JP2011193052A - Antenna device and wireless communication apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small antenna device capable of freely setting or selecting a resonance frequency of an antenna element, and to provide a wireless communication apparatus using the same. <P>SOLUTION: The antenna device includes: an antenna element having a feed point; a capacitor hat provided separately from an end side different from an end where the feed point of the antenna element is located; and a switching circuit provided between the antenna element and the capacitor hat to switch a connection state between the antenna element and the capacitor hat. The resonance frequencies is switched by switching the connection state between the antenna element and the capacitor hat in the switching circuit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antenna device and a wireless communication device using the antenna device.

  Conventionally, in order to obtain a plurality of resonance frequencies, there is an antenna device including a plurality of antenna elements (see, for example, Patent Document 1).

  In addition, there is an antenna device that uses a chip antenna and a pattern antenna, switches the chip antenna and the pattern antenna, and tunes the pattern antenna to the high frequency side of the required frequency band, tunes the chip antenna to the low frequency side. (For example, refer to Patent Document 2).

  As described above, conventionally, in order to obtain a plurality of resonance frequencies, an antenna device including a plurality of antenna elements having different resonance frequencies or an antenna device including a chip antenna and a pattern antenna having different tuning bands has been used. .

  By the way, in an environment where communication in a plurality of frequency bands can be performed, instead of increasing the number of antenna elements, chip antennas, pattern antennas, etc. as in the past, the antenna user can freely set the resonance frequency of the antenna element or If it can be selected, both miniaturization and convenience can be achieved.

  However, in the conventional antenna device, the user of the antenna device cannot freely set or select the resonance frequency of the antenna element. For this reason, the conventional antenna device includes a plurality of antenna elements, chip antennas, pattern antennas, or the like corresponding to the number of frequency bands to be used, and has been increased in size.

  Therefore, an object of the present invention is to provide a small antenna device that can freely set or select a resonance frequency of an antenna element, and a wireless communication device using the antenna device.

  An antenna device according to an aspect of an embodiment of the present invention includes an antenna element having a feeding point and a capacitor hat that is spaced apart on an end side different from the end side on which the feeding point of the antenna element is located. And a switching circuit disposed between the antenna element and the capacitor hat and switching a connection state between the antenna element and the capacitor hat, wherein the switching circuit connects the antenna element and the capacitor hat. The resonance frequency is switched by switching the state.

  In addition, one or a plurality of sets of connection switching circuits and capacitor hats different from the capacitor hat and the connection switching circuit may be connected to the capacitor hat.

  The antenna element may be an inverted L type or an inverted F type.

  The antenna element may have a first antenna part and a second antenna part having different resonance frequencies.

  A wireless communication device according to an aspect of the present invention includes any one of the antenna devices described above.

  It is possible to provide a small antenna device that can freely set or select the resonance frequency of the antenna element, and a wireless communication device using the antenna device.

1 is a diagram illustrating an antenna device according to a first embodiment. 3 is a diagram illustrating a circuit configuration of a switching circuit 50 of the antenna device 100 according to Embodiment 1. FIG. 3 is an enlarged perspective view showing a mounting state of a switching circuit 50 of the antenna device 100 according to Embodiment 1. FIG. 1 is a block diagram illustrating a configuration of a wireless communication device including an antenna device 100 according to a first embodiment. It is a figure which shows the characteristic of the S11 parameter with respect to the frequency of the antenna device 100 of Embodiment 1. FIG. It is a figure which shows the modification of the antenna device 100 of Embodiment 1. FIG. It is a figure which shows the antenna apparatus 200 of Embodiment 2. FIG. 6 is a flowchart illustrating switching processing of switching circuits 251 to 254 in the antenna device 200 according to the second embodiment. It is a figure which shows the characteristic of the S11 parameter with respect to the frequency of the antenna device 200 of Embodiment 2. FIG. It is a figure which shows the antenna apparatus 300 of Embodiment 3. FIG. It is a figure which shows the frequency characteristic of the S11 parameter of the antenna device 300 of Embodiment 3.

  Hereinafter, an embodiment in which an antenna device of the present invention and a wireless communication device using the antenna device are applied will be described.

<Embodiment 1>
FIG. 1 is a diagram illustrating the antenna device according to the first embodiment.

  Here, a mode in which antenna device 100 of Embodiment 1 is mounted on a wireless communication device will be described.

  The antenna device 100 according to the first embodiment includes an antenna element 10, a ground element 20, a capacitor hat 30, a PCB (Printed Circuit Board) substrate 40, and a switching circuit 50. Here, in describing the structure of each component, the XY coordinates shown in FIG. 1 are used.

  The antenna element 10 is an inverted L-type antenna element, and is connected to the corner portion 21 of the ground element 20 at the connection portion 11.

  The antenna element 10 extends from the connection portion 11 along the long side 41A of the PCB substrate 40 in a direction away from the ground element 20 (the + Y direction in FIG. 1), and is a bent portion near the corner portion 43A of the PCB substrate 40. 12 is bent at a right angle (perpendicular to the + X direction in FIG. 1) and extends to the end portion 13 along the short side 42A of the PCB substrate 40. The end 13 is located in the vicinity of the corner 43B of the PCB substrate 40.

  The antenna element 10 also has a feed line 14 that branches at a right angle from between the connection portion 11 and the bent portion 12. The feed line 14 is bent at a right angle to the direction of the ground element 20 (the −Y direction in FIG. 1) by the bent portion 15 and has an end portion that becomes the feed portion 16.

  Such an antenna element 10 is formed, for example, by patterning a copper foil on the surface of the PCB substrate 40. Further, the end portion 13 is an end portion different from the end portion side that becomes the power feeding portion 16 of the inverted L-type antenna element 10.

  The ground element 20 is patterned in a square shape on the surface of the PCB substrate 40, and is formed of, for example, copper foil. The ground element 20 has corner portions 21, 22, 23, and 24. The corner portion 21 is connected to the connection portion 11 of the antenna element 10, and the corner portions 23 and 24 are located in the vicinity of the corner portions 43 </ b> C and 43 </ b> D of the PCB substrate 40, respectively.

  The ground element 20 is grounded, for example, with a portion of the antenna element 10 that faces the power feeding unit 16 as a ground point 25.

  Power feeding to the antenna element 10 and grounding of the ground element 20 are realized, for example, by connecting a core wire of a coaxial cable (not shown) to the power feeding unit 16 and connecting a shield wire of the coaxial cable to the ground point 25. Is done.

  The capacitor hat 30 is a pad that is formed in the vicinity of the end 13 of the antenna element 10 on the surface of the PCB substrate 40. The capacitor hat 30 can be formed of, for example, copper foil, and functions as an element such as a capacitance formed with a distributed constant with respect to a high frequency component.

  The capacitor hat 30 is connected to the end 13 of the antenna element 10 via the switching circuit 50. The switching circuit 50 is a circuit that switches an electrical connection state (connected or disconnected) between the capacitor hat 30 and the antenna element 10. The connection state of the switching circuit 50 is controlled by the controller 120 of the wireless communication device described later. The switching circuit 50 and the controller 120 will be described later.

  The antenna element 10, the ground element 20, and the capacitor hat 30 can be simultaneously formed by patterning a copper foil formed on the surface of the PCB substrate 40.

  The PCB substrate 40 may be, for example, an FR4 substrate obtained by impregnating a glass fiber cloth with an epoxy resin and performing a thermosetting process. The PCB substrate 40 is a rectangular substrate having a long side 41A, 41B, short sides 42A, 42B, and corners 43A to 43D in plan view.

  In the antenna device 100 of the first embodiment, the resonance frequency f1 when the antenna element 10 and the capacitor hat 30 are not connected by the switching circuit 50, and the antenna element 10 and the capacitor hat 30 by the switching circuit 50 are F1> f2 holds between the resonance frequency f2 and the resonance frequency f2. That is, when the capacitor hat 30 is connected to the antenna element 10, the resonance frequency shifts to the low frequency side.

  Therefore, the antenna device 100 can select two resonance frequencies by switching the connection state between the antenna element 10 and the capacitor hat 30 by the switching circuit 50.

  As an example, when the dimensions of the antenna device 100 are given, the length from the connecting portion 11 to the bent portion 12 of the antenna element 10 is 5 mm, the length from the bent portion 12 to the end portion 13 is 22 mm, and the antenna element 10 The line width is 1 mm. The ground element 20 has a length from the corner portion 21 to the corner portion 22 of 22 mm and a length from the corner portion 22 to the corner portion 23 of 22 mm.

  Next, the switching circuit 50 will be described.

  FIG. 2 is a diagram illustrating a circuit configuration of the switching circuit 50 of the antenna device 100 according to the first embodiment.

  The switching circuit 50 includes a capacitor 51, a PIN (p-intrinsic-n) diode 52, a capacitor 53, a high frequency choke coil (RFC) 54, a resistor 55, and a high frequency choke coil (RFC) 56.

  The capacitor 51 has one end connected to the end 13 of the antenna element 10 and the other end connected to the input end of the PIN diode 52.

  The output terminal of the PIN diode 52 is connected to the capacitor hat 30 via the capacitor 53.

  The PIN diode 52 has an input terminal connected to the controller 120 via a high frequency choke coil 54 and an output terminal grounded via a resistor 55 and a high frequency choke coil 56. The controller 120 controls supply of a DC voltage for controlling on / off of the PIN diode 52. The high-frequency choke coil 56 is grounded by being connected to the ground element 20 (see FIG. 1) by, for example, wiring or the like (not shown).

  In the switching circuit 50 having such a circuit configuration, when a predetermined DC voltage is applied from the controller 120 to the input terminal of the PIN diode 52, the PIN diode 52 is turned on, and the antenna element 10 and the capacitor hat 30 are in high frequency. Connected. Further, when the DC voltage applied from the controller 120 to the input terminal of the PIN diode 52 is cut off, the PIN diode 52 is turned off, and the antenna element 10 and the capacitor hat 30 are cut off at a high frequency to be disconnected. The controller 120 controls on / off of the PIN diode 52 of the switching circuit 50.

  Hereinafter, switching the switching circuit 50 to a state where the antenna element 10 and the capacitor hat 30 are connected is referred to as turning on the switching circuit 50, and the antenna element 10 and the capacitor hat 30 are not connected. The switching of the switching circuit 50 is referred to as turning off the switching circuit 50.

  Next, the mounting state of the switching circuit 50 will be described.

  FIG. 3 is an enlarged perspective view showing a mounting state of the switching circuit 50 of the antenna device 100 according to the first embodiment.

  The capacitor 51, the PIN diode 52, the capacitor 53, the high frequency choke coil 54, the resistor 55, and the high frequency choke coil 56 included in the switching circuit 50 are connected through pads 57 and 58 as shown in FIG. .

  As the capacitor 51, PIN diode 52, capacitor 53, high-frequency choke coil 54, resistor 55, and high-frequency choke coil 56, chip-type elements may be used as shown in FIG. The pads 57 and 58 can be formed of, for example, a copper foil, and can be formed together with the antenna element 10 and the ground element 20.

  The high frequency choke coil 56 is connected to the ground element 20.

  Next, the wireless communication apparatus according to the first embodiment including the controller 120 will be described.

  FIG. 4 is a block diagram showing a configuration of a wireless communication apparatus including antenna apparatus 100 according to the first embodiment.

  The wireless communication device 110 is, for example, a copy machine, a FAX machine, a printer, or a multifunction machine having these functions, and is configured to perform communication in a plurality of frequency bands.

  The wireless communication device 110 includes a CPU (Central Processing Unit) 111, a RAM (Random Access Memory) 112, a ROM (Read Only Memory) 113, a GUI (Graphic User Interface) operation unit 114, a wireless control unit 115, The controller 120 and the antenna device 100 are included.

  The CPU 111, RAM 112, ROM 113, GUI operation unit 114, and wireless control unit 115 are connected by a bus 116. Further, the controller 120 shown in FIG. 2 is the controller 120 shown in FIG.

  The CPU 111 executes a program stored in the ROM 113 and performs processing for switching the frequency band of the antenna device 100.

  The RAM 112 is a memory that develops a program executed by the CPU 111 and serves as a work place.

  The ROM 113 is a non-volatile memory that stores a program executed by the CPU 111.

  The GUI operation unit 114 is, for example, a display operation unit in which a coordinate input device (typically a touch panel) and a display device (typically a liquid crystal panel) are overlapped, and operation buttons necessary for operation of the wireless communication device 110. Etc., and accepts user operation input. User operation input is transmitted to the CPU 111.

  The wireless control unit 115 performs a process of switching the frequency used by the wireless communication apparatus 110 according to the content of the operation input input to the GUI operation unit 114. For example, as described above, when the antenna device 100 has the two resonance frequencies f1 and f2, the resonance frequencies f1 and f2 are selected according to the content of the operation input to the GUI operation unit 114.

  The controller 120 switches the connection state of the switching circuit 50 of the antenna device 100 according to the selection result of the radio control unit 115. When the resonance frequency f1 is selected by the wireless control unit 115, the switching circuit 50 is turned off (not connected). On the contrary, when the resonance frequency f2 is selected by the wireless control unit 115, the switching circuit 50 is turned on (connected state).

  Here, a mode in which the wireless communication device 110 switches the resonance frequency of the antenna device 100 using a computer including the CPU 111, the RAM 112, the ROM 113, the GUI operation unit 114, the wireless control unit 115, and the controller 120 will be described. Switching of the resonance frequency of 100 is not limited to that realized by a computer. For example, using an ASIC (Application Specific Integrated Circuit) that is an integrated circuit designed and manufactured for a specific application, the resonance frequency of the antenna device 100 is switched in accordance with an operation input input to the GUI operation unit 114. May be.

  Next, frequency characteristics will be described using S parameters of antenna apparatus 100 of the first embodiment.

  5A and 5B are diagrams illustrating the characteristics of the S11 parameter with respect to the frequency of the antenna device 100 according to the first embodiment. FIG. 5A is a characteristic diagram in a state where the capacitor hat 30 is not connected, and FIG. It is a characteristic view of the connected state. 5A and 5B are S11 parameters measured by the power feeding unit 16.

  In a state where the switching circuit 50 does not connect the antenna element 10 and the capacitor hat 30, as shown in FIG. 5A, the value of the S11 parameter is a minimum value (about −− when the frequency is about 5.2 GHz. 18 dB). Thus, it can be seen that the resonance frequency f1 when the antenna element 10 and the capacitor hat 30 are not connected by the switching circuit 50 is about 5.2 GHz.

  Next, in a state where the switching circuit 50 connects the antenna element 10 and the capacitor hat 30, as shown in FIG. 5B, the value of the S11 parameter is a minimum value when the frequency is about 4.8 GHz. (About -18 dB). Thereby, it can be seen that the resonance frequency f2 when the antenna element 10 and the capacitor hat 30 are connected by the switching circuit 50 is about 4.8 GHz.

  From this result, it is understood that the resonance frequency of the antenna device 100 can be switched by switching the connection state between the antenna element 10 and the capacitor hat 30 by the switching circuit 50.

  As described above, according to the first embodiment, it is possible to provide a small antenna device 100 in which the resonance frequency of the antenna element 10 can be freely set or selected, and a wireless communication device 110 using the same.

  Here, an example of a usage mode when the wireless communication device 110 including the antenna device 100 of the first embodiment is, for example, a multifunction device will be described.

  For example, when a user of a mobile phone A (not shown) wants to print data stored in his / her mobile phone A, the user can use his / her mobile phone A with the GUI operation unit 114 of the multifunction peripheral as the wireless communication device 110. Frequency band can be selected, data can be transmitted from the mobile phone A to the multifunction peripheral by wireless communication, and printing processing can be performed. Further, when another user wants to transmit data stored in his / her mobile phone B (not shown) having a different frequency from that of the mobile phone A by FAX, the user can use his / her mobile phone B with the GUI operation unit 114. Frequency band can be selected, data can be transmitted from the cellular phone B to the multi-function device by wireless communication, and FAX transmission processing can be performed. The application of the wireless communication device 110 described here is merely an example, but the wireless communication device 110 including the antenna device 100 according to Embodiment 1 can be used by an antenna user in an environment where communication in a plurality of frequency bands can be performed. Since the resonance frequency of the element can be set or selected freely, it is very convenient. Moreover, since it is not necessary to use a plurality of antennas corresponding to each resonance frequency as in the prior art, a small antenna device 100 can be provided.

  In addition, although the form using the switching circuit 50 as shown in FIG. 2 was demonstrated above, the circuit structure of the switching circuit 50 is not limited to what was shown in FIG. Further, instead of the PIN diode 52, for example, a high-frequency FET (Field effect transistor) may be used.

  Further, the antenna device 100 according to the first embodiment can be modified as follows, for example.

  FIGS. 6A to 6D are diagrams illustrating modifications of the antenna device 100 according to the first embodiment. Here, the same components as those of the antenna device 100 shown in FIG. 1 are denoted by the same reference numerals, description thereof will be omitted, and differences will be described. Further, since the difference is mainly the arrangement of the constituent elements, the different constituent elements such as the arrangement are the corresponding constituent elements of the antenna device 100 of the first embodiment in FIGS. 6 (A) to (D). The reference numerals with alphabets A, B, C, and D are attached.

  As shown in FIG. 6A, in the antenna device 100A of the first modified example, the antenna element 10A is formed in an inverted F type. The antenna element 10A is different from the antenna device 100 according to the first embodiment in that the feed line 14A is formed in an inverted F shape by extending in the direction of the ground element 20 from between the bent portion 12 and the end portion 13. . The power feeding unit 16 is the tip of the power feeding line 14A, and the position thereof is the same as that of the power feeding unit 16 of the antenna device 100 according to the first embodiment.

  Also in the first modification example, similarly to the antenna device 100 of the first embodiment, the small antenna device 100A capable of freely setting or selecting the resonance frequency of the antenna element 10A, and the radio using the same A communication device 110 can be provided.

  Next, a second modification, a third modification, and a fourth modification in which the position of the capacitor hat 30 is changed will be described with reference to FIGS.

  As shown in FIG. 6B, in the antenna device 100B of the second modified example, the capacitor hat 30B is separated from the ground element 20 at the end 13 of the antenna element 10 (the + Y direction in FIG. 6B). ) Separated from each other. Therefore, the switching circuit 50B is disposed so as to connect between the capacitor hat 30B and the end 13.

  Since capacitor hat 30B is spaced away from ground element 20 (the + Y direction in FIG. 6B), substrate 40B is made slightly larger than substrate 40 of antenna device 100 of the first embodiment. Although it is necessary, the capacitance of the capacitor hat 30B is made larger than the capacitance of the capacitor hat 30 of the first embodiment, so that it can be accommodated in the same size as the substrate 40 of the antenna device 100 of the first embodiment. It is also possible.

  As shown in FIG. 6C, in the antenna device 100C of the third modified example, the capacitor hat 30C is configured to extend the end 13 at the end 13 of the antenna element 10 (+ X in FIG. 6C). In the direction). For this reason, the switching circuit 50 </ b> C is disposed so as to connect the capacitor hat 30 </ b> C and the end portion 13.

  Since capacitor hat 30C is spaced apart in the direction of extending end 13 (the + X direction in FIG. 6C), substrate 40C is slightly larger than substrate 40 of antenna device 100 of the first embodiment. Although it is necessary to make the capacitance of the capacitor hat 30C larger than the capacitance of the capacitor hat 30 of the first embodiment, it is made the same size as the substrate 40 of the antenna device 100 of the first embodiment. It can also be accommodated.

  As shown in FIG. 6D, in the antenna device 100D of the fourth modified example, the capacitor hat 30D is obliquely separated from the end 13 and the ground element 20 at the end 13 of the antenna element 10 (FIG. D) in the direction represented by Y = X). For this reason, the switching circuit 50 </ b> D is disposed so as to connect between the capacitor hat 30 </ b> D and the end portion 13.

  In addition, since the capacitor hat 30D is spaced apart from the end portion 13 and the ground element 20 in an oblique direction (a direction represented by Y = X in FIG. 6D), the substrate 40D is the first embodiment. The antenna device 100 of the first embodiment needs to be slightly larger than the substrate 40, but the capacitance of the capacitor hat 30D is made larger than the capacitance of the capacitor hat 30 of the first embodiment, whereby the antenna of the first embodiment. It is also possible to fit the same size as the substrate 40 of the apparatus 100.

  Also in the antenna devices 100B to 100D of the second to fourth modifications described above, the resonance frequencies of the antenna elements 10B to 10D can be freely set or selected as in the antenna device 100 of the first embodiment. The small antenna devices 100B to 100D and the wireless communication device 110 using the antenna devices 100B to 100D can be provided.

<Embodiment 2>
The antenna device of the second embodiment is different from the antenna device 100 of the first embodiment in that it includes a plurality of sets of capacitor hats and switching circuits. Since other configurations are the same as those of the antenna device 100 according to the first embodiment, the same components are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 7 is a diagram illustrating the antenna device 200 according to the second embodiment.

  The antenna device 200 according to the second embodiment includes four sets of capacitor hats 231 to 234 and switching circuits 251 to 254 in the vicinity of the end 13 of the antenna element 10.

  Among these, the capacitor hat 231 and the switching circuit 251 are the same as the capacitor hat 30 and the switching circuit 50 of the antenna device 100 of the first embodiment. Capacitor hats 231 to 234 are all the same as capacitor hat 30 of antenna apparatus 100 of the first embodiment, and switching circuits 251 to 254 are all the same as switching circuit 50 of antenna apparatus 100 of the first embodiment. It is the same circuit.

  The capacitor hat 232 is disposed at a position further away from the capacitor hat 231 in the direction of the ground element 20 (−Y direction in FIG. 7). The capacitor hat 232 is connected to the capacitor hat 231 by the switching circuit 252. The capacitor hat 232 is connected to the end portion 13 by turning on the switching circuit 252 while the end portion 13 and the capacitor hat 231 are connected with the switching circuit 251 turned on.

  The capacitor hat 233 is disposed at a position spaced from the capacitor hat 231 in the direction of the bent portion 12 (−X direction in FIG. 7). The capacitor hat 233 is connected to the capacitor hat 231 by the switching circuit 253. The capacitor hat 233 is connected to the end portion 13 by turning on the switching circuit 253 while the end portion 13 and the capacitor hat 231 are connected with the switching circuit 251 turned on.

  The capacitor hat 234 is disposed at a position further away from the capacitor hat 233 in the direction of the ground element 20 (−Y direction in FIG. 7). The capacitor hat 234 is connected to the capacitor hat 233 by the switching circuit 254. The capacitor hat 234 is connected to the end portion 13 by turning on the switching circuit 254 while the end portion 13 and the capacitor hats 231 and 233 are connected with the switching circuit 251 and the switching circuit 253 turned on.

  When the above four capacitor hats 231 to 234 are connected in a switching manner, when no capacitor hat is connected to the antenna element 10, all the switching circuits 251 to 254 are turned off. In this case, the resonance frequency of the antenna device 200 is set to f1.

  When one capacitor hat is connected to the antenna element 10, the switching circuit 251 is turned on and the capacitor hat 231 is connected to the antenna element 10. In this case, the resonance frequency of the antenna device 200 is set to f2.

  When two capacitor hats are connected to the antenna element 10, the switching circuits 251 and 252 are turned on and the capacitor hats 231 and 232 are connected to the antenna element 10. In this case, the resonance frequency of the antenna device 200 is set to f3.

  When three capacitor hats are connected to the antenna element 10, the switching circuits 251, 252, and 253 are turned on, and the capacitor hats 231, 232, and 233 are connected to the antenna element 10. In this case, the resonance frequency of the antenna device 200 is assumed to be f4.

  When four capacitor hats are connected to the antenna element 10, all the switching circuits 251 to 254 are turned on, and all the capacitor hats 231 to 234 are connected to the antenna element 10. In this case, the resonance frequency of the antenna device 200 is set to f5.

  Note that the controller 120 switches on / off of the switching circuits 251 to 254.

  Further, in order to switch each of the switching circuits 251 to 254 in the above-described pattern, for example, an identifier is allocated to the switching circuits 251 to 254, and the switching circuits 251 to 254 are turned on / off by using a 3-bit control signal. Can be controlled. In this case, the identifier may be stored in the ROM 113 (see FIG. 4) in the switching circuits 251 to 254.

  Next, the switching process of the switching circuits 251 to 254 will be described with reference to FIG.

  FIG. 8 is a flowchart showing switching processing of switching circuits 251 to 254 in antenna apparatus 200 of the second embodiment. This switching process is a process executed by the CPU 111 (see FIG. 4) based on an operation input to the GUI operation unit 114 (see FIG. 4).

  When the process starts, the CPU 111 determines whether or not the input to the GUI operation unit 114 is an input for selecting the resonance frequency f1 (step S1).

  If the CPU 111 determines that the resonance frequency f1 is selected in step S1, the controller 111 sends a signal for selecting the resonance frequency f1 to the wireless control device 115 (a signal for turning off all the switching circuits 251 to 254). It transmits to 120 (step S2). As a result, all of the switching circuits 251 to 254 are turned off by the controller 120, and the resonance frequency is set to f1.

  If the CPU 111 determines in step S1 that the selected resonance frequency is not f1, the CPU 111 determines whether or not the input to the GUI operation unit 114 is an input for selecting the resonance frequency f2 (step S3).

  When the CPU 111 determines that the resonance frequency f2 is selected in step S3, the CPU 111 transmits a signal for selecting the resonance frequency f2 (a signal for turning on the switching circuit 251) to the controller 120 to the wireless control device 115. (Step S4). As a result, the switching circuit 251 is turned on by the controller 120, and the resonance frequency is set to f2.

  If the CPU 111 determines in step S3 that the selected resonance frequency is not f2, the CPU 111 determines whether or not the input to the GUI operation unit 114 is an input for selecting the resonance frequency f3 (step S5).

  When the CPU 111 determines that the resonance frequency f3 is selected in step S5, the CPU 111 sends a signal for selecting the resonance frequency f3 to the wireless control device 115 (a signal for turning on the switching circuits 251 and 252) to the controller 120. Transmit (step S6). As a result, the switching circuits 251 and 252 are turned on by the controller 120, and the resonance frequency is set to f3.

  If the CPU 111 determines in step S5 that the selected resonance frequency is not f3, the CPU 111 determines whether or not the input to the GUI operation unit 114 is an input for selecting the resonance frequency f4 (step S7).

  If the CPU 111 determines that the resonance frequency f4 is selected in step S7, the CPU 111 sends a signal for selecting the resonance frequency f4 to the wireless control device 115 (a signal for turning on the switching circuits 251, 252, and 253). The data is transmitted to the controller 120 (step S8). As a result, the switching circuit 251, 252, and 253 are turned on by the controller 120, and the resonance frequency is set to f4.

  If the CPU 111 determines in step S7 that the selected resonance frequency is not f4, the CPU 111 determines whether or not the input to the GUI operation unit 114 is an input for selecting the resonance frequency f5 (step S9).

  If the CPU 111 determines that the resonance frequency f5 is selected in step S9, the controller 111 sends a signal for selecting the resonance frequency f5 (a signal for turning on all of the switching circuits 251 to 254) to the radio control device 115. It transmits to 120 (step S10). As a result, all of the switching circuits 251 to 254 are turned on by the controller 120, and the resonance frequency is set to f5.

  If CPU 111 determines in step S9 that the selected resonance frequency is not f5, CPU 111 returns the flow to step S1.

  As described above, according to the antenna device 200 of the second embodiment, the user can select five resonance frequencies by including the four capacitor hats 231 to 234.

  Next, frequency characteristics will be described using S parameters of antenna apparatus 200 of the second embodiment.

  FIG. 9 is a diagram illustrating the characteristics of the S11 parameter with respect to the frequency of the antenna device 200 according to the second embodiment. The S11 parameter shown in FIG. 9 is measured by the power feeding unit 16.

  The frequency characteristics of the five S11 parameters shown in FIG. 9 are obtained by switching the connection state of the capacitor hats 231 to 234 as described above.

  As shown in FIG. 9, it can be seen that the resonance frequencies f1 to f5 are gradually shifted from the high frequency side to the low frequency side, and the value of the S11 parameter is also gradually improved. The resonance frequencies f1 to f5 are shifted from the high frequency side to the low frequency side because the capacitance of the antenna element 10 is increased as the number of capacitor hats connected to the antenna element 10 is increased stepwise. It is done. In addition, the value of the S11 parameter gradually decreased and the reflected power decreased because the capacitor hat gradually increased and the impedance matching gradually changed.

  As a result, the resonance frequency f1 is about 5.2 GHz, the value of the S11 parameter at that time is about −4.5 dB, the resonance frequency f2 is about 4.8 GHz, and the value of the S11 parameter at that time is about −6. 0 dB, the resonance frequency f3 is about 4.6 GHz, the value of the S11 parameter at that time is about −6.5 dB, the resonance frequency f4 is about 4.4 GHz, and the value of the S11 parameter at that time is about −7.5 dB, The resonance frequency f5 was about 4.2 GHz, and the value of the S11 parameter at that time was about −9 dB.

  From this result, it is understood that the resonance frequency of the antenna device 200 can be switched by switching the connection state between the antenna element 10 and the capacitor hat 30 by the switching circuit 50.

  As described above, according to the second embodiment, the small antenna device 200 capable of freely selecting various resonance frequencies by adjusting the capacitances of the capacitor hats 231 to 234, and the same are used. A wireless communication device 110 (see FIG. 4) can be provided.

  In the second embodiment, an example including four capacitor hats 231 to 234 has been described as an example. However, the number of capacitor hats may be any number, and the arrangement thereof may be arbitrarily set. .

<Embodiment 3>
The antenna device 300 of the third embodiment is implemented in that the antenna element is branched, includes a first antenna unit and a second antenna unit having different resonance frequencies, and a capacitor hat is disposed at each end. This is different from the antenna device 100 of the first embodiment.

  FIG. 10 shows an antenna device 300 according to the third embodiment.

  The antenna device 300 includes an antenna element 310, a ground element 320, capacitor hats 330A and 330B, and switching circuits 350A and 350B.

  The antenna element 310, the ground element 320, and the capacitor hats 330A and 330B are formed on the surface of the PCB substrate 340. The antenna element 310, the ground element 320, and the capacitor hats 330A and 330B can be formed, for example, by patterning a copper foil formed on the surface of the PCB substrate 340.

  Capacitor hats 330A and 330B are basically the same as capacitor hat 30 of antenna apparatus 100 of the first embodiment.

  Switching circuits 350A and 350B are the same as switching circuit 50 of antenna apparatus 100 of the first embodiment.

  The PCB substrate 340 may be, for example, an FR4 substrate in which a glass fiber cloth is impregnated with an epoxy resin and subjected to a thermosetting process. The PCB substrate 340 is a rectangular substrate in plan view having short sides 341A and 41B, long sides 342A and 342B, and corners 343A to 343D. The PCB substrate 340 has a relationship between the long side and the short side with the PCB substrate 40 of the first embodiment.

  The antenna element 310 is connected to the ground element 320 at the connecting portion 311, extends in a direction away from the ground element 320 (+ Y direction in FIG. 10), and is perpendicular to the bent portion 312A (+ X direction in FIG. 10). Further, the bent portion 312B is bent at a right angle in a direction away from the ground element 320 (perpendicular to the + Y direction in FIG. 1), and extends to the branch portion 312C.

  The antenna element 310 is branched to the left and right by a branching section 312C, the first antenna section 310A is branched to the left side of the branching section 312C, and the second antenna section 310B is branched to the right side of the branching section 312C.

  The first antenna portion 310A extends to the end portion 313A. The end portion 313A is located in the vicinity of the corner portion 343A of the PCB substrate 340. The length from the branch part 312C to the end part 313A of the first antenna part 310A is set according to the first resonance frequency f11.

  The second antenna portion 310B extends to the end portion 313B. The end portion 313B is located in the vicinity of the corner portion 343B of the PCB substrate 340. The length from the branch part 312C to the end part 313B of the second antenna part 310B is set according to the second resonance frequency f12.

  The capacitor hat 330A is formed in the vicinity of the end 313A of the first antenna unit 310A, and the capacitor hat 330B is formed in the vicinity of the end 313B of the second antenna unit 310B.

  The ground element 320 has corner portions 321, 322, 323, and 324. Of the corner portions 321 to 324, the corner portions 323 and 324 are positioned in the vicinity of the corner portions 343 </ b> C and 343 </ b> D of the PCB substrate 340, respectively.

  The ground element 320 is grounded, for example, with a portion of the antenna element 310 facing the power feeding unit 316 as a ground point 325.

  Capacitor hat 330A is connected to end 313A of first antenna unit 310A via switching circuit 350A. The switching circuit 350A is a circuit that switches an electrical connection state (connected or not connected) between the capacitor hat 330A and the first antenna unit 310A. The connection state of the switching circuit 350A is controlled by the controller 120 of the wireless communication device.

  Capacitor hat 330B is connected to end portion 313B of second antenna portion 310B through switching circuit 350B. The switching circuit 350B is a circuit that switches an electrical connection state (connected or disconnected) between the capacitor hat 330B and the second antenna unit 310B. The connection state of the switching circuit 350B is controlled by the controller 120 of the wireless communication device.

  As described above, the antenna device 300 according to the third embodiment including the first antenna unit 310A and the second antenna unit 310B having the line lengths corresponding to the two resonance frequencies f11 and f12 includes the switching circuits 350A and 350B in the controller 120, respectively. By switching, the two resonance frequencies f11 and f12 can be shifted to the low frequency side.

  As an example, when the dimensions of the antenna device 300 are given, the length from the end portion 313A to the branch portion 312C is 22 mm, the length from the branch portion 312C to the end portion 313B is 9 mm, and the line width of the antenna element 310 is 1 mm. is there. The ground element 320 has a length from the corner 321 to the corner 322 of 32 mm and a length from the corner 322 to the corner 323 of 22 mm.

  FIG. 11 is a diagram illustrating the frequency characteristics of the S11 parameter of the antenna device 300 according to the third embodiment.

  Here, when both the switching circuits 350A and 350B are turned off (that is, when the capacitor hats 330A and 330B are not connected to the antenna element 310), only when the switching circuit 350A is turned on (that is, Characteristic B when only capacitor hat 330A is connected to antenna element 310), characteristic C when only switching circuit 350B is turned on (that is, when only capacitor hat 330B is connected to antenna element 310), and switching circuit The characteristic D when 350A and 350B are both turned on (that is, when both the capacitor hats 330A and 330B are connected to the antenna element 310) was obtained by simulation.

  As shown in FIG. 11, it can be seen that both of the two resonance frequencies f11 and f12 shift from the characteristic A to the characteristic D toward the low frequency side. Among them, the difference between the characteristic A and the characteristic B is very small. Similarly, the difference between the characteristic C and the characteristic D is very small, but the difference between the characteristic C and the characteristic D is large.

  The first resonance frequency f11 of the characteristic A is about 2.4 GHz, and the value of the S11 parameter at that time is about −19 dB. The resonance frequency f12 was about 4.9 GHz, and the value of the S11 parameter at that time was about -17 dB.

  The first resonance frequency f11 of the characteristic B is about 2.4 GHz, and the value of the S11 parameter at that time is about −19 dB. The resonance frequency f12 was about 4.8 GHz, and the value of the S11 parameter at that time was about -17 dB.

  The first resonance frequency f11 of characteristic C was about 2.2 GHz, and the value of the S11 parameter at that time was about −19 dB. Further, the resonance frequency f12 was about 4.3 GHz, and the value of the S11 parameter at that time was about −18 dB.

  The first resonance frequency f11 of characteristic D was about 2.2 GHz, and the value of the S11 parameter at that time was about −19 dB. Further, the resonance frequency f12 was about 4.2 GHz, and the value of the S11 parameter at that time was about −18 dB.

  As described above, even in the antenna device 300 having the first antenna unit 310A and the second antenna unit 310B having different resonance frequencies, the switching circuits 350A and 350B control various connection states of the capacitor hats 330A and 330B. It is possible to provide a small antenna device 300 that can freely select a resonance frequency, and a wireless communication device 110 (see FIG. 4) using the antenna device 300.

  Although the antenna device according to the exemplary embodiment of the present invention and the wireless communication device using the antenna device have been described above, the present invention is not limited to the specifically disclosed embodiment, and the patent Various modifications and changes can be made without departing from the scope of the claims.

100, 100A, 100B, 100C, 100D, 200, 300 Antenna device 10, 310 Antenna element 11, 311 Connection portion 12, 15 Bending portion 13 End portion 14 Feeding line 16 Feeding portion 20 Ground element 21, 22, 23, 24 Angle Part 25 Grounding point 30 Capacitor hat 40 PCB board 41A, 41B Long side 42A, 42B Short side 43A-43D Corner part 50 Switching circuit 51, 53 Capacitor 52 PIN diode 54, 56 High frequency choke coil 55 Resistor 57, 58 Pad 110 Wireless Communication device 111 CPU
112 RAM
113 ROM
114 GUI operation unit 115 Wireless control unit 16 Bus 1
120 Controller 231, 232, 233, 234 Capacitor hat 251, 252, 253, 254 Switching circuit 310 Antenna element 310A First antenna unit 310B Second antenna unit 311 Connection unit 312A, 312B Bending unit 312C Branch unit 313A, 313B End unit 320 Ground element 330A, 330B Capacitor hat 340 PCB substrate 41A, 41B Short side 3
342A, 342B Long side 343A-343D Corner portion 350A, 350B Switching circuit

JP 2004-201278 A JP 2008-017426 A

Claims (5)

An antenna element having a feed point;
A capacitor hat disposed apart from an end side different from the end side where the feeding point of the antenna element is located;
A switching circuit that is disposed between the antenna element and the capacitor hat and switches a connection state between the antenna element and the capacitor hat. The connection state between the antenna element and the capacitor hat in the switching circuit. An antenna device that switches a resonance frequency by switching.   The antenna device according to claim 1, wherein one or a plurality of sets of connection switching circuits and capacitor hats different from the capacitor hat and the connection switching circuit are connected to the capacitor hat.   The antenna device according to claim 1, wherein the antenna element is an inverted L type or an inverted F type.   The antenna device according to any one of claims 1 to 3, wherein the antenna element includes a first antenna unit and a second antenna unit having different resonance frequencies.   A wireless communication device including the antenna device according to claim 1.

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