JP2008172295A - Antenna device and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device and a receiver capable of receiving different frequency bands while suppressing upsizing. <P>SOLUTION: A mobile phone has: antenna wires A1, A2 and ground wires G1, G2 composing an antenna; a tuner section 3; and a substrate 4 on which the tuner section 3 is mounted. The antenna wires A1, A2 are connected to a signal terminal 3a at the tuner section 3. The ground wires G1, G2 are connected to a ground terminal 3g at the tuner section 3. The antenna wire A1 is longer than the antenna wire A2. The length of the antenna wire A1 is the same as that of the ground wire G1. The length of the antenna wire A2 is the same as that of the ground wire G2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna device and a receiving device used for a portable information terminal such as a mobile phone and an electronic information terminal such as a personal computer.

  For example, mobile phones are added not only with a call function but also with a communication function such as mail and the Internet with the development of technology. And because of its convenience and ease, mobile phones are rapidly spreading worldwide.

  With the spread of such mobile phones, mobile phones having various functions other than a call function and a communication function have been proposed (see, for example, Patent Document 1). This Patent Document 1 discloses a mobile phone having a function of receiving a radio broadcast or a television broadcast.

JP 2002-101164 A

  By the way, in recent years, terrestrial digital broadcasting started using the terrestrial UHF band has been started, and even when received by a portable information terminal, it is possible to view clear video. As described above, the television broadcasting is shifted to digital, and terrestrial digital radio broadcasting (terrestrial digital audio broadcasting) that enables high-quality audio and various data broadcasting is also scheduled to start. When terrestrial digital radio broadcasting is started in earnest, it is expected that the user desires to view on the portable information terminal, and further, one portable information terminal is used for viewing the terrestrial digital broadcast and viewing the terrestrial digital radio broadcast. The user's desire to do this is also expected.

  However, since the frequency band of terrestrial digital broadcasting is different from the frequency band of terrestrial digital radio broadcasting, when a conventional antenna technology is used, a receiving antenna for terrestrial digital broadcasting and a receiving antenna for terrestrial digital radio broadcasting are provided in one terminal. Must be provided separately. The two external antennas have different lengths. For this reason, various problems, such as the enlargement of an apparatus and the difficulty of the external appearance design process by having two broadcast receiving external antennas, generate | occur | produce.

The present invention has been made to solve the technical problems as described above, and an object of the present invention is to provide an antenna device and a receiving device that enable reception in different frequency bands while suppressing an increase in size. It is to provide.
Another object of the present invention is to provide an antenna device that facilitates appearance design processing even if it has a function of receiving different frequency bands.

  For this purpose, an antenna device to which the present invention is applied includes a first antenna element having a predetermined antenna length, a second antenna element having an antenna length different from the first antenna element, A first ground having a ground length substantially the same as the antenna length of the first antenna element; a second ground having a ground length substantially the same as the antenna length of the second antenna element; And a tuner unit to which the first antenna element, the second antenna element, the first ground, and the second ground are connected.

  Here, a change element for changing a tuning frequency of the second antenna element and the second ground may be further included. The antenna further includes an element that is provided on the second antenna element and the second ground and that realizes an antenna length different from that of the first antenna element by the length of the antenna of the first antenna element. Can be characterized. In addition, the first antenna element and the second antenna element are disposed substantially parallel to each other, and the first ground and / or the second ground are disposed substantially parallel to the first antenna element. It can be characterized by being.

  From another point of view, the antenna device to which the present invention is applied uses a part of a plurality of core wires incorporated in a cable having a predetermined length as an antenna wire and another part or the remaining part of the plurality of core wires. Is used as a ground line corresponding to the antenna line, and a changing element that changes the resonance frequency of the antenna is connected to some or all of the plurality of core lines, thereby making the antenna lengths of the core lines used as antenna lines different from each other The ground lengths of the core wires used as the ground wires are different from each other, and the plurality of core wires used as the antenna wires and the ground wires are connected to the tuner portion so that radio waves received by the plurality of core wires are input to the tuner portion. It is characterized by.

  Here, the change element may be a shortening capacitor or an extension coil.

  Further, taking another aspect of the present invention, a receiving apparatus to which the present invention is applied includes an apparatus body having a tuner unit, a first antenna element connected to the tuner unit and having a predetermined antenna length, A second antenna element connected to the tuner section and having an antenna length different from that of the first antenna element; and a ground length connected to the tuner section and substantially the same as the antenna length of the first antenna element. And a second ground connected to the tuner section and having a ground length substantially the same as the antenna length of the second antenna element.

  According to the present invention, it is possible to receive different frequency bands while suppressing an increase in size.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing an appearance of a mobile phone 1 according to the present embodiment.
A cellular phone (receiving device) 1 shown in FIG. 1 has a function (antenna device) for receiving and viewing a desired radio wave broadcast such as FM radio broadcast, terrestrial digital broadcast, digital radio broadcast, or the like. That is, the mobile phone 1 includes an antenna (rod antenna) 2 for receiving a radio broadcast, a tuner unit 3 (see FIG. 2) connected to the antenna 2 and viewing the radio broadcast received by the antenna 2; Have As described above, the mobile phone 1 is configured such that the radio wave received by the antenna 2 is input to the tuner unit 3 (see FIG. 2). Note that a quarter wavelength antenna is used as the antenna 2.

  In addition, the mobile phone 1 has a music playback function for playing back music recorded in advance in a predetermined data format such as MP3 format in an internal memory or external memory (not shown). The term “external memory” as used herein refers to a storage medium that can be detachably attached to the mobile phone 1, such as an SD memory card. In addition, the mobile phone 1 has a jack (not shown) to which an earphone (not shown) is connected.

  One end of the antenna 2 is pivotally supported on the main body (device main body) 11 of the mobile phone 1. That is, the user can change the attitude of the antenna 2 with respect to the mobile phone 1. For this reason, the user changes the direction of the antenna 2 while holding the mobile phone 1 in his / her hand, for example, so that the directivity of the antenna 2 matches the arrival direction of the radio wave so that the reception state is optimized. Can do. The main body 11 of the mobile phone 1 has an outer shape so that the antenna 2 can be accommodated. It is also conceivable to use a multistage telescopic antenna.

  In the present embodiment, the case where the present invention is applied to the mobile phone 1 has been described. However, it may be applied to other terminals such as a personal computer. Further, it may be applied to a device that can be connected to a USB (Universal Serial Bus) connector of a personal computer.

[First Embodiment]
FIGS. 2A and 2B are schematic configuration diagrams for explaining a main part of the mobile phone 1 according to the first embodiment.
As shown in FIG. 2A, the cellular phone 1 (see FIG. 1) includes an antenna line (first antenna element) A1 and an antenna line (second antenna element) A2 that constitute a part of the antenna 2. , A ground line (first ground) G1 and a ground line (second ground) G2. The mobile phone 1 (see FIG. 1) includes a substrate 4 on which a tuner unit 3 is mounted.

  The plurality of antenna lines A1 and A2 are connected to the signal terminal 3a of the tuner section 3, and the plurality of ground lines G1 and G2 are connected to the ground terminal 3g of the tuner section 3. That is, the plurality of antenna lines A1 and A2 are directly connected to the tuner unit 3 through the signal terminal 3a, and the plurality of ground lines G1 and G2 are directly connected to the tuner unit 3 through the ground terminal 3g. Yes. It is also conceivable that the ground line G1 or the ground line G2 is grounded to the main body.

The plurality of antenna lines A1 and A2 and the plurality of ground lines G1 and G2 are arranged in parallel to each other. The antenna lines A1 and A2 and the ground lines G1 and G2 are bundled to constitute the antenna 2 (see FIG. 1).
Here, normally, the antenna line and the ground line are used in a widened state. In the expanded state, a single peak characteristic is obtained, and a necessary gain characteristic is obtained. On the other hand, when the antenna lines A1, A2 and the ground lines G1, G2 are used in parallel with each other as in the present embodiment, the antenna 2 (see FIG. 1) can be configured compactly, The gain characteristic becomes narrow and the band becomes narrow. Therefore, the antenna lines A1 and A2 and the ground lines G1 and G2 that have antenna resonance frequencies slightly shifted from each other are connected to the tuner unit 3 to obtain a wide band.

  In the equivalent circuit shown in FIG. 2B, the antenna line A1 and the antenna line A2 have different antenna lengths (electrical lengths) and have length dimensions (mechanical lengths, physical lengths). Different. That is, the antenna length of the antenna line A1 is longer than the antenna length of the antenna line A2. Moreover, the length dimension of the antenna line A1 is longer than the length dimension of the antenna line A2.

Further, the antenna length of the antenna line A1 and the ground length (electrical length) of the ground line G1 are substantially the same, and the length dimension of the antenna line A1 and the length dimension of the ground line G1 are substantially the same. Are the same.
The antenna length of the antenna line A2 and the ground length of the ground line G2 are substantially the same, and the length dimension of the antenna line A2 and the length dimension of the ground line G2 are substantially the same.

FIGS. 3A and 3B are graphs for explaining the characteristics of the antenna 2 in the mobile phone 1 according to the first embodiment. Specifically, the horizontal axis of (a) is frequency (f), and the vertical axis is gain (GAIN). In addition, the horizontal axis of (b) is the frequency (f), and the vertical axis is the impedance (Z).
By using antenna lines A1 and A2 having different antenna lengths and ground lines G1 and G2 having different ground lengths, as shown in FIGS. 3A and 3B, two center frequencies f1 and f2 are provided. ing. That is, the center frequency f1 is due to the antenna line A1 and the ground line G1, and the center frequency f2 is due to the antenna line A2 and the ground line G2. Therefore, it can be said that the antenna 2 has two frequency bands. That is, the antenna 2 can be said to be a multiband antenna.

FIG. 4 is a schematic configuration diagram for explaining the configuration of the antenna 2 in a modification of the present embodiment.
In the modification shown in FIG. 4, the antenna 2 includes antenna lines A1, A2, A3 and ground lines G1, G2, G3. Each of the plurality of antenna lines A1, A2, A3 is connected to the signal terminal 3a of the tuner unit 3, and each of the plurality of ground lines G1, G2, G3 is connected to the ground terminal 3g of the tuner unit 3. Yes.
The antenna lines A1, A2, and A3 have different antenna lengths and length dimensions. That is, the antenna length of the antenna line A2 is shorter than the antenna length of the antenna line A1 and longer than the antenna length of the antenna line A3. The length of the antenna line A2 is shorter than the length of the antenna line A1 and longer than the length of the antenna line A3.

  The ground length of the ground line G1 is substantially the same as the ground length of the antenna line A1, and the length dimension of the ground line G1 is substantially the same as the length dimension of the antenna line A1. The ground length of the ground line G2 is substantially the same as the ground length of the antenna line A2, and the length dimension of the ground line G2 is substantially the same as the length dimension of the antenna line A2. The ground length of the ground line G3 is substantially the same as the ground length of the antenna line A3, and the length dimension of the ground line G3 is substantially the same as the length dimension of the antenna line A3.

  As described above, in the modification, a plurality of antenna lines A1, A2, and A3 having different antenna lengths are directly connected to one tuner unit 3, and the same number of ground lines G1 as the plurality of antenna lines A1, A2, and A3 are connected. , G2 and G3 are connected directly to constitute the antenna 2. The ground lengths of the plurality of ground lines G1, G2, G3 are substantially the same as the antenna lengths of the corresponding plurality of antenna lines A1, A2, A3.

FIGS. 5A and 5B are graphs for explaining the characteristics of the antenna 2 in the modification shown in FIG. Specifically, the horizontal axis of (a) is frequency (f), and the vertical axis is gain (GAIN). In addition, the horizontal axis of (b) is the frequency (f), and the vertical axis is the impedance (Z).
By using antenna lines A1, A2 and A3 having different antenna lengths and ground lines G1, G2 and G3 having different ground lengths, as shown in FIGS. 5A and 5B, three center frequencies f1 are obtained. , F2 and f3. That is, the center frequency f1 is due to the antenna line A1 and the ground line G1, the center frequency f2 is due to the antenna line A2 and the ground line G2, and the center frequency f3 is due to the antenna line A3 and the ground line G3. It is. Therefore, it can be said that the antenna 2 is a multiband antenna having three frequency bands.

  Here, the difference between the center frequency f2 and the center frequency f3 is smaller than the difference between the center frequency f1 and the center frequency f2. For example, by increasing the number of antenna lines and ground lines so that the center frequencies of the antenna lines and the ground lines are close to each other, the receivable frequency band can be widened. As shown in FIG. 6 to be described later, the digital radio band is relatively narrow, but the terrestrial digital band is relatively wide. For this reason, the wide band as described above enables reception over the entire range of the terrestrial digital band. Note that the number of antenna lines (ground lines) and the numerical value of the antenna length (ground length) can be determined according to the specifically required antenna characteristics.

FIGS. 6A and 6B are graphs for explaining the reception sensitivity of the antenna 2 of the present embodiment. Specifically, FIG. 6 (a) shows the amplitude characteristics when a 12 cm transmission antenna is used, and the vertical axis indicates the spectrum level (dB) obtained by measuring the received radio wave with a spectrum analyzer, and the horizontal axis. The axis is frequency (MHz). FIG. 6B shows VSWR (Voltage Standing Wave Ratio) characteristics, where the vertical axis represents the VSWR value and the horizontal axis represents the frequency (MHz).
The solid lines in FIGS. 6A and 6B indicate the reception sensitivity of the antenna 2 composed of the antenna lines A1 and A2 and the ground lines G1 and G2, and the broken line indicates an ideal antenna with a 12 cm antenna. This shows the receiving sensitivity.
Here, the frequency band (digital radio band) of digital radio broadcasting is, for example, 188 MHz to 198 MHz, and in this case, the center frequency fc = 192 MHz. The frequency band (terrestrial digital band) of terrestrial digital broadcasting is 470 MHz to 770 MHz (analog TV 13 to 62 CH).

  As shown in FIG. 6A, the antenna 2 of the present embodiment shows amplitude characteristics that are substantially equal to or exceeding the ideal antenna in the digital radio band and the terrestrial digital band. In particular, a plurality of antenna elements and a plurality of ground wires are used, and the resonance frequency of each antenna is shifted little by little, thereby forming a trapezoidal shape in the terrestrial digital band and widening the band. Further, the antenna 2 of the present embodiment has a VSWR characteristic superior to that of an ideal antenna in the digital radio band, as shown in FIG. 6B. Also, in the terrestrial digital band, there is a section having a VSWR characteristic superior to that of an ideal antenna.

  Thus, in this embodiment, a plurality of bands can be received with one antenna. For this reason, it is not necessary to separately provide a receiving antenna for terrestrial digital broadcasting and a receiving antenna for terrestrial digital radio broadcasting. More specifically, one of the two broadcast receiving antennas may be a conventionally proposed earphone antenna. That is, it is also conceivable to apply a technique of using an earphone (headphone) cable as an external antenna so that one of the antennas is an earphone antenna. However, it is necessary for the user to connect the earphone antenna to a portable information terminal, an electronic information terminal or the like when only viewing the digital terrestrial broadcast video or only the digital terrestrial radio broadcast data broadcasting. It is. From this point of view, the antenna device or the receiving device according to the present embodiment can configure two broadcast receiving antennas without using the earphone antenna, and thus can be said to be user-friendly.

[Second Embodiment]
FIG. 7 is a schematic configuration diagram for explaining a main part of the mobile phone 1 (see FIG. 1) according to the second embodiment.
As shown in FIG. 7, antenna lines (antenna elements) AA1 and AA2 and ground lines GG1 and GG2 constituting a part of the antenna 2 and a tuner unit 3 are included. The plurality of antenna lines AA1 and AA2 are connected to the signal terminal 3a of the tuner unit 3, and the plurality of ground lines GG1 and GG2 are connected to the ground terminal 3g of the tuner unit 3.
The length dimension of the antenna line AA1 and the length dimension of the antenna line AA2 are substantially the same. The length dimension of the ground line GG1 and the length dimension of the ground line GG2 are substantially the same.

  Here, the changing element (element) La1 is provided (connected) to the antenna line AA1, and the changing element La2 is provided to the antenna line AA2. The ground line GG1 is provided with a changing element Lg1, and the ground line GG2 is provided with a changing element Lg2. Due to the action of these changing elements La1, La2, Lg1, and Lg2, the antenna line AA1 and the antenna line AA2 are different from each other in spite of having substantially the same length as described later, and the ground line GG1. The ground lines GG2 are different in ground length from each other even though the lengths are substantially the same.

  The operation of the changing elements La1, La2, Lg1, and Lg2 will be described. These change elements La1, La2, Lg1, and Lg2 are elements that change the tuning frequency or elements that change the resonance frequency of the antenna. As the change elements La1, La2, Lg1, and Lg2, for example, a loading coil (chip inductor) or a shortening capacitor as an extension coil can be used. This loading coil is an element for lowering the tuning frequency or the resonance frequency of the antenna, and acts to lower the center frequency fc. The shortening capacitor is an element for increasing the tuning frequency or the resonance frequency of the antenna, and acts to increase the center frequency fc. Therefore, for example, when a loading coil is used for the antenna line AA1 as the changing element La1, the antenna length of the antenna line AA1 is increased, and as a result, the length dimension of the antenna line AA1 can be shortened. For example, when a shortening capacitor is used for the antenna line AA2 as the changing element La2, the antenna length of the antenna line AA2 is shortened, and as a result, the length of the antenna line AA2 can be increased.

  More specifically, the changing elements La1, La2, Lg1, and Lg2 to be used satisfy the specifically required antenna length and ground length, and the lengths of the antenna lines AA1, AA2, and the ground lines GG1, GG2 are aligned. Can be determined. In other words, by appropriately combining the changing elements La1, La2, Lg1, and Lg2, different antenna lengths and ground lengths can be realized with the same length dimension. Of course, depending on the required antenna characteristics, it is conceivable to use an extension coil for a part of the changing elements La1, La2, Lg1, and Lg2 and a shortening capacitor for the other part.

  In the present embodiment, the changing elements La1, La2, and A2 are connected to the antenna lines AA1 and AA2 and the ground lines GG1 and GG2 in order to align the lengths of the antenna lines AA1 and AA2 and the lengths of the ground lines GG1 and GG2. Lg1 and Lg2 are provided, but depending on the required antenna characteristics, only a part of them, for example, the changing elements La1 and Lg1 are provided only on the antenna line AA1 and the ground line GG1, and the changing elements are provided on the antenna line AA2 and the ground line GG2. There may be a case where it is not necessary to provide La2 and Lg2.

FIG. 8 is a diagram for explaining the configuration of the antenna 2 and the tuner unit 3.
As shown in FIG. 8, the antenna 2 includes a cover member 2a, and a cable 6 containing four core wires is placed inside the cover member 2a. After the cable 6 is cut to a predetermined length, the covering of one end thereof is removed and the four core wires are exposed. The four core wires have substantially the same length. Part of the four core wires is used as the antenna wires AA1 and AA2, and the remaining portions are used as the ground wires GG1 and GG2.

The change elements La1, La2, Lg1, and Lg2 are attached to the substrate 5. The antenna line AA1 is connected to the changing element La1 of the substrate 5, and the antenna line AA2 is connected to the changing element La2 of the substrate 5. The antenna wires AA1 and AA2 are connected to the signal terminal 5a provided on the substrate 5.
The ground line GG1 is connected to the changing element Lg1 of the substrate 5, and the ground line GG2 is connected to the changing element Lg2 of the substrate 5. The ground lines GG1 and GG2 are connected to the ground terminal 5g provided on the substrate 5.

  The signal terminal 5a of the substrate 5 is connected to the signal terminal 3a of the tuner unit 3 by a wire, and the ground terminal 5g of the substrate 5 is connected to the ground terminal 3g of the tuner unit 3 by a wire. Note that it is conceivable that the antenna 2 has a diameter of 3 mm and a length of 40 mm, for example.

  When the configuration shown in FIG. 8 is adopted, the antenna 2 can be manufactured using the cable 6 incorporating a plurality of core wires, so that the manufacturing becomes easy and the cost can be reduced. In the present embodiment, the cable 6 including four core wires is used, but a cable 6 including a larger number of core wires than four can also be used.

FIG. 9 is a diagram for explaining the configuration of the antenna 2 and the tuner unit 3 different from those in FIG.
The configuration shown in FIG. 9 has many in common with the configuration shown in FIG. That is, a cable 6 containing four core wires is placed inside the cover member 2 a of the antenna 2. The cable 6 is cut to a predetermined length, and then one end of the cable 6 is removed. Of the four core wires, three core wires are exposed, and the remaining one core wire is cut. The three exposed core wires have substantially the same length. Part of the four core wires is used as the antenna lines AA1 and AA2, and the other part is used as the ground line GG2. That is, all four core wires built in the cable 6 are not used.

  In the configuration shown in FIG. 9, the ground line GG2 of the two ground lines GG1 and GG2 uses the core wire of the cable 6, but the other ground line GG1 does not use the core wire of the cable 6. Instead, a pattern provided on the substrate 5 is used. This means that even if the number of core wires of the cable 6 is not an even number but an odd number, it can be handled. Moreover, it means that it is not always necessary to use all the core wires of the cable 6.

It is the schematic which shows the external appearance of the mobile telephone which concerns on this Embodiment. It is a schematic block diagram for demonstrating the principal part of the mobile telephone which concerns on 1st Embodiment. It is a graph for demonstrating the characteristic of the antenna in the mobile telephone based on 1st Embodiment, The horizontal axis of (a) is a frequency (f), a vertical axis | shaft is a gain (GAIN), The horizontal axis | shaft of (b) The axis is frequency (f), and the vertical axis is impedance (Z). It is a schematic block diagram for demonstrating the structure of the antenna in the modification of 1st Embodiment. 5 is a graph for explaining the characteristics of the antenna in the modification shown in FIG. 4, where the horizontal axis of (a) is frequency (f), the vertical axis is gain (GAIN), and the horizontal axis of (b) is frequency f), the vertical axis represents impedance (Z). It is a graph explaining the receiving sensitivity of the antenna of 1st Embodiment, a vertical axis | shaft is a spectrum level (dB), a horizontal axis is a frequency (MHz), (b) is a vertical axis | shaft, VSWR value, horizontal The axis is frequency (MHz). It is a schematic block diagram for demonstrating the principal part of the mobile telephone which concerns on 2nd Embodiment. It is a figure for demonstrating the structure of an antenna and a tuner part. It is a figure for demonstrating the structure of the antenna and tuner part different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mobile phone, 11 ... Main body, 2 ... Antenna, 2a ... Cover member, 3 ... Tuner part, 3a, 5a ... Signal terminal, 3g, 5g ... Ground terminal, 4, 5 ... Substrate, 6 ... Cable, A1, A2 , A3, AA1, AA2 ... antenna wire, G1, G2, G3, GG1, GG2 ... ground wire, La1, La2, Lg1, Lg2 ... change element

Claims (7)

A first antenna element having a predetermined antenna length;
A second antenna element having an antenna length different from the first antenna element;
A first ground having a ground length substantially the same as the antenna length of the first antenna element;
A second ground having a ground length substantially the same as the antenna length of the second antenna element;
A tuner unit to which the first antenna element, the second antenna element, the first ground, and the second ground are connected;
An antenna device including:   The antenna device according to claim 1, further comprising a changing element that changes a tuning frequency of the second antenna element and the second ground.   It further includes an element that is provided on the second antenna element and the second ground and that realizes an antenna length different from that of the first antenna element by the length of the antenna of the first antenna element. The antenna device according to claim 1. The first antenna element and the second antenna element are arranged substantially parallel to each other;
2. The antenna device according to claim 1, wherein the first ground and / or the second ground is disposed substantially parallel to the first antenna element. Using a part of a plurality of core wires built in a cable of a predetermined length as an antenna line and using the other part or the remaining part of the plurality of core wires as a ground line corresponding to the antenna line,
By connecting a changing element that changes the resonance frequency of the antenna to some or all of the plurality of core wires, the antenna lengths of the core wires used as the antenna wires are made different from each other, and the ground lengths of the core wires used as the ground wires are made different from each other. ,
An antenna device, wherein the plurality of core wires used as an antenna line and a ground line are connected to the tuner unit so that radio waves received by the plurality of core wires are input to the tuner unit.   The antenna device according to claim 5, wherein the changing element is a shortening capacitor or an extension coil. An apparatus main body having a tuner section;
A first antenna element connected to the tuner unit and having a predetermined antenna length;
A second antenna element connected to the tuner section and having an antenna length different from that of the first antenna element;
A first ground connected to the tuner unit and having a ground length substantially the same as the antenna length of the first antenna element;
A second ground connected to the tuner section and having a ground length substantially the same as the antenna length of the second antenna element;
Including a receiving device.

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