JP2000165122A - Antenna structure for radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna structure for a radio communication terminal by which a directivity pattern is improved and currents on an enclosure are reduced while keeping the input impedance of the antenna low. SOLUTION: The antenna structure is used for a radio communication terminal 50 that has an enclosure 51 having an electric circuit 11 in its inside and a telescopic antenna 30 mounted on the enclosure 51. While the extraction length of the telescopic antenna 30 from the enclosure 51 is adjusted to a prescribed amount, antenna elements 1, 6 are connected electrically to the electric circuit 11 via a feeding terminal. Simultaneously, the electric length of the upper parts 1b, 6a and the lower parts 1a, 6b from the position of the feeding terminal of the antenna elements 1, 6 can be set independently. The electric length of the upper parts 1b, 6a of the antenna elements 1, 6 is adjusted to 3/8λ and the electric length of the lower parts 1a, 6b of the antenna elements 1, 6 is adjusted to 1/8λfrom the boundary of the feeding terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna structure of a wireless communication device such as a portable telephone.

[0002]

2. Description of the Related Art An antenna structure of a conventional wireless communication apparatus will be described with reference to FIGS. 7 is a perspective view showing the conventional wireless communication apparatus 100 when the antenna 101 is housed, and FIG. 8 is an antenna 10 of the conventional wireless communication apparatus 100.
FIG. 9 is a front view showing the structure of a conventional antenna 101, and FIG. 10 is a perspective view showing a state where a 3 / 8λ rod-shaped antenna 103 is arranged on the back of a radio unit mounting board 107. 11 is a diagram showing the directivity pattern of the XZ plane horizontal polarization component at 1.9 [GHz] when the 3 / 8λ rod-shaped antenna 103 is arranged as shown in FIG.
FIG. 8 is a diagram showing a state of a current distribution simulated at an input of 1 [W] modeled by a wire grid under the same conditions.

[0003] In a radio portable communication device 100 such as a portable car telephone or a PHS as shown in FIGS. 7 and 8, a monopole antenna 1 is used as a transmitting / receiving antenna.
01 is used. The antenna 101 is configured so as to be able to be taken in and out of the case 102 (housing) in consideration of the portability of the portable communication device (extendable / contractible). The antenna 101 has two antennas, a rod antenna element 103 for extension used at the time of extension as shown in FIG. 8 and a helical antenna element 104 for storage used at the time of storage as shown in FIG. (See FIG. 9).

[0004] The antenna 101 is extended and retracted.
Connection (power supply) terminals 105 and 1 corresponding to each state
Reference numeral 06 is connected to the wireless unit mounting board 107 via a power supply fitting 108 in the housing 102.

The electrical length of each of the antennas 103 and 104 is ideally set to λλ in consideration of the directivity pattern. In this case, however, the input impedance becomes very high because of bottom feeding. In order to make it difficult to realize an efficient matching circuit configuration, and to reduce the storage space of the antenna 103 for expansion when the antenna is housed in the housing 102, each of the antennas is set to have an electric length of ３λ. I have. Thereby, an optimal matching circuit is realized between each of the antennas 103 and 104 and the radio unit 107, and the vertical space when the extension antenna 103 is housed can be reduced. 100 could be reduced in size.

[0006]

However, in the conventional wireless communication apparatus, since the electric length of each of the antennas 103 and 104 is set to λλ, the current on the housing 102 increases, and the directional distortion increases. (As apparent from the directivity pattern of the horizontal polarization component in the XZ plane shown in FIG. 11, the directivity narrows in the most important horizontal directions (X and -X directions), Sex level has been reduced). Further, at the time of a call, a hand, an ear, and a head of a communication device user such as a telephone are close to the housing 102, so that a current may be loaded on the housing 102, and in this case, radiation efficiency may decrease. (In FIG. 12, all the wire elements are superimposed and displayed with the Z axis as the location. As shown in FIG. 12, a large mountain portion in the + Z direction is The current on the antenna and the -Z direction is the current on the wireless circuit board, but these currents can be absorbed by the hand or head when the user talks in the hand. There is).

An object of the present invention is to provide an antenna structure of a radio communication device which can improve the directivity pattern and reduce the current on a housing while keeping the input impedance of the antenna low.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a wireless communication system having a housing having an electric circuit therein and a telescopic antenna attached to the housing. In the antenna structure of the device, the antenna element of the telescopic antenna is electrically connected to the electric circuit via a feed terminal by adjusting a length of the telescopic antenna drawn out from the housing to a predetermined amount. In addition, the electrical lengths of the upper and lower portions of the antenna element bordering on the power supply terminal are set independently of each other.

The power supply terminal is, for example, fixed to an antenna element of a telescopic antenna. in this case,
When the telescopic antenna is fixed to the housing by the feeder terminal, the length of the telescopic antenna drawn out of the housing can be adjusted to a predetermined amount at the same time, and a special fixing mechanism is omitted. can do. Alternatively, a mechanism for fixing the telescopic antenna to the housing may be provided separately from the power supply terminal. in this case,
The power supply terminal may be fixed to the antenna element or may be fixed to the housing.

According to the first aspect of the invention, by adjusting the length of the retractable antenna from the housing to a predetermined amount,
The antenna element of the telescopic antenna is electrically connected to the electric circuit via the feed terminal, and the electrical lengths of the upper and lower parts of the antenna element bordering on the feed terminal are independently set to desired values. Is done.

According to a second aspect of the present invention, there is provided the antenna structure of the wireless communication apparatus according to the first aspect, wherein an upper part of the antenna element has an electrical length of 3/8 from the power supply terminal.
λ, the lower part of the antenna element has an electrical length of 1 / 8λ
Are respectively set.

According to the second aspect of the present invention, the upper part of the antenna element is separated from the power supply terminal by an electrical length of 3 / 8λ.
In addition, since the lower part of the antenna element is set to have an electrical length of 1 / 8λ, the directivity can be improved without impairing the realization of an efficient matching circuit, and an excellent gain in the horizontal direction can be obtained. Stable communication becomes possible. Also,
The current on the housing can be reduced, and during communication, the reduction in radiation efficiency due to the proximity of the body of the user of the wireless communication device to the housing can be suppressed, enabling more stable communication Becomes

According to a third aspect of the present invention, there is provided the antenna structure of the wireless communication device according to the first or second aspect, wherein the telescopic antenna is electrically connected to the electric circuit via the first power supply terminal at the time of extension. And a second antenna element electrically connected to the electric circuit via the second power supply terminal during storage. And provided on the same axis.

According to the third aspect of the present invention, when the telescopic antenna is extended, the first antenna element is used by being electrically connected to the electric circuit via the first feed terminal;
The second antenna element, which is electrically connected to the electric circuit via the second power supply terminal at the time of storage, is electrically separated from the second antenna element and provided on the same axis. The first antenna element and the second antenna element can be separately used depending on whether or not the antenna is stored.

According to a fourth aspect of the present invention, there is provided the antenna structure of the wireless communication device according to the third aspect, wherein the second antenna element is a helical antenna.

According to the fourth aspect of the present invention, since the second antenna element is a helical antenna, the wireless communication device when the telescopic antenna is stored can be made compact.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment>
A first embodiment according to the present invention will be described with reference to FIGS. FIGS. 1A and 1B are diagrams showing a wireless communication device to which an antenna structure of a wireless communication device according to the present invention is applied, wherein FIG. 1A is a front sectional view and FIG. 1B is a side sectional view. FIG.
3 is an enlarged cross-sectional view of a main part showing an extended state of the antenna, FIG. 3 is an enlarged cross-sectional view of a main part showing a stored state of the antenna, and FIG.
FIG. 5 is a diagram showing a directivity pattern of a Z-plane vertical polarization component, and FIG. 5 is a diagram showing a state of a current distribution modeled by a wire grid and simulated at an input of 1 [w].

First, as shown in FIG. 1, a wireless communication device 50 is a case (casing) 5 made of an insulator (for example, made of resin).
1. Telescopic antenna 3 attached to the upper part of case 51 via antenna (eg, metal) antenna holder 5 or the like
0, a wireless unit mounting board (electric circuit) 11 for performing signal processing of transmission / reception signals by the telescopic antenna 30, and other internal devices (not shown) housed in a case 51.

The telescopic antenna 30 includes an extension antenna 31 having an extension antenna element (first antenna element) 1 (see FIG. 2) which is electrically connected to the radio unit mounting board 11 at the time of extension. And a storage antenna unit 32 having a storage antenna element (second antenna element) 6 (see FIG. 3) electrically connected to the wireless unit mounting board 11 during storage. The antenna part 31 for extension and the antenna part 32 for storage are
These are connected by a joint 13 of an insulator (for example, made of resin) that electrically separates them.

The extension antenna element 1 of the extension antenna section 31 is used for transmission and reception when the antenna is extended. As shown in FIG. 2, connection (feeding) of a conductor (for example, made of metal) is performed. By penetrating through a mounting hole 3a corresponding to the diameter of the antenna element 1 for extension formed in the terminal (first power supply terminal) 3, it is fixed to the connection terminal 3 and electrically connected to the connection terminal 3. Connected.
In this state, the lower portion 1a as an open stub element portion of the extension-time antenna element 1 protruding below the connection terminal 3 is set to have an electrical length of ８λ. On the other hand, an upper portion 1b of the extension antenna element 1 protruding above the connection terminal 3
(Refer to FIG. 1 because the entire upper portion 1b is not shown in FIG. 2), the electrical length is set to be 3 / 8λ.
The upper portion 1b is covered with, for example, a resin cover 2. Here, in FIG. 1, the upper portion 1b is actually hidden by the cover 2 and cannot be seen, but is given a reference numeral for convenience of explanation.

On the upper part of the case 51, for example, an antenna holder 5 formed in a cylindrical shape is fixed. Along the inner circumference of the antenna holder 5, a conductor (for example, metal) contact spring 4 is fixed, and the contact spring 4 and the antenna holder 5 are electrically connected. The connection terminal 3 is formed in a cylindrical shape corresponding to the inner periphery of the contact spring 4. As shown in FIG. 2, the connection terminal 3 is fitted into the inner periphery of the contact spring 4 until the large-diameter portion 3 b of the connection terminal 3 that cannot pass through the inner periphery of the contact spring 4 contacts the lower end of the contact spring 4. By doing so, the connection terminal 3 is held by the contact spring 4 and the extendable antenna 30 is held in an extended state, and the connection terminal 3 and the contact spring 4 are electrically connected. The antenna holder 5 is electrically connected to the wireless unit mounting board 11 via a power supply fitting 10 made of a conductor (for example, made of metal). That is, in the antenna extended state shown in FIG. 2, the extended antenna element 1 includes the connection terminal 3, the contact spring 4, the antenna holder 5, and the power supply fitting 10.
Is electrically connected to the wireless unit mounting board 11 via the.

On the other hand, the stowed antenna element 6 of the stowed antenna portion 32 is for transmission and reception when the antenna is stowed, and as shown in FIG. Is fixed to the connection terminal 7 and electrically connected to the connection terminal 7 by penetrating through the mounting hole 7a corresponding to the diameter of the storage antenna element 6 formed in the power supply terminal 7). I have. In this state, the upper part of the storage antenna element 6 protruding above the connection terminal 7 is a helical structure (upper part) 6a of a helical structure. This helical structure 6
a is set so that the electrical length is ／ λ. On the other hand, of the antenna elements 6 for storage, the connection terminals 7
The electric length of the lower portion 6b as an open stub element portion protruding downward is set to 1 / 8λ. The helical structure 6a is made of an insulating (eg, resin) cap 8
The lower portion 6b is covered with a cover 9 made of an insulator (for example, made of resin). Here, in FIG. 1, the antenna element 6 for storage is actually hidden by the cap 8 and the cover 9 and cannot be seen, but is given a reference numeral for convenience of explanation.

As shown in FIG. 3, the connection terminal 7 is formed in a cylindrical shape corresponding to the inner periphery of the contact spring 4, and the upper portion of the connection terminal 7 cannot pass through the inner periphery of the contact spring 4. The large diameter portion 7b is provided. The lower end of the large diameter portion 7b is covered by the lower end 8a of the cap 8. By connecting the connection terminal 7 to the inner periphery of the contact spring 4 until the lower end 8a of the cap 8 contacts the upper end of the antenna holder 5, the connection terminal 7 is held by the contact spring 4 and the telescopic antenna 30 is stored. While being kept in the state, the connection terminal 7 and the contact spring 4 are electrically connected. In other words, in the antenna storage state shown in FIG. 3, the storage antenna element 6 is electrically connected to the wireless unit mounting board 11 via the connection terminal 7, the contact spring 4, the antenna holder 5, and the power supply fitting 10. The upper part 6 of the antenna element 6 for storage
Since a has a helical structure, the wireless communication device 50 in the antenna housed state can be made compact. In addition, the setting of each electric length is set including the power supply fitting 10 in detail.

As described above, the housing 5 of the telescopic antenna 30
By adjusting the length of the drawer from the antenna 1 to a predetermined amount (extended or retracted), the antenna element of the telescopic antenna 30 (extended antenna element 1 or retracted antenna element 6) is connected to a connection terminal (connection). It is electrically connected to the radio unit mounting board 11 via the terminal 3 or the connection terminal 7), and the upper part (upper part 1b, upper part 6a) and the lower part (lower part 1a) of the antenna element at the connection (feed) terminal. , And the lower portion 6b) are independently set to desired values (3 / 8λ, 1 / 8λ).

Further, the extendable antenna 30 is used by being electrically connected to the radio unit mounting board 11 via the connection terminal 3 at the time of extension, and the extension antenna element 1 is used at the time of storage via the connection terminal 7 at the time of storage. Since the storage antenna element 6 electrically connected to the component mounting board 11 is electrically separated by the joint 13 and provided on the same axis, the telescopic antenna 30 is extended and stored. Thus, the antenna element 1 for extension and the antenna element 6 for storage can be separately used.

Next, FIG. 4 shows the directivity pattern of the XZ plane vertical polarization component at 1.9 [GHz] when the antenna is extended according to the present embodiment. In FIG. 4, both the coordinate system and the substrate size are the same as the conventional example. As is clear from FIG. 4, the directivity pattern (see FIG. 11) that was split in the conventional example is improved, and the most important horizontal directions (X,
The gain in the −X direction) is improved by about 3 [dB].

FIG. 5 shows a current distribution state simulated with an input 1 [w], modeled by a wire grid, similarly to the conventional example. It is superimposed and displayed). In FIG. 5, a large mountain portion in the + Z direction is a current riding on the extension antenna element 1, and a −Z direction is a current riding on the wireless unit substrate 11. From this figure, a large current flows in the lower part 1a,
(Z = -2 to 0: large mountain portion) It is shown that the current on the housing 51 is reduced accordingly. Although the data when the antenna is stored is omitted, the same electrical length as when the antenna is extended is set, so that the same effect can be obtained.

According to the first embodiment having the above configuration, as is apparent from the current distribution of the antenna, the input impedance is kept equivalent to that of the rod-shaped antenna having an electric length of ／ λ. The realization of an efficient matching circuit can be maintained without impairing, the directivity can be improved, the gain in the horizontal direction can be improved (about 3 [dB]), and stable communication can be performed.

Also, since the current on the housing 51 is reduced, the radiation efficiency due to a part of the user's hand, ear, head, or the like of the wireless communication device 50 approaching the housing 51 during communication. Can be suppressed, and more stable communication can be performed.

<Second Embodiment> A second embodiment according to the present invention will be described with reference to FIG. FIGS. 6A and 6B are views showing a wireless communication device 60 to which a second embodiment of the antenna structure of the wireless communication device according to the present invention is applied, wherein FIG. 6A is a front sectional view, and FIG. FIG.

In the wireless communication device 60, the antenna element 22 for extension of the antenna section 61 for extension (indicated by reference numerals in FIG. 6 for the sake of explanation, but is not actually covered by the cover 2) is the first antenna. Wireless communication device 50 of the embodiment
The lower antenna 1 is removed from the antenna element 1 at the time of extension, and the antenna element 23 at the time of storage of the antenna unit 62 at the time of storage (similarly, in FIG. However, the difference is that the lower portion 6b is removed from the storage antenna element 6 and that the power supply fitting 24 has an open stub element portion 24a. In addition, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 6 shows a state in which the antenna is extended. The extendable antenna 63 is fixed to the housing 51 by the connection terminal 3, and the antenna for extension is connected via the connection terminal 3, the power supply fitting 24 and the like. The element 22 is electrically connected to the wireless unit mounting board 11. Here, the power supply fitting 2
4 has an electric length of 1 /
8λ, which is used as a substitute for the lower portion 1a of the antenna element 1 for extension in the first embodiment.

Although not shown, when the antenna is housed, the telescopic antenna 63 is fixed to the housing 51 by the connection terminal 7, and the connection terminal 7 and the power supply fitting 2 are fixed.
The antenna element 23 for storage is electrically connected to the wireless unit mounting board 11 via 4 or the like. At this time,
The open stub element part 24a of the power supply fitting 24 is used as a substitute for the lower part 6b of the antenna element 6 for storage in the first embodiment.

According to the second embodiment having the above-described structure, the open stub element portion 24a is provided in the power supply fitting 24 and can be arranged separately from the telescopic antenna 63. The dimensions of the conventional
The open stub element portion 24a can be used for both extension and storage without deteriorating the storage space, and the input impedance of the conventional antenna having an electrical length of 3 / 8λ is reduced as in the first embodiment. While keeping the same,
The horizontal gain is improved, and a reduction in efficiency due to the human body during communication is suppressed, thereby enabling stable communication. Note that the characteristic patterns of the directivity pattern and the current distribution are the same as those of the first embodiment, and therefore will not be described.

In the first and second embodiments described above, the contact spring 4 and the antenna holder 5 are formed of metal parts and are brought into contact with the connection terminal 3 or the connection terminal 7 to make connection. Although the terminal 3 or the connection terminal 7 is electrically connected to the contact spring 4 and the antenna holder 5,
The contact spring and antenna holder are made of resin, and the contact spring and antenna holder only have the function of fixing the telescopic antenna to the housing. It can also be realized by combining them. Further, the antenna may be a fixed type antenna that is arranged so as to be in either the extended state or the retracted state without taking an elastic structure.

[0036]

According to the antenna structure of the wireless communication apparatus according to the first aspect of the present invention, the antenna element is electrically connected to the electric circuit by adjusting the extension length of the extendable antenna from the housing to a predetermined amount. And the electrical lengths of the upper and lower portions of the antenna element with the power supply terminal as a boundary are set to desired values.

According to the antenna structure of the radio communication apparatus according to the second aspect of the present invention, the directivity can be improved without impairing the realization of an efficient matching circuit, and excellent gain in the horizontal direction can be obtained. Stable communication becomes possible. In addition, the current on the housing can be reduced, and a decrease in radiation efficiency due to a part of the body of the user of the wireless communication device approaching the housing during communication can be suppressed, and more stable communication can be achieved. Becomes possible.

According to the antenna structure of the wireless communication apparatus according to the third aspect of the present invention, the first antenna element and the second antenna element can be used separately when the telescopic antenna is extended and when it is stored. it can.

According to the antenna structure of the wireless communication device according to the fourth aspect of the present invention, the wireless communication device when the retractable antenna is stored can be made compact.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wireless communication device to which an antenna structure of a wireless communication device according to the present invention is applied, wherein (a) is a front sectional view and (b) is a side sectional view.

FIG. 2 is a sectional view showing an extended state of the antenna.

FIG. 3 is a cross-sectional view showing a stored state of the antenna.

FIG. 4 shows 1.9 [GH] when the antenna is extended according to the present embodiment.
FIG. 7 is a diagram illustrating a directivity pattern of an XZ plane vertical polarization component at [z].

[Fig. 5] Input 1 [w] modeled by wire grid
FIG. 6 is a diagram showing a state of a current distribution simulated in FIG.

FIGS. 6A and 6B are diagrams showing a wireless communication apparatus to which a second embodiment of the antenna structure of the wireless communication apparatus according to the present invention is applied, wherein FIG. 6A is a front sectional view and FIG. FIG.

FIG. 7 is a perspective view showing a conventional wireless communication apparatus when an antenna is housed.

FIG. 8 is a perspective view showing a conventional wireless communication apparatus when an antenna is extended.

FIG. 9 is a front view showing the structure of a conventional antenna.

FIG. 10 is a perspective view showing a state in which a 3 / 8λ rod-shaped antenna is arranged on the back surface of the radio unit mounting board.

11 is a diagram showing a directivity pattern of an XZ plane horizontal polarization component at 1.9 [GHz] when a 3 / 8λ rod-shaped antenna is arranged as in FIG. 10;

FIG. 12 is a diagram showing a state of a current distribution simulated at an input of 1 [W] by modeling with a wire grid under the same conditions as in FIG. 11;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st antenna element (extension antenna element) 1a lower part 1b upper part 3 1st feeding terminal (connection terminal) 6 2nd antenna element (storage antenna element) 6a upper part 6b lower part 7 2nd feeding terminal (Connection terminal) 11 electric circuit (wireless unit mounting board) 30 telescopic antenna 31 antenna unit for extension 50 wireless communication device 51 housing

Claims (4)

[Claims] 1. An antenna structure of a wireless communication device having a housing having an electric circuit therein and a telescopic antenna attached to the housing, wherein the extension length of the telescopic antenna from the housing is determined. By adjusting to a fixed amount, the antenna element of the telescopic antenna is electrically connected to the electric circuit via a power supply terminal, and an electric connection between an upper part and a lower part of the antenna element bordering on the power supply terminal. An antenna structure for a wireless communication device, wherein the lengths are set independently of each other. 2. An upper part of the antenna element is set to an electric length of ３λ, and a lower part of the antenna element is set to an electric length of ８λ with respect to the power supply terminal. The antenna structure of the wireless communication device according to claim 1. 3. The telescopic antenna according to claim 1, further comprising: a first antenna element electrically connected to the electric circuit via the first power supply terminal during extension, and a second power supply terminal during storage. And a second antenna element used by being electrically connected to the electric circuit via the first antenna element and the second antenna element are electrically separated from each other and provided on the same axis. Antenna structure of wireless communication device. 4. The antenna structure according to claim 3, wherein said second antenna element is a helical antenna.