JP2007060349A - Inverse f-shaped antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provde an inverse F antenna used for the mobile communication of a cellular phone set or the like by which a broad band communication can be attained. <P>SOLUTION: A capacitor 11 is inserted between a line from a feeder line 2 and a line from a short circuit line 3. Thus, in a high frequency band, the feeder line 2 and the short circuit line 3 are made to be conductive in a high frequency to operate as the inverse F-shaped antenna fed through two paths 12 and 13 to widen the band. Moreover, between the short circuit line 3 and the ground 10, a prescribed inductor 20 is inserted, and the short circuit line 3 and the ground 10 are disconnected in a high frequency at a high frequency band to operate as a monopole antenna. Thus, the band is made more broad. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inverted-F antenna mounted on mobile communication such as a mobile phone.

  In recent years, mobile communications including cellular phones have diversified services for voice communications, data communications such as text and moving images, and high performance wireless devices are required. In particular, the performance of an antenna serving as an entrance through which radio waves are transmitted and received is one of the major factors affecting the performance of a wireless device, and a high-performance antenna is desired.

  Here, a conventional inverted-F antenna will be described with reference to FIG.

  FIG. 5 is a perspective view schematically showing a conventional inverted-F antenna. As shown in the figure, the conventional inverted-F antenna includes an antenna element 1 that resonates in two frequency bands, and an antenna element 1 below. A ground plate 4 disposed on the ground plate 4, a feed line 2 connecting the feed terminal 5 on the ground plate 4 and the antenna element 1, a terminal 6 connected to the ground 10 on the ground plate 4 via the inductor 9, and the antenna element 1. It is comprised from the short circuit wire 3 which connects. The power supply terminal 5 is connected to the radio circuit 8 via the transmission line 7. Here, it is assumed that the antenna element 1 resonates with GSM (880 to 960 MHz) and DCS (1710 to 1880 MHz).

  In the above configuration, when GSM is received, the current excited by the radio wave received by the antenna element 1 is transmitted from the feed line 2 to the radio circuit 8 via the feed terminal 5 and the transmission line 7, thereby generating the radio wave. Receive. When transmitting GSM, a signal generated in the radio circuit 8 is transmitted from the transmission line 7 through the power supply terminal 5 and the power supply line 2. This signal is transmitted by being excited by the antenna element 1 and radiated as a radio wave. Next, in DCS, radio waves are transmitted and received by the antenna element 1 on the same principle as when GSM is transmitted and received.

  The inverted F antenna has a terminal 6 connected to a ground 10 on the ground plane 4 via an inductor 9. The inductor 9 is provided for impedance adjustment. When the inductor 9 is interposed, the electrical length connected from the short-circuit line 3 to the ground 10 via the terminal 6 and the inductor 9 becomes GSM. It also has the function of widening the band by taking advantage of the feature of the inductor that the electrical length when operating with a DCS having a higher frequency than GSM is longer than the electrical length when operating with.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2005-109636 A

  However, in the conventional inverted-F antenna, a wide-band inverted-F antenna is used by utilizing the fact that the electrical length including the short-circuit wire 3 is changed in a high frequency by the inductor 9, but the configuration is only reversed. Only the electrical length on the short-circuit side of the F antenna is changed, and with this configuration, it has been difficult to further increase the bandwidth.

  The present invention solves such a conventional problem, and an object thereof is to provide an inverted-F antenna in which a wider band is achieved by a simple measure.

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided an antenna element that resonates in at least two frequency bands, a ground plane disposed under the antenna element, and the ground plane connected to a radio circuit and a transmission line. A power supply line connecting the power supply terminal and the antenna element; a terminal connected to the ground on the ground plane; and a short-circuit line connecting the antenna element; a line connected to a radio circuit of the antenna element; This is an inverted-F antenna characterized in that a capacitor is connected between lines connected to the ground of the antenna element.

  With this configuration, the two lines are cut off at a high frequency by a capacitor in a low frequency band, and operate as an inverted F antenna that is fed to an antenna element at one location, and the two lines by a capacitor in a high frequency band. Two lines are made conductive at high frequencies, and a path for feeding power from the feeder line to the antenna element and a path for feeding power from the capacitor to the antenna element via the short-circuit line are formed, and the power fed by the two paths is reversed. Since the antenna can operate as an F antenna, an inverted F antenna with a wide band can be easily realized.

  According to a second aspect of the present invention, in the first aspect of the invention, a line that connects an inductor that is in a high-frequency cutoff state in a higher frequency band of the corresponding frequency bands in the antenna element to the ground of the antenna element. The antenna element is further arranged between the point where the capacitor is connected and the ground, and the inductance of the inductor cuts off the connection to the ground in a high frequency band due to the inductance of the inductor, resulting in the monopole operation of the antenna element. In addition, the number of paths through which power is fed from the capacitor to the antenna element via the short-circuit line is increased, so that it is possible to obtain an inverted-F antenna with a further increased bandwidth.

  The invention according to claim 3 is the invention according to claim 1, wherein a part or all of the ground plate under the antenna element is not disposed. The ratio of capacitive coupling can be controlled, and when setting the optimization of the coefficient of the capacitor, etc., the degree of freedom of design is increased, and it is possible to realize a further widened band.

  As described above, according to the present invention, by inserting a capacitor between the line connected to the radio circuit of the antenna element and the line connected to the ground, the two lines are cut off at high frequencies by the capacitor in a low frequency band. It operates as an inverted F antenna fed at one point, and in the high frequency band, the two lines are brought into a high-frequency conduction state by a capacitor, and in addition to a path for feeding power from the feeder line to the antenna element, Since a path to be fed to the antenna element can be formed and to operate as an inverted F antenna to be fed by the two paths, an advantageous effect that a wideband inverted F antenna can be realized is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  In addition, the same code | symbol is attached | subjected to the part of the structure same as the structure demonstrated in the term of the prior art, and detailed description is simplified.

(Embodiment)
FIG. 1 is a perspective view schematically showing an inverted F antenna according to an embodiment of the present invention. As shown in FIG. 1, the inverted F antenna includes an antenna element 1 that resonates in two frequency bands, and A ground plane 4 disposed under the antenna element 1, a feed line 2 connecting the feed terminal 5 on the ground plane 4 and the antenna element 1, and a terminal 6 connected to the ground 10 on the ground plane 4 via an inductor 20. And a short-circuit wire 3 for connecting the antenna element 1 to each other. The power supply terminal 5 is connected to the radio circuit 8 via the transmission line 7.

  In addition to the above configuration, a capacitor 11 is inserted and connected between a line from the power supply terminal 5 connected to the power supply line 2 and a line from the terminal 6 connected to the short-circuit line 3. Here, it is assumed that the antenna element 1 resonates with GSM (880 to 960 MHz) and DCS (1710 to 1880 MHz).

  According to the present embodiment configured as described above, in GSM, which is a low frequency band, the feed line 2 and the short-circuit line 3 are cut off at high frequency by the capacitor 11, and the antenna element 1 is fed from the feed line 2. It operates as an inverted F antenna that is fed through the path. On the other hand, in DCS, which is a high frequency band, the antenna element 1 is also fed from the short-circuit line 3 when the feed line 2 and the short-circuit line 3 are brought into conduction at high frequencies by the capacitor 11. The operating principle at this time is shown in FIG. As shown in FIG. 2, in addition to a path 12 indicated by a solid line fed from the feeder line 2 to the antenna element 1, a path 13 indicated by a dotted line fed from the capacitor 11 via the short-circuit line 3 to the antenna element 1 Increase. As described above, there are two types of paths for feeding power to the antenna element 1, resulting in a wideband inverted F antenna.

  Further, as described above, the inductor 20 is inserted between the short-circuit line 3 and the ground 10. The inductor 20 is a DCS which is a high frequency band and is selected and mounted so as to be in a high-frequency cutoff state. The mounting position is such that one end of the inductor 20 is connected to the ground 10 on the ground plane 4 and one end of the capacitor 11 is connected to the other end of the inductor 20.

  By the action of the inductance of the inductor 20, the antenna element 1 can operate as a monopole antenna in a high frequency band DCS with a high frequency connection to the ground 10 in a cutoff direction. Therefore, by adding the capacitor 11 and the inductor 20 in the above-described state, it can be realized as an inverted-F antenna that is supplied with power from two types of paths and performs a monopole operation, thereby further widening the band. Note that the inductor 20 is not always necessary, and the one with only the capacitor 11 added can have a wide band as described above.

  In addition, a part of the ground plane disposed below the antenna element 1 or a ground plane 14 that is not entirely disposed as shown in FIG. 3, that is, the area where the ground plane 14 and the antenna element 1 face each other is controlled. By doing so, the ratio of capacitive coupling between the ground plane 14 and the antenna element 1 can be controlled. Since the capacitive coupling state can be controlled, an effect of increasing the degree of design freedom can be obtained when setting the optimization of the coefficients of the capacitor 11 and the inductor 20 in order to realize a wide band of the antenna.

  As described above, the same effect can be obtained even if the antenna element is configured to resonate in three or more frequency bands other than the antenna element 1 that resonates in two frequency bands. Further, the pattern of the antenna element 1 is not limited to the pattern shown in FIG. 1 and may be configured with a free pattern, and the same effect can be obtained.

  As shown in FIG. 1, the feeder 2 is connected in the vicinity of the left end of the ground plane 4, but the same effect can be obtained even if it is connected at an arbitrary location on the ground plane 4. Similarly, the short-circuit wire 3 may be connected at an arbitrary place on the ground plane 4.

  As shown in FIG. 1, in addition to inserting and connecting the capacitor 11 between the line from the power supply terminal 5 and the line from the terminal 6, as shown in FIG. The same effect can be obtained by inserting and connecting the capacitor 15 between them. That is, the main purpose of the present invention is to increase the bandwidth by connecting the line connected to the radio circuit 8 of the antenna element 1 and the line connected to the ground 10 of the antenna element 1 with a capacitor. It is.

  In FIG. 1, the power supply terminal 5 is connected to the wireless circuit 8 via the transmission line 7. However, a matching circuit can be inserted between the power supply terminal 5 and the wireless circuit 8. Thus, the impedance may be freely adjusted.

  The inverted-F antenna according to the present invention has an effect that it can be realized in a wide band by a simple measure of inserting a capacitor between a line connected to the radio circuit of the antenna element and a line connected to the ground, This is useful for mobile communications such as mobile phones.

The perspective view which represented typically the inverted F antenna by one embodiment of this invention Diagram showing the operating principle of the antenna The perspective view which represented typically the inverted F antenna which does not arrange | position a ground plane under the antenna element A perspective view schematically showing an inverted-F antenna in which a capacitor is inserted and connected between the feeder line and the short-circuit line A perspective view schematically showing a conventional inverted-F antenna

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna element 2 Feed line 3 Short-circuit line 4, 14 Ground plane 5 Feed terminal 6 Terminal 7 Transmission line 8 Radio circuit 10 Ground 11, 15 Capacitor 12, 13 Path | route 20 Inductor

Claims (3)

An antenna element that resonates in at least two frequency bands, a ground plane disposed below the antenna element, and a feed line that connects the antenna element and the feed terminal on the ground plane that is connected to a radio circuit and a transmission line. And a short circuit line connecting the antenna element and a terminal connected to the ground on the ground plane, and a capacitor between a line connected to the radio circuit of the antenna element and a line connected to the ground of the antenna element Inverted F antenna characterized by being connected. An inductor that is in a high-frequency cutoff state in the higher frequency band of the corresponding frequency bands in the antenna element is further arranged between the point where the capacitor is connected in the line connecting to the ground of the antenna element and the ground. The inverted-F antenna according to claim 1. The inverted F antenna according to claim 1, wherein a part or all of the ground plane under the antenna element is not disposed.

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