JP2013017112A - Antenna and radio communication device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna and a radio communication device, applicable for a low frequency band and a high frequency band, and capable of switching a communication bandwidth in the low frequency band, while suppressing an influence on antenna characteristics in the high frequency band.SOLUTION: An antenna, capable of communication in a plurality of communication bands, includes: a first line of which one end is connected to a power feed point and the other end is an open end; a ground line for grounding the one end side of the first line; and a second line, shorter than the first line, of which one end is connected to the power feed point and the other end is an open end. The antenna further includes: a switch circuit connected to the middle of the first line; and an inductance element of which one end is connected to the switch circuit and the other end is grounded. By means of the switch circuit, the connection state between the inductance element and the first line is switched.

Description

  The present invention relates to an antenna used in a wireless communication device, and more particularly to a multiband antenna capable of changing a resonance frequency in a wireless communication device communicating in a wide frequency band.

In recent years, wireless communication devices such as mobile phones have rapidly spread, and the frequency bands used for communication are also wide-ranging. In particular, in recent mobile phones, there are an increasing number of examples in which a plurality of transmission / reception bands are provided in one mobile phone as called a dual band method, a triple band method, a quad band method, or the like.
For example, in a quad-band mobile phone compatible with GSM (registered trademark) 850/900 band, DCS band, PCS band, and UMTS band communication systems, the frequency band used in each system is GSM850 / 900 band: 824 960 MHz, DCS band: 1710 to 1850 MHz, PCS band: 1850 to 1990 MHz, UMTS band: 1920 to 2170 MHz, an antenna that can accommodate a plurality of frequency bands as an antenna constituting an antenna circuit built in a mobile phone Is required.

A radiating element (also referred to as a radiating electrode, a radiation path, or a line) that normally constitutes an antenna resonates at a fundamental frequency and also resonates at a higher frequency. For example, if resonance at a quarter wavelength is set as a fundamental mode, resonance at a quarter wavelength occurs in a higher-order mode. Accordingly, even with a single radiating element, if a plurality of frequency bands are in a relationship of 1: 3, it can be dealt with, but there is a problem that the bandwidth of the higher-order mode resonance is narrow.
If the fundamental mode resonance is obtained in the GSM850 / 900 band, the DCS band or the like is handled by the higher order mode resonance. However, the DCS band, the PCS band, and the UMTS band are approximately 2 to 2.5 times the frequency of the GSM band, and cannot simply be handled.
Furthermore, the GSM850 / 900 band has a frequency bandwidth of 136 MHz and a specific bandwidth of about 15.3% [136 MHz / 892 MHz], and the DCS, PCS, and UMTS bands have a frequency bandwidth of 460 MHz. Is about 23.7% [460 MHz / 1940 MHz], and each has a wide bandwidth, and there is a problem that a sufficient bandwidth cannot be secured only by resonance by one radiating element.

For such a problem, Patent Document 1 includes a radiation electrode connected to a feeding point, a parasitic radiation electrode electromagnetically coupled to the radiation electrode, and a gap between the open end of the radiation electrode and the ground. An antenna is disclosed in which the amount of capacitance to be connected is variable by a switch unit. This antenna widens the high-order frequency band by double resonance of the radiation electrode and the parasitic radiation electrode, and the high-order mode frequency band of the high-order mode is used for wireless communication as well as the fundamental mode frequency band of the basic mode. Multiband. And by changing the capacitance value of the capacitance formed between the ground side electrode and the open end of the radiation electrode, the resonance frequency of the fundamental frequency band based on the antenna operation of the radiation electrode is changed to the frequency to be used. It is also proposed to make adjustments and enable wireless communication at different frequencies.
In the following description, in a plurality of communication systems, a frequency band of a system using a relatively low frequency such as GSM850 / 900 is set as a low frequency band, and a relatively high frequency such as DCS, PCS, and UMTS is used. The system frequency band is the high frequency band.

JP 2005-150937 A

  In conventional antennas, the higher-order mode frequency band is broadened by a plurality of radiation electrodes, and the amount of capacitance applied between the open end of the radiation electrode and the ground is switched to reduce the resonance frequency in the fundamental mode frequency band. Although it is variable, because of the configuration of the antenna, the capacitance is connected to the open end of the radiation electrode of the antenna and grounded, so that the reactance is connected in series to the open end of the radiation electrode as a circuit. Become. In such a configuration, as the resonance frequency in the fundamental mode frequency band changes, the resonance frequency in the higher order mode frequency band also changes easily, and the VSWR characteristics in the higher order mode frequency band deteriorate, There was a problem that it could not function as a multiband antenna corresponding to the communication system in the frequency band.

  Therefore, in the present invention, an antenna and a wireless communication that can cope with a low frequency band and a high frequency band and can switch a communication band of a low frequency band while suppressing an influence on antenna characteristics of the high frequency band. An object is to provide an apparatus.

In the present invention, one end is connected to a feeding point, the other end is an open end, a grounding line that grounds one end of the first line, one end is connected to the feeding point, An antenna having an open end, a second line shorter than the first line, a switch circuit connected in the middle of the first line, and one end connected to the switch circuit And an inductance element whose other end is grounded, and the connection state between the inductance element and the first line is switched by the switch circuit. According to this configuration, it is possible to switch the communication band of the low frequency band while suppressing the influence on the antenna characteristics of the high frequency band configured using the second line.

In the antenna, by switching the connection state, the communication band of the lowest frequency band among the plurality of communication bands is switched,
In at least one of the connection states, it is preferable that VSWR in a plurality of communication bands on a higher frequency side than the communication band of the low frequency band is 3 or less. According to this configuration, it is possible to provide a tunable multiband antenna in which the communication band on the low frequency side is made variable while covering a plurality of communication bands on the high frequency side.

  Further, in the antenna, the switch circuit is an FET switch that switches connection between a common terminal and a plurality of branch terminals, the common terminal is connected to the first line, and at least one of the plurality of branch terminals It is preferable that the inductance element is connected.

  Furthermore, in the antenna, it is preferable that one of the plurality of branch terminals is open.

  On the other hand, in the antenna, it is also preferable that the inductance elements having different inductance values are connected to the plurality of branch terminals.

The wireless communication device of the present invention uses the antenna.

  According to the present invention, an antenna and a radio that can cope with a low frequency band and a high frequency band and can switch a communication band of a low frequency band while suppressing an influence on antenna characteristics of the high frequency band. A communication device can be provided.

It is a figure which shows one Embodiment of the antenna which concerns on this invention. It is a figure which shows an example of a switch circuit. It is a figure which shows other embodiment of the antenna which concerns on this invention. It is a figure which shows the other example of a switch circuit. It is an equivalent circuit which shows other embodiment of the antenna which concerns on this invention. It is a perspective view which shows the Example of the antenna which concerns on this invention. It is a figure which shows the VSWR characteristic of the antenna of the Example shown in FIG. It is a figure which shows the connection position dependence of a connection line of a VSWR characteristic.

  Hereinafter, embodiments of an antenna and a wireless communication device according to the present invention will be specifically described with reference to the drawings. However, the present invention is not limited thereto. Moreover, the structure demonstrated in each embodiment is applicable also in other embodiment, unless the meaning of other embodiment is impaired, In that case, the overlapping description is abbreviate | omitted suitably.

  In the embodiment described below, the basic configuration of the antenna is an inverted-F antenna. The present invention can be applied to a monopole antenna other than the inverted F antenna, for example, an inverted L antenna or a T antenna, and is not particularly limited.

  An antenna 10 according to the first embodiment shown in FIG. 1 includes a first line 1 having one end connected to a feeding point 5 and the other end being an open end, and a ground line that grounds one end of the first line. 3 and a second line 2 shorter than the first line, one end of which is connected to the feeding point 5 and the other end is an open end.

  In general, when the line is resonated with λ / 4 (λ: wavelength) of the fundamental wave (first resonance frequency f1r), the current is maximum at the feeding point and the current is zero at the open end. Become. The voltage is maximum at the open end. Considering impedance matching at the feeding point, the line can be resonated with the third harmonic of the fundamental wave, and a multiband antenna with a frequency ratio of 1 (fundamental wave) to 3 can be obtained simply. However, taking the frequency band of a typical mobile phone as an example, high-order mode resonance is obtained in a high-frequency band such as DCS with respect to GSM in a low-frequency band of 1000 MHz or less, and desired only by high-order mode resonance. It is difficult to make the voltage standing wave ratio VSWR below a predetermined numerical value in the frequency band of. Therefore, in the antenna of the present invention, by using a line for a low frequency band and a line for a high frequency band in combination, a high frequency band including a frequency about twice the first resonance frequency f1r (low frequency band) is used. The second resonance that resonates is obtained.

  The length of the first line 1 is substantially ¼ of the wavelength λ1 of the resonance frequency f1r that resonates in series in a substantially low frequency band, and constitutes a first radiating element that operates in the series resonance mode. doing. The current distribution when the first radiating element resonates in series is 0 (zero) at the open end, and is maximum near the connection point 4 with the ground line 3. At the connection point 4, the voltage is substantially 0 (zero), and the impedance is in a short state. The length of the second line 2 is substantially ¼ of the wavelength λ2 of the resonance frequency f2r that resonates in series in the high frequency band, and constitutes a second radiating element that operates in the series resonance mode. doing. The current distribution when the second radiating element resonates in series is the same as that of the first radiating element. The line from the connection point between the first line and the second line to the feeding point 5 is shared by the first line and the second line. By adjusting the position of the connection point 4 of the ground line, the impedance of the first radiating element and the second radiating element can be adjusted. In addition, the impedance of the first radiating element and the second radiating element can be adjusted by connecting a reactance element between the first line and / or the second line and the ground.

  The first line 1 is configured to extend horizontally with respect to the ground plane GND. However, the first line 1 may be configured as a line that is folded back in the middle, and the folding may be multiplexed. The second line 2 may also be configured as a folded line, or may be a meander-shaped folded line.

  The antenna according to the first embodiment shown in FIG. 1 includes a switch circuit SW1 connected in the middle of the first line 1, and an inductance element L1 having one end connected to the switch circuit SW1 and the other end grounded. . A capacitance element C1 disposed between the first line 1 and the switch circuit SW1 and a capacitance element C2 disposed between the switch circuit SW1 and the inductance element L1 are DC cut capacitors. The connection state between the inductance element L1 and the first line 1 is switched by the switch circuit SW1. The positions of the inductance element L1 and the capacitance element C2 may be interchanged. In the embodiment shown in FIG. 1, the switch circuit SW1 is an SPST type, that is, an ON / OFF type switch circuit. The switch circuit SW1 has a state where the inductance element L1 is connected to the first line 1 and a state where it is not connected. Switch. By switching by the switch circuit SW1, the resonance frequency of the first resonance mode of the first radiating element configured by the first line 1 is changed, and a tunable antenna is realized. For example, when SW1 is turned on and the inductance element L1 is connected, the resonance in the series resonance mode of the first radiating element can be moved to the high frequency side by about 50 MHz compared to when SW1 is off. Therefore, by adjusting the SW1 OFF state to the GSM850 band and the SW1 ON state to the GSM900 band, it is possible to cope with the plurality of communication bands. The shift amount of the communication band can be changed by changing the inductance value of the inductance element L1. Since the inductance element L1 is connected in the middle of the first line, the communication band on the low frequency side can be made variable while suppressing the influence on the main resonance of the second line corresponding to the communication band on the high frequency side. Can do.

  A configuration example of the switch circuit SW1 is shown in FIG. The switch circuit SW1 shown in FIG. 2A is an SPST type switch circuit configured using a diode. The diode is connected between two DC cut capacitors, and is controlled ON / OFF by applying a control voltage Vc via an inductance element. Further, as shown in FIG. 2B, by arranging the anode of the diode as the first line side and the cathode as the ground side of the inductance element L1 and grounding via the inductor element L1, the number of parts is increased. Can be reduced. The configuration of the switch circuit SW1 is not limited to that shown in FIG. For example, a switch circuit using a field effect transistor (FET) may be used.

  Next, the antenna 20 of 2nd Embodiment is shown in FIG. The embodiment shown in FIG. 3 is different from the first embodiment in the configuration of the part related to the switch circuit, and the other configurations are the same, so the description thereof will be omitted. The capacitance elements C3 and C4 are arranged as DC cut capacitors with the switch circuit SW2 interposed therebetween, as in the first embodiment. In the second embodiment, the switch circuit SW2 is an SPDT type FET switch that switches the connection between the common terminal and the two branch terminals, and the common terminal is connected to the first line 1 and the two of the two branch terminals are connected. One of them is connected to an inductance element L2. The other branch terminal is not connected to an inductance element or the like and is open. By switching the connection between the common terminal and each branch terminal, the state where the inductance element L2 is connected to the first line 1 and the state where it is not connected can be switched. Further, instead of the configuration in which the ground end side of the ground line 3 shown in FIG. 3 is directly grounded, the resonance impedance can be finely adjusted by grounding via an inductance element.

  A configuration example of the switch circuit SW2 is shown in FIG. The switch circuit SW2 shown in FIG. 4 is an SPDT type FET switch configured using a plurality of field effect transistors Tr1 to Tr4. A control voltage Vc2 is applied to the gates of Tr1 and Tr4 from a common control power supply, and a control voltage Vc1 is applied to the gates of Tr2 and Tr4 from a common control power supply. The connection between the common terminal Pc and the branch terminal P1 or P2 is switched by the control voltages Vc1 and Vc2. Note that since the switch circuit only needs to have a plurality of branch terminals, the switch circuit is not limited to the SPDT type switch circuit, and may have three or more branch terminals. In this case, it is sufficient that an inductance element is connected to at least one of the plurality of branch terminals, and one of the branch terminals is open.

  A third embodiment is shown in FIG. 5 as another embodiment in which an inductance element is connected to at least one of a plurality of branch terminals. The antenna 30 of the third embodiment is different from the second embodiment in the configuration of the portion connected to the branch terminal of the switch circuit, and the other configurations are the same, so the description thereof is omitted. The common terminal is connected to the first line 1, and one of the two branch terminals is connected to the inductance element L3, and the other branch terminal is connected to the inductance element L4. Further, a capacitance element C5 is connected to the common terminal side of the switch circuit SW2, and capacitance elements C6 and C7 are connected to the two switching terminals as DC cut capacitors, respectively. According to the configuration of the third embodiment in which the inductance elements having different inductance values are connected to the two branch terminals, the degree of freedom in selecting the inductance value by switching and, in turn, the degree of freedom in adjusting the communication band is increased. . Such a configuration is effective when the shape and size of the first line are limited.

  In the embodiment shown in FIGS. 3 and 5, an example of the FET switch is shown as the SPDT type switch circuit. However, the SPDT type switch circuit is not limited to this, and may be configured using a diode. However, from the viewpoint of miniaturization, an FET switch having a single function such as a GaAs switch or a CMOS switch is more preferable. In the embodiment shown in FIG. 3 and FIG. 5, an example of an SPDT type switch circuit having two branch terminals as the switch circuit is shown. However, a plurality of branch terminals may be used, and the present invention is limited to the SPDT type switch circuit. There may be three or more branch terminals. In that case, the inductance element may be connected to all of the branch terminals, or a part of the branch terminals may be open or the inductance element may not be connected. However, when using an SPnT (single-pole, double-throw, n is a natural number of 2 or more) type switch circuit using an FET, an SPnT type switch circuit having three or more branch terminals (n is a natural number of 3 or more) is used. A configuration in which three or more states are switched is preferable in taking advantage of the double throw (nT) function of the SPnT switch circuit.

  The first line, the second line, and the ground line are preferably composed of a conductor thin plate made of Cu or phosphor bronze, and are preferably integrated by injection molding using an engineering plastic such as a liquid crystal polymer. In this case, it is possible to mold simultaneously with the casing portion of the portable terminal. If the radiation electrode is formed of an alloy such as phosphor bronze, the radiation electrode itself is easy to process and has a characteristic that it is not easily deformed by an external force. Therefore, it is possible to form the radiation element in a free shape regardless of the support. It is possible and preferable. In addition, by forming the line conductor using a flexible printed circuit (FPC) or the like, it is possible to install the line conductor regardless of the mounting surface of the portable terminal, and to improve the mounting flexibility. is there.

  Each line may be formed on a printed circuit board or a ceramic body, or a part of the antenna may be a thin conductor plate such as phosphor bronze, and the other part may be configured on a printed circuit board or the like. The ceramic body may be formed on a ceramic substrate made of alumina or other dielectric ceramic material with a good conductor such as Au, Ag, or Cu having a low resistance by a known method such as a printing method or an etching method. The printed board is a so-called flexible board made of a rigid board such as FR4 (glass epoxy resin board), a polyimide such as polyimide, polyetherimide, and polyamideimide, a polyamide such as nylon, and a polyester such as polyethylene terephthalate. It is formed on a printed board by a known method such as an etching method or a photolithography method. In the case of a flexible substrate, it can be easily deformed according to the shape of the support, so that the limited space in the casing in which the antenna is arranged can be used effectively. A mounting board having the ground plane GND can also be formed of a printed board or the like.

  A wireless communication device such as a mobile phone can be configured using the antenna according to the present invention. The antenna according to the present invention may be configured directly on the main circuit board of the wireless communication device, for example, or may be configured on a mounting substrate different from the main circuit substrate, and the mounting substrate may be incorporated in the wireless communication device.

  FIG. 6 shows a specific configuration example of the antenna according to the present invention. The antenna 40 is an inverted F antenna that resonates at a frequency within a low frequency band and a high frequency band by a first radiating element and a second radiating element, and is a main circuit board (not shown) that constitutes a power feeding circuit. Is a configuration using a separate mounting substrate 49. Connection to the high-frequency signal path between the mounting board 49 and the main circuit board is made by a coaxial cable. Note that the effect of the present invention is not changed even when the first radiating element and the second radiating element are provided on the main circuit board.

  On the mounting board 49 configured as a copper-clad double-sided conductor board (glass epoxy board), a plurality of radiating elements formed integrally with a thin plate made of Cu sheet metal and having a thickness of 0.2 mm are erected on the mounting board 49. Is done. A DC cut capacitor, an inductance element, and the like, which will be described later, are mounted on the mounting board 49, and each is appropriately connected by wiring formed on the mounting board 49.

  One end side of the integrally formed radiating element provided upright on the mounting substrate 49 is connected to the feeding point 45. The opposite side extends in a direction away from the ground plane GND of the mounting board 49 (a direction perpendicular to the mounting board in FIG. 6; hereinafter also referred to as a vertical direction), and constitutes the first radiating element at a predetermined height. 1 line 41 and a second line 42 constituting the second radiating element. In general, the radiation gain improves as the antenna is separated from the ground plane. Therefore, in the present embodiment, the first line and the second line are arranged at a predetermined height with respect to the mounting substrate 49 to ensure the distance from the ground plane GND. In the embodiment shown in FIG. 6, the second line 42 branches off at a position closer to the ground plane GND than the first line 41. The first line and the second line are formed in a band shape having a width of 1 mm to 1.5 mm. The first line 41 is bent at the end in the vertical direction so that the wide main surface faces the main surface of the mounting substrate 49. The first line 41 extends in a direction away from the feeding point substantially parallel to the main surface of the mounting substrate 49, and its tip is an open end. The mounting substrate 49 is formed in a substantially rectangular shape having dimensions of 9 mm in length × 48 mm in width × 0.9 mm in thickness, and the first line 41 is disposed along the long side. The length from the feeding point is about 55 mm. Below the first line, a second line 42 extends in the same direction as the first line 41, and its tip is an open end. The second track is bent halfway so that the direction of the main surface changes by 90 °. The length of the second line is shorter than the first line and is about 18 mm. In this way, a multiband antenna having a length of 10 mm or less, a width of 48 mm or less, and a height of 6 mm or less can be configured.

  In the embodiment shown in FIG. 6, a switch 48 is connected via a connection line 46 in the middle of the first line 41 extending in a direction away from the feed point substantially parallel to the main surface of the mounting substrate 49. The connection position is a position 14 mm from the position of the feeding point along the first line, that is, a position that is 25% of the total length of the first line from the feeding point. The equivalent circuit of the embodiment shown in FIG. 6 is the same as that shown in FIG. In the embodiment shown in FIG. 6, the first line 41 has a branch portion on the side close to the open end, and is provided with a dielectric element 47 for the purpose of wavelength shortening, etc. What is necessary is just to change according to the required characteristic.

  The inductance value of the inductance element L2 was set to 15 nH, switching between open and open, and VSWR at that time was evaluated. The capacitance values of the capacitance elements C3 and C4 are 220 pF and 100 pF. The evaluation results are shown in FIG. In FIG. 7, markers 1 to 5 indicate 824 MHz, 880 MHz, 960 MHz, 1710 MHz, and 2170 MHz, respectively. By switching between the inductance of 15 nH and open, the peak of the low frequency band can be switched between 850 MHz and 900 MHz. When switching to open, the VSWR was 3 or less at the center frequency of 850 MHz, and the VSWR was 4 or less at 824 to 894 MHz corresponding to the GSM850 communication band. When switching to the inductance of 15 nH, the VSWR was 3 or less at the center frequency of 900 MHz, and the VSWR was 4 or less at 880 to 960 MHz corresponding to the communication band of the GSM900.

  Even when these low frequency bands were switched, the peak in the vicinity of 1710 MHz, which is a high frequency band located on the high frequency side of 700 MHz or higher, was hardly affected. The peak near 1710 MHz is due to resonance of the second radiating element formed by the second line. In the configuration of the embodiment, since the connection line for connecting the switch circuit is connected in the middle of the first line, the connection is less likely to affect the resonance of the second radiating element. . Furthermore, in a band of 1710 MHz to 2170 MHz that covers a plurality of high frequency communication systems such as DCS, PCS, and UMTS, a good VSWR of 3 or less was obtained even when switched to any band. That is, in the configuration of the embodiment shown in FIG. 6, the VSWR fluctuation due to switching is suppressed not only in the band near 1710 MHz corresponding to the series resonance of the second radiating element but also in the wide band on the high frequency side. It can also be seen that VSWR is 4 or less in any switching state in the bandwidth of at least 550 MHz including the above-mentioned band of 1710 MHz to 2170 MHz. In order to obtain a VSWR of 3 or less in the band of 1710 MHz to 2170 MHz when the first line has branch portions arranged parallel to each other on the tip side of the connection point 4 as in the embodiment shown in FIG. In this case, it is preferable to take an average of the length from each tip of the branch portion to the feeding point, and connect the switch circuit at a position of 20% or more of the average length from the feeding point. Such a connection position is more preferably a position of 25% or more.

  Next, in the embodiment shown in FIG. 3, the VSWR was evaluated by changing the connection position of the connection line to the first line. The first line has no branching portions arranged parallel to each other on the tip side from the connection point 4, and the length of the first line from the feeding point is about 55 mm. The connection position is 20 mm, 25 mm, 30 mm, 35 mm from the position of the feeding point along the first line (24%, 30%, 37% of the total length of 82 mm of the first line from the feeding point, respectively) FIG. 8 shows the VSWR in the high frequency band when the position is changed to (43% position). The results shown in FIG. 8 are for the case where a 12 nH inductance element is connected as the switching state. Similar to the case of FIG. 7, even if the connection position changes, the peak near 1.71 GHz is not greatly affected. On the other hand, the VSWR varies depending on the connection position on the high frequency side from the peak near 1.71 GHz, and the VSWR is large when the connection position of the connection line is close to the feeding point. In the case where the first line has no substantial branching portion, the connection position of the connection line is set to 37% or more of the total length of the first line, so that it is excellent in a wide band from 1.71 GHz to 2.17 GHz in a wide band. VSWR was obtained. The peak near 2.17 GHz adjacent to the peak near 1.71 GHz is considered to be derived from the resonance of the higher-order mode of the first radiating element constituted by the first line, but the frequency band between these peaks Also, a good VSWR was obtained. Although omitted because they overlap in the drawing, even if the connection positions are separated from each other by more than 35 mm (for example, 40 mm and 45 mm), the same results as in the connection positions of 30 mm and 35 mm are obtained. As described above, 1.71 GHz to 2.17 GHz cover a plurality of communication bands on the high frequency side. As described above, the low-frequency communication band having the lowest frequency among the plurality of communication bands is switched by switching the connection state, and in each connection state before and after the switching, a plurality of higher-frequency communication bands than the low-frequency communication band are switched. By adopting a configuration in which the VSWR in the communication band is 3 or less, a tunable multi-band antenna is realized in which the communication band on the low frequency side is made variable while covering a plurality of communication bands on the high frequency side. A tunable multiband antenna having such a function can be realized by using a configuration in which VSWR in a plurality of communication bands on the high frequency side is 3 or less in at least one of the connection states. Thus, in each connection state before and after switching, it is more preferable that VSWR in a plurality of communication bands on the high frequency side is 3 or less.

DESCRIPTION OF SYMBOLS 1, 41: 1st track | line 2, 42: 2nd track 3: Grounding track 4: Connection point 5, 45: Feeding point 10, 20, 30, 40: Antenna 46: Connection track 47: Dielectric element 48: switch

Claims (6)

A first line having one end connected to the feed point and the other end being an open end;
A grounding line for grounding one end of the first line;
An antenna having one end connected to the feeding point and the other end being an open end, a second line shorter than the first line, and enabling communication in a plurality of communication bands,
A switch circuit connected in the middle of the first line;
An inductance element having one end connected to the switch circuit and the other end grounded;
An antenna, wherein the connection state between the inductance element and the first line is switched by the switch circuit. By switching the connection state, the communication band of the lowest frequency band among the plurality of communication bands is switched,
2. The antenna according to claim 1, wherein in at least one of the connection states, VSWR in a plurality of communication bands on a higher frequency side than the communication band of the low frequency band is 3 or less. The switch circuit is an FET switch that switches connection between a common terminal and a plurality of branch terminals, and the common terminal is connected to the first line,
The antenna according to claim 1, wherein the inductance element is connected to at least one of the plurality of branch terminals.   4. The antenna according to claim 3, wherein one of the plurality of branch terminals is open.   The antenna according to claim 3, wherein the inductance elements having different inductance values are connected to the plurality of branch terminals.   A wireless communication apparatus using the antenna according to any one of claims 1 to 5.

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