JP4875594B2 - Parallel 2-wire antenna - Google Patents

Description

  The present invention relates to an antenna built in a wireless communication device such as a portable terminal, and more particularly to a multi-frequency parallel two-wire antenna having a small size and wideband characteristics.

  With the spread of terminal devices such as mobile phones and sophistication of their functions, not only miniaturization but also multi-frequency common characteristics that operate at multiple frequencies with one antenna are required as antennas built into terminal devices. Furthermore, the frequency band used tends to expand. As an example of a miniaturized antenna used for a cellular phone or the like, for example, an antenna 900 described in Patent Document 1 as shown in FIG. 8 is known.

  In the antenna 900, a ground electrode 902 is formed on one main surface of a base body 901 made of a rectangular parallelepiped insulator, and first and second electrodes are arranged to face each other through a slit s1 provided obliquely on the other main surface. The radiation electrodes 903 and 904 of the first radiation electrode 903 are formed, the end of the first radiation electrode 903 close to one end of the slit s1 is connected to the ground electrode 902 via the first connection electrode 905, and the first radiation electrode 903 The feeding electrode 907 is disposed close to the end portion separated from the end portion to which the first connection electrode 905 is connected via the gap g2, and the end portion spaced apart from the one end of the slit s1 of the second radiation electrode 904 by a predetermined distance. Is connected to the ground electrode 902 through the second connection electrode 906.

In the antenna 900 configured as described above, the first radiating electrode 903 is resonated by capacitive coupling with the feeding electrode 907, and the second radiating electrode 904 is resonated with the first connecting electrode 905 and the second connecting electrode 906. By resonating via magnetic field coupling between the two, double resonance is obtained. The antenna 900 can achieve a wide band in a predetermined frequency band due to this multiple resonance.
JP 2000-151258 A

  However, the conventional antenna described in Patent Document 1 has the following problems. Broadbanding by “double resonance” is possible but not sufficient. Further, since the two elements are arranged on the same plane, the area of the element tends to increase. Considering the size of the element added for widening the band (enhancement of the element area) and the obtained effect (band expansion), there is a problem that the effect of widening the band is not so great.

  Accordingly, the present invention has been made to solve the above-described problem, and an object of the present invention is to provide an antenna having a wide band so that excitation can be performed in a wide frequency band in a use frequency band.

  The first aspect of the parallel two-wire antenna of the present invention is a multi-frequency parallel parallel having a resonance frequency corresponding to the first frequency band on the low frequency side and a resonance frequency corresponding to the second frequency band on the high frequency side. A two-wire antenna having a total length corresponding to the first frequency band, a first start end connected to a feeding point at one end, and a first end open at the other end A first radiation conductor having one or more first folded portions that are folded back by 180 °, and a second starting end having a total length corresponding to the first frequency band and connected to a ground point at one end And a second radiating portion having one or more second folded portions that are folded back by 180 ° between the first radiating conductor and the second radiating end that is open at the other end, and arranged in close proximity to the first radiating conductor. Arranged by branching from the conductor and between the first start end and the first folded portion A third radiating conductor, wherein the first starting end and the second starting end, and the first ending end and the second ending end are arranged in the vicinity, respectively, and the feeding of the third radiating conductor The length from the point corresponds to a resonance frequency lower than the center frequency of the second frequency band.

  Another aspect of the parallel two-wire antenna of the present invention is characterized in that the third radiating conductor is disposed inside the folded first radiating conductor and the second radiating conductor.

  In another aspect of the parallel two-wire antenna of the present invention, the first radiating conductor has a shortest distance from the third radiating conductor in the section from the first folded portion to the first terminal. It is shorter than the shortest distance with the said 3rd radiation | emission conductor in the area from a 1st start end to a said 1st folding | turning part, It is characterized by the above-mentioned.

  In another aspect of the parallel two-wire antenna of the present invention, in the first radiating conductor, at least a part from the first starting end to the first folded portion has a line width wider than the other part. It is characterized by being.

  According to another aspect of the parallel two-wire antenna of the present invention, the first radiating conductor and the second radiating conductor are bent at approximately 90 ° at least once in the first folded portion and the second folded portion. It is characterized by being.

  According to the present invention, by providing branch conductors corresponding to the high frequency band in the conductor connected to the feeding point for the two substantially parallel radiating conductors that are close and folded at least once by 180 °, the low frequency is reduced with respect to the high frequency band. It becomes possible to provide a broadening condition independent of the band, and it is possible to provide a multi-frequency shared parallel two-wire antenna in which both bandwidths are maximized.

  A parallel two-wire antenna according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  FIG. 1 shows a plan view of a parallel two-wire antenna according to a first embodiment of the present invention. The parallel two-wire antenna 100 of this embodiment includes a first radiating conductor 111 having a first folded portion 112 folded back by 180 °, and a second radiating conductor 121 having a second folded portion 122 folded back by 180 °. The two radiation conductors are provided.

  One end (first start end 113) of the first radiation conductor 111 is connected to the feeding point 101. The second radiating conductor 121 has one end (second starting end 123) connected to the ground point 102. Each of the first start end 113 and the second start end 123 and the first end 114 and the second end 124 are arranged in the vicinity.

  The parallel two-wire antenna 100 of the present embodiment configured as described above is a multi-frequency shared antenna having a first resonance frequency on the low frequency side and a second resonance frequency on the high frequency side. That is, the first radiating conductor 111 and the second radiating conductor 121 are arranged close to each other in parallel in a shape (first folded portion 112 and second folded portion 122) folded back by 180 °, respectively. The line antenna 100 can have two resonant frequencies.

  In the parallel two-wire antenna 100 of the present embodiment, as a means for widening the band of the second resonance frequency on the high frequency band side with respect to the antenna of this configuration, the feed point 101 and the first A third radiating conductor 131 branched from a predetermined position between the first folded portion 112 is added. The third radiating conductor 131 is formed to have a length corresponding to a frequency lower than the second resonance frequency on the high frequency side from the feeding point 101 to the open end. By changing the length of the third radiation conductor 131, the second resonance frequency band on the high frequency band side can be widened.

  FIG. 2 shows simulation results of impedance (FIG. 2 (a)) and VSWR (FIG. 2 (b)). FIG. 3 shows the current distribution for each frequency on the radiation conductors 111, 121, 131 corresponding to FIG. Here, FIG. 3A shows the current distribution of each radiating conductor at 880 MHz, FIG. 3B shows the current distribution of each radiating conductor at 1825 MHz, and FIG. 3C shows the current of each radiating conductor at 2375 MHz. Distribution. From FIG. 3A, it can be confirmed that the main modes of the first radiation conductor 311 and the second radiation conductor 321 correspond in the first frequency band on the low frequency side. Further, from FIG. 3B, it can be confirmed that the third radiation conductor 331 corresponds to the low frequency side in the second frequency band on the high frequency side. Further, from FIG. 3C, it can be seen that the harmonics of the first radiation conductor 311 and the second radiation conductor 321 are switched as the frequency increases. As the operation of the third radiating conductor 331, the first radiating conductor 311, and the second radiating conductor 321 is continuously switched, as can be seen from FIG. It is planned.

  A parallel two-wire antenna according to another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a plan view showing a parallel two-wire antenna 400 according to another embodiment. Similar to the parallel two-wire antenna 100 shown in FIG. 1, the parallel two-wire antenna 400 includes a first radiating conductor 411 having a first folded portion 412 folded back by 180 ° and a second folded back similarly folded by 180 °. Two radiation conductors of a second radiation conductor 421 having a portion 422 are provided.

  One end of the first radiation conductor 411 is connected to the feeding point 401. One end of the second radiation conductor 421 is connected to the ground point 402.

  Further, a third radiating conductor 431 branched from a predetermined position between the feeding point 401 and the first folded portion 412 is added to the first radiating conductor 411. The third radiating conductor 431 has a length corresponding to a frequency lower than the second resonance frequency on the high frequency side from the feeding point 401 to the open end, and the third radiating conductor 431 is folded back. The first radiating conductor 411 and the second radiating conductor 421 are disposed inside.

  With the arrangement as described above, the third radiating conductor 431 can form a capacitive coupling portion with both the first radiating conductor 411 and the second radiating conductor 421 before and after the folded portions 412, 422. A wide band can be realized.

  A parallel two-wire antenna according to still another embodiment of the present invention will be described with reference to FIG. FIG. 5 is a plan view showing the parallel two-wire antenna 500 of the present embodiment. Similar to the parallel two-wire antenna 400 shown in FIG. 4, the parallel two-wire antenna 500 includes a first radiating conductor 511 and a first folded portion 512, and a second radiating conductor 521 and a second folded portion 522. They are arranged on the same plane. The first radiating conductor 511 and the second radiating conductor 521 are arranged in parallel and close to each other on the same plane, and the first folded portion 512 and the second folded portion 522 are arranged close to each other in parallel.

  In addition, a third radiating conductor 531 branched from a predetermined position between the feeding point 501 and the first folded portion 512 is added to the first radiating conductor 511. The third radiation conductor 531 is formed to have a length corresponding to a frequency lower than the second resonance frequency on the high frequency side from the feeding point 501 to the open end, and the third radiation conductor 531 is folded. The first radiating conductor 511 and the second radiating conductor 521 are disposed inside.

  Further, a part of the protrusion 541 is provided in a pattern ahead of the folded portion 512 when viewed from the feeding point 501 of the first radiating conductor 511 so that the distance from the third radiating conductor 531 is smaller than the other part. A part is provided. Similarly, the second radiation conductor 521 is provided with a protrusion 542 corresponding to the protrusion 541, and the distance between the first radiation conductor 511 and the second radiation conductor 521 is kept substantially constant. Thereby, a strong capacitive coupling part can be provided and it becomes possible to implement | achieve broadband. Note that the protrusions 541 and 542 are not a part, and the distance from the radiation conductor 531 may be closer to the radiating conductor 531 than the other parts over almost all of the folded portions 512 and 522 and thereafter.

  A parallel two-wire antenna according to still another embodiment of the present invention will be described below with reference to FIG. FIG. 6 is a plan view showing a parallel two-wire antenna 600 according to another embodiment. Similar to the parallel two-wire antenna 400 shown in FIG. 4, the parallel two-wire antenna 600 includes a first radiating conductor 611 having a first folded portion 612 folded back by 180 ° and a second folded back similarly folded by 180 °. Two radiation conductors of a second radiation conductor 621 having a portion 622 are provided.

  One end of the first radiation conductor 611 is connected to the feeding point 601. One end of the second radiation conductor 621 is connected to the ground point 602.

  Further, a third radiation conductor 631 branched from a predetermined position between the feeding point 601 and the first folded portion 612 is added to the first radiation conductor 611. The third radiating conductor 631 has a length corresponding to a frequency lower than the second resonance frequency on the high frequency side from the feeding point 601 to the open end, and the third radiating conductor 631 is folded back. Arranged inside the first radiation conductor 611 and the second radiation conductor 621.

  Here, between the first folded portion 612 of the first radiating conductor 611 and the feeding point 601, a wide portion 651 having a radiating conductor width wider than other portions is provided. By changing the line width of a part of the element, an inductance component can be added, and a wide band can be realized.

  A parallel two-wire antenna according to still another embodiment of the present invention will be described below with reference to FIG. FIG. 7 is a perspective (three-dimensional) view showing a parallel two-wire antenna 700 of another embodiment. Similar to the parallel two-wire antenna 400 shown in FIG. 4, the parallel two-wire antenna 700 includes a first radiating conductor 711 having a first folded portion 712 folded back by 180 °, and a second folded back similarly folded by 180 °. Two radiation conductors of a second radiation conductor 721 having a portion 722 are provided.

  One end of the first radiation conductor 711 is connected to the feeding point 701. One end of the second radiation conductor 721 is connected to the ground point 702. Further, a third radiating conductor 731 branched from a predetermined position between the feeding point 701 and the first folded portion 712 is added to the first radiating conductor 711. The third radiating conductor 731 has a length corresponding to a frequency lower than the second resonance frequency on the high frequency side from the feeding point 701 to the open end, and the third radiating conductor 731 is folded. Arranged inside the first radiation conductor 711 and the second radiation conductor 721.

  Here, the first radiating conductor 711 and the second radiating conductor 721 are bent at approximately 90 ° at bending points 761 and 762 without changing the relative positional relationship between them. By doing in this way, even when an actual terminal or the like on which the antenna is mounted cannot secure a planar mounting space, the antenna can be arranged. In addition, after the 90 ° folding, the first radiation conductor 711 and the second radiation conductor 721 before and after the folding may be arranged to face each other by further folding by approximately 90 ° at the bent portions 771 and 772.

It is a top view of the parallel 2-wire antenna which concerns on embodiment of this invention. It is a figure which shows the bandwidth by electromagnetic field simulation. It is a figure which shows the electric current distribution on the radiation | emission conductor by electromagnetic field simulation. It is a top view which shows the parallel 2 wire antenna which concerns on another embodiment of this invention. It is a top view which shows the parallel 2 wire antenna which concerns on another embodiment of this invention. It is a top view which shows the parallel 2 wire antenna which concerns on another embodiment of this invention. It is a top view which shows the parallel 2 wire antenna which concerns on another embodiment of this invention. It is a perspective view which shows the conventional antenna.

Explanation of symbols

100, 300, 400, 500, 600, 700 Parallel two-wire antenna 101, 301, 401, 501, 601, 701 Feed point 102, 302, 402, 502, 602, 702 Ground point 111, 311, 411, 511, 611 , 711 First radiation conductor 112, 312, 412, 512, 612, 712 First folded portion 113, 313, 413, 513, 613.713 First starting end 114, 413, 414, 514, 614.714 First 1 end 121, 321, 421, 521, 612, 712 second radiation conductor 122, 322, 422, 522, 622, 722 second folded portion 123, 323, 423, 523, 623, 723 second start end 124, 324, 424, 524, 624, 724 second termination 131, 331, 431, 31,631,731 third radiating conductor 541, 542 protrusions 651 wide portion 761 and 762 bending point 1
771, 772 Bending point 2

Claims (5)

A multi-frequency parallel two-wire antenna having a resonance frequency corresponding to the first frequency band on the low frequency side and a resonance frequency corresponding to the second frequency band on the high frequency side,
The first length is a length corresponding to the first frequency band, and is turned back by 180 ° between a first start end connected to a feeding point at one end and a first end open at the other end. A first radiation conductor having one or more folded portions of
The total length is a length corresponding to the first frequency band, and the second folded back 180 ° between the second start end connected to the ground point at one end and the second end open at the other end. A second radiating conductor having one or more folded portions, and being arranged close to and substantially parallel to the first radiating conductor;
A third radiating conductor arranged and branched from between the first starting end and the first folded portion,
Each of the first start end and the second start end, and the first end and the second end are arranged in the vicinity, and the length of the third radiation conductor from the feeding point is the second A parallel two-wire antenna characterized in that it corresponds to a resonance frequency lower than the center frequency of the frequency band. The parallel two-wire antenna according to claim 1, wherein the third radiating conductor is disposed inside the folded first radiating conductor and the second radiating conductor. The first radiating conductor has a shortest distance from the first starting end to the first folded portion in a section from the first folded portion to the first terminal. The parallel two-wire antenna according to claim 1 or 2, wherein the parallel two-wire antenna is shorter than a shortest distance from the third radiation conductor in the section. 4. The line according to claim 1, wherein, in the first radiation conductor, a line width is at least a part from the first start end to the first folded portion, and the line width is wider than the other part. A parallel two-wire antenna according to claim 1. The first and second radiating conductors are bent at approximately 90 ° at least once at the first and second folded portions, respectively. The parallel two-wire antenna according to any one of the above.

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