JP3991954B2 - Antenna structure and communication device having the same - Google Patents

Description

  The present invention relates to an antenna structure for performing wireless communication and a communication device including the antenna structure.

FIG. 9 is a schematic cross-sectional view illustrating an example of an antenna structure provided in a wireless communication device (see, for example, Patent Document 1). A circuit board 31 is accommodated in the housing 30 of the communication device, and a gap 32 is provided between the front end side end surface 31a of the circuit board 31 and the inner wall surface portion of the communication device case facing the front end side end surface 31a. It has been. The antenna structure in this example uses the gap 32. In other words, the antenna grounding surface 34 is disposed along the inner wall surface of the front cover 30 </ b> A constituting the housing 30 on the tip side of the circuit board 31, and the inner wall surface of the rear cover 30 </ b> B constituting the housing 30. A radiation electrode (antenna) 35 is disposed along the line. The antenna ground plane 34 is connected to the ground of the circuit board 31 via a conductor 36, and the radiation electrode 35 is connected to a high-frequency circuit for radio communication (not shown) formed on the circuit board 31 via a conductor 37. The In addition, the code | symbol 38 in FIG. 9 has shown the speaker provided in the radio | wireless communication apparatus.

Japanese Patent Laid-Open No. 2002-124811

  The radiation electrode 35 is a λ / 4 type radiation electrode, and current is induced in the ground of the circuit board 31 according to the resonance operation of the radiation electrode 35, so that not only the radiation electrode 35 but also the ground of the circuit board 31. The radio wave is radiated.

  However, as the size of the communication board is reduced, the circuit board 31 is also reduced in size, and as the length of the circuit board 31 becomes shorter with respect to ¼ of the wavelength λ of the radio wave at the set resonance frequency used for wireless communication, the circuit board 31 becomes smaller. The emission of radio waves from 31 is suppressed. As a result, the antenna gain is reduced, and a satisfactory frequency bandwidth cannot be obtained.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an antenna structure that can easily improve the antenna gain and widen the frequency bandwidth without hindering the miniaturization of the communication device. It is to provide a communication device provided.

In order to achieve the above object, the present invention has the following configuration as means for solving the above problems. That is, the present invention includes a circuit board on which electronic components are mounted and a radiation electrode that performs antenna operation, and is narrowed on one end side of the circuit board through a step portion that narrows the width on both sides in the width direction. The radiated electrode is formed with a projecting portion that is widened toward the front, and the radiation electrode has a hole that is open at both ends in the width direction of the electrode surface on the base end side. Each end in the width direction of the radiation electrode on the outside is connected to the substrate surface on the wide side of the step portion of the circuit board, and the radiation electrode starts from the connection part with the circuit board. board table through a loop-shaped path successive folded bulges above the substrate surface while surrounding the tip of the overhang advances toward the distal end of the projecting portion while bulging in a direction away to the rear surface side of the lower of the substrate Along the surface with a gap Is formed, the previous end of the folding direction of the radiation electrode is forms an open end are arranged to form a capacitor via a circuit board and spacing, groups of the radiation electrode in the loop path of the radiation electrode The hole opened on the end side is arranged at a position facing the substrate surface of the overhanging portion of the circuit board, and circuit components are mounted on the substrate surface portion of the overhanging portion facing the hole. configuration and forms that are, in the circuit board is provided a ground electrode, and the circuit board on either side position in the width direction of the substrate, floating from ground is arranged through the ground electrode and the distance potential and each provided with separate and independent ground floating electrode with, the respective ground floating electrodes are respectively connected to the ground electrode via individual reactance adding circuit having a reactance component, the release Each end directly or indirectly the ground electrode via a separate ground is connected to the floating electrode the ground floating electrode and reactance adding circuit together radiation electrode serving as the both outer sides of the hole portion of the base end side of the electrode It is characterized by being connected to. In addition, the communication device of the present invention is characterized in that an antenna structure having a configuration unique to the present invention is provided.

In the present invention, the radiation electrode is a loop around to the substrate surface of the surface side of the circuit board through the outer position of the end portion of the circuit board while bulging in a direction away to the back side of the lower circuit board from the board surface of the circuit board Shaped. For this reason, the loop-shaped radiation electrode in the present invention does not increase the occupied area of the radiation electrode on the circuit board as compared with, for example, the radiation electrode arranged only on the one substrate surface side of the circuit board. The electrical length (electric length) of the radiation electrode can be increased. As a result, the antenna structure can be miniaturized while the radiation electrode has a set resonance frequency. Further, the communication device provided with the antenna structure of the present invention can be miniaturized.

Further, for example, the loop-shaped radiation electrode according to the present invention is from the substrate surface side on one side (back surface side) of the circuit board as compared with the radiation electrode disposed only on the substrate surface side on one side of the circuit board. Since it is formed so as to wrap around the substrate surface side on the other side (surface side) , the electrical volume of the radiation electrode can be increased by the amount formed around the substrate surface side on the other side. The electrical volume of the radiation electrode is related to the frequency bandwidth and antenna gain of wireless communication. The larger the electrical volume, the wider the frequency bandwidth, and the antenna gain can be improved. By providing a loop-shaped radiation electrode as in the invention and increasing the electrical volume of the radiation electrode, it is possible to improve the antenna gain and widen the frequency band. Thereby, the performance of the wireless communication of the communication device provided with the antenna structure of the present invention can be improved.

  Instead of the continuous loop-shaped radiation electrode surrounding the end portion of the circuit board as described above, the first loop radiation portion disposed on the front surface side of the circuit board and the first loop radiation surface disposed on the back surface side of the circuit board. Even if the radiation electrode separated into the two loop radiation portions is provided, the radiation electrode has the second loop radiation portion, so that the area occupied by the radiation electrode on the circuit board is increased as described above. Therefore, the electrical length of the radiation electrode can be increased, and the antenna structure can be reduced in size. Further, the electrical volume of the radiation electrode can be increased, and the antenna gain can be improved and the frequency band can be increased. Furthermore, the wireless communication performance of the communication device provided with the antenna structure of the present invention can be improved.

  In the present invention, the circuit board is provided with a ground electrode and a ground floating electrode which is disposed at a distance from the ground electrode and has a potential floating from the ground. The ground floating electrode is provided via a reactance addition circuit. Connected to the ground electrode. One end of the radiation electrode is connected to the ground floating electrode and connected to the ground electrode via the ground floating electrode and a reactance addition circuit.

  In the antenna structure of the present invention, not only does the current be induced in the ground electrode of the circuit board based on the current flowing through the radiation electrode and the radio wave is emitted from the radiation electrode, but also the ground electrode (circuit Substrate). In order to make the ground electrode have an antenna function in this way, it is desirable that the ground electrode has a length of ¼ or more of the wavelength λ of the radio wave having a resonance frequency set for wireless communication.

  In the present invention, by providing the reactance addition circuit on the connection path between the radiation electrode and the ground electrode as described above, the reactance component of the reactance addition circuit causes the radiation electrode to have an electrical length rather than the electrical length of the ground electrode itself. The electrical length of the ground electrode when viewed from the ground electrode side can be shown long. For this reason, for example, even if the circuit board is shortened due to miniaturization of the communication device and the physical length of the ground electrode is shortened, the ground electrode as viewed from the radiation electrode due to the reactance component of the reactance addition circuit Can be made longer than 1/4 of the wavelength λ of the radio wave having the resonance frequency set for wireless communication, for example. Accordingly, while avoiding the problem that the emission of radio waves from the circuit board is suppressed, that is, while preventing the antenna gain from being lowered and the frequency band from being narrowed, the circuit board can be downsized and the antenna of the present invention can be used. A communication device having a structure can be reduced in size.

  Also, in the present invention, as described above, the reactance component of the reactance addition circuit can make the electrical length of the ground electrode long when viewed from the radiation electrode, so that the reactance component of the reactance addition circuit is increased. The electrical length of the ground electrode can be easily increased, and the amount of radio wave radiation from the ground electrode (circuit board) can be increased. By the way, when the amount of radio wave radiation from the circuit board increases, for example, when a moving object such as a human body approaches the circuit board (communication device) and radio waves radiated from the circuit board are attracted to the moving object, Although the problem that the antenna efficiency decreases may occur, the antenna structure of the present invention can be regarded as a magnetic current type antenna, and even if a moving object approaches the circuit board, it becomes a source of radio wave radiation. Since the magnetic current is hardly affected by the moving object, it is possible to prevent the antenna efficiency from being lowered due to the approach of the moving object.

  As described above, by providing the configuration of the present invention, the electrical length of the ground electrode as viewed from the radiation electrode is increased by the reactance component of the reactance addition circuit without increasing the physical length of the ground electrode. Increase the electrical length of the ground electrode while reducing the size of the circuit board and preventing the decrease in antenna efficiency due to the proximity of moving objects because it has the characteristics of a magnetic current antenna. As a result, the antenna gain and the frequency bandwidth can be improved.

  In the present invention, since the electrical connection state between the radiation electrode and the ground electrode can be varied simply by changing the magnitude of the reactance component of the reactance addition circuit, the electrical connection between the radiation electrode and the ground electrode is possible. By changing the state, the matching state between the radiation electrode and the high-frequency circuit side for wireless communication of the communication device can be easily changed, and the radiation electrode can be easily matched. Thereby, the antenna gain can be improved.

  Furthermore, a reactance addition circuit is configured by a circuit pattern formed on the circuit board, and a reactance addition circuit is configured on a chip component, thereby suppressing an increase in the size of the circuit board, and by such a reactance addition circuit. The ground electrode and the ground floating electrode can be connected.

  Furthermore, the circuit board part surrounded by the radiation electrode is used effectively by using the circuit board part surrounded by the radiation electrode as the antenna internal part mounting area and mounting the components in the antenna internal part mounting area. can do. In addition, for example, components constituting a speaker of a mobile phone (communication device) are generally attached to the casing of the mobile phone, and it takes time to attach the speaker component. On the other hand, the speaker component is mounted in the antenna internal component mounting area surrounded by the radiation electrode, so that the speaker can be mounted at the same time as other circuit components in the mounting process of the component on the circuit board. These components can be automatically reflow-mounted by soldering, for example, in the antenna internal component mounting region of the circuit board. Thereby, the manufacturing process of the portable telephone (communication device) can be simplified, and the manufacturing cost can be reduced.

  Further, by forming at least a part of the radiation electrode part (second loop radiation part) swelled downward from the circuit board into a shape provided with a detour part, radiation swelled downwardly is formed. The electrical length of the electrode portion (second loop radiating portion) can be increased. Increasing the electrical length of the radiation electrode portion (second loop radiation portion) that bulges downward is equivalent to increasing the electrical length of the ground electrode when viewed from the radiation electrode. The reactance of the reactance adding circuit is increased by increasing the electrical length of the ground electrode when viewed from the radiation electrode by increasing the electrical length of the radiation electrode portion (second loop radiation portion) that bulges downward in this way. Ingredients can be reduced. For example, when the reactance addition circuit is formed on a chip component, the variation of the reactance component of the chip component increases as the reactance component of the reactance addition circuit of the chip component increases. On the other hand, by reducing the reactance component of the reactance addition circuit as described above, the variation in the reactance component of the chip component can be reduced, and the variation in antenna characteristics due to the variation in the reactance component is suppressed. can do.

  By providing a dielectric in at least a part of the region where the radiation electrode and the circuit board face each other, the electrical length of the radiation electrode can be increased by the wavelength shortening effect of the dielectric, and the antenna structure can be further downsized. Can be planned. Furthermore, the dielectric material is constituted by a mixed dielectric material to which a material having a higher dielectric constant than the resin is added by a thermoplastic resin, so that a material having a high dielectric constant is not added to the thermoplastic resin. Compared to the case, since the dielectric constant of the dielectric is increased, the electrical length of the radiation electrode can be further increased, and the miniaturization of the antenna structure can be further promoted.

  An opening for radiating infrared rays from the infrared radiation portion provided on the radiation electrode formation side end portion side of the circuit board to the outside is provided in the radiation electrode top portion on the radiation electrode formation side of the circuit board. Accordingly, the radiation electrode may be provided so as to surround the end portion side of the circuit board on the radiation electrode formation side, or the first loop radiation portion and the second loop may be provided on the end portion side of the circuit board on the radiation electrode formation side. Even if the radiation electrode separated from the radiation part is provided, the infrared rays of the infrared radiation part provided on the end side of the circuit board on the radiation electrode forming side can be externally radiated to the top side.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1 (a) shows a schematic perspective view of the antenna structure of the first embodiment, and FIG. 1 (b) shows the antenna structure of the first embodiment viewed from the left side of FIG. 1 (a). FIG. 1C schematically shows a plan view of the antenna structure of the first embodiment viewed from the upper side of FIG. 1A.

  The antenna structure 1 according to the first embodiment includes a circuit board 2, a radiation electrode 3 provided on one end side of the circuit board 2, and a dielectric 4. Type phone. FIG. 2 shows a schematic plan view of the circuit board 2 extracted from the antenna structure 1 and viewed from the lower side of FIG.

  By the way, as shown in the simplified cross-sectional view of the mobile phone in FIG. 3, the top side of the casing 6 of the mobile phone at the top side of the mobile phone facing the zenith side during a call of the mobile phone. For example, a gap may be provided between the end surface portion 6T and the top-side end surface 7T of the circuit board 7 accommodated in the housing 6 so that the speaker component 8 can be disposed, for example. In addition, the code | symbol 9 in FIG. 3 has shown the liquid crystal screen.

  In the first embodiment, the position A of the circuit board 2 shown in FIG. 2 corresponds to the position of the top side end surface 7T of the circuit board 7 shown in FIG. 3, and the circuit board 2 in the first embodiment is shown. 3 has a shape in which one end side projects to the top side than the circuit board 7 of FIG. In the first embodiment, a ground electrode 10 is provided on the back surface of the circuit board 2 so as to avoid the projecting portion 2V and a ground floating electrode 12 formation region described below.

  In addition, a ground floating electrode 12 is disposed adjacent to the circuit board 2 via a gap (slit) with the ground electrode 10. The ground floating electrode 12 is disposed with a gap from the ground electrode 10 as described above, and has a potential floating from the ground. In the first embodiment, the chip component 13 is provided so as to straddle the gap between the ground electrode 10 and the ground floating electrode 12 disposed adjacent to each other. For example, one or both of a coil and a capacitor are provided in the chip component 13 to form a reactance addition circuit 14 that is a lumped constant circuit having a reactance component. The ground electrode 10 and the ground floating electrode 12 are connected via the reactance addition circuit 14.

  The radiating electrode 3 is a λ / 4 type radiating electrode composed of a conductor plate, and this radiating electrode 3 is provided on the top side end side of the circuit board 2, and the top side of the circuit board 2 (radiating electrode formation) Side) and a loop shape surrounding the end (see, for example, FIG. 1B). That is, the radiation electrode 3 is connected to the surface of the circuit board 2 at the proximal end 3 a. The radiation electrode 3 swells in a direction away from the circuit board 3 starting from the connection part with the circuit board, and passes through a loop path surrounding the end of the circuit board, and is a board opposite to the bulging direction. It is formed so as to go around the surface (that is, the surface) and follow the surface. The extended distal end side 3b of the radiation electrode 3 forms an open end disposed with a distance from the surface of the circuit board 2.

  As described above, the radiation electrode 3 has a loop shape that goes from the back surface side of the circuit board 2 to the front surface side of the circuit board 2 through a position outside the top side end 2T of the circuit board 2. In the first embodiment, the radiation electrode 3 has a loop shape along the inner wall surface on the top side of the housing 6 of the portable telephone (communication device) as indicated by a chain line K in FIG. ing. Thereby, the loop-like length of the radiation electrode 3 can be made as long as possible in a limited space called the radiation electrode formation region set in the housing 6 of the mobile phone.

  In the first embodiment, the ground floating electrode 12 is formed on the back side of the circuit board 2, and the base end side end 3 a of the radiation electrode 3 is the surface of the circuit board 2 facing the ground floating electrode 12. The proximal end 3 a of the radiation electrode 3 is indirectly connected to the ground floating electrode 12 through a through hole 16 formed in the circuit board 2. That is, the proximal end 3 a of the radiation electrode 3 is connected to the ground electrode 10 via the ground floating electrode 12 and the reactance addition circuit 14 of the chip component 13.

  In the first embodiment, the circuit board portion surrounded by the radiation electrode 3, that is, the projecting portion 2V of the circuit board 2 forms the antenna internal component mounting region. In the antenna internal component mounting area of the circuit board 2, circuit components and circuit patterns constituting the mobile phone are formed. For example, the speaker component 20 as shown by the dotted line in FIG. 1B is mounted on the back surface of the projecting portion 2V of the circuit board 2. In the first embodiment, the downward bulge portion 3s (the portion surrounded by the dotted line in FIG. 1B) of the radiation electrode 3 is for component placement so as not to disturb the placement of the speaker component 20. Are formed (see, for example, FIGS. 1A and 1C). The speaker component 20 can be automatically mounted on the circuit board 2 by reflow, for example, by soldering at the same time as other components in the process of mounting the other components on the circuit board 2. Of course, components and circuit patterns may be formed on the circuit board 2 not only on the projecting portion 2V but also on the circuit board portion where the open end side of the radiation electrode 3 faces.

  When the antenna structure 1 of the first embodiment is built in a mobile phone to constitute a mobile phone, the circuit board 2 is formed with a high-frequency circuit 23 for wireless communication, A feed line 24 extending from the high frequency circuit 23 into the antenna internal component mounting region is formed. A power feeding means 25 is connected to the tip of the power feeding line 24. The power supply means 25 connects the tip of the power supply line 24 and a predetermined power supply part Q of the radiation electrode 3.

  Thus, for example, when a signal for transmission is supplied from the high frequency circuit 23 in a state where the radiation electrode 3 is connected to the high frequency circuit 23 for wireless communication via the power supply means 25 and the power supply line 24, By supplying the signal, a current is passed through the radiation electrode 3 in a loop from the proximal end 3a to the open end 3b, and the radiation electrode 3 resonates, whereby a signal for transmission is wirelessly transmitted. Further, when a signal arrives at the radiation electrode 3 from the outside and the radiation electrode 3 resonates and receives the signal, the reception signal is supplied from the radiation electrode 3 to the high-frequency circuit 23 through the power feeding means 25 and the power feeding line 24.

  In the first embodiment, the electrical length from the proximal end 3a to the open end 3b of the radiation electrode 3 is such that the radiation electrode 3 can resonate at a resonance frequency set for wireless communication. The size and shape of the radiation electrode 3 are designed so as to be long. In the first embodiment, a slit 17 for resonance frequency control is formed in the radiation electrode 3 in order to facilitate control of the resonance frequency of the radiation electrode 3. That is, by changing the length of the slit 17, the routing route, and the slit width, the electrical length of the radiating electrode 3 can be changed without changing the size or the outer peripheral shape of the radiating electrode 3 itself. The resonance frequency can be easily controlled. As a result, the radiation electrode 3 can be resonated with high accuracy at a predetermined resonance frequency for wireless communication.

  Further, in the first embodiment, in order to reduce the size of the radiation electrode 3, the dielectric electrode 4 is disposed between the surface of the circuit board 2 and the radiation electrode portion disposed on the surface side of the circuit board 2. In addition, a dielectric 4 is provided between the top side of the radiation electrode 3 on the top side of the top side end 2T of the circuit board 2 and the top side end 2T of the circuit board 2. Due to the wavelength shortening effect of the dielectric 4, it is possible to reduce the size of the radiation electrode 3 while giving the electrical length that allows the radiation electrode 3 to resonate at a set resonance frequency.

  The constituent material of the dielectric 4 is not particularly limited as long as it is a dielectric, but examples of the constituent material of the dielectric 4 will be described below. For example, when the dielectric 4 and the radiation electrode 3 are integrally formed by a molding technique such as insert molding or outsert molding, the dielectric 4 is made of a thermoplastic resin. Further, when the dielectric 4 is constituted by a thermoplastic resin, for example, when the dielectric 4 is assumed to be exposed to a high temperature (for example, a high temperature of 280 ° C. or higher) (for example, integral formation of the radiation electrode 3 and the dielectric 4). When the body is attached to the circuit board 2 using solder, the circuit board 2 on which the integrally formed body is mounted must be equal to or higher than the melting point of the solder in order to attach the integrally formed body of the radiation electrode 3 and the dielectric 4 to the circuit board 2. For example, PPS (polyphenylene sulfide) or LCP (liquid crystal polymer), which has heat resistance against high temperatures such that the dielectric 4 does not deform even at high temperatures. Etc.) to form the dielectric 4. Furthermore, since the wavelength shortening effect by the dielectric 4 is enhanced by increasing the dielectric constant of the dielectric 4, for example, a thermoplastic resin having a higher dielectric constant than the resin (for example, filler (for example, titanium oxide or alumina) The dielectric 4 may be made of a mixed dielectric material added with the above.

  In the first embodiment, the base end side end 3 a of the radiation electrode 3 is connected to the ground electrode 10 via the ground floating electrode 12 and the reactance adding circuit 14. With this configuration, it is possible to obtain an effect that the frequency band for radio communication of the antenna structure 1 can be widened and an effect that the antenna gain can be improved. This has been confirmed by the inventors' experiments. In the experiment, the antenna structure 1 of the first embodiment having the following dimensions was used. That is, the width W (see FIG. 4A) of the radiation electrode 3 of the antenna structure 1 is 40 mm, and the length La from the open end 3b of the radiation electrode 3 to the top end surface of the radiation electrode 3 is 20 mm. Further, the distance H (see FIG. 4B) between the surface of the circuit board 2 and the radiation electrode portion facing the surface of the circuit board 2 is 3.0 mm, which is lower than the circuit board 2. The swollen amount D of the swollen radiation electrode 3 is 3.5 mm. The length Lg from the top side end to the bottom side end of the ground electrode 10 formed on the circuit board 2 is 90 mm.

  Further, the lumped constant of the reactance adding circuit 14 of the chip component 13 connecting the ground floating electrode 12 and the ground electrode 10 in the antenna structure 1 used in the experiment is 5.6 nH.

  An antenna structure for comparison with the antenna structure 1 of the first embodiment was prepared. In the antenna structure of this comparative example, the ground floating electrode 12 and the chip component 13 are not provided, and the proximal end portion 3 a of the radiation electrode 3 is directly connected to the ground electrode 10. Other configurations and dimensions are the same as those of the antenna structure 1 of the first embodiment.

  Return loss and antenna gain were determined for each of the antenna structure 1 of the first embodiment having the above dimensions and the antenna structure of the comparative example. The results are shown in FIGS. 4 (c) and (d). FIG. 4C relates to the return loss, FIG. 4D relates to the antenna gain, and in both of FIGS. 4C and 4D, the solid line A represents the antenna of the first embodiment. This relates to the structure 1, and the chain line a relates to the antenna structure of the comparative example.

  As also shown in these experimental results, the one having the configuration of the first embodiment (that is, the configuration in which the radiation electrode 3 is connected to the ground electrode 10 via the ground floating electrode 12 and the reactance addition circuit 14). However, compared with the comparative example (that is, the configuration in which the radiation electrode 3 is directly connected to the ground electrode 10), the return loss and the antenna gain in the set frequency band for wireless communication (900 MHz band) are improved and the frequency band is increased. Broadband has been achieved.

  In the first embodiment, the ground floating electrode 12 is connected to the ground electrode 10 via the reactance addition circuit 14 of the chip component 13. For example, as shown in FIG. Instead of the chip component 13, for example, a circuit pattern 26 having a reactance component for connecting the ground floating electrode 12 and the ground electrode 10 is provided as the reactance addition circuit 14 on the projecting portion 2 </ b> V of the circuit board 2. The ground floating electrode 12 and the ground electrode 10 may be connected. 5B, the ground floating electrode 12 and the ground electrode 10 are connected by both the reactance addition circuit 14 of the chip component 13 and the reactance addition circuit 14 including the circuit pattern 26. It is good also as composition to do.

  Further, in the first embodiment, ground floating electrodes 12 are provided on both the left and right sides of the circuit board 2 shown in FIG. 2, for example, and both of these ground floating electrodes 12 are reactance addition circuits 14 ( For example, the left and right ground floating electrodes 12 are connected to the ground electrode 10 via the reactance addition circuit 14 composed of the circuit pattern 26. The ground floating electrode 12 on the other side is connected to the ground electrode 10 via the reactance adding circuit 14 of the chip component 13 so that the left and right ground floating electrodes 12 are grounded by the reactance adding circuit 14 having different configurations. It is good also as a structure connected to the electrode 10. FIG.

  Furthermore, for example, the size restriction on the radiation electrode 3 is loose, and the radiation electrode 3 can have a set resonance frequency within the allowable range of the size of the radiation electrode 3 without providing the dielectric 4 on the radiation electrode 3. In this case, for example, the dielectric 4 need not be provided on the radiation electrode 3.

  The second embodiment will be described below. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the duplicate description of the common portions is omitted.

  In the second embodiment, as shown in the schematic perspective view of FIG. 6A and the schematic side view of FIG. 6B, the radiation electrode 3 is arranged on the surface side of the circuit board 2. The first loop radiating portion 27 and the second loop radiating portion 28 disposed on the back side of the circuit board 2 are separated. In the antenna structure 1 of the second embodiment, the configuration other than the radiation electrode 3 is the same as that of the first embodiment.

  The base end side end portion 28a (3a) of the second loop radiation portion 28 of the radiation electrode 3 is connected to the surface of the circuit board 2 and is connected to the ground on the back side of the circuit board through the through hole 16 formed in the circuit board 2. It is connected to the floating electrode 12. The second loop radiating portion 28 extends downward from the proximal end 28 a along the end surface of the circuit board 2 and then extends toward the top side. The extended distal end 28 b is the top of the circuit board 2. It is connected to the back surface portion of the end portion 2T on the side (radiation electrode forming side). In other words, the second loop radiating portion 28 has one end side 28b connected to the back surface portion of the top side end portion 2T of the circuit board 2 and swelled away from the circuit board back surface starting from the connection portion. It is connected to the circuit board 2 later and connected to the ground floating electrode 12.

  The first loop radiation portion 27 of the radiation electrode 3 has one end side 27 a connected to the surface portion of the top side end portion 2 T of the circuit board 2, and the top side end portion 28 b of the second loop radiation portion 28 and the circuit. It is connected via the substrate 2. The first loop radiating portion 27 is formed so as to rise from the connection portion with the second loop radiating portion 28 and extend along the surface of the circuit board 2 with a gap therebetween, and the extended tip portion 27b (3b) is an open end. It is made.

  Even in the case where the radiation electrode 3 including the first loop radiation portion 27 and the second loop radiation portion 28 as described above is provided, the radiation electrode 3 is connected to the feed line 24 in the same manner as in the first embodiment. The high frequency circuit 23 is connected to the power supply unit Q via the power supply means 25. In the second embodiment, when the signal is transmitted wirelessly from the radiation electrode 3 or when the radiation electrode 3 receives the signal from the outside and the radiation electrode 3 resonates, the radiation electrode 3 Similarly to the first embodiment, from the proximal end 28a (3a) of the second loop radiating portion 28 to the top end 28b of the second loop radiating portion 28 and the first loop radiating portion 27. Current flows through a loop-shaped path that passes through the top end portion 27a of the first loop radiation portion 27 and reaches the open end 27b (3b) of the first loop radiation portion 27.

  In the second embodiment, the proximal end 28a (3a) of the second loop radiation portion 28 of the radiation electrode 3 is connected to the ground floating electrode 12, and the ground floating electrode 12 is the same as in the first embodiment. In addition, since it is configured to be connected to the ground electrode 10 via the reactance addition circuit 14, the effects of widening the frequency band and improving the antenna efficiency can be obtained as in the first embodiment.

  In addition, the radiation electrode 3 shown in the first embodiment is produced by, for example, processing a single conductor plate into a loop shape, which is troublesome. In contrast, in the second embodiment, the radiation electrode 3 is separated into the first loop radiation portion 27 and the second loop radiation portion 28, so that the conductor plate need not be processed into a loop shape. The production of the radiation electrode 3 can be facilitated. Further, for example, when there is a design change only on one side of the first loop radiating portion 27 and the second loop radiating portion 28 of the radiation electrode 3, only the one with the design change is selected. Anyone who has made a design change and has not changed the design can be employed as it is, and the waste of parts due to the design change can be reduced.

  The third embodiment will be described below. The third embodiment relates to a communication device. The communication device of the third embodiment is a mobile phone, and the mobile phone is provided with one side of the antenna structure 1 shown in the first and second embodiments. There are various configurations of the mobile phone other than the antenna structure 1, and any configuration may be adopted here, and the description thereof is omitted. Further, since the description of the antenna structure 1 has been described above, the description thereof is omitted.

  In addition, this invention is not limited to the form of each 1st-3rd embodiment, Various embodiments can be taken. For example, in each of the first to third embodiments, an example in which the speaker component 20 is mounted in the antenna internal component mounting region of the circuit board 2 has been described. However, in addition to the speaker component 20 or the speaker Instead of the component 20, another component may be mounted in the antenna internal component mounting region of the circuit board 2.

  For example, as shown in the simplified side view of FIG. 7A, the infrared radiation portion 29 may be mounted in the antenna internal component mounting region of the circuit board 2. The infrared radiation unit 29 outputs infrared rays for performing infrared communication between portable telephones or between an electronic device such as a television and a portable telephone, for example. For example, the infrared ray output from the infrared radiation unit 29 may be radiated to the outside from the side surface of the mobile phone, but there may be a desire to radiate the infrared ray to the outside from the top side of the mobile phone. . In such a case, for example, in the antenna structure 1 of the first embodiment, as shown in the model diagram of FIG. You may provide the opening part 18 for making it radiate to. Similarly, in the antenna structure 1 of the second embodiment, as shown in the model diagram of FIG. 7C, the infrared radiation of the infrared radiation section 29 is radiated to the outside at the top portion of the radiation electrode 3. The opening 18 may be provided.

  Further, in each of the first to third embodiments, the base end side end portion 3a of the radiation electrode 3 (base end side end portion 28a of the second loop radiation portion 28) is connected to the ground floating electrode via the through hole 16. 12, for example, the proximal end 3 a of the radiation electrode 3 (the proximal end 28 a of the second loop radiation 28) is directly connected to the ground floating electrode 12. May be.

  Further, in each of the first to third embodiments, the ground electrode 10 is not formed on the projecting portion 2V of the circuit board 2, but the ground electrode 10 may be formed on the projecting portion 2V.

  Furthermore, an example in which the reactance adding circuit 14 is configured by a circuit pattern 26 is shown. The circuit pattern 26 is formed on the projecting portion 2V of the circuit board 2, but for example, in the circuit board 2 portion other than the projecting portion 2V, In addition to the formation region of the ground floating electrode 12, a non-ground region where the ground electrode 10 is not formed is formed in a portion connected to the formation region of the ground floating electrode 12, and the circuit pattern 26 (reactance) is formed in the non-ground region. An additional circuit 14) may be formed.

Further, as shown in the model diagram of FIG. 8 , at least a part of the radiation electrode portion 3 </ b> S that bulges downward from the circuit board 2 has a shape (a meander shape in the example of FIG. 8 ) having a detour portion 22. You may do it. In the example of FIG. 8, the shape having the bypass portion 22 is a meander shape, and a plurality of bypass portions are provided. However, for example, the shape having only one bypass portion 22 may be used. shape with is not limited to the example of FIG. 8.

  As described above, at least a part of the radiation electrode portion 3S swelled below the circuit board 2 has a bypass portion, so that the electrical length of the radiation electrode portion 3S is increased by the amount of the bypass portion. Can be long. This is equivalent to increasing the electrical length of the ground electrode 10 viewed from the radiation electrode 3 side. Therefore, the ground electrode 10 viewed from the radiation electrode 3 side is equivalent to the increase in the electrical length of the radiation electrode portion 3S. The reactance component of the reactance adding circuit 14 can be reduced. For example, when the reactance addition circuit 14 is formed in the chip component 13, the variation in the reactance component of the reactance addition circuit 14 of the chip component 13 increases as the reactance component increases. By reducing the reactance component of the reactance adding circuit 14, the variation in the reactance component of the reactance adding circuit 14 can be reduced, and the performance variation of the antenna structure 1 can be suppressed. Thereby, the reliability of the antenna structure 1 can be improved.

  Further, in each of the first and second embodiments, a direct power feeding method in which the power feeding means 25 is directly connected to the radiation electrode 3 is adopted as a method of connecting the radiation electrode 3 to the high frequency circuit 23 side. A capacitive power feeding method in which the electrode 3 is connected to the high-frequency circuit 11 side through a capacitor may be employed.

  Further, in each of the first and second embodiments, the radiation electrode 3 is formed with the slit 17 for controlling the resonance frequency. However, the resonance frequency set in the radiation electrode 3 can be easily set without providing the slit 17. If it can be provided, the slit 17 may be omitted.

  Furthermore, in the third embodiment, an example of a mobile phone has been given as an example of a communication device incorporating the antenna structure 1 of the first and second embodiments. However, the antenna structure of the present invention is other than a mobile phone. The same effects as described above can be obtained.

It is a figure for demonstrating the antenna structure of the example of 1st Embodiment. It is a top view of the circuit board which extracted the circuit board from the antenna structure of the example of the 1st embodiment, and was shown typically. It is the simplified sectional view showing an example of arrangement relation between the case of a communication machine, and the circuit board stored in this case. It is a figure for demonstrating the dimension of the antenna structure and experiment result which were used in the experiment which this inventor conducted. It is a model figure for demonstrating the other structural example of a reactance addition circuit. It is a figure for demonstrating the antenna structure of the example of 2nd Embodiment. It is a figure for demonstrating one example of a radiation electrode when an infrared radiation part is provided in the circuit board. It is a figure for demonstrating the other example of a radiation electrode. It is a figure for demonstrating the antenna structure described in patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna structure 2 Circuit board 3 Radiation electrode 4 Dielectric 10 Ground electrode 12 Ground floating electrode 13 Chip component 14 Reactance addition circuit 18 Opening 26 Circuit pattern 27 1st loop radiation part 28 2nd loop radiation part 29 Infrared radiation part

Claims (11)

A projecting portion having a circuit board on which electronic components are mounted and a radiation electrode for performing antenna operation, and having a narrowed width at one end side of the circuit board through stepped portions on both sides in the width direction. Projecting forward, and the radiation electrode is formed on the base end side thereof with a hole portion having openings between both ends in the width direction of the electrode surface, and the radiation electrode on both outer sides of the hole portion. Each end portion in the width direction is connected to the substrate surface on the wide side of the step portion of the circuit board, and the radiation electrode starts from the connection portion with the circuit board from the circuit board to the back side of the board. along through the gap to the overhang board table surface through a looped path successive folded bulges above the substrate surface while surrounding the tip of the overhang advances distally while bulge away downwards It is formed as, the radiation collector The previous end of the folding direction is forms an open end are arranged to form a capacitor via a circuit board and spacing, said the base end side of the opening of the radiation electrode in the loop path of the radiation electrode The hole portion is arranged at a position facing the substrate surface of the protruding portion of the circuit board, and the circuit component is mounted on the substrate surface portion of the protruding portion facing the hole portion , the circuit in board is provided ground electrode, also, the circuit board on either side position in the width direction of the substrate, each independently of with floating potential from the ground is disposed through the ground electrode and the distance ground floating electrodes are provided, the respective ground floating electrodes are respectively connected to the ground electrode via individual reactance adding circuit having a reactance component, the base end side of the hole portion of the radiation electrode Respective ends of the outer radiation electrode is characterized in that it is directly or indirectly connected to the ground electrode via a separate ground floating are electrodes connected the ground floating electrode and reactance additional circuit to each other Antenna structure.   2. The antenna structure according to claim 1, wherein the reactance adding circuit includes a circuit pattern formed on a circuit board.   Instead of the reactance adding circuit formed of the circuit pattern formed on the circuit board or in addition to the reactance adding circuit formed of the circuit pattern, the circuit board includes a gap between the ground electrode and the ground floating electrode arranged adjacent to each other. The chip component is arranged in a manner straddling the chip, a reactance addition circuit is formed in the chip component, and the ground electrode and the ground floating electrode are connected via the reactance addition circuit formed in the chip component. The antenna structure according to claim 2. Instead of a continuous loop-shaped radiation electrode surrounding the end of the circuit board, a first loop radiation section disposed on the front surface side of the circuit board and a second loop radiation disposed on the back surface side of the circuit board parts and are separated radiation electrode provided on the second loop radiating portion, beyond end is connected with one end of the first loop radiating portion through the end portion of the circuit board, the second The base end side of the loop radiating portion is a stepped portion in which the protruding portion of the circuit board bulges after bulging in a direction away from the back surface of the circuit board starting from the connecting portion with the one end side of the first loop radiating portion. The ends of the radiation electrodes connected to the substrate surface on the wide side and on the outer sides of the holes provided on the base end side of the second loop radiation portion are directly or indirectly separated from each other. It is configured to be connected to the ground floating electrode, and the first loop radiating portion is 2. The device according to claim 1, wherein the second loop radiating portion is formed so as to rise from a connecting portion with the second loop radiating portion and extend along the surface of the circuit board with a space therebetween, and an extended tip side thereof is an open end. The antenna structure according to claim 2 or claim 3. Radiation electrode formation side of the circuit board surrounded by the loop of the radiation electrode, any one of claims 1 to 4, characterized in that it forms an antenna internal component mounting region where components are mounted antenna structure according to. 6. The antenna structure according to claim 5, wherein a circuit pattern constituting a reactance addition circuit is formed in an antenna internal component mounting region of the circuit board. The antenna structure according to any one of claims 1 to 6 , wherein at least a part of the radiating electrode portion that bulges downward from the circuit board has a shape having a detour portion. . The antenna structure according to any one of claims 1 to 7 , wherein a dielectric is provided in at least a part of a region where the radiation electrode and the circuit board face each other. 9. The antenna structure according to claim 8, wherein the dielectric is made of a mixed dielectric material obtained by adding a material having a dielectric constant higher than that of the thermoplastic resin to the thermoplastic resin. An opening for radiating infrared rays output from the infrared radiation portion provided on the end portion side of the circuit board on the radiation electrode formation side to the radiation electrode top portion on the radiation electrode formation side of the circuit board to the outside antenna structure according to any one of claims 1 to 9, characterized in that is provided. A communication apparatus, comprising the antenna structure according to any one of claims 1 to 10 .

Images