JP4317577B2 - Antenna for mobile communication terminal - Google Patents

Description

  The present invention relates to an antenna 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. .

  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. There is also known a helical antenna that protrudes to the outside of the case.

  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, since the helical antenna is composed of an antenna element composed of an air-core coil, the communication sensitivity is likely to change depending on the usage posture, the direction of the base station, etc., and it is difficult to maintain a good communication state, and the communication distance is long. The problem of not being big was inevitable.

  Therefore, in view of the problems of the prior art, the object of the present invention is to keep the communication state good by minimizing the external dimensions and improving the communication sensitivity and communication distance by combining the main element and the sub element. An object of the present invention is to provide an antenna for a portable communication terminal.

  In order to achieve this object, the structure of the invention of claim 1 is a combination of a main element and a sub-element which are not electrically connected and form a coil via separate substrates. Are arranged so that the central axes of the coils are orthogonal to each other and the substrates are included in two planes orthogonal to each other, and the coils are resonated at the operating frequency, and the main element is combined with the ground plane. As a monopole antenna, each of the main element and sub-element is formed with two sets of coils having different lengths on the same substrate in the same direction, and one end of each coil is used as a common terminal. The gist is to draw out.

  According to the configuration of the invention, the main element and the sub-element are formed with coils having a predetermined pitch via separate substrates, and can resonate each coil at a predetermined use frequency. However, the main element is used as a monopole antenna in combination with a sufficiently large ground plane, and the sub element is not electrically connected to the main element. In addition, the coils of the main element and the sub element are each formed to have a length corresponding to an odd multiple of λ / 4 with respect to the wavelength λ of the operating frequency.

  When the main element and sub-element are arranged so that their central axes are included in two planes orthogonal to each other, the coil of the sub-element resonates with vertical polarization when the coil of the main element resonates with horizontal polarization. However, when the coil of the main element resonates with vertical polarization, it can resonate with horizontal polarization, and as a whole, polarization synthesis that can transmit and receive both horizontal and vertical polarized waves well An array-type antenna can be configured.

  When the main element and the sub-element are arranged so that each substrate is included in two planes orthogonal to each other, the main element and the sub-element have a three-dimensional broad directional characteristic, and easy omnidirectionality is easily achieved. Can be realized.

  When the main element and the sub-element are arranged so that the respective substrates are included in the same plane, the average gain in the directivity becomes large, and high communication sensitivity can be realized as a whole.

  In other words, according to the present invention, each of the main element and the sub element can resonate at a predetermined operating frequency and improve the directivity characteristics as a whole, so that communication sensitivity and communication distance can be improved. In addition, the communication state can be kept good, and the external dimensions of each can be minimized and attached to the case of the mobile communication terminal. Further, since the sub element is not electrically connected to the main element, the influence on the VSWR characteristic of the main element is small, and the overall adjustment is easy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An antenna for a mobile communication terminal is formed by combining a main element 10 and a sub-element 20 disposed in the vicinity of the main element 10 (FIGS. 1 and 2).

  The main element 10 is a coil having a predetermined pitch d1a through a conductor 12a, 12a ..., 12b, 12b ... formed on the front and back surfaces of the substrate 11 and through holes 12c, 12c ... 12 is formed. The substrate 11 is a double-sided printed circuit board having good high-frequency characteristics such as ceramics, fluororesin, or epoxy resin. A terminal 11a for connecting a cable having a through hole 11a1 is formed on both sides at one end of the substrate 11. ing.

  The conductors 12a, 12a,... Are arranged in parallel at the pitch d1a on the surface of the substrate 11, and the conductors 12b, 12b,... Have one end of each conductor 12a at the other end via the through holes 12c, 12c at both ends. They are connected in order. Therefore, the conductors 12a, 12a..., 12b, 12b... Form a coil 12 having a length d1b and a width d1c as a whole via the substrate 11. However, the first conductor 12a on the proximal end side of the coil 12 is connected to the terminal portion 11a via a connecting wire 12d.

  The sub-element 20 connects the conductors 22a, 22a,..., 22b, 22b... Formed on the front and back surfaces of the substrate 21 at predetermined pitches d2a through the through holes 22c, 22c. The coil 22 is formed. However, the coil 22 has a pitch d2a = d1a, a length d2b = d1b, a width d2c = d1c, the number of turns is the same as that of the coil 12, and the thickness of the substrate 21 is t2 = t1 and is formed in the same shape as the coil 12. ing.

  The main element 10 and the sub element 20 are attached to, for example, a case B of a mobile phone (FIGS. 1 and 3). However, the main element 10 is protected via a vertically long tapered dome-shaped cover material 13. The cover member 13 is integrally formed in a predetermined shape with the terminal portion 11a exposed in the case B. The main element 10 is fixed so as to protrude from the tip of the case B with the substrate 11 parallel to the front surface of the case B, and the sub-element 20 has the substrate 21 parallel to the tip surface of the case B. Built into the tip. That is, the sub-element 20 is disposed in the vicinity of the main element 10, and the coils 12 and 22 of the main element 10 and the sub-element 20 are arranged so that the respective central axes C1 and C2 are included in two planes orthogonal to each other. Has been placed. Further, the substrates 11 and 21 of the main element 10 and the sub-element 20 are arranged so as to be included in two planes orthogonal to each other.

  Case B incorporates a handset B1, a display B2, various operation keys including numeric keys B3, B3..., A transmitter B4, and the like. The main element 10 is connected to a communication unit (not shown) in the case B via a core wire of a coaxial cable (not shown) connected to the terminal portion 11a, and the shield jacket of the coaxial cable is not shown in the case B. Connected to the main plate.

  The antenna of FIG. 1 has a pitch d1a = d2a = 0.5 mm, a length d1b = d2b = 22 mm, and a width d1c = d2c = 3 with respect to epoxy resin substrates 11 and 21 having a thickness t1 = t2 = 0.5 mm. When the 1 mm coils 12 and 22 are formed and operated as a monopole antenna together with the ground plane, the horizontal direction as shown by the solid lines in FIGS. Directional characteristics and vertical directivity characteristics were obtained. However, in these drawings, the alternate long and short dash line is a comparative characteristic when only the main element 10 is used, and the attached schematic diagram shows the 0 ° direction in which the received radio waves Sh and Sv arrive. The radial direction is reception sensitivity dB (dBd). That is, the main element 10 operates as a director element or a reflector element when the sub-element 20 resonates with respect to the received radio waves Sh and Sv, thereby improving the reception sensitivity dB as compared with the case of the main element 10 alone. The directivity characteristics are improved broadly, and good operating characteristics can be realized.

  Further, in the antenna of FIG. 1, the reception limit position of the communication wave S from the oscillation source P is expanded by the distance L and the height H, compared to the case of the main element 10 only (FIG. 7). However, in FIG. 7A, when there is no obstacle in the middle of the flat ground, the reception limit position is enlarged by a distance L = 15.5 m compared to the case of only the main element 10, and FIG. When F is an obstacle, the reception limit position is enlarged by a distance L = 4 m and a height H = 0.5 m as compared with the case of only the main element 10.

Other embodiments

  In the main element 10, the substrate 11 may be arranged in the thickness direction of the case B (FIGS. 8A and 8B). Moreover, the subelement 20 may arrange | position the board | substrate 21 in parallel with the front surface of case B (the figure (B), (C)). That is, the main element 10 and the sub-element 20 may be arranged so that the respective substrates 11 and 21 are included in two planes orthogonal to each other (FIGS. 8A and 8B) and included in the same plane. (Fig. 5C). However, in FIG. 8C, the sub element 20 may be offset in the thickness direction of the case B with respect to the main element 10.

  In the above description, the sub-element 20 may protect the entire surface through an appropriate cover material and may be attached to the front end surface of the case B from the outside. Further, the sub-element 20 is protected by the cover member 23 (FIG. 9), and can be detachably connected to the cover member 13 for the main element 10 through the mounting opening 23a formed in the cover member 23. Good.

  The main element 10 and the sub-element 20 can be formed by dividing the coils 12 and 22 on a plurality of substrates 11, 11... 21, 21. However, only the main element 10 is shown in FIG.

  The coil 12 has a base side 12e corresponding to ½ of the whole formed on the intermediate substrate 11 (FIGS. 10A and 10B), and a distal end side 12f corresponding to the other ½ is up and down. The base portion 12e and the tip end sides 12f, 12f are connected to each other via a connecting line 12g that penetrates the substrates 11, 11,. In addition, the board | substrates 11,11 ... can be finished integrally by adhering and laminating | stacking (FIG. (C)). A terminal portion 11a with a through hole 11a1 is integrally formed at one end of each substrate 11. The terminal portions 11a, 11a,... Connected to one end of the coil 12 via the connecting wire 12d are connected in common to the core wire 15a of the coaxial cable 15, and the shield jacket 15b of the coaxial cable 15 is connected to the ground plane 14. Yes.

  The main element 10 may be formed with a plurality of sets of coils 12 and 12 having different lengths at the same position on the substrate 11 (FIG. 11A). , 12... May be formed at different positions in the same direction (FIG. (B)), and a plurality of sets of coils 12, 12 having the same length may be formed at different positions in the direction perpendicular to each other (same as above). (C). In addition, in FIG. 11 (A)-(C), each coil 12 is each pulled out by the terminal part 11a via the connection line 12d. The sub-element 20 can be configured in exactly the same way.

Overall configuration perspective view Coil main part explanatory drawing Usage diagram Operating characteristic diagram (1) Operating characteristic diagram (2) Operating characteristic diagram (3) Operating characteristic diagram FIG. 1 equivalent view (1) showing another embodiment FIG. 1 equivalent view (2) showing another embodiment Structure explanatory drawing which shows other embodiment (1) Structure explanatory drawing which shows other embodiment (2)

Explanation of symbols

d1a, d2a ... pitch C1, C2 ... central axis 10 ... main element 20 ... sub-element 11, 21 ... substrate 12, 22 ... coil

Patent Applicant FCE Co., Ltd.
Shigeru Sugimura
Attorney Tadaaki Matsuda, Attorney

Claims (1)

  Combining main elements and sub-elements that form coils via separate substrates without being electrically connected to each other, the main elements and sub-elements have their respective center axes orthogonal to each other, And the main element is operated as a monopole antenna in combination with a ground plane, and the main element and the sub-element Is an antenna for a portable communication terminal, wherein two sets of coils having different lengths are formed at the same position in the same direction on one substrate, and one end of each coil is drawn out to a common terminal portion. .

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