JP2007049668A - Wideband antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wideband antenna apparatus which can be miniaturized and have wideband characteristics. <P>SOLUTION: A hole 12 is provided on a center of a planar conductor plate 11 of a radius of about λ<SB>0</SB>/4, and a coaxial connector 13 is attached in this hole 12. The center conductor 14 of the coaxial connector 13 is led out from the hole 12 to an opposite side, and is connected to a feeding point 18 of a first radiation element 17. The first radiation element 17 employs a plate-like element and is arranged perpendicularly to the planar conductor plate 11. For the first radiation element 17, its whole length is set at about λ<SB>0</SB>/9, and its lateral width of an upper part is set at about λ<SB>0</SB>/3. Strip-like second radiation elements 21a, 21b are provided so as to be positioned obliquely from the upper center of the first radiation element 17 in directions of both sides, and the tips thereof are fixed on the planar conductor plate 11. A plate-like third radiation element 22 is provided in the same direction as that of the first radiation element 17 on the upper side of the second radiation elements 21a, 21b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wideband antenna apparatus having wideband characteristics used for wireless communication having wideband characteristics such as UWB (Ultra Wide Band: 3.1 GHz to 10.6 GHz) and a base station of a mobile phone.

  In mobile phone base stations, for example, 800 MHz band, 1.5 GHz band, 1.7 GHz band, and 2 GHz band are generally used. Conventionally, a monopole antenna is generally known as an antenna for a mobile phone base station.

  However, the monopole antenna has a narrow frequency band, and when used as a mobile phone base station antenna, it is necessary to install the monopole antenna for each band. As described above, when four bands of 800 MHz band, 1.5 GHz band, 1.7 GHz band, and 2 GHz band are used, four monopole antennas are required, and four input / output terminals are also required. become.

Conventionally, as an antenna to be mounted and used on a moving body, a high frequency antenna having a wide band by providing a derivative substrate on a flange and configuring a stub element, a radiating element, a capacitor plate element, and the like on the derivative substrate has been proposed. It is known (for example, refer to Patent Document 1).
JP-A-53-30252

  When a system is constructed by connecting the above-described conventional monopole antenna to a device, when four frequency bands are used, four antennas are required and four connectors and four cables are used. There is a problem that it becomes necessary and the system becomes expensive. In addition, when used as a repeater antenna on a ceiling or the like in a building, it has been pointed out that the conventional monopole antenna has a high antenna height in a low frequency band of 800 MHz, and is difficult to install. .

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a wideband antenna device that can achieve a low profile and a small size and can have a wideband characteristic.

A wideband antenna device according to the present invention includes a planar conductor plate, a first radiating element that is provided vertically on the planar conductor plate, and uses a plate-like element, and both sides from the center of the outer end of the first radiating element. A second radiating element in the form of a band whose tip is fixed to the planar conductor plate, and the first radiating element at a common connection of the first and second radiating elements, And a plate-like third radiating element provided in parallel to the same direction.
Further, the first radiating element is characterized in that plate-like matching elements are provided on both sides near the lower end.
Further, the third radiating element is characterized in that a notch is provided on both side portions in the direction of the second radiating element.

  According to the present invention, by combining a plurality of radiating elements, the antenna can be reduced in height, size and bandwidth, and one antenna can be shared by multiple frequencies.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view of a broadband antenna device 10 according to the first embodiment of the present invention, and FIG. 2 is a front view of the main part in FIG.

1, 11 is a circular flat conductor plate, the radius is set to about λ _0/4. The λ ₀ is a wavelength at the lowest operating frequency, for example, 800 MHz. A hole 12 is provided at the center of the planar conductor plate 11, and a coaxial connector 13 is attached to the hole 12 by a support plate 15 and screws 16 as shown in FIG. At this time, the central conductor 14 of the coaxial connector 13 is led out through the hole 12 to the opposite side. The feeding point 18 of the first radiating element 17 is connected to the tip of the central conductor 14 by soldering or the like. The first radiating element 17 is disposed perpendicular to the planar conductor plate 11 and has a polarization plane of vertical polarization.

The first radiating element 17 is obtained by forming a plate-shaped element operating as a monopole antenna as shown in FIG. 2, the overall length L of about λ _0/9 (approximately 40 mm), the width W of the upper about lambda It is set to _0/3 (about 115 mm). The first radiating element 17 is formed, for example, so that the width is gradually reduced from the upper end to the lower side, and the impedance is set to an appropriate value, for example, 50Ω. The first radiating element 17 has a feeding point 18 at the center of the lower end.
By arranging the first radiating element 17 vertically on the planar conductor plate 11 as described above, the planar conductor plate 11 operates as a monopole antenna in which a mirror image of the first radiating element 17 is formed.

  Then, the strip-shaped second radiating element 21a is positioned obliquely in the direction of both sides from the center of the outer end of the first radiating element 17, that is, the upper (top) center of the first radiating element 17 shown in the drawing. , 21b are provided. The second radiating elements 21 a and 21 b are integrally formed in this example, and are provided so as to intersect with the first radiating element 17. A portion where the upper portion of the first radiating element 17 and the second radiating elements 21a and 21b intersect is fixed by soldering.

The second radiating elements 21 a and 21 b are bent outward or inward so that the tip located on the planar conductor plate 11 side is parallel to the planar conductor plate 11, and are screwed and soldered to the planar conductor plate 11. It is fixed by attaching or the like, and its length (excluding the tip portion in contact with the planar conductor plate 11) is about λ ₀ /5±1.25λ ₀ (about 60 to 80 mm), and the element width Wa is λ It is set to ₀ / _{25~λ 0} /10.5 (about 15~35.7mm). The second radiating elements 21a and 21b are formed in a mountain shape and also have a function of holding the first radiating element 17 at the top.

  Further, the upper side of the second radiating elements 21a and 21b, that is, at the common connection portion of the first radiating element 17 and the second radiating elements 21a and 21b, a plate-like second in the same direction as the first radiating element 17 is provided. Three radiating elements 22 are provided. The third radiating element 22 is formed, for example, in a substantially trapezoidal shape at both ends, and the total length is set to be substantially the same as or slightly shorter than the width W of the upper part of the first radiating element 17. Notches 23a and 23b are provided in portions corresponding to the radiating elements 21a and 21b. The notches 23a and 23b are provided so as not to prevent radio wave radiation of the second radiating elements 21a and 21b.

  Further, the third radiating element 22 is formed with, for example, a rectangular opening 24 at the center, and is fixed by soldering to the second radiating elements 21 a and 21 b in the opening 24. It is desirable to form the third radiating element 22 in a vertically and horizontally symmetrical manner. By forming the third radiating element 22 so as to be vertically and horizontally symmetrical, it is possible to eliminate the disturbance of the horizontal plane directivity and make it non-directional.

In the antenna device 10, as shown in FIG. 1, a screw groove 31 is formed on the outer periphery of the coaxial connector 13, and an antenna mounting nut 32 is screwed into the screw groove 31. In this case, the coaxial connector 13 is provided with a circular antenna mounting plate 33 so as to be positioned between the planar conductor plate 11 and the nut 32. The antenna mounting plate 33 has a hole at the center, and the coaxial connector 13 is inserted through the hole. That is, the antenna device 10 is fixed by interposing a member such as a ceiling member at the antenna mounting position between the planar conductor plate 11 and the antenna mounting plate 33 and tightening the nut 32.
FIG. 3 shows a state in which an antenna cover 35 made of synthetic resin is attached to the antenna device 10. In this case, the antenna cover 35 is fixed to the flat conductor plate 11 with screws or the like.

  FIG. 4 shows the VSWR characteristics when only the first radiating element 17 is provided on the planar conductor plate 11 in the antenna device 10. The horizontal axis represents the frequency GHz and the vertical axis represents VSWR. . When only the first radiating element 17 is provided on the planar conductor plate 11 as described above, the VSWR is 2 in the frequency range of about 1.6 to 1.75 GHz and the range of about 2.2 to 3.1 GHz. It becomes the following, and favorable reception is possible.

  FIG. 5 shows the VSWR characteristics when the first radiating element 17 and the second radiating elements 21 a and 21 b are provided on the planar conductor plate 11 in the antenna device 10. When the first radiating element 17 and the second radiating elements 21a and 21b are provided, the VSWR is 2 or less in the frequency range of about 1.0 to 1.95 GHz and the range of about 2.3 to 3.35 GHz. Good reception is possible. When the first radiating element 17 and the second radiating elements 21a and 21b are used as described above, the antenna can be used as a dual-frequency antenna, for example, in a cellular phone frequency band of 1.5 GHz and 1.7 GHz. Is possible.

FIG. 6 shows VSWR characteristics when the first radiating element 17, the second radiating elements 21 a and 21 b, and the third radiating element 22 are provided on the planar conductor plate 11 in the antenna device 10. In this case, the frequency characteristics are such that the VSWR is 2 or less in a frequency range of about 0.75 to 0.95 GHz and a range of about 1.8 to 2.8 GHz, and good reception is possible. Therefore, the antenna device 10 shown in the above embodiment can be used as a dual-frequency antenna, for example, in a mobile phone frequency band of 800 MHz and 2 GHz.
In addition, the directivity of the antenna device 10 is omnidirectional in the vertical polarization horizontal plane.

  According to the above-described embodiment, it is possible to achieve wideband characteristics while achieving miniaturization, and it can be used as a multi-frequency shared antenna.

  In the above-described embodiment, the case where the third radiating element 22 is provided on the second radiating elements 21a and 21b has been described, but the upper part of the first radiating element 17, that is, the first radiating element 17 and A third radiating element 22 may be provided between the second radiating elements 21a and 21b.

In the above-described embodiment, the case where the end portion of the third radiating element 22 is formed in a square shape is shown, but other shapes, for example, an elliptical shape as shown in FIG. 7 may be used. In this case, the ratio of the elliptical major axis to the minor axis is set to, for example, about 1: 0.7.
Furthermore, as shown in FIG. 8, notches 23a and 23b may be provided at the center of both sides of the third radiating element 22 formed in an elliptical shape. By providing the notches 23a and 23b as described above, the directivity deviation in the horizontal plane can be reduced without disturbing the radio wave radiation of the second radiating elements 21a and 21b.

  In the above-described embodiment, the second radiating elements 21a and 21b and the third radiating element 22 are separately formed. However, as shown in FIGS. The radiating elements 21a and 21b and the third radiating element 22 may be integrally formed. FIG. 9A shows a case where the third radiating element 22 formed in an elliptical shape is integrally formed in the central portion with respect to the band-like second radiating elements 21a and 21b, and FIG. In this example, the third radiating element 22 formed in a square shape is integrally formed at the center with respect to the radiating elements 21a and 21b. Note that the width of the slit formed between the second radiating elements 21a and 21b and the third radiating element 22 can be arbitrarily set since it hardly affects the characteristics.

  By integrating the second radiating elements 21a and 21b and the third radiating element 22 as described above, the number of parts and the number of assembling steps can be reduced, and it can be manufactured at low cost.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
FIG. 10 is a perspective view of a broadband antenna apparatus 10A according to the second embodiment of the present invention. Fig.11 (a) is a front view which shows only the 1st radiation | emission element 17 part in FIG. 10, (b) is the same side view.

  The antenna device 10 </ b> A according to the second embodiment is the antenna device 10 according to the first embodiment shown in FIG. 1, in which a matching element portion 41 is provided for the first radiating element 17. Since other configurations are the same as those in the first embodiment, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

The first radiating element 17 is obtained by forming a plate-shaped element operating as a monopole antenna as described in the first embodiment, the length L of about lambda _0/9, the width W of the upper about lambda ₀ / 3. In addition, the first radiating element 17 is formed so that the width becomes narrower sequentially from the upper end to the lower side, for example, so that the impedance becomes an appropriate value, for example, 50Ω. The first radiating element 17 has a feeding point 18 at the center of the lower end.

The first radiating element 17 is provided with a matching element portion 41 at an upper position by a distance La from the lowermost side portion. Height La of the matching element 41 is set, for example, about λ _0/25. lambda ₀ is the wavelength in the case of the lowest operating frequency of the antenna device for example, 800 MHz, a value of the lambda _0/25 is about 15 mm.

The matching element section 41 is configured by providing, for example, rectangular plate-shaped matching elements 42 a and 42 b on both surfaces of the first radiating element 17. In this case, for example, the matching elements 42 a and 42 b are bent in an L shape on the first radiating element 17 side, and the bent portions are attached to the first radiating element 17. The matching elements 42a and 42b are set such that the lateral width Wb is about λ ₀ /4.5 (about 80 mm) and the protruding width Wc from the first radiating element 17 is about λ ₀ /37.5 (about 10 mm). .

FIG. 12 shows the VSWR characteristics of the antenna device 10A. In the range of about 0.75 to 2.15 GHz, the VSWR is 2 or less, and the ratio band is about 92%. Therefore, the antenna device 10A shown in the above embodiment can be used as, for example, a broadband antenna in a mobile phone frequency band from 800 MHz to 2 GHz. In addition, the directivity of the antenna device 10A is omnidirectional in the vertical polarization horizontal plane.
According to the second embodiment, it is possible to further broaden the frequency characteristics by attaching the matching element unit 41 to the first radiating element 17.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

1 is a perspective view of an antenna device according to a first embodiment of the present invention. It is a front view of the principal part of the antenna device in the same embodiment. It is a perspective view which shows the state which mounted | wore the antenna device in the embodiment with the antenna cover. In the same embodiment, it is a VSWR characteristic figure at the time of providing only the 1st radiation element on a plane conductor board. In the same embodiment, it is a VSWR characteristic view at the time of providing the 1st and 2nd radiation element on a plane conductor board. In the same embodiment, it is a VSWR characteristic view at the time of providing the 1st thru / or the 3rd radiation element on a plane conductor board. It is a figure showing other examples of shape of the 3rd radiation element in the embodiment. It is a figure showing other examples of shape of the 3rd radiation element in the embodiment. It is a figure which shows the structural example at the time of forming the 2nd radiation element and 3rd radiation element in the same embodiment integrally. It is a perspective view of the antenna device which concerns on 2nd Embodiment of this invention. (A) is a front view of the 1st radiation element in the embodiment, (b) is the side view. It is a VSWR characteristic view in the same embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 10A ... Antenna apparatus, 11 ... Planar conductor plate, 12 ... Hole, 13 ... Coaxial connector, 14 ... Center conductor, 15 ... Support plate, 16 ... Screw, 17 ... First radiation element, 18 ... Feed point, 21a 21b ... second radiating element, 22 ... third radiating element, 23a, 23b ... notch, 24 ... opening, 31 ... thread groove, 32 ... nut for attaching antenna, 33 ... antenna attaching plate, 35 ... Antenna cover, 41... Matching element portion, 42a, 42b.

Claims (3)

  A planar conductor plate, a first radiating element provided vertically on the planar conductor plate, using a plate-like element, and provided obliquely on both sides from the center of the outer end of the first radiating element; A strip-shaped second radiating element fixed to the planar conductor plate, and a plate provided in parallel to the first radiating element in the common connection portion of the first radiating element and the second radiating element And a third radiating element in a shape.   The broadband antenna apparatus according to claim 1, wherein the first radiating element is provided with plate-like matching elements on both sides in the vicinity of the lower end.   The wide-band antenna device according to claim 1, wherein the third radiating element is provided with notches on both sides of the third radiating element in the direction of the second radiating element.

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