JP5721796B2 - antenna - Google Patents

Description

  The present invention relates to an antenna that can be suitably used as a base station antenna in a mobile communication system or the like.

  Patent Document 1 discloses a sector antenna used as a base station antenna. This antenna is disposed on the back of a dipole element that shares a horizontally polarized wave in a lower frequency band (for example, 1.5 GHz band) and a horizontally polarized wave in a higher frequency band (for example, 2 GHz band). And a directivity adjusting plate positioned on the outer side of each tip of the dipole element. Each directivity adjusting plate is disposed so as to be in a non-conductive state with respect to the reflecting plate and to face each other.

  In this antenna, horizontal polarization is radiated from the dipole element, and at that time, the horizontal polarization is reflected by the reflector in the main radiation direction (center direction of the sector). The directivity adjustment plate has the effect of expanding the polarization beam width of the higher frequency band without expanding the polarization beam width of the lower frequency band, and thereby the polarization beam width of both frequency bands. The difference is suppressed. In addition, each side surface reflecting plate part raised and formed at both ends of the reflecting plate suppresses the horizontally polarized wave from going around to the back side of the reflecting plate.

JP 2012-147086 A

By the way, in the sector antenna for sector division, the beam width is an important factor, but when considering the degree of interference given to adjacent sectors, the front side ratio and the front back ratio are more important than the beam width. become.
The reflector of the antenna according to Patent Document 1 acts to suppress unnecessary radiation outside the desired horizontal angle range by suppressing back lobes and the like. However, since this reflector is set based on the polarization wavelength in the frequency band on the side with the lower horizontal width, when the width is converted into the polarization wavelength on the higher frequency band side, May exceed one wavelength. In this case, the difference between the beam width of the polarized wave in the high frequency band and the beam width of the polarized wave in the lower frequency band increases, and the front side ratio and the front back ratio that become the interference direction level ratio also deteriorate.

  Therefore, even when the horizontal width of the reflector exceeds one wavelength of the polarized wave in the higher frequency band, the present invention has a directivity in the horizontal plane in the higher frequency band and that in the lower frequency band. It is an object of the present invention to provide an antenna capable of reducing the difference and improving the front side ratio and the front back ratio as the interference direction level ratio.

An antenna according to a first aspect of the present invention includes a dipole element that transmits and receives horizontally polarized waves, and a reflector disposed on the back of the dipole element, and the horizontal width of the reflector is equal to the transmission frequency (> reception frequency). ) Is set to be larger than one wavelength. The antenna includes directivity adjustment plates opposed to each other on each part on the reflection plate located on the outer side of each tip of the dipole element, and on the outer side of each directivity adjustment plate. Each of the positions of the reflector is positioned, and each of the holes reduces the horizontal width of the reflector as viewed with respect to the transmission frequency, and each directivity adjustment plate. The influence of the reflecting plate on the radio wave having the transmission frequency diffracted in (1) is suppressed.

  The antenna may further include a dipole element that transmits and receives vertically polarized waves. The hollow is formed in a square shape, for example, and the horizontal length and vertical length are set to be 0.15 times or more and 0.25 times or more of the wavelength of the transmission frequency. Side reflector parts for adjusting the directivity in the horizontal plane can be formed at both ends of the reflector.

An antenna according to a second aspect of the present invention includes individual horizontal polarization dipole elements applied to a plurality of different frequency bands, and a reflector disposed on the back of each horizontal polarization dipole element, The horizontal width of the reflector is set to be larger than one wavelength of the polarized wave in the highest frequency band in each frequency band. This antenna is a directivity adjusting plate opposed to each other, which is erected at each part on the reflecting plate located on the outer side of each tip of the dipole element applied to the highest frequency band, and Each of the reflecting plates located on the outer side of each directivity adjusting plate, and each of the reflectors is formed with a hollow hole, and the horizontal width of the reflector plate with respect to the transmission frequency is determined by the hollow hole . While narrowing, the influence of the reflecting plate on the radio wave of the transmission frequency diffracted by each directivity adjusting plate is suppressed.

The antenna may further include individual vertically polarized dipole elements applied to the plurality of different frequency bands. The hollow is formed in, for example, a square shape, and the horizontal length and the vertical length are set to 0.15 times or more and 0.25 times or more of the wavelength of the transmission frequency in the highest frequency band, respectively. . Side reflectors for adjusting the directivity in the horizontal plane can be formed upright at both ends of the reflector.

According to the antenna according to the first aspect of the present invention, the horizontal width of the reflector is set to be larger than one wavelength of the transmission frequency (> reception frequency), and the directivity in the horizontal plane with respect to the transmission frequency is It is possible to reduce the difference with respect to the reception frequency, and it is also possible to improve the front side ratio and the front back ratio that are the interference direction level ratio.
Further, according to the antenna of the second invention, although the horizontal width of the reflector is set to be larger than one wavelength of the polarized wave in the highest frequency band in each frequency band, The difference between the polarization beam width of the highest frequency band and the polarization beam width of the other frequency band can be reduced, and the interference direction level ratio can be improved.

It is a perspective view which shows the basic composition of an antenna provided with the dipole element for horizontal polarization. 2 is a graph showing a relationship between a reflector width and a beam width in the antenna of FIG. 2 is a graph showing a relationship between a reflector width and an interference direction level ratio in the antenna of FIG. FIG. 2 is a perspective view showing a state in which a directivity adjusting plate is disposed on the antenna of FIG. It is a front view of the antenna of FIG. It is a graph which shows the relationship between the position of the directivity adjustment board and beam width in the antenna of FIG. It is a graph which shows the relationship between the position of the directivity adjustment board and the interference direction level ratio in the antenna of FIG. FIG. 2 is a front view showing a state in which a hole is formed in the antenna of FIG. It is a graph which shows the relationship between the vertical direction length of the hollow and the beam width in the antenna of FIG. It is a graph which shows the relationship between the perpendicular direction length of the hollow and the interference direction level ratio in the antenna of FIG. It is a graph which shows the relationship between the horizontal direction length of the hollow and the beam width in the antenna of FIG. It is a graph which shows the relationship between the horizontal direction length of the hollow and the interference direction level ratio in the antenna of FIG. 1 is a perspective view showing an embodiment of an antenna according to the present invention. FIG. 14 is a front view of the antenna of FIG. It is sectional drawing by the AA line of FIG. It is a graph which shows the relationship between the perpendicular direction length of a hollow and the beam width in the antenna of FIG. It is a graph which shows the relationship between the vertical direction length of the hollow and the interference direction level ratio in the antenna of FIG. It is a graph which shows the relationship between the horizontal direction length of the hollow and the beam width in the antenna of FIG. It is a graph which shows the relationship between the horizontal direction length of the hollow and the interference direction level ratio in the antenna of FIG. 2 is a graph showing the directivity in the horizontal plane of the antenna of FIG. It is a graph which shows the directivity in the horizontal surface of the antenna which concerns on an Example. It is a perspective view which shows other embodiment of the antenna which concerns on this invention. It is a perspective view which shows another embodiment of the antenna which concerns on this invention. It is a front view of the antenna of FIG.

The antenna shown in FIG. 1 includes a half-wave dipole element 1 and a rectangular reflector 3 disposed on the back of the dipole element 1.
The dipole element 1 is disposed above the central portion of the reflector 3 so that the longitudinal axis thereof is in the horizontal direction (x direction) so as to transmit and receive horizontally polarized waves in the used frequency band. The reflection plate 3 is arranged in such a manner that its longitudinal axis is directed in the vertical direction (z direction), and side reflection plate portions 3a are respectively formed upright on both side ends.

  The transmission frequency and the reception frequency in this antenna are set to have a relationship of (wavelength of transmission frequency) = 0.864 × (wavelength of reception frequency). Therefore, when the frequency band used for this antenna is 2 GHz, for example, the transmission frequency is set to 2.2 GHz and the reception frequency is set to 1.9 GHz. The use frequency band, reception frequency, and transmission frequency are not limited to the above.

In this antenna, with respect to a change in the horizontal width W of the reflector 3, the horizontal plane beam width corresponding to the reception frequency 1.9 GHz (hereinafter referred to as 1.9 GHz beam width) and the horizontal plane corresponding to the transmission frequency 2.2 GHz. The inner beam width (hereinafter referred to as 2.2 GHz beam width) varies in the form shown in FIG. 2 is a wavelength λ _2.2 with a transmission frequency of 2.2 GHz.
The horizontal width W of the reflector 3 is set based on the wavelength λ _{1.9 of the} reception frequency so as to match the reception frequency of 1.9 GHz, which is the lower frequency. For this reason, when the width W of the reflecting plate 3 is converted into a wavelength λ _2.2 of a transmission frequency of 2.2 GHz, which is a higher frequency, it may exceed 1.0 × λ _2.2 .
When the horizontal width W of the reflector 3 exceeds the wavelength λ _2.2 , the difference between the 1.9 GHz beam width and the 2.2 GHz beam width increases as shown in FIG. As shown, the front side ratio (hereinafter referred to as FS ratio) and the front back ratio (hereinafter referred to as FB ratio), which are the interference direction level ratio, also deteriorate.

On the other hand, the side reflection plate portion 3a of the reflection plate 3 acts to adjust the beam width in the horizontal plane. However, the side reflector 3a is designed to be optimal for a reception frequency of 1.9 GHz, similarly to the horizontal width W of the reflector 3, so that the beam width for a transmission frequency of 2.2 GHz is used. It does not function effectively as an adjustment means.
In this antenna, the horizontal width W of the reflecting plate 3 is 1.28λ ₂ , ₂ , the height of the side reflecting plate portion 3a is 0.11λ _2.2 , and the dipole element 1 from the surface of the reflecting plate 3 is used. Are set to 0.33λ _2.2 .

The antenna shown in FIG. 4 has a configuration in which a pair of directivity adjusting plates 5 is added to the antenna of FIG. Each directivity adjusting plate 5 is erected on each part of the reflecting plate 3 located on the outer side of each tip of the dipole element 1. In other words, the directivity adjusting plates 5 are erected symmetrically with respect to the yz plane including the longitudinal axis of the reflecting plate 3 and facing each other. In this antenna, the y-direction length and the z-direction length of the directivity adjusting plate 5 are set to 0.168λ _2.2 and 0.293λ _2.2 , respectively.

As shown in FIG. 5, when the distance from the directivity adjusting plate 5 to the horizontal end of the corresponding reflecting plate 3 is D, as the distance D changes, that is, the interval between the directivity adjusting plates 5 is changed. With the change, the 1.9 GHz beam width and the 2.2 GHz beam width are changed as shown in FIG. 6, and the 1.9 GHz FS ratio, 1.9 GHz FB ratio, 2.2 GHz FS ratio, and 2.2 GHz FB ratio are shown in FIG. Changes as shown.
As apparent from FIGS. 6 and 7, the directivity adjusting plate 5 alone cannot sufficiently reduce the difference between the 1.9 GHz beam width and the 2.2 GHz beam width, and the FS ratio and the FB ratio are also improved. Not. This is because the radio wave diffracted by the directivity adjusting plate 5 is affected by the reflector 3 ahead.

The antenna shown in FIG. 8 has a configuration in which a pair of rectangular holes 7 are formed in the reflector 3 of the antenna shown in FIG. The cut-out hole 7 is located on the outer side of each tip of the dipole element 1 and is formed so as to go from the lower end of the inner surface of the side reflection plate portion 3a toward the inside of the reflection plate 3.
As described above with reference to FIG. 2, when the horizontal width W of the reflector 3 exceeds 1.0 × λ ₂ , the directivity deteriorates. Based on such considerations, the cutout hole 7 narrows the horizontal width of the reflector 3 at the position where the dipole element 1 is disposed while suppressing the influence on the operation with respect to the reception frequency of 1.9 GHz, which is the lower frequency. It was formed with the intention of

Figure 9 shows the change in the 1.9GHz beamwidth and 2.2GHz beam width to change in the vertical direction length _{L V} of the hollowed hole 7, 1.9GHzFS ratio in FIG. 10 with respect to change in the vertical length _{L V,} 1 The change of .9 GHz FB ratio, 2.2 GHz FS ratio and 2.2 GHz FB ratio is shown.
Also shows a change in the 1.9GHz beamwidth and 2.2GHz beam width to change in the horizontal direction length _{L H} of the hollowed hole 7 in FIG. 11, 1.9GHzFS ratio 12 to changes in the horizontal direction length _{L H} The change of 1.9 GHz FB ratio, 2.2 GHz FS ratio, and 2.2 GHz FB ratio is shown.
As is apparent from FIGS. 9 to 12, the difference between the 1.9 GHz beam width and the 2.2 GHz beam width cannot be sufficiently reduced only by the hollow 7 and the FS ratio and the FB ratio are also improved. Not.

FIG. 13 is a perspective view of an antenna according to an embodiment of the present invention, FIG. 14 is a front view of the antenna, and FIG. 15 is a sectional view taken along line AA of FIG.
The antenna according to the present embodiment has a configuration in which the directivity adjusting plate 5 shown in FIG. 5 and the hollow 7 shown in FIG. In this case, each hollow 7 is formed in each part of the reflecting plate 3 located on the outer side of each directivity adjusting plate 5. Also in this antenna, the horizontal width W of the reflecting plate 3 is set to 1.28 × λ _2.2 , the height of the side reflecting plate portion 3a is set to 0.11λ _2.2 , and directivity is set. The length in the y direction and the length in the z direction of the property adjusting plate 5 are set to 0.168λ _2.2 and 0.293λ _2.2 , respectively. The directivity adjusting plate 5 is erected on the portion of the reflecting plate 3 facing the inner edge of the corresponding cutout hole 7.

Here, when changing the vertical length _{L V} of the voids 7 in the horizontal direction length _{L H} of the hollowed out hole 7 in a state set to 0.33? _2.2, 1.9 GHz beamwidth and 2.2GHz beam width 16 changes in the form shown in FIG. 16, and the 1.9 GHz FS ratio, 1.9 GHz FB ratio, 2.2 GHz FS ratio, and 2.2 GHz FB ratio change in the form shown in FIG.
As apparent from FIGS. 16 and 17, when the vertical length _{L V} of the coring hole 7 is 0.25 [lambda _2.2 or more, the difference between the 1.9GHz beam width and 2.2GHz beam width is reduced At the same time, the interference direction level ratio is improved.

On the other hand, changing the horizontal length _{L H} of the hollowed out hole 7 a vertical length _{L V} of the coring holes 7 in a state set to 0.33? _2.2, 1.9 GHz beamwidth and 2.2GHz beamwidth 18 changes, and the 1.9 GHz FS ratio, 1.9 GHz FB ratio, 2.2 GHz FS ratio, and 2.2 GHz FB ratio change in the form shown in FIG.
As apparent from FIGS. 18 and 19, when the horizontal length L _H of the hollow 7 is 0.15λ _2.2 or more, the beam width characteristic of the transmission frequency of 2.2 GHz and the beam of the reception frequency of 1.9 GHz are obtained. The difference in width characteristic is reduced, and the interference direction level ratio is improved.
Thus, according to the antenna of the present embodiment, when the horizontal width of the reflection plate 3 is greater than the wavelength lambda _2.2 also in HPBW in the horizontal plane characteristic of the transmission frequency and the reception frequency of the dipole elements 1 The difference can be reduced, and the level of the interference direction can be greatly improved.

As the embodiment dipole element 1, a half-wave horizontally polarized dipole element usable in the 2 GHz band is used.
The reception frequency is 1.9 GHz, and the transmission frequency is 2.2 GHz.
The horizontal width W of the reflector 3 is set to 1.28λ _2.2.
Set startup height of the side reflectors portion 3a of the (y-direction height) to 0.11λ _2.2.
The horizontal length L _H and the vertical length L _V of the cut-out hole 7 are set to 0.238λ _2.2 and 0.33λ _2.2 , respectively.
The directivity adjusting plate 5 is positioned at the inner edge portion of the corresponding cut-out hole 7, and the y-direction length and the z-direction length of the directivity adjusting plate 5 are 0.168λ _2.2 and 0.293λ ₂ , respectively _. Set to ₂ .

  FIG. 20 shows the directivity in the horizontal plane of the antenna shown in FIG. 1, and FIG. 21 shows the directivity in the horizontal plane of the antenna according to the above embodiment. As shown in FIG. 21, according to the antenna according to the above-described embodiment, the horizontal plane directivity for the reception frequency of 1.9 GHz and the horizontal plane directivity for the transmission frequency of 2.2 GHz can be substantially matched. Also, the level of interference direction is improved.

  FIG. 22 shows another embodiment of the antenna according to the present invention. The antenna according to this embodiment has a configuration in which a dipole element 9 for vertical polarization is added to the antenna shown in FIG. The dipole element 9 is arranged so that the longitudinal axis thereof is directed in the vertical direction (z direction) in order to transmit and receive vertical polarization, and is orthogonal to the dipole element 1 for horizontal polarization. This antenna can be operated as a dual polarization antenna.

FIG. 23 and FIG. 24 are a perspective view and a front view showing still another embodiment of the antenna according to the present invention that shares frequency and polarization.
The antenna of this embodiment includes a horizontally polarized dipole element 11 used in the 0.8 GHz band, a horizontally polarized dipole element 13 used in the 2 GHz band, and a vertically polarized wave used in the 0.8 GHz band. Dipole element 15, a vertically polarized dipole element 17 used in the 2 GHz band, and a reflector 19 provided on the back of these dipole elements 11 to 17. Each of the dipole elements 11 to 17 is a half-wave dipole element, and can be applied to an arbitrary use frequency band different from the above by changing its length or the like.

Here, it is assumed that the wavelength of the frequency of 0.8 GHz is λ _0.8 and the wavelength of the frequency of 2.2 GHz is λ _2.2 . 0.8GHz band horizontal polarization dipole element 11 are two-stage arranged at intervals of 0.676Ramuda _0.8 in the vertical direction (z-direction). The horizontal polarization dipole element 11 has a height from the reflecting plate 19 is set to, for example 0.155Ramuda _0.8, and its center point is located yz plane including the longitudinal axis of the reflector 19 Yes.
Further, 2 GHz band horizontal polarization dipole element 13 are four stages arranged at intervals of 0.88Ramuda _2.2 in the vertical direction. The horizontal polarization dipole element 13 has a height from the reflecting plate 19 is set to, for example, 0.33? _2.2, and its center point is located yz plane including the longitudinal axis of the reflector 19 Yes.

On the other hand, 0.8 GHz band vertically polarized wave dipole elements 15 are arranged symmetrically about the yz plane containing the longitudinal axis of the reflector 19, and the spacing 0.676Ramuda _0.8 in the vertical direction (z-direction) Two stages are arranged. Each vertical polarization dipole element 15 has a height from the reflecting plate 19 is set to, for example 0.099Ramuda _0.8, and the arrangement interval in the horizontal direction (x direction) is set to 0.352Ramuda _0.8 ing.
2GHz band vertically polarized wave dipole elements 17 are arranged symmetrically about the yz plane containing the longitudinal axis of the reflector 19, and, at intervals of 0.88Ramuda _2.2 in the vertical direction (z-direction) 4 They are arranged in stages. Each vertical polarization dipole element 17 has a height from the reflecting plate 19 is set to, for example, 0.33? _2.2, and the arrangement interval in the horizontal direction (x direction) is set to 0.416Ramuda _2.2 ing.

The horizontal width of the reflecting plate 19 is set to 1.28 × λ _2.2, and the height of the side reflecting plate portion 19a of the reflecting plate 19 is set to 0.11 × λ _2.2 . A hollow 21 and a directivity adjusting plate 23 are formed in the reflecting plate 19. The cutout hole 21 and the directivity adjusting plate 23 correspond to the cutout hole 7 and the directivity adjusting plate 5 shown in FIG. 14 and are located on the outer side of each tip of the dipole element 13. Then, y-direction length and the z-direction length of the directivity adjustment plate 23 is set to 0.168Ramuda _2.2 and 0.293Ramuda _2.2 respectively.

The antenna according to the present embodiment can share two frequency bands of 0.8 GHz band and 2 GHz band, and can share horizontal polarization and vertical polarization of these frequency bands. As a result of the simulation, the x-direction length (horizontal direction length) and the z-direction length (vertical direction length) of the cutout hole 21 are 0.15 times or more and 0.25 times or more of the wavelength λ _2.2 (for example, x When the direction length = 0.238λ _2.2 and the z-direction length = 0.33λ _2.2 ), the horizontal width beam width characteristics of the horizontal polarization of the 2 GHz band reception frequency (1.9 GHz or its vicinity) It was found that the difference between the horizontal polarization of the horizontally polarized wave of the 2 GHz band transmission frequency (2.2 GHz or the vicinity thereof) and the beam width characteristic in the horizontal plane is reduced, and the level of the interference direction is improved. .
As described above, the antenna according to this embodiment can be applied to two frequency bands different from the above by changing the lengths of the dipole elements 11 to 17 and the like. Further, the antenna according to the present embodiment can be configured to be applicable to frequency bands of three or more frequency bands.

DESCRIPTION OF SYMBOLS 1 Horizontally polarized dipole element 3 Reflector 3a Side reflector 5 Directionality adjusting plate 7 Hollow hole 9 Vertically polarized dipole element 11 Horizontally polarized dipole element 13 Horizontally polarized dipole element 15 Vertically polarized dipole Element 17 Dipole element for vertical polarization 19 Reflector 19a Side reflector 21 Hole cutout 23 Directivity adjustment plate

Claims (8)

It has a dipole element that transmits and receives horizontally polarized waves, and a reflector disposed on the back of the dipole element, and the horizontal width of the reflector is set to be larger than one wavelength of the transmission frequency (> reception frequency). Antenna,
Directivity adjusting plates opposed to each other, each erected on each part on the reflector located on the outer side of each tip of the dipole element;
A hollow formed in each part of the reflection plate located on the outer side of each directivity adjustment plate,
The respective cutout holes narrow the horizontal width of the reflection plate as viewed with respect to the transmission frequency, and suppress the influence of the reflection plate on the radio waves of the transmission frequency diffracted by the directivity adjustment plates. An antenna characterized by.   The antenna according to claim 1, further comprising a dipole element that transmits and receives vertically polarized waves.   2. The cutout hole is formed in a square shape, and a horizontal length and a vertical length are set to be not less than 0.15 times and not less than 0.25 times the wavelength of the transmission frequency, respectively. Or the antenna of 2.   The antenna according to any one of claims 1 to 3, wherein side reflectors for adjusting directivity in a horizontal plane are formed upright at both ends of the reflector. A dipole element for horizontal polarization applied to a plurality of different frequency bands, and a reflector disposed at the back of each dipole element for horizontal polarization, the horizontal width of the reflector is An antenna set to be larger than one wavelength of a transmission frequency among transmission / reception frequencies (transmission frequency> reception frequency) included in the highest frequency band in each frequency band,
Directivity adjusting plates opposed to each other, each erected on each part on the reflecting plate located on the outer side of each tip of the dipole element applied to the highest frequency band;
A hollow formed in each part of the reflection plate located on the outer side of each directivity adjustment plate,
The respective cutout holes narrow the horizontal width of the reflection plate as viewed with respect to the transmission frequency, and suppress the influence of the reflection plate on the radio waves of the transmission frequency diffracted by the directivity adjustment plates. An antenna characterized by.   The antenna according to claim 5, further comprising individual dipole elements for vertical polarization applied to the plurality of different frequency bands. The hollow is formed in a square shape, and the horizontal length and the vertical length are set to be 0.15 times or more and 0.25 times or more of the wavelength of the transmission frequency in the highest frequency band, respectively. The antenna according to claim 5 or 6.   The antenna according to any one of claims 5 to 7, wherein side reflectors for adjusting directivity in a horizontal plane are formed upright at both ends of the reflector.

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