JP3826370B2 - Antenna element for portable communication terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna element for a mobile communication terminal that can be suitably used for a mobile communication terminal such as a mobile phone, a simple mobile phone (so-called PHS mobile phone, hereinafter the same), a pager, and a portable information processing terminal. About.
[0002]
[Prior art]
As the antenna used for the mobile communication terminal, a rod antenna that is incorporated in a case constituting the mobile communication terminal so as to be extendable and contracted is mainly used. Also known is a helical antenna that always protrudes short outside the case.
[0003]
[Problems to be solved by the invention]
When using such a prior art, the rod antenna must be pulled out of the case for a long time each time it is used. Therefore, the operation is troublesome, and the rod antenna can be easily damaged by a slight external force, or the eyes can be caught during use. There was a problem that there was. In addition, the helical antenna is constructed by protecting the antenna element consisting of the air-core coil with a cover material such as silicone rubber, so the outer diameter tends to be large. The problem of being bad was inevitable.
[0004]
Therefore, in view of the problems of the prior art, an object of the present invention is to form a coil with the first and second conductors on the substrate, thereby minimizing the outer dimensions and attaching the coil to the case of the mobile communication terminal in a good manner. An object of the present invention is to provide an antenna element for a portable communication terminal.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the structure of the present invention includes a substrate provided with through holes, a first conductor arranged in parallel at a predetermined pitch on the surface of the substrate, and one end of each first conductor on the back surface of the substrate. Are connected in order to the other end, and are provided with a second conductor forming a coil through the substrate, a terminal of a double-sided printed board standing on one end of the substrate, and a cover material for protecting the substrate. Is formed with a through hole that pulls out one end of the coil and connects the core wire of the coaxial cable for the feeder, and the cover material is made of a synthetic resin material having elasticity, and is transparent when the terminal is exposed to the outside and integrally molded. The gist of the present invention is to fill the inside of the hole and to provide an engaging projection for fixing in the same direction as the terminal.
[0010]
[Action]
According to the configuration of the invention, the first conductors are arranged in parallel at a predetermined pitch on the surface of the substrate, and the second conductors are arranged on the back surface of the substrate with one end of each first conductor at the other end. Connect in order. Therefore, the first and second conductors can form a coil having a predetermined length as a whole on both surfaces of the substrate and can resonate at a predetermined use frequency. However, the first and second conductors at this time electrically form a coil having a length corresponding to an odd multiple of λ / 4 with respect to the wavelength λ of the operating frequency, combined with a sufficiently large ground plane, It shall be used as a monopole antenna.
[0011]
If the first and second conductors are connected through the through-holes, the first and second conductors can be connected at once through a through-hole plating process to form a coil.
[0012]
When a coil is formed by dividing it on a plurality of stacked substrates, the coil has a broad resonance characteristic and can easily realize a broadband characteristic. However, the coil at this time is formed, for example, by using three substrates, so that 1/2 on the base side is formed on the intermediate substrate and 1/2 on the tip side is formed on the upper and lower substrates. be able to.
[0013]
If a plurality of sets of coils having different lengths are formed at the same position in the same direction on the substrate, each coil resonates at a different frequency, for example, in an optimum state for two frequencies for transmission and reception. Can be used. Note that the coils at this time can be formed at the same position by shifting the positions in the axial direction by ½ pitch from each other.
[0014]
If multiple sets of coils with different lengths are formed at different positions in the same direction, each coil can resonate at a different frequency to achieve a broader bandwidth. For example, it is close to the body like a mobile phone or a simple mobile phone. In the device to be used, the resonance frequency fluctuation due to the body effect can be easily covered.
[0015]
If multiple sets of coils with the same length are formed at different positions in the perpendicular direction, both horizontally polarized waves and vertically polarized waves can be received and transmitted satisfactorily. An antenna element can be configured.
[0016]
When the substrate is protected by the cover material, the coil formed on the substrate can be effectively protected against a mechanical external force via the cover material. Note that the cover material at this time is made of a synthetic resin material having moderate elasticity, such as silicone rubber, and good radio wave transmittance, and covers the entire substrate except the terminals. Thus, it shall integrally mold to a predetermined external shape.
[0017]
If a through hole is provided in the substrate, a part of the cover material is filled in the through hole at the time of molding, and the integrity with the substrate can be enhanced. Moreover, if an engagement protrusion is provided in the cover material, the whole can be easily fixed to the case of the mobile communication terminal or the like via the engagement protrusion.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
The antenna element 10 for a portable communication terminal includes a substrate 11 and first conductors 21, 21..., Second conductors 22, 22... Arranged on the substrate 11 (FIG. 1).
[0020]
The substrate 11 is a double-sided printed circuit board having good high-frequency characteristics such as a fluororesin system or an epoxy resin system. A large-diameter through hole 11 a is formed at one end of the substrate 11, and a small-diameter through hole 11 b penetrating through both surfaces of the substrate 11 is formed at the other end of the substrate 11. The substrate 11 is formed in a rectangular shape having a length d4 and a width d5.
[0021]
The first conductors 21, 21... Are arranged in parallel at a predetermined pitch d1 on the surface of the substrate 11 (FIGS. 1 and 2). The second conductors 22, 22... Connect one end of each first conductor 21 to the other end in order through the through holes 23, 23 at both ends, respectively. Therefore, the first and second conductors 21, 21 are connected. .., 22, 22... Form a coil 20 having a length d 2 and a width d 3 as a whole through the substrate 11. However, the first first conductor 21 on the proximal end side of the coil 20 is connected to the through hole 11a of the substrate 11 through the connecting wire 24a. In addition, the coil 20 bypasses the through hole 11b of the substrate 11 via another connecting line 24b. That is, the length d2 of the coil 20 is divided into a long proximal end portion d2a and a short distal end portion d2c through the portion d2b of the through hole 11b, and d2 = d2a + d2b + d2c.
[0022]
A terminal 12 made of a double-sided printed board is attached to the through hole 11a of the substrate 11 (FIGS. 1 and 3). The terminal 12 is erected on the substrate 11 by inserting the protrusion 12a at the base end into the through hole 11a and soldering, and a through hole 12b is formed at the distal end. However, the core wire 13a of the feeder coaxial cable 13 is inserted into the through hole 12b and soldered, and the ground plate 14 is connected to the shield jacket 13b of the coaxial cable 13.
[0023]
The antenna element 10 is protected via a cover material 15 (FIGS. 1 and 4). The cover member 15 is integrally formed in a predetermined shape with the terminal 12 exposed to the outside, and a fixing engagement protrusion 15 a is provided on the lower surface of the tip portion in the same direction as the terminal 12. However, an engagement rib 15a1 is formed at the base of the engagement protrusion 15a. The cover material 15 is also filled in the through holes 11 b of the substrate 11.
[0024]
The antenna element 10 can be compactly attached to the case C of the mobile phone, for example, via the cover member 15 (FIGS. 4 and 5). However, the case C is configured by attaching an opening / closing lid C1 to the main body C2, and the antenna element 10 is attached to the inner surface of the front end of the opening / closing lid C1. A transmitter C1a is incorporated at the tip of the opening / closing lid C1, and various operation keys including numeric keys C2a, C2a, etc., a display C2b, a receiver C2c, and the like are incorporated into the main body C2. In the antenna element 10, the terminal 12 and the engaging protrusion 15a are inserted into the mounting holes C1b and C1c of the opening / closing lid C1, respectively, and are fixed via the engaging ribs 15a1. The coaxial cable 13 attached to the antenna element 10 is connected to a communication unit (not shown) in the main body C2, and the ground plane 14 is incorporated in the open / close lid C1.
[0025]
The antenna element 10 has a pitch d1 = 0.5 mm, d2a = 0.5 × 38 = 19 mm on an epoxy resin substrate 11 having a length d4 = 27 mm, a width d5 = 4.5 mm, and a thickness 0.5 mm. When the coil 20 having the length d2 = d2a + d2b + d2c = 22 mm and the width d3 = 3.1 mm is formed and operated as a monopole antenna together with the ground plane 14, the frequency shown in FIG. Characteristics were obtained. However, the horizontal axis of FIG. 6 indicates the frequency f (MHz), and the vertical axis indicates the voltage standing wave ratio SWR. Further, this antenna has horizontal directivity characteristics as indicated by solid lines in FIGS. 7 to 9 with respect to received radio waves Sh and Sv composed of horizontal polarization and vertical polarization for each installation direction. However, in these drawings, the alternate long and short dash line is a comparative characteristic of the rod antenna RD, and the attached schematic diagram shows the 0 ° direction in which the received radio waves Sh and Sv arrive. The radial direction is the received voltage V (dBμV). That is, the antenna element 10 can realize good operating characteristics that are not inferior to the rod antenna RD.
[0026]
[Other embodiments]
The antenna element 10 may be formed with the terminal 12 as a part of the substrate 11 (FIG. 10). The cover member 15 is formed in a vertically long tapered dome shape that protrudes the terminal 12 to the lower surface, and is protruded and fixed to the surface of the case C. Further, the substrate 11 is formed with through holes 11b and 11b in the upper end portion and the lower portion, and one end on the terminal 12 side of the coil 20 is drawn out to the terminal 12 through a connecting wire (not shown). Therefore, the antenna element 10 can be operated as a monopole antenna by inserting and connecting the core wire 13a of the coaxial cable 13 to the through hole 12b of the terminal 12 and connecting the ground plane 14 to the shield jacket 13b.
[0027]
The antenna element 10 can be formed by dividing the coil 20 on a plurality of stacked substrates 11, 11,... (FIG. 11). The coil 20 has a base side 20a corresponding to 1/2 of the whole formed on the intermediate substrate 11, and a tip side 20b corresponding to the other 1/2 overlapped with the upper and lower substrates 11 and 11. Cage (FIGS. 11A and 11B), the base side 20a and the tip side 20b, 20b are connected via a connecting line 24c that penetrates the substrates 11, 11. In addition, the board | substrates 11,11 ... can be finished integrally by adhering and laminating | stacking (FIG. (C)). However, the terminal 12 with the through-hole 12b is integrally formed at one end of each substrate 11, and the cores 13a of the coaxial cable 13 are connected to the terminals 12, 12... That connect one end of the coil 20a through the continuous wire 24a. Shall be connected in common.
[0028]
The antenna element 10 of FIG. 11 has the frequency characteristics as shown in FIG. 12 when the dimensions of each part are formed substantially the same as those of FIG. In other words, the antenna element 10 is formed by dividing the coil 20 on the plurality of substrates 11, 11,.
[0029]
In the antenna element 10, a plurality of sets of coils 20 and 20 having different lengths may be formed on the substrate 11 at the same position in the same direction (FIG. 13). The coils 20 and 20 are each pulled out to the common terminal 12 through the connecting wire 24a. Since the coils 20 and 20 resonate at different frequencies, the antenna element 10 can realize a double peak frequency characteristic as a whole (FIG. 14).
[0030]
The antenna element 10 may be formed on the substrate 11 with a plurality of sets of coils 20, 20... Having different lengths at different positions in the same direction (FIG. 15). Each coil 20 on the substrate 11 has a different resonance frequency, and thus the antenna element 10 exhibits a multi-peak wideband frequency characteristic as a whole (FIG. 16). Note that when the single-coil antenna element is used for a simple mobile phone, for example, the resonance frequency varies greatly depending on the use state (FIG. 17), but the antenna element 10 of FIG. Can be effectively covered. However, the solid line, the one-dot chain line, and the two-dot chain line in FIG. 17 are when a simple mobile phone incorporating a single-coil antenna element as a monopole antenna is attached to the ear and is being held by hand. FIG. 4 shows an example of each frequency characteristic when left on a desk.
[0031]
In the antenna element 10, a plurality of sets of coils 20, 20 having the same length may be formed on the substrate 11 at different positions in the direction perpendicular to each other (FIG. 18). The antenna element 10 operates as a so-called polarization combining array type antenna element through the coils 20 and 20 as a whole, and is substantially uniform with respect to both the received radio waves Sh and Sv composed of horizontal polarization and vertical polarization. Horizontal directional characteristics can be realized (FIG. 19). However, the solid line in FIG. 19 shows the characteristic with respect to the received radio wave Sv consisting of vertical polarization, and the alternate long and short dash line shows the characteristic with respect to the received radio wave Sh consisting of horizontal polarization.
[0032]
【The invention's effect】
As described above, according to the present invention, the first conductors arranged on the surface of the substrate and the second conductors that sequentially connect one end of each first conductor to the other end on the back surface of the substrate are provided. Thus, the first and second conductors can form a coil through the substrate, so that the overall outer dimensions can be minimized and attached to the case of the portable communication terminal in a very attractive manner. There is an excellent effect that good operating characteristics comparable to those of conventional antennas can be realized.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of the overall configuration. FIG. 2 is an explanatory view of the main part of the coil. FIG. 3 is an enlarged cross-sectional view of the main part of FIG. [Fig. 6] Operating characteristic diagram (1)
[Figure 7] Operating characteristic diagram (2)
[Figure 8] Operating characteristic diagram (3)
[Figure 9] Operating characteristic diagram (4)
FIG. 10 is an explanatory diagram of a use state showing another embodiment. FIG. 11 is an explanatory diagram of a configuration showing another embodiment. FIG. 12 is an operating characteristic diagram (5).
FIG. 13 is a conceptual diagram (1) showing another embodiment.
[Fig. 14] Operating characteristic diagram (6)
FIG. 15 is a conceptual diagram (2) showing another embodiment.
FIG. 16: Operating characteristic diagram (7)
[Fig. 17] Operating characteristic diagram (8)
FIG. 18 is a conceptual diagram (3) showing another embodiment.
FIG. 19: Operating characteristic diagram (9)
[Explanation of symbols]
d1 ... pitch 11 ... substrate 11b ... through hole 12 ... terminal 15 ... cover material 15a ... engagement protrusion 20 ... coil 21 ... first conductor 22 ... second conductor 23 ... through hole

Claims (1)

  A substrate provided with a through hole, a first conductor arranged in parallel at a predetermined pitch on the surface of the substrate, and one end of each first conductor on the back surface of the substrate connected in order to the other end, the substrate A second conductor that forms a coil via a terminal, a terminal of a double-sided printed board that stands on one end of the substrate, and a cover material that protects the substrate, and the terminal includes one end of the coil And forming a through hole for connecting the core wire of the coaxial cable for the feeder, and the cover material is made of a synthetic resin material having elasticity, and the inside of the through hole is formed when the terminal is exposed to the outside and integrally molded. The antenna element for a mobile communication terminal is characterized in that an engaging protrusion for fixing is provided in the same direction as the terminal.

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