JP2006020127A - Portable communication terminal and antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve antenna characteristics by making a length of a ground conductor sufficiently long in terms of the wavelength of an operating frequency. <P>SOLUTION: The portable communication terminal has an antenna 2, a metal housing 1 obtained by continuously forming a plurality of recessed parts 3 at even intervals on an outer wall in a longitudinal direction, and an antenna feeding part 4 for connecting the metal housing 1 to the ground conductor that operates as ground of the antenna 2 in a high frequency manner. In the metal housing 1, a length of its longitudinal direction is not larger than 1/4 wavelength with respect to the wavelength of an operating radio frequency. Each recessed part 3 provided in the metal housing 1 is formed, satisfying a relation that a ratio L/P of width L between both projections constituting one recessed part to an interval P between respective recessed parts is ≥0. 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a portable communication terminal and an antenna device that transmit and receive signals using radio waves.

  Conventionally, in portable wireless communication terminals such as mobile phone terminals, it has been desired to reduce the size of the housing. Particularly in recent portable wireless communication terminals, the size of a conductive part that operates as a ground conductor of an antenna has a length that is equal to or less than 0.25 wavelengths (1/4 wavelength) of the wavelength of the used frequency, as the housing is downsized. There are many cases where this happens.

  Here, as described above, in the case of a small portable wireless communication terminal in which the size of the ground conductor is equal to or shorter than the 0.25 wavelength of the use frequency wavelength, for example, even if the same antenna is used, There is a problem that the antenna characteristics are deteriorated as compared with a terminal in which the length of the conductor is about a length corresponding to 0.3 wavelength of the use frequency wavelength. In FIG. 6, using the same antenna, the length of the ground conductor with respect to the used frequency wavelength is, for example, 0.22, 0.25, 0.29, 0.32, 0.35, In the case of a length corresponding to 38 wavelengths, the antenna radiation efficiency with respect to the length of each conductor is indicated. As can be seen from FIG. 6, when the size of the ground conductor is equal to or shorter than the 0.25 wavelength of the use frequency wavelength, the length of the ground conductor is equal to or greater than the 0.3 wavelength of the use frequency wavelength. Compared with the case of the length, the antenna characteristics are remarkably deteriorated.

  For this reason, for example, in Japanese Patent Application Laid-Open No. 6-169207 (Patent Document 1), a metal casing is connected to a ground conductor that operates as an antenna ground in an antenna power feeding section at high frequency, and the metal A portable radio device has been proposed in which a long notch is formed in a side surface portion in a longitudinal direction of a housing so that a ground conductor is long in terms of high frequency and antenna characteristics are improved.

JP-A-6-169207 (FIG. 1)

  However, when the structure as described in Patent Document 1 described above is actually configured, the cut amount of the cutout portion provided in the metal casing increases, and for example, a large amount of electricity is generated inside the casing. There is a problem that it is difficult to realize in a portable wireless communication terminal in which a circuit or the like is arranged.

  The present invention has been proposed in view of such a situation, and a metal housing in which a desired electric circuit can be arranged is used in a high frequency with a ground conductor that operates as an antenna ground in an antenna feeding unit. In the case of connection, a portable communication terminal capable of enhancing the antenna characteristics even when the longitudinal dimension of the metal casing does not have a sufficient length with respect to the wavelength of the used frequency And it aims at providing an antenna device.

  The portable communication terminal of the present invention includes an antenna and a conductive member, and a casing formed by continuously forming a plurality of recesses in the longitudinal direction on an outer wall surface in the longitudinal direction. The above-described problems are solved by having an antenna power supply unit that is connected in high frequency with a ground conductor that operates as a ground.

  Further, the antenna device of the present invention is connected to the antenna element through the antenna element, the antenna feeding unit, and the antenna feeding unit, operates as an antenna ground, and has a plurality of concave portions on the longitudinal surface. By having a conductive member formed continuously in the direction, the above-described problems are solved.

  Here, the casing, which is a conductive member, has a length in the longitudinal direction equal to or shorter than a quarter wavelength with respect to the wavelength of the radio frequency used, and each of the recesses constitutes one recess. The ratio L / P between the width L between the protruding portions and the interval P between the recesses is 0.7 or more.

  That is, according to the mobile communication terminal and the antenna device of the present invention, the length of the ground conductor is increased by continuously forming a plurality of recesses on the outer wall surface in the longitudinal direction with respect to the conductive member that operates as the ground conductor of the antenna. The length is increased in terms of high frequency.

  In the present invention, a plurality of recesses are continuously formed on the surface in the longitudinal direction of the conductive member, and in particular, each recess has a width L between both protrusions constituting one recess and each recess. By satisfying the relation L / P with the distance P between the two in the range of 0.7 or more, the dimension in the longitudinal direction of the metal casing has a sufficient length with respect to the wavelength of the used frequency. Even if it is not, highly efficient antenna characteristics can be realized.

  Hereinafter, an embodiment of a mobile communication terminal and an antenna device of the present invention will be described with reference to the drawings. In the following description, a mobile phone terminal is cited as an embodiment of the present invention. Of course, the content described here is merely an example, and it goes without saying that the present invention is not limited to this example.

[Configuration of metal housing]
FIG. 1 shows a schematic external configuration of a metal casing 1 included in a mobile phone terminal according to an embodiment of the present invention.

  In the mobile phone terminal according to the present embodiment, the metal casing 1 is disposed, for example, inside a non-metallic casing 10 indicated by a dotted line in the figure, and an antenna feeding unit 4 is provided at one end in the longitudinal direction. The antenna (antenna element) 2 is connected via the antenna power feeding unit 4.

  The metal casing 1 is composed of a metal member, that is, a conductive member, and is connected to the ground conductor that operates as the ground of the antenna 2 at a high frequency in the antenna feeding unit 4. The metal casing 1 is partially hollow inside, and various electronic circuits and the like necessary for the terminal of this embodiment to function as a mobile phone terminal can be placed in the hollow portion. It has become.

  Furthermore, the metal housing 1 of the present embodiment is provided with a plurality of recesses 3 on the outer wall surface in the longitudinal direction at regular intervals and continuously in the longitudinal direction. In the example of FIG. 1, in order to make the shape of the plurality of recesses 3 easy to understand on the drawing, the size of each recess 3 is drawn larger than the actual size of the metal housing 1. Yes. Therefore, the volume of the cavity inside the metal casing 1 is large enough to arrange an electronic circuit or the like necessary for the terminal of this embodiment to function as a mobile phone terminal.

[Relationship between the width between the protrusions constituting the recess and the interval between the recesses]
Here, in this embodiment, as shown in FIG. 2, the width between the two protrusions constituting one recess 3 is L, the interval (pitch) between the recesses 3 is P, and the depth of the recess 3 is D. In this case, the width L and the pitch P have a relationship in which the ratio L / P is 0.7 or more.

  That is, according to the mobile phone terminal of the present embodiment, when the metal housing 1 is connected to the ground conductor that operates as the ground of the antenna 2 at the antenna power feeding unit 4 at a high frequency, As described above, the width L of each recess 3 of the metal casing 1 is equal to or less than 0.25 wavelength (1/4 wavelength) of the wavelength of the operating frequency. And the pitch P have a relationship in which the ratio L / P is 0.7 or more, the ground conductor length can be made sufficiently long in view of the wavelength of the operating frequency. The antenna characteristics in free space can be improved.

[Specific example of antenna characteristics calculation]
3 and 4, as in the present embodiment, there are some examples having a relationship in which the ratio L / P is 0.7 or more between the width L and the pitch P of the recesses 3, and The result of calculating the antenna radiation efficiency in free space will be shown by giving some examples where the ratio L / P is smaller than 0.7. In the examples of FIGS. 3 and 4, the frequency used is 950 MHz, the antenna 2 used is a modified monopole antenna, and when a series inductor is inserted in the antenna matching circuit, the value of the ratio L / P The correspondence relationship of the antenna radiation efficiency is shown, FIG. 3 shows the correspondence relationship in a table, and FIG. 4 shows the correspondence relationship in a grab.

  3 and 4, as an example in which the ratio L / P is 0.7 or more, the width L is 3.5 mm, the depth D is 4.0 mm, and the pitch P is 4.0 mm. Thus, when the ratio L / P is 0.88, the antenna radiation efficiency is -2.04 dB, the width L is 7.5 mm, the depth D is 4.0 mm, and the pitch P is 8.0 mm. When the ratio L / P is 0.94, the antenna radiation efficiency is -2.04 dB. Similarly, the width L is 1.5 mm, the depth D is 4.0 mm, and the pitch When P is 2.0 mm and the ratio L / P is 0.75, the antenna radiation efficiency is -2.13 dB, the width L is 7.5 mm, the depth D is 2.0 mm, and the pitch P Is 8.0 mm and the ratio L / P is 0.94. The antenna radiation efficiency is -2.41 dB, the width L is 3.5 mm, the depth D is 2.0 mm, the pitch P is 4.0 mm, and the ratio L / P is 0.88. The radiation efficiency is -2.43 dB.

  On the other hand, in FIG. 3 and FIG. 4, as an example in which the ratio L / P is smaller than 0.7, the width L is 0.5 mm, the depth D is 4.0 mm, and the pitch P is 1.0 mm. When the ratio L / P is 0.50, the antenna radiation efficiency is -2.53 dB, the width L is 0.5 mm, the depth D is 4.0 mm, and the pitch P is 8 When the ratio L / P is 0.06 by being 0.0 mm, the antenna radiation efficiency is -2.76 dB, the width L is 2.0 mm, the depth D is 2.0 mm, and the pitch P is When the ratio L / P is set to 4.0 mm and the ratio L / P is 0.50, the antenna radiation efficiency is -2.69 dB. Further, when the recess 3 is not provided, the antenna radiation efficiency is -2. 79 dB.

  As can be seen from FIG. 3 and FIG. 4, in the case where the ratio L / P has a relationship of 0.7 or more and the case where the ratio L / P has a relationship smaller than 0.7, The antenna radiation efficiency is higher when the ratio L / P has a relationship of 0.7 or more.

[Schematic circuit configuration example of the mobile phone terminal of this embodiment]
Next, as an embodiment of the mobile communication terminal of the present invention, FIG. 5 shows a schematic circuit configuration example of a mobile phone terminal including the metal casing 1 of the present embodiment. In the present embodiment, the main functions of the configuration shown in FIG. 5 are executed by an electronic circuit provided in the metal casing 1.

  In FIG. 5, the control unit 21 is, for example, a CPU that operates based on a program that controls each function of the mobile phone terminal, and controls various functions via a bus according to the program.

  The communication circuit 22 communicates with the base station through the antenna 2 of the present embodiment.

  The display unit 23 includes a liquid crystal device or the like provided on the non-metal casing 10 that covers the metal casing 1 of the present embodiment, and an image signal supplied from the control unit 21 via the bus is the liquid crystal. Displayed on the device screen.

  The operation unit 24 has operation devices such as a numeric keypad and a jog dial provided on the non-metal housing 10 that covers the metal housing 1 of the present embodiment, and generates an operation signal corresponding to the operation of these operation devices. And sent to the control unit 21 via the bus.

  The memory 29 is, for example, a memory-holding rewritable memory, and holds phone book data, schedule management software, a program for operating the control unit 21, and the like.

  The data holding unit 30 is a memory-holding rewritable memory like the memory 29, and stores, for example, user schedule data, various image data, for example, various information acquired via the Internet or the like. Note that the data holding unit 30 may be included in the memory 29.

  The speaker drive circuit 25 drives a speaker 26 provided on the non-metallic housing 10 and outputs a call sound, a ring tone, and the like.

  The microphone input signal generation unit 27 amplifies the call voice signal collected by the microphone 28 provided on the non-metallic housing 10 and sends the amplified signal to the communication circuit 22 via the bus.

  In addition, although not shown, the mobile phone terminal according to the present embodiment has a function of reproducing music data downloaded via the Internet or music data held in a memory card or the like, for example, Bluetooth (Bluetooth : A camera unit including a circuit for performing short-range wireless such as a trademark), infrared communication (IrDA), UWB (Ultra Wide Band), a lens system, and an image sensor such as a charge coupled diode (CCD), GPS (Global (Positioning System) A GPS function unit for receiving a signal from a satellite and detecting the current position of the terminal may be provided.

[Summary]
As described above, according to the mobile phone terminal of the embodiment of the present invention, the length of the ground conductor can be extended from the wavelength of the operating frequency, and the antenna characteristics in free space can be improved.

  The above description of the embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made according to the design or the like as long as the technical idea according to the present invention is not deviated.

  For example, the antenna 2 may be of any type as long as the antenna element and the ground conductor are balanced and fed, and may be a monopole antenna, a helical antenna, an inverted F antenna, a composite antenna of these, or the like.

  Regarding the depth D of the recess 3, the effect of improving the antenna radiation efficiency increases as the depth increases. However, the size of the electronic circuit disposed inside the metal housing 1, the size of the mobile phone terminal itself, 3 and 4 are selected in consideration of the relationship between the ratio L / P and the depth D in the calculation results of FIG.

  Moreover, although the shape of each recessed part 3 is made into the linear shape in the example of FIG.1 and FIG.2, it may be curvilinear shapes, such as what is called a C surface and R, for example.

  Further, in the present embodiment, the configuration example in which the metal casing 1 is covered with the non-metallic casing 10 has been described, but the metal casing 1 can be used as it is as the casing of the mobile phone terminal. Thus, when the metal casing 1 is used as it is as the casing of the mobile phone terminal, the mobile phone terminal can be used by the user by the unevenness formed by the plurality of recesses 3 formed on the outer wall surface of the metal casing 1. When the is held in the hand, the area of the portion that touches the user's hand is reduced, and it is possible to reduce the deterioration of the antenna characteristics due to the influence of the hand. In addition, when the metal casing 1 is used as it is as the casing of the mobile phone terminal, dust or the like may accumulate in the recesses 3 of the outer wall surface of the metal casing 1. In this case, dust can be prevented from adhering by filling each of the recesses 3 with a nonconductive material.

  Furthermore, in the case of this embodiment, although the example which provided each recessed part 3 uniformly over the whole outer wall surface part of the metal housing | casing 1 is given, for example, the recessed part 3 is provided in a part of outer wall surface part. There may be no part (non-formation region). However, in that case, the effect of improving the antenna characteristics as described above may be somewhat reduced. The effect of improving the antenna characteristics is that the recess 3 is provided on the side closer to the antenna feeding portion 4 (the formation region is reduced). Therefore, it is desirable that the non-formation region where the concave portion 3 is not provided is located far from the antenna power supply portion 4.

It is a figure which shows the schematic external appearance structure of the metal housing | casing with which the mobile telephone terminal of this invention embodiment was equipped. It is a figure used for description of the relationship between the width | variety L between the both protrusion parts of the recessed part provided in the outer wall surface part of the metal housing of this embodiment, and the space | interval (pitch) P of each recessed part. It is a figure which shows the correspondence table of ratio L / P of width L and pitch P, and antenna radiation efficiency. It is the figure which showed the corresponding relationship of ratio L / P of the width | variety L and the pitch P, and antenna radiation efficiency with the graph. It is a block diagram which shows the schematic internal circuit structural example of the mobile telephone terminal of this embodiment. It is the figure which showed the correspondence of the ground conductor length and antenna radiation efficiency in the conventional portable radio | wireless communication terminal with the graph.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Metal housing | casing, 2 antenna, 3 recessed part, 4 antenna electric power feeding part, 10 nonmetallic housing | casing, 21 control part, 22 communication circuit, 23 display part, 24 operation part, 25 speaker drive circuit, 26 speaker, 27 microphone input Signal generation unit, 28 microphone, 29 memory, 30 data holding unit, L width between both projections constituting the recess, P interval between each recess (pitch), D depth of the recess

Claims (13)

An antenna,
A casing made of a conductive member and having a plurality of recesses formed continuously in the longitudinal direction on an outer wall surface in the longitudinal direction;
A portable communication terminal, comprising: an antenna power supply section that connects the housing to a ground conductor that operates as a ground of the antenna at a high frequency. The mobile communication terminal according to claim 1,
The portable communication terminal characterized in that the length of the casing in the longitudinal direction is a length equal to or less than a quarter wavelength with respect to the wavelength of the radio frequency used. The mobile communication terminal according to claim 1,
Each of the recesses provided on the outer wall surface of the housing has a relationship in which a ratio L / P between a width L between both protrusions constituting the one recess and an interval P between the recesses is 0.7 or more. A mobile communication terminal characterized by being formed to satisfy the above. The mobile communication terminal according to claim 1,
A portable communication terminal characterized in that the antenna is an antenna of a system in which an antenna element and a ground conductor are balancedly fed. The mobile communication terminal according to claim 1,
The portable communication terminal, wherein the casing is filled with a non-conductive member in each of the recesses. The mobile communication terminal according to claim 1,
The housing includes a formation region in which the plurality of recesses are continuously formed and a non-formation region in which the recesses are not formed, and the formation region is provided in the vicinity of the antenna feeding portion. A characteristic mobile communication terminal. The mobile communication terminal according to claim 1,
A portable communication terminal characterized in that the inside of the casing is hollow and an electronic circuit is provided in the hollow. An antenna element;
An antenna feeder,
A conductive member that is connected to the antenna element via the antenna feeding portion, operates as an antenna ground, and has a plurality of concave portions formed continuously in the longitudinal direction on the surface in the longitudinal direction; An antenna device characterized by the above. The antenna device according to claim 8, wherein
The antenna device according to claim 1, wherein the conductive member has a length in the longitudinal direction equal to or shorter than a quarter wavelength with respect to a wavelength of a used radio frequency. The antenna device according to claim 8, wherein
Each recess provided on the surface of the conductive member has a relationship in which the ratio L / P between the width L between both protrusions constituting the one recess and the interval P between the recesses is 0.7 or more. An antenna device characterized by being formed to satisfy the above. The antenna device according to claim 8, wherein
The antenna device is characterized in that the antenna feeding unit feeds balanced power to the antenna element and the conductive member. The antenna device according to claim 8, wherein
The antenna device, wherein the conductive member is filled with a non-conductive member in each of the recesses. The antenna device according to claim 8, wherein
The conductive member has a formation region in which the plurality of recesses are continuously formed and a non-formation region in which the recesses are not formed, and the formation region is provided in the vicinity of the antenna feeding portion. An antenna device characterized by that.

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