JP4241464B2 - Broadband antenna for portable radio - Google Patents

Description

  The present invention relates to an antenna structure suitable for a portable wireless device.

  An antenna of a portable wireless device typified by a mobile phone or a portable information terminal needs to be small and lightweight in order to be housed in a case, and is further required to have high efficiency and wideband characteristics. Many such antenna structures have been proposed.

  For example, in Japanese Patent Laid-Open No. 2002-50924 (Patent Document 1), the electrical length of a plate antenna is λ / 4, and the plate antenna and the antenna exciter are double-resonated to obtain broadband tuning performance. A structure of a wideband built-in antenna is disclosed.

  Japanese Patent Laid-Open No. 3-293803 (Patent Document 2) discloses an antenna structure in which element groups parallel to two different directions are arranged on a surface of a substrate folded in a bellows shape.

JP 2002-50924 A JP-A-3-293803

  However, the antenna described in Patent Document 1 is complicated and not easy to manufacture. In addition, the antenna disclosed in Patent Document 2 has a structure in which antenna elements are respectively arranged on different surfaces of a substrate folded in a bellows shape, and mainly receives radio waves in two different directions from a satellite. Was devised.

  An object of the present invention is to provide an antenna suitable for a portable radio having a small size and light weight and wide band characteristics.

A broadband antenna for a portable wireless device according to a first invention has an antenna substrate having a three-dimensional structure, and the three-dimensional structure is a convex portion projecting from a reference plane of the antenna, and is recessed from the reference plane. At least one of the concave portions is provided, and the three-dimensional structure has a regular convex and concave repeating structure when viewed from either the vertical direction or the horizontal direction of the reference plane.

According to a second invention, in the invention described in the first invention, the antenna substrate is supported by wrapping the antenna substrate with an outer packaging member.

According to a third invention, in the invention described in the first invention or the second invention , the antenna substrate is supported by a frame.

  Each of the above inventions will be further described.

  Examples of the “antenna substrate” include a copper foil substrate, but the material is not particularly limited as long as it has a predetermined radio wave receiving function.

  An example of the “reference plane” is a horizontal plane where the antenna extends. The “three-dimensional structure” includes a case where only convex portions and concave portions are included. If the “predetermined direction of the reference plane” is described by taking the first embodiment described below as an example, it is a direction in which a substantially triangular mountain shape that repeats regularly on the substantially bellows surface can be seen. Further, the “predetermined direction of the reference plane” will be described by taking a fourth embodiment to be described later as an example.

  “Regular protrusions and recesses” are not only the case where at least one of the protrusions and recesses is continuously repeated in the same pattern as in the above-described substantially bellows surface, but also antennas that appear irregular in a narrow range. This includes cases that are regular in a wide range.

  The portable wireless device to which the present invention is applied is preferably configured to supply high-frequency power between the ground and the antenna substrate.

If it is the first invention, the three-dimensional structure includes at least one of a convex part and a concave part and is provided with a regular convex part and a concave part, so that the surface area can be increased compared to a case where it is constituted by a plane in the same occupied space, The antenna can be wideband. In other words, the antenna can be reduced in size when a predetermined band is to be secured. Furthermore, since the regular convex portions and concave portions are configured to be regular convex portions and concave portions when viewed from either the vertical direction or the horizontal direction of the reference plane, the arrangement form of the convex portions and concave portions is Even if it is dense and has a small occupied area, the surface area can be increased and a wide band can be realized.

According to the second aspect of the invention, since the antenna substrate is supported by wrapping it with the outer packaging member, it can be stably supported even when the antenna substrate is thin and cannot maintain its outer shape.

If it is the 3rd invention, since the said board | substrate for antennas is supported by the frame, even if it is a case where the board | substrate for antennas is thin and the external shape cannot be maintained, it can support stably.

  Hereinafter, specific embodiments will be shown and described with reference to the drawings.

  FIG. 1A is a perspective view of a wideband antenna according to the first embodiment of the present invention, and FIG. 1B is a perspective view of a conventional L-shaped antenna as a comparative example. As shown in FIG. 1 (A), the broadband antenna 1 according to the present embodiment is connected to the same power supply unit 3 of the radio printed circuit board 2 used in the L-shaped antenna 4 shown in FIG. 1 (B). It has become.

  The broadband antenna according to the present embodiment is configured by a copper foil substrate 10 having a small thickness, and the copper foil substrate 10 is in a direction (height H direction) perpendicular to the horizontal plane of the antenna to be the reference plane 8. It has a three-dimensional structure in which convex portions and concave portions formed in a triangular mountain shape so as to protrude or be recessed are regularly repeated. This three-dimensional structure appears as a substantially bellows surface in plan view.

  FIG. 1A illustrates a configuration in which the wide-band antenna 1 has a lateral width W, a longitudinal length L, and three rows of roof-shaped chevron having a Λ-shaped cross section extending in the lateral direction. The height of the triangular chevron from the reference plane 8 is H. The means for supporting the chevron shape is not particularly limited in the first embodiment as long as it can stably maintain the one bent into a substantially triangular chevron. In addition to the mountain-shaped configuration shown in FIG. 1A, the number of peaks formed in the vertically long L, the shape of the peaks (symmetric or laterally asymmetric with respect to the center line of the peaks), etc. are changed. It is possible.

The configuration of the L-shaped antenna 4 in FIG. 1B is also the same in width W and length L, so that the planar occupation area of the wideband antenna of this embodiment should be the same as that of the conventional L-shaped antenna 4. it can. However, in the case of the configuration of the first embodiment shown in FIG. 1A, an antenna having a large surface area is arranged in a small space by bending the copper foil substrate 10 into a triangular mountain shape and forming a substantially bellows shape. Therefore, a broadband antenna can be provided as shown by the data described above.
(Second Embodiment)
FIG. 2 is a perspective view of a broadband antenna according to a second embodiment of the present invention. As shown in FIG. 2, this embodiment has a configuration in which the outside of the broadband antenna 1 is wrapped by an outer packaging member 5, and the broadband antenna 1 is accommodated by housing the outer packaging member 5 in a portable wireless device such as a mobile phone. Can be stably supported without deforming the shape.

The outer packaging member 5 may be any material that has a small decrease in radio wave reception efficiency and can protect the broadband antenna against vibration and impact assumed when used in a portable wireless device. In addition, it is good also as a structure which comprised the envelope member 5 by the case body and accommodated the wideband antenna 1 in the case body.
(Third embodiment)
FIG. 3 is a perspective view of a broadband antenna according to a third embodiment of the present invention. As shown in FIG. 3, this embodiment has a configuration in which the broadband antenna 1 is surrounded by a frame 6 such as a rectangle or a rectangle. By being surrounded by the frame body 6, it is possible to stably support the external shape of the broadband antenna 1 without deforming it.

In order to fix the thin copper foil substrate having the chevron shape by the frame body 6, a support bar (not shown) is horizontally placed at the apex position of the triangle constituting the chevron, and the thin copper foil substrate is interposed between the support rods. It is conceivable to use a method of supporting the material in the shape of a fabric. When the thickness of the copper foil substrate is considerable and the shape holding ability of the copper foil substrate is large, the outer edge position of the copper foil substrate is fixed to the frame material surface of the frame body 6 to be supported on the frame body 6. it can.
(Fourth embodiment)
FIG. 4 is a perspective view of an example of a broadband antenna according to the fourth embodiment of the present invention. The feature of this embodiment is that the broadband antenna is further composed of a three-dimensional object including three-dimensional regular convex portions and concave portions as compared with the configurations of the first to third embodiments, and the surface of the convex portion. The concave surface is used as a power receiving surface of the antenna.

  Specifically, the broadband antenna has a three-dimensional structure having at least one of a convex portion protruding from the reference plane 8 and a concave portion recessed from the reference plane 8, and the three-dimensional structure is formed from a predetermined direction of the reference plane. It is characterized by having regular convex portions and concave portions when viewed.

  The configuration shown in FIG. 4 shows a configuration in which a total of nine protrusions 20 are projected from the reference plane 8 of the antenna to the upper side of the sheet in a 3 × 3 horizontal and vertical direction. In the configuration of FIG. 1A shown in the first embodiment, the repetition of the regular convex portion of the triangular chevron appears only in the vertical direction. In this embodiment, however, 2 in the vertical and horizontal directions. The three-dimensional structure of the convex part 20 is formed in the direction.

According to this embodiment, since the repeating structure of the convex part and the concave part is arranged more three-dimensionally and the interval between them is close, the surface area of the antenna in the same three-dimensional volume can be increased, and a wider band antenna is configured. It becomes possible to do. In the antenna shown in the fourth embodiment, the support structure using the outer packaging member (case body) shown in FIG. 2 and the frame shown in FIG. 3 can be similarly adopted.
(Fifth embodiment)
FIG. 5 is a block diagram showing an example of a portable wireless device using a broadband antenna according to the present invention. The printed circuit board of the portable wireless device 100 is connected to the broadband antenna 1 by the power feeding unit 3. The portable wireless device 100 includes a wireless transmission / reception unit 101 for performing wireless communication with a wireless base station, a control unit 102 for controlling channel control and other operations, and a user interface 103 including a display unit, a keypad, and the like. It has been. As described above, the wide-band antenna 1 according to the present invention is small and light, and can provide a wide band, so that it is suitable for a portable radio device.

  As shown in FIG. 1 (A), the size of the board 2 for a radio device is set to a width Ws = 45 mm and a length Ls = 163 mm. The wide-band antenna 1 according to the first embodiment was manufactured with the distance d between the lower end of the wide-band antenna 1 and the radio substrate 2 being d = 3 mm and the height of the triangular chevron H = 5 mm.

  Further, as a comparative example, a copper wire L-shaped antenna 4 using the same wireless device substrate 2 was manufactured. The antenna was manufactured with a width W = 25 mm and a length L = 18 mm so that the occupied area of the antenna was the same as that of the wideband antenna 1 according to this embodiment and the conventional L-shaped antenna 4.

  As a result of comparing the bandwidths of the two antennas with a return loss of -5 dB near 2 GHz, the wideband antenna 1 is 584 MHz and the L-shaped antenna 4 is 548 MHz. It was confirmed that the band was wider than that of the antenna 4.

(A) is a perspective view of the wideband antenna by 1st Embodiment of this invention, (B) is a perspective view of the L-shaped antenna as a comparative example. It is a perspective view of the wideband antenna by 2nd Embodiment of this invention. It is a perspective view of the wideband antenna by 3rd Embodiment of this invention. It is a perspective view of the wideband antenna by 4th Embodiment of this invention. It is a block diagram which shows an example of the portable radio | wireless machine using the broadband antenna by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Broadband antenna 5 Outer packaging member 6 Frame 8 Reference plane 10 Copper foil board | substrate 20 Convex part 100 Portable radio

Claims (3)

The antenna substrate has a three-dimensional structure, and the three-dimensional structure has at least one of a convex portion protruding from the reference plane of the antenna and a concave portion recessed from the reference plane, and the three-dimensional structure is a reference plane. A broadband antenna for a portable radio device, characterized by having a regular convex and concave structure when viewed from either the vertical direction or the horizontal direction . Broadband antenna for a portable radio apparatus according to claim 1, in the envelope member supported by encasing substrate the antenna. The broadband antenna for a portable radio according to claim 1 or 2 , wherein the antenna substrate is supported by a frame.

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