impedance matching is optimal, and power from the signal source 5 is not reflected at all and is supplied to the chip antenna 1.

  FIG. 6 shows the VSWR on the low frequency side and the high frequency side measured for the antenna device 10 of this example when the distance D is changed. It can be seen that the VSWR on both the low frequency side and the high frequency side becomes smaller as the distance D is larger, and particularly shows a good characteristic of VSWR = 3 or less when the distance D is 5 mm or more.

  FIG. 7 shows the influence of the chip antenna 1 mounted on the mounting board 8 on the circuit board 11 facing the mounting board 8 (for example, a circuit board such as a liquid crystal panel when the mobile phone is closed). As shown in FIG. 7A, when a radiation current 12 flows through the radiation electrode 3, an electric field 13 proportional to the capacitance between the radiation electrode 3 and the circuit 11b of the circuit board 11 is induced, and the circuit 11b is induced. An image current 12a flows in the opposite direction to the radiation current 12. However, in the chip antenna 1 of the present invention, as shown in FIG. 7B, since the radiation electrode 3 is perpendicular to the circuit board 11, the area where the radiation electrode 3 and the circuit 11b face each other is small. Therefore, the capacitance between the radiation electrode 3 and the circuit 11b is small, and the induced electric field 13 is also small. Therefore, the image current 12a flowing through the circuit 11b is small, so that the sensitivity of the chip antenna 1 can be suppressed and the bandwidth can be widened.

  Since the folded portion 33 and the circuit 11b of the circuit board 11 are parallel to each other, an electric field is generated between them, but the folded portion 33 has a significantly smaller area than the first and second strip electrode portions 31 and 32. Therefore, the effect can be ignored.

[2] Another embodiment
(1) Single-layer chip antenna FIGS. 8 to 14 show other examples of the chip antenna 1 of the present invention. In the chip antenna 1 shown in FIG. 8, the feeding electrode 34 extends to the side surface 2 b in the longitudinal direction and is close to the open end 32 a of the second strip electrode portion 32. When the feeding electrode 34 and the open end 32a of the second strip electrode part 32 are brought close to each other in this way, the capacitance C between them (see FIG. 3 (a)) increases, and the series resonance circuit on the low frequency side The resonance frequency of A is lowered. This reduces bandwidth and increases gain and sensitivity. On the contrary, when the feeding electrode 34 and the open end 32a of the second strip electrode portion 32 are moved away from each other, the capacitance C therebetween decreases, and the resonance frequency of the series resonance circuit A on the low frequency side increases. This increases bandwidth and decreases gain and sensitivity. Thus, by changing the length of the feed electrode 34, the resonance frequency of the series resonance circuit A on the low frequency side can be adjusted.

  In the chip antenna 1 shown in FIG. 9, a strip-like extension 35 connected to the end 32 a of the second strip-like electrode portion 32 extends to the vicinity of the feeding electrode 34. In this case as well, as in the example of FIG. 8, the capacitance C can be changed by changing the distance between the feeding electrode 34 and the belt-like extension 35, and the resonance frequency of the series resonance circuit A on the low frequency side is adjusted. can do.

  In the chip antenna 1 shown in FIG. 10, the folded portion 33 is formed on the end surface 2 c of the base 2. By providing the folded portion 33 on the end surface 2c, the folded portion 33 becomes perpendicular to the circuit board 11, and thus the influence of the electric field on the circuit board 11 is reduced. In addition, when the folded portion 33 is formed on the upper surface of the base 2 as shown in FIG. 11, the distance between the folded portion 33 and the circuit board 11 is increased, so that the influence of the electric field on the circuit board 11 is reduced. In addition, the embodiment shown in FIGS. 10 and 11 also has an effect that the variation of the resonance frequency due to the variation in relative permittivity and thickness of the circuit board 11 is small.

In the chip antenna 1 shown in FIG. 12 (a), a short-circuit portion 36 is provided in the vicinity of the folded portion 33 of the first and second strip electrode portions 31, 32. In this example, the short-circuit portion 36 is formed on the bottom surface of the base 2, but may be formed on the top surface of the base 2 as shown in FIG. 13. Figure 12 (b), the short strip-shaped electrode portions 31 having the radiation electrode is reduced by the short circuit section 36 (Lg ₁ and Lg ₂ is less than Lg ₁ 'and Lg _2' '+ short strip-shaped electrode portions 32' ), The radiated current 12 that resonates at that length flows. Since L ₁ ′ and L ₂ ′ are related to the resonance frequency on the low frequency side, the resonance frequency of the series resonance circuit A on the low frequency side becomes high. When the distance s between the folded portion 33 and the short-circuit portion 36 is increased, Lg ₁ ′ and Lg ₂ ′ are decreased, so that the resonance frequency on the low frequency side is increased. On the other hand, in the series resonance circuit B on the high frequency side, the resonance frequency is solely due to the radiated current 12 flowing through the first strip electrode portion 31, and is not affected by the short circuit portion. Accordingly, by changing the distance s between the folded portion 33 and the short-circuit portion 36, the resonance frequency on the low frequency side can be adjusted with little influence on the resonance frequency on the high frequency side.

  In the chip antenna 1 shown in FIG. 14, a ground electrode 37 is provided on the bottom surface of the substrate 2 in the vicinity of the feeding electrode 34 of the first strip electrode portion 31. In the example shown in FIG. 14 (a), the ground electrode 37 is outside the power supply electrode 34, but in the example shown in FIG. 14 (b), the ground electrode 37 is inside the power supply electrode 34. Since the chip antenna 1 of FIGS. 14A and 14B is the same as that shown in FIG. 1 except for the ground electrode 37, the description other than the ground electrode 37 will be omitted. In the case of FIG. 14 (a), the first strip electrode portion 31 is the distance from the ground electrode 37 to the folded portion 33, and the impedance changes according to the increase / decrease in the distance d between the feeding electrode 34 and the ground electrode 37. On the other hand, in the case of FIG. 14 (b), the first strip electrode portion 31 is shortened by the distance d 'between the feeding electrode 34 and the ground electrode 37, and therefore, the series resonance circuits A and B on the low frequency side and the high frequency side. The resonance frequency of each increases. Further, the impedance of the chip antenna 1 changes according to the increase or decrease of the distance d ′. 14A and 14B, the impedance of the chip antenna 1 can be adjusted by changing the distances d and d '. By providing the ground electrode 37, even if a metal or a human body (head, hand) or the like is in the vicinity of the chip antenna 1, the influence of the capacitance between the chip antenna 1 and the human body is reduced. There is also an effect that the resonance frequency hardly changes.

  FIG. 15 shows another example of the substrate 2 constituting the chip antenna of the present invention. The base 2 shown in FIG. 15 (a) is provided with a hole 20a penetrating from the top surface to the bottom surface. The effective dielectric constant of the substrate 2 is lowered by the through hole 20a, and the resonance frequency of the chip antenna 1 is increased. The effect is more remarkable as the frequency is higher. Further, the sensitivity of the chip antenna is improved and the bandwidth is widened. In addition, a hole 20b penetrating in the longitudinal direction of the substrate 2 is formed as shown in FIG. 15 (b), or a groove portion 21 extending in the longitudinal direction is formed in the bottom surface of the substrate 2 as shown in FIG. 15 (c). It may be formed. In order to adjust the dielectric constant, it suffices if a part of the substrate 2 is deleted. Therefore, the dielectric constant is not limited to the through hole or the groove, but may be a notch or a recess.

(2) Multilayer Chip Antenna FIG. 16 schematically shows a multilayer chip antenna according to a preferred embodiment of the present invention. The multilayer chip antenna 25 is connected to a signal source 5 via a feeder 4 at one end of the radiation electrode 3 and a meandering radiation electrode 3 formed inside the substrate 22, a long and thin rectangular body 22. A power supply electrode. Since the meandering radiation electrode 3 is perpendicular to the upper and lower surfaces of the base 22, there is substantially no influence on the circuit board 11 as described above. In addition, the meandering radiation electrode 3 generates capacitance at a plurality of locations of the radiation electrode 3, and resonance operation occurs in a plurality of current paths corresponding to these capacitances, so that it supports multibands of three frequencies or more. A chip antenna is obtained.

FIG. 17 shows each layer constituting the multilayer chip antenna 25. Each layer has a sheet substrate G ₁ ~G _5, a via hole B ₁ .about.B ₅ and strip-shaped electrode portions 3a ₁ to 3 A ₅ formed therein. The first strip electrode portions 3a ₁ to form the feeding electrode 34. Each of the sheet-like substrates G _{1 to} G ₅ is formed of a green sheet 26 made of a dielectric material such as ceramic or resin that can be fired at a low temperature. The strip electrode portions 3a _{1 to} 3a ₅ , the electrodes of the via holes B _{1 to} B ₅ , and the feeding electrode 34 are formed by printing a conductive paste mainly composed of Ag or Cu. A multilayer chip antenna having a structure shown in FIG. 16 is obtained by arranging and laminating the respective sheet-like substrates G _{1 to} G ₅ as shown in the figure, followed by firing.

In the example shown in FIGS. 16 and 17, the five strip electrode portions 3a _{1 to} 3a ₅ are coupled in a meander shape, but the multilayer chip antenna of the present invention is not limited to this structure, and the number of strip electrode portions is It is sufficient if there are three or more. As in the example of FIG. 14, a ground electrode may be provided in the vicinity of the feeding electrode 34 of the radiation electrode 3.

(3) Another Example of Antenna Device FIG. 18 shows an antenna device 10 having a structure in which the chip antenna 1 is mounted on the sub board 18 and the sub board 18 is mounted on the mounting board 8. The feed electrode 34 is connected to a feed pin 14 erected from the mounting board 8 via a feed line 4a on the sub-board 18, the feed pin 14 is connected to the signal source 5 via the feed line 4, and the sub-board 18 is It is supported by the base 27 and is separated from the mounting substrate 8. Thus, since the chip antenna 1 is separated from the ground conductor 9 and the circuit board 11, the gain of the antenna device 10 is improved and the VSWR (voltage standing wave ratio) is reduced. However, the sub board 18 does not necessarily need to be supported by the pedestal 27 and may be appropriately fixed in the radio communication apparatus in which the antenna apparatus 10 is incorporated.

[3] Wireless communication device The wireless communication device in which the chip antenna (antenna device) of the present invention can be incorporated is not limited. For example, it is used for the folding mobile phone 40 and the sliding mobile phone 50 shown in FIGS. It is preferable to do this. In the closed state, as shown in FIGS. 20 (b) to (d) and FIGS. 22 (b) to (d), the chip antenna 1 is close to the elements such as the liquid crystal panels 41 and 51. In the chip antenna 1, since the radiation electrode 3 is perpendicular to the elements such as the liquid crystal panel 41, the electric field induced between them is small. The same applies to the multilayer chip antenna 25 shown in FIG. Since the induced electric field is small, the wireless communication device incorporating the chip antenna 1 or the multilayer chip antenna 25 of the present invention has an advantage that the specific absorption rate SAR value of electromagnetic waves is low.

1 is a perspective view showing a chip antenna according to an embodiment of the present invention. 1 is a perspective view illustrating an antenna device according to an embodiment of the present invention. 2 shows the antenna device of FIG. 2, (a) is a top view, and (b) is a bottom view. FIG. It is a figure which shows the equivalent circuit of the antenna apparatus of FIG. 3 is a graph showing a relationship between a length Lg ₂ of a second strip electrode part and a resonance frequency on a low frequency side and a high frequency side in the antenna device of FIG. 2. It is a graph which shows the relationship between the distance D and VSWR in the antenna apparatus of FIG. The influence of the chip antenna on the circuit board is shown, (a) is a partial sectional side view, and (b) is an AA sectional view of (a). It is a perspective view which shows the chip antenna by another Example of this invention. It is a perspective view which shows the chip antenna by another Example of this invention. It is a perspective view which shows the chip antenna by another Example of this invention. It is a perspective view which shows the chip antenna by another Example of this invention. The chip antenna by another Example of this invention is shown, (a) is a perspective view, (b) is a top view. It is a perspective view which shows the chip antenna by another Example of this invention. It is a perspective view which shows the chip antenna by another Example of this invention. FIG. 2 shows a substrate constituting the chip antenna of the present invention, (a) is a perspective view showing a substrate having a hole penetrating from the top surface to the bottom surface, and (b) is a perspective view showing a substrate having a longitudinal through hole. (C) is a perspective view which shows the board | substrate which has a longitudinal direction groove part. 1 shows a multilayer chip antenna according to an embodiment of the present invention, where (a) is a perspective view and (b) is a top view. FIG. FIG. 17 is an exploded view showing the internal structure of the multilayer chip antenna of FIG. It is a perspective view which shows the antenna apparatus by another Example of this invention. The folding cellular phone in an open state is shown, (a) is a perspective view, and (b) to (d) are sectional views. FIG. 19 shows a closed state of the foldable mobile phone of FIG. 19, (a) is a perspective view, and (b) to (d) are sectional views. The slide type mobile phone in an open state is shown, (a) is a perspective view, and (b) to (d) are sectional views. FIG. 21 shows a closed state of the slide type mobile phone of FIG. 21, (a) is a perspective view, and (b) to (d) are sectional views. It is a perspective view which shows an example of the conventional antenna device.

Explanation of symbols

1 ... Chip antenna 2,22 ... Base
2a, 2b ... Longitudinal facing side
2c ... End face 3 ... Radiation electrode
31 ... First strip electrode part
31 '・ ・ ・ Short-circuited strip electrode
32 ... Second strip electrode
32 '・ ・ ・ Short-circuited strip electrode
33 ・ ・ ・ Folding part
34 ... Power supply electrode
35 ・ ・ ・ Strip electrode
36 ... Short-circuit part
37 ... Ground electrode
3a ₁ , 3a ₂ , 3a ₃ , 3a ₄ , 3a ₅ ... strip electrode 4, 4a ... feed line 5 ... signal source 8, 8a ... mounting board 9, 9a ... ground conductor Part
10, 10a, 10b, 10c, 10d, 10e, 10f ... Antenna device
11 ... Circuit board
12 ... Radiation electrode
12a ・ ・ ・ Image current
13 Electric field
14 ... Power supply pin
18 ... Sub-board
20 ... Through hole
21 ・ ・ ・ Groove
25 ... Multilayer chip antenna
26 ... Green sheet
G ₁ , G ₂ , G ₃ , G ₄ , G ₅ ... Sheet-like substrate
_{B 2, B 3, B 4} , B 5 ··· via holes
27 ... pedestal
40 ・ ・ ・ Folding mobile phone
50 ・ ・ ・ Slide mobile phone
41, 51 ... LCD panel
42, 52 ... Dial keys
43, 53 ... Speaker
60 ・ ・ ・ Dielectric
61, 62 ... Radiation conductor
63a, 63b ... feed point
64a, 64b ・ ・ ・ Grounding point
65 ・ ・ ・ Grounding conductor
66 ・ ・ ・ Insulating spacer

Claims (12)

A chip antenna corresponding to a multiband in which a radiation electrode is formed on a rectangular parallelepiped base,
The radiation electrode includes first and second strip electrode portions extending on a longitudinally opposite side surface with a predetermined distance from the bottom surface of the base, a folded portion connecting both the strip electrode portions, and the first strip shape. A power supply electrode connected to the electrode portion ,
The feeding electrode is coupled to the second strip electrode portion via a first capacitance,
The first strip electrode portion is grounded through a second capacitance,
Therefore, a first series resonance circuit constituted by the radiation electrode and the first capacitance, and a second series resonance circuit constituted by the first strip electrode portion and the second capacitance. And a chip antenna characterized by double resonance . The chip antenna according to claim 1,
The feeding electrode is formed on the bottom surface of the substrate;
A chip antenna characterized in that a strip-shaped extension extending to the bottom surface of the substrate is connected to an end of the second strip-shaped electrode portion and faces the feeding electrode . The chip antenna according to claim 1 or 2,
The chip antenna, wherein the folded portion extends to an end surface, an upper surface, or a bottom surface of the base. In the chip antenna according to any one of claims 1 to 3,
It has a short circuit part which connects between the 1st and 2nd strip electrode part between the above-mentioned return part and the above-mentioned feeding electrode, and the above-mentioned short circuit part is provided in the upper surface or the bottom of the above-mentioned substrate, Chip antenna. In the chip antenna according to any one of claims 1 to 4,
A chip antenna, wherein the base is provided with a through hole, a groove, a notch or a recess. In the chip antenna according to any one of claims 1 to 5,
A chip antenna, wherein a ground electrode is connected to the radiation electrode at a position in the vicinity of the feeding electrode. The chip antenna according to claim 6, wherein
The chip antenna, wherein the ground electrode is connected to an end of the radiation electrode, and the feeding electrode is connected to the radiation electrode in the vicinity of the ground electrode. The chip antenna according to claim 6, wherein
The chip antenna, wherein the feeding electrode is connected to an end of the radiation electrode, and the ground electrode is connected to the radiation electrode in the vicinity of the feeding electrode. An antenna device in which the chip antenna according to any one of claims 1 to 8 is installed on a mounting substrate,
The antenna device according to claim 1, wherein the mounting substrate has a ground conductor at a position spaced apart from the chip antenna. An antenna device in which the chip antenna according to claim 1 is installed on a sub-board provided on a mounting board,
The antenna device according to claim 1, wherein the mounting board has a ground conductor at a position separated from the sub-board.   A wireless communication device comprising the antenna device according to claim 9.   12. The wireless communication device according to claim 11, wherein the wireless communication device is a foldable or slide type mobile phone, and the mounting substrate of the antenna device faces another circuit substrate when the wireless communication device is closed. Wireless communication device.

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