JP2002094320A - Antenna for multi-frequency use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-frequency use antenna that can be operated over two different broad frequency bands. SOLUTION: A body case 3 contains an antenna board 5, on which a DCS(digital cellular system) antenna pattern is formed. An external antenna 2 fitted to the body case 3 by screwing a fixed screw section 31 is connected to an upper end of the antenna board 5. Then a GSM(global system for mobile communications) antenna is structured with a D-net element 12 for the external antenna 2 and the antenna pattern formed on the antenna board 5. Thus, the reduced-size antenna can be operated over two different broad frequency bands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-frequency antenna operable in a first mobile radio band, a second mobile radio band, and an FM / AM radio band.

[0002]

2. Description of the Related Art There are various types of antennas mounted on a vehicle body. However, if the antenna is mounted on the roof located at the highest position in the vehicle body, the receiving sensitivity can be increased. Preferred by Since an FM / AM radio is generally provided in the vehicle body, the FM / AM radio is provided.
Since an antenna that can receive both radio bands is convenient, a roof antenna that can receive two radio bands in common has become widespread.

[0003] When a mobile telephone is mounted, an antenna for the mobile telephone is installed on the vehicle body. However, when the number of subscribers is insufficient and the available frequency is insufficient, the frequency band of the mobile telephone is almost equal. There are cases where two frequency bands are assigned, a frequency band available in the whole area and a frequency band available in urban areas. For example, in Europe 90
A GSM mobile phone in the 0 MHz band can be used throughout Europe, but a DCS mobile phone in the 1.8 GHz band can be used in an urban area to compensate for a shortage in frequency usage. It is problematic in terms of design to separately install such various antennas on the vehicle body, and maintenance and mounting work are complicated. Therefore, one antenna can be used for a mobile phone band or a FM band having two frequency bands. A multi-frequency antenna for receiving the / AM radio band has been proposed.

As this type of multi-frequency antenna, a multi-frequency antenna described in Japanese Patent Application Laid-Open No. 6-132714 is known. This multi-frequency antenna includes a telescopic rod antenna, which is a three-wave antenna capable of receiving a mobile phone band, an FM radio band, and an AM radio band, and a GPS.
It is composed of a planar radiator that is a GPS antenna for receiving a signal, and a loop radiator that is a keyless entry antenna for receiving a keyless entry signal. Each of these antennas is installed on the upper surface of the main body, but a metal plate is provided on the upper part of the main body, and a planar radiator and a loop radiator are formed on the plate via a dielectric layer. ing. Since this plate becomes a ground plane, the plane radiator and the loop radiator operate as a microstrip antenna. Note that a protective cover is formed on the plane radiator and the loop radiator.

In such a multi-frequency antenna,
Since the antenna is provided with a rod antenna which can be extended and contracted, a space for accommodating the rod antenna is required at the time of attachment. Therefore, a multi-frequency antenna can be attached to a trunk lid or a fender of a vehicle body in which a space can be formed, but such a storage space does not exist in a roof suitable for installing the antenna. Therefore, it cannot be attached.

Therefore, a multi-frequency antenna designed to solve this problem is disclosed in Japanese Patent Application Laid-Open No. Hei 10-93327. This multi-frequency antenna is composed of an antenna element that resonates at multiple frequencies by providing a trap coil, and a main body case in which a matching board and the like to which the antenna element is attached are built. By fixing the main body case to the roof, a multi-frequency antenna can be attached to the roof.

[0007]

By the way, as described above, a plurality of frequency bands are allocated to the frequency band used for the mobile telephone as the number of users increases. For example, the PDC system (Personal Digital Cellu
lar telecommunication system), 800 MHz band (810 MHz to 956 MHz) and 1.4 GHz band (1
429 MHz to 1501 MHz) and 800 MHz band (870 MHz to 9 MHz) in Europe.
60MHz) GSM (Global System for Mobile com)
munications) system and 1.7 GHz band (1710 MH)
z-1880MHz) DCS (Digital Cellular Sys)
tem) method. In order to operate the antennas in such a plurality of frequency bands, antennas operating in each frequency band are provided, but the two antennas are connected via choke coils so as not to affect each other's operation. It is common.

However, it is difficult for a choke coil such as a trap coil to separate signals over a wide frequency band. That is, even if a choke coil is provided between antennas operating in each frequency band, in the case of a wide frequency band such as a mobile telephone band, each antenna cannot operate independently over that frequency band. However, there is a problem that they cannot affect each other and operate satisfactorily. In addition, there is a problem that the provision of the choke coil increases the size of the antenna.

Accordingly, an object of the present invention is to provide a multi-frequency antenna which operates over at least two different wide frequency bands and is downsized.

[0010]

To achieve the above object, a multi-frequency antenna according to the present invention comprises a first antenna pattern formed on a front surface or a back surface of a printed circuit board, and a first antenna pattern formed on the back surface or a front surface of the printed circuit board. A second antenna pattern that is formed, and the upper ends of the first antenna pattern and the second antenna pattern are connected,
First antenna means operable in a first frequency band;
Second antenna means operable in a second frequency band lower than the first frequency band, comprising antenna means, and an external element connected to the upper end of the first antenna means; And a main body case in which the first antenna means is built-in.

Further, in the multi-frequency antenna according to the present invention, the first frequency band is a first mobile radio band, and the second frequency band is a frequency which is approximately 1/2 of the first mobile radio band. The second mobile radio band may be used as the band. Furthermore, in the multi-frequency antenna according to the present invention, a matching inductor may be connected between a lower end of the first antenna pattern and a lower end of the second antenna pattern. Furthermore, in the multi-frequency antenna according to the present invention, a third element operating in a third frequency band which is much lower than the first frequency band is provided at a tip of the external element via a choke coil. , The first
A demultiplexing unit for demultiplexing the frequency band, the second frequency band, and the third frequency band may be incorporated in a circuit board built in the main body case. Still further, in the multi-frequency antenna according to the present invention, the first frequency band and the second
A matching capacitor may be connected between an output terminal that outputs a reception signal in a frequency band and ground.

According to the present invention, the first antenna means operating in the first frequency band is constituted by the first antenna pattern and the second antenna pattern formed on the front and back surfaces of the printed circuit board. Since the printed circuit board on which the antenna means is formed is incorporated in the main body case, the size can be reduced. Further, when an external antenna is connected to the upper end of the first antenna means, the antenna operates in the second frequency band, and the second antenna means including the external antenna and the first antenna means is used as an antenna for the second frequency band. Can be. Thus, the antenna can operate over two different wide frequency bands and can be a miniaturized multi-frequency antenna. Further, a matching inductor may be connected between the lower end of the first antenna pattern and the lower end of the second antenna pattern, or a matching inductor may be connected between the output terminal for outputting the received signal of the first frequency band and the second frequency band and the ground. By connecting the capacitor, the antenna characteristics of the multi-frequency antenna can be improved, and the antenna can operate in a wider frequency band.

[0013]

1 to 3 show the configuration of an embodiment of a multi-frequency antenna according to the present invention. However, FIG. 1 is a diagram showing the entire configuration of the multi-frequency antenna of the present invention, FIG. 2 is a plan view showing the configuration of the multi-frequency antenna of the present invention in a state where the cover is removed, and FIG. It is a front view. As shown in these drawings, the multi-frequency antenna 1 according to the first embodiment of the present invention includes an external antenna 2 serving as a whip antenna and a main body case 3 to which the external antenna 2 is detachably attached. It is configured. The main body case 3 includes a metal antenna base 4
And a resin cover 9 fitted to the antenna base 4. The external antenna 2 includes a bendable flexible element portion 14a, a helical element portion 14b provided at an upper end of the flexible element portion 14a, and an upper end of the helical element portion 14b. Antenna top 14c provided. Further, one end of the choke coil 13 is connected to the lower end of the flexible element portion 14a,
The other end of the choke coil 13 is connected to a D-net element 12 corresponding to a D-net (GSM) upper element. At the lower end of the D-net element 12, a fixing screw portion 31 is provided. The lower part of the helical element part 14b and the flexible element part 14
The upper part of a, the choke coil 13, the D-net element 12, and the fixing screw part 31 is molded to form the antenna base 30.

Here, the D-net means the first mobile telephone band based on the GSM system, and the E-net described later means the second mobile telephone band based on the DCS system. Note that a wind noise preventing means wound in a coil shape is provided on the helical element portion 14b. The flexible element portion 14a is connected to the external antenna 2
This is a portion for preventing bending due to bending when a lateral load is applied to the horn. The flexible element portion 14a can be configured by a flexible wire cable or coil spring.

Cover 9 formed by resin molding
Is fitted to a metal antenna base 4 shown in FIGS. 2 and 3, from which a cylindrical mounting portion 4 b for mounting on a roof or the like of a vehicle body projects. A screw is cut on the outer peripheral surface of the mounting portion 4b, and by screwing a nut to the mounting portion 4b, the vehicle body can be fixed to be sandwiched between the antenna base 4 and the nut. Note that the antenna base 4 and the cover 9 are integrated by inserting a pair of screws from the back surface into a pair of screw insertion holes 4 a formed in the antenna base 4 and screwing to the cover 9. . The attachment portion 4b has a through hole formed along its axis, and the first cable 7 and the second cable 8 can be led out of the main body case 3 through the through hole. At this time, a cutout groove is formed in the through hole in the axial direction, and by using the cutout groove, the first cable 7 and the second cable 8 are connected to the antenna base 4 as shown in FIGS. Can be led out substantially in parallel to the back surface of. First cable 7
Is provided with a plug 7a at the end thereof, and a plug 8a is provided at the end of the second cable 8, and these plugs 7a and 8a are respectively connected to corresponding devices mounted in the vehicle.

At the upper end of the main body case 3, there is provided a connection portion to which the external antenna 2 can be detachably attached. The external antenna 2 can be mechanically and electrically fixed to the main body case 3 by screwing the fixing screw portion 31 of the external antenna 2 to the connection portion. In the body case 3,
As shown in FIGS. 2 and 3, two printed boards, an antenna board 5 and a circuit board 6, are housed. A characteristic configuration of the multi-frequency antenna 1 of the present invention is a configuration of the antenna substrate 5 built in the main body case 3. On the antenna substrate 5, a DCS element 11 for an E-net is formed. The DCS element 11 also operates as a part of a D-net element. here,
The configuration of the antenna substrate 5 will be described with reference to FIG.

FIG. 4A shows the structure of the surface of the antenna substrate 5.
FIG. 4B shows the configuration of the back surface of the antenna substrate 5. As shown in these drawings, the antenna substrate 5 is formed in a substantially rectangular shape deformed according to the shape of the internal space of the main body case 3. A wide first antenna pattern 11a is formed to be bent on the front surface of the antenna substrate 5, and a wide second antenna pattern 11b is formed in a substantially rectangular shape on the back surface of the antenna substrate 5. A through hole 5d is formed at the lower end of the first antenna pattern 11a, and the through hole 5d is connected to a connection pattern 5c formed on the back surface. That is, the first
The antenna pattern 11a is connected to the connection pattern 5c. The upper end of the first antenna pattern 11a and the upper end of the second antenna pattern 11b are
Are connected by a pattern formed on the side surface of.

As an example of the dimensions of the antenna substrate 5, the width W1 of the antenna substrate 5 is about 37.8 mm.
Height H1 is about 25.6 mm. The width W2 of the first antenna pattern 11a is about 8 mm, and the width W3 where the lower end through hole 5d is formed is about 4 mm. Further, the width W of the second antenna pattern 11b
4 is about 12.5 mm, and the length H2 is about 20.1 mm
It has been. However, the dimensions of the first antenna pattern 11a and the second antenna pattern 11b are for E-net, and the above dimensions will be different if the applied frequency band is different. The first antenna pattern 1
Instead of forming 1a on the front surface of antenna substrate 5, it may be formed on the back surface, and second antenna pattern 11b may be formed on the front surface of antenna substrate 5.

Returning to FIGS. 2 and 3, a metal external antenna connecting piece 5a is provided at the upper end of the antenna substrate 5, and the external antenna connecting piece 5a is connected to the upper end of the first antenna pattern 11a and the second antenna pattern. It is connected to a pattern connecting the upper end with the pattern 11b. And
The fixing screw portion 31 of the external antenna 2 is
Is externally connected to the external antenna connecting piece 5a connected to the connecting portion. The multi-frequency antenna 1 according to the present invention having the above-described configuration has the F
It is possible to receive the M broadcast while resonating with the M broadcast and to receive the AM broadcast. Also, the choke coil 13
In this case, the element is resonated with the D-net by the element 12 or less for the D-net and can transmit and receive in the GSM frequency band. You will be able to send and receive.

The antenna substrate 5 is provided with a matching inductor L1.
Is the lower end of the second antenna pattern 11b and the connection pattern 5
c. This matching inductor L1
Is provided, the antenna characteristics of the multi-frequency antenna 1 in the D-net and the E-net can be improved as described later. The circuit board 6 has an AM / FM
And an amplifying circuit that amplifies the signal of the divided AM / FM frequency band.
Further, on the circuit board 6, a matching capacitor C1 described later is provided between the output terminals of the D net and the E net and the ground.

The multi-frequency antenna 1 configured as described above
6 and a circuit assembled on the circuit board 6 are shown in circuit blocks in FIG. As shown in FIG. 6, the multi-frequency antenna 1 includes an external antenna 2 and an internal antenna 10 built in a main body case 3. External antenna 2
Is an upper element 14 composed of a flexible element portion 14a and a helical element portion 14b shown in FIG.
It is configured by connecting the net element 12 via a choke coil 13. Internal antenna 1
Reference numeral 0 denotes a DCS element 11 including a first antenna pattern 11a formed on the front surface of the antenna substrate 5 and a second antenna pattern 11b formed on the back surface. In such a multi-frequency antenna 1, as shown in the drawing, the antenna composed of the DCS element 11 operates in the DCS frequency band, and the antenna composed of the DCS element 11 and the D-net element 12 becomes the GSM frequency band. To work with. Further, the antenna composed of the internal antenna 10 and the external antenna 2 operates in the AM / FM frequency band.

The output terminal of the multi-frequency antenna 1 is connected to a high-pass filter (HPF) 20 and a low-pass filter (LPF).
The frequency band components of the D-net and the E-net are split by the HPF 20, and the split signal is output from the GSM / DCS output terminal. Also, LP
The frequency band component of AM / FM is demultiplexed by F21,
The split signal is amplified by the AM / FM amplifier 22 and output from the AM / FM output terminal. In order to improve the antenna characteristics of the multi-frequency antenna 1, a matching inductor L1 is connected between the lower end of the second antenna pattern 11b and the first antenna pattern 11a.
Matching capacitor C between SM / DCS output terminal and ground
1 is connected.

Next, the DCS formed on the antenna substrate 5
Another configuration of the element 11 is shown in FIG. FIG. 5A shows another configuration of the front surface of the antenna substrate 5, and FIG. 5B shows the configuration of the rear surface of the antenna substrate 5. On the surface of the antenna substrate 5, a wide first antenna pattern 51a is formed so as to be bent so as to gradually become narrower, and on the back surface of the antenna substrate 5, a wide second antenna pattern 51b is formed. . A through hole 5d is formed at a lower end of the first antenna pattern 51a, and the through hole 5d is connected to a connection pattern 5c formed on the back surface. That is, the first antenna pattern 51a is connected to the connection pattern 5c. Also, the upper end of the first antenna pattern 51a and the second antenna pattern 51b
Are connected to each other by a pattern formed on the side surface of the antenna substrate 5.

The upper portion of the first antenna pattern 51a has a width W5 of about 8 mm, and the lower end of the through hole 5d has a width W6 of about 4 mm. further,
The width W7 of the second antenna pattern 51b is about 12.5 mm
And the length H3 is about 20.1 mm. However, the dimensions of the first antenna pattern 51a and the second antenna pattern 51b are for E-net, and the above dimensions will be different if the applied frequency band is different. Even if the antenna pattern 5 shown in FIG. 5 is used instead of the antenna pattern 5 shown in FIG. 4, the multi-frequency antenna 1 according to the present invention can obtain almost the same antenna characteristics. . The first antenna pattern 51a may be formed on the back surface instead of being formed on the front surface of the antenna substrate 5, and the second antenna pattern 51b may be formed on the front surface of the antenna substrate 5.

Next, the multi-frequency antenna 1 according to the present invention.
GSM frequency band (870MHz to 960MHz)
7 is a Smith chart shown in FIG. 7, and its voltage standing wave ratio (VSWR) characteristics are shown in FIG. However, the antenna characteristics shown in FIGS. 7 and 8 assume that the matching inductor L1 and the matching capacitor C1 are not connected. Referring to the antenna characteristics shown in FIGS. 7 and 8, VS in the GSM frequency band
The WR is less than about 2.5, which is not a very good characteristic but is somehow usable.

FIG. 9 is a Smith chart showing impedance characteristics of the multi-frequency antenna 1 according to the present invention in the frequency band of DCS (1710 MHz to 1880 MHz), and its voltage standing wave ratio (VSWR) characteristic is shown in FIG.
0 is shown. However, the antenna characteristics shown in FIGS. 9 and 10 assume that the matching inductor L1 and the matching capacitor C1 are not connected. Referring to the antenna characteristics shown in FIG. 9 and FIG. 10, the antenna characteristics are good in the middle to wide band of the DCS frequency band, but are difficult to use in the low band and the high band. ing.

Next, in order to show the action of the matching inductor L1 and the matching capacitor C1, the case where the matching inductor L1 and the matching capacitor C1 are connected in the multi-frequency antenna 1 according to the present invention. FIG. 11 is a Smith chart showing impedance characteristics in the GSM frequency band (870 MHz to 960 MHz), and FIG. 12 shows its VSWR characteristics. Referring to the antenna characteristics shown in FIGS. 11 and 12, the VSWR is less than about 2.0 in the GSM frequency band, which is a sufficiently usable characteristic.

Further, in the multi-frequency antenna 1 according to the present invention, the DCS (1710 MHz) when the matching inductor L1 and the matching capacitor C1 are connected.
FIG. 13 is a Smith chart showing the impedance characteristic in the frequency band of 〜1880 MHz).
The characteristics are shown in FIG. Referring to the antenna characteristics shown in FIGS. 13 and 14, VSWR in the DCS frequency band is obtained.
Is less than about 2.0, which is a sufficiently usable characteristic. The above-mentioned impedance characteristics and VSW
Referring to the R characteristic, even if the first antenna pattern 11a and the second antenna pattern 11b are formed on the front surface and the back surface of the antenna substrate 5 built in the main body case 3,
It can be seen that good antenna characteristics can be obtained in two frequency bands, GSM and DCS, by connecting matching inductor L1 and matching capacitor C1. Note that the antenna characteristics shown in FIGS.
This is an antenna characteristic when the matching inductor L1 is about 18 nH and the matching capacitor C1 is about 0.5 pF.

Next, the multi-frequency antenna 1 according to the present invention.
15 to 18 show the directional characteristics in the horizontal plane of FIG. However, FIG. 15A shows that the multi-frequency antenna 1 is about 1 m in diameter.
In the horizontal plane when it is arranged on the ground plane 50, and this angle corresponds to the angle of the directional characteristic in the horizontal plane described below. FIG. 15B shows the directional characteristics in the horizontal plane at 870 MHz, which is the lower limit frequency of GSM, and circles on concentric circles are drawn every -3 dB. That is, it can be seen that, although a deviation of about 4 dB occurs in the horizontal plane, the directional characteristics are almost circular and good.
The antenna gain in this case is a high gain of about +0.23 dB in comparison with the 波長 wavelength whip antenna.

FIG. 16A shows the directional characteristics in the horizontal plane at 915 MHz, which is the central frequency of GSM, and concentric circles are drawn every -3 dB. In other words, in this case, although a deviation of about 4 dB occurs in the horizontal plane, it is understood that the directional characteristics are almost circular and good. In this case, the antenna gain is about +0.06 dB, which is equivalent to the ratio of a quarter-wave whip antenna. FIG. 16C shows the upper limit frequency of GSM of 96.
This is the directional characteristic in the horizontal plane at 0 MHz, and concentric circles are drawn every -3 dB. That is, it can be seen that although a deviation of about 5 dB occurs in the horizontal plane, the directional characteristics are almost circular and good. The antenna gain in this case is about-
It is 1.79 dB.

FIG. 17A shows the directivity in a horizontal plane at 1710 MHz, which is the lower limit frequency of DCS, and circles on concentric circles are drawn every -3 dB. That is, in the horizontal plane, a deviation of about 8 dB occurs in the ± 110 degrees direction, but it is understood that good directional characteristics are obtained in other directions. The antenna gain in this case is about +
The gain is 0.11 dB. FIG. 17 (b)
This is the directional characteristic in the horizontal plane at 1795 MHz, which is the central frequency of DCS, and concentric circles are drawn every -3 dB. That is, it can be seen that although a deviation of about 5 dB occurs in the horizontal plane, the directional characteristics are almost circular and good. The antenna gain in this case is 1/4
The gain is about -0.72 dB in the wavelength whip antenna ratio.

FIG. 18 shows the upper limit frequency 18 of the DCS.
This is the directional characteristic in the horizontal plane at 80 MHz, and concentric circles are drawn every -3 dB. That is, in the horizontal plane, a deviation of about 5 dB occurs in the +100 degree direction, and a deviation of 6 dB occurs in the -90 degree direction. The antenna gain in this case is a gain of about -0.58 dB at a 1/4 wavelength whip antenna ratio. Referring to these in-horizontal directional characteristics, even if the first antenna pattern 11a and the second antenna pattern 11b are formed on the front surface and the back surface of the antenna substrate 5 built in the main body case 3, the GSM and DCS It can be seen that a substantially circular directional characteristic in a horizontal plane can be obtained in one frequency band.

[0033]

As described above, according to the present invention, the first antenna means operating in the first frequency band is connected to the first antenna pattern formed on the front and back surfaces of the printed circuit board by the second antenna means.
Since the printed circuit board having the antenna pattern and the first antenna means formed therein is incorporated in the main body case, the size can be reduced. Further, when an external antenna is connected to the upper end of the first antenna means, the antenna operates in the second frequency band, and the second antenna means including the external antenna and the first antenna means is used as an antenna for the second frequency band. Can be. Thus, the antenna can operate over two different wide frequency bands and can be a miniaturized multi-frequency antenna. Further, a matching inductor may be connected between the lower end of the first antenna pattern and the lower end of the second antenna pattern, or a matching inductor may be connected between the output terminal for outputting the received signal of the first frequency band and the second frequency band and the ground. By connecting the capacitor, the antenna characteristics of the multi-frequency antenna can be improved, and the antenna can operate in a wider frequency band.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a multi-frequency antenna according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of the multi-frequency antenna according to the embodiment of the present invention, from which a cover is removed.

FIG. 3 is a front view showing the configuration of the multi-frequency antenna according to the embodiment of the present invention, from which a cover is removed.

FIG. 4 is a diagram showing a configuration of an antenna substrate in the multi-frequency antenna according to the embodiment of the present invention.

FIG. 5 is a diagram showing another configuration of the antenna substrate in the multi-frequency antenna according to the embodiment of the present invention.

FIG. 6 is a diagram showing an equivalent circuit of the multi-frequency antenna according to the embodiment of the present invention, and a circuit incorporated in a circuit board.

FIG. 7 is a Smith chart showing impedance characteristics in a GSM frequency band of the multi-frequency antenna according to the embodiment of the present invention.

FIG. 8 is a diagram illustrating a voltage standing wave ratio (VSW) in a GSM frequency band of the multi-frequency antenna according to the embodiment of the present invention.
It is a figure which shows R) characteristic.

FIG. 9 is a Smith chart showing impedance characteristics in a DCS frequency band of the multi-frequency antenna according to the embodiment of the present invention.

FIG. 10 is a diagram showing VSWR characteristics in a GSM frequency band of the multi-frequency antenna according to the embodiment of the present invention.

FIG. 11 is a Smith chart showing impedance characteristics in a GSM frequency band when a matching element is connected in the multi-frequency antenna according to the embodiment of the present invention.

FIG. 12 is a diagram showing VSWR characteristics in a GSM frequency band when a matching element is connected in the multi-frequency antenna according to the embodiment of the present invention.

FIG. 13 is a Smith chart showing impedance characteristics in a DCS frequency band when a matching element is connected in the multi-frequency antenna according to the embodiment of the present invention.

FIG. 14 is a diagram showing VSWR characteristics in a GSM frequency band when a matching element is connected in the multi-frequency antenna according to the embodiment of the present invention.

FIG. 15 is a diagram illustrating a measurement mode of directional characteristics in a horizontal plane of the multi-frequency antenna according to the embodiment of the present invention, and 870 MH
It is a figure which shows the directional characteristic in a horizontal plane in z.

FIG. 16 is a diagram showing directional characteristics in a horizontal plane at 915 MHz and 960 MHZ of the multi-frequency antenna according to the embodiment of the present invention.

FIG. 17 is a diagram showing directional characteristics in a horizontal plane at 1710 MHz and 1795 MHZ of the multi-frequency antenna according to the embodiment of the present invention.

FIG. 18 is a diagram showing directional characteristics in a horizontal plane at 1880 MHZ of the multi-frequency antenna according to the embodiment of the present invention.

[Explanation of symbols]

1 Multi-frequency antenna, 2 External antenna, 3 Body case, 4 Antenna base, 4a Screw insertion hole, 4b
Mounting part, 5 antenna board, 5a external antenna connection piece, 5c connection pattern, 5d through hole, 6 circuit board, 7 first cable, 7a plug, 8 second cable, 8a plug, 9 cover, 10 internal antenna, 11 DCS element, 11a first antenna pattern, 11b second antenna pattern, 12D net element 13 choke coil, 14 upper element, 14a flexible element section, 14b helical element section, 14c antenna top, 20 HP
F, 21 LPF, 22 amplifier, 30 antenna base, 31 fixing screw, 50 ground plane, 51
a first antenna pattern, 51b second antenna pattern, C1 matching capacitor, L1 matching inductor

Claims (5)

[Claims] A first antenna pattern formed on a front surface or a back surface of a printed circuit board; and a second antenna pattern formed on a back surface or a front surface of the printed circuit board, wherein the first antenna pattern and the second antenna are provided. The upper end of the pattern is connected, the first antenna means is operable in a first frequency band, the first antenna means, and an external element connected to the upper end of the first antenna means. A second antenna unit operable in a second frequency band lower than the first frequency band, a main body case in which the external element is detachably attachable, and the first antenna unit is incorporated, A multi-frequency antenna, comprising: 2. The first frequency band is a first mobile radio band, and the second frequency band is substantially one of the first mobile radio bands.
2. The multi-frequency antenna according to claim 1, wherein the second mobile radio band is set to a frequency band twice as high as the second mobile radio band. 3. The multi-frequency antenna according to claim 1, wherein a matching inductor is connected between a lower end of the first antenna pattern and a lower end of the second antenna pattern. 4. A third element operating in a third frequency band, which is much lower than the first frequency band, is provided at a tip of the external element via a choke coil. 2. The multi-frequency device according to claim 1, wherein a splitter for splitting the second frequency band and the third frequency band is incorporated in a circuit board built in the main body case. antenna. 5. The first demultiplexing device according to claim 1, wherein:
5. The multi-frequency antenna according to claim 4, wherein a matching capacitor is connected between an output terminal for outputting a reception signal of a frequency band and the second frequency band and ground.