JP2004228863A - 3-frequency shared antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an antenna capable of being shared by three frequency bands and having horizontal plane directivity for which the beam angle of the three frequency bands is roughly 60 degrees with a compact and inexpensive constitution. <P>SOLUTION: A pair of first antenna element parts 10 of dipole constitution capable of cross power feed which resonate to a first frequency f<SB>1</SB>and a second frequency f<SB>2</SB>(>f<SB>1</SB>) are formed on individual dielectric substrates 13 respectively, and a second antenna element part 20 of 2 dipole constitution which resonates to a third frequency f<SB>3</SB>(>f<SB>2</SB>) is formed. The second antenna element part 20 is positioned between the pair of the first antenna element parts 10, and the relative positions of dipoles 11 and 12 of the first antenna element parts 10 to a main reflector 30 and the relative position of the dipole 21 of the second antenna element part 20 to the main reflector 30 and a sub reflector 40 are set so as to obtain the horizontal plane directivity of 60° beams. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[Industrial application fields]
The present invention relates to a three-frequency shared antenna suitable as a base station antenna for a mobile communication system (for example, a mobile phone or a PHS), and more particularly to a three-frequency shared antenna that can obtain a beam angle of approximately 60 degrees in a horizontal plane. Is.
[0002]
[Prior art]
A dual-band antenna that can obtain a beam angle in the horizontal plane of approximately 60 degrees over two frequency bands is known (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-8-181538 [0004]
[Problems to be solved by the invention]
However, recently, in order to expand the applicable frequency band, there is a demand for an antenna that can be shared in three frequency bands.
The present invention has been made in view of such a situation, and the object thereof can be shared in three frequency bands, and the horizontal plane directivity with a beam angle of approximately 60 degrees is achieved by a compact and inexpensive configuration. The object is to provide a three-frequency shared antenna that can be realized.
[0005]
[Means for Solving the Problems]
The three-frequency antenna according to the present invention includes a main reflector, a dielectric substrate, a first dipole that resonates at a _first frequency f _1, and a second that resonates at a second frequency f ₂ (> f ₁ ). A pair of first antenna element portions formed in parallel to each other and capable of cross-feeding, and a pair of third dipoles that resonate at a _third frequency f ₃ (> f ₂ ) on the dielectric substrate And a second antenna element unit formed symmetrically at an interval of about 0.5 times the wavelength λ ₃ of the third frequency f ₃ , and each of the first antenna element units includes: about 0 to wavelength lambda ₁ in said formed their first dipole mutual spaced first about 0.25 times the distance of the wavelength lambda ₁ of the frequency f ₁ from the main reflector surface. And the second dipoles formed on them are formed at a distance of 5 times. It comes from the main reflector to form a second approximately 0.5 times the interval of the wavelength lambda ₂ in a plane spaced about 0.25 times the distance of the wavelength lambda ₂ of frequency f _2, the main The second antenna element unit is symmetrically disposed on both sides of the vertical plane including the center line of the reflector, and each of the first antenna elements is arranged so that each of the third dipoles is symmetrically positioned on both sides of the vertical plane. Auxiliary reflectors are disposed between the antenna element portions and symmetrically arranged on both sides of the vertical plane to define the beam angle of the second antenna element portion to about 60 °.
[0006]
The auxiliary reflectors are set so that the interval between them is about 0.8 times the wavelength λ ₂ of the second frequency f ₂ and the height is about 0.3 times the wavelength λ _2. can do.
[0007]
The first antenna element section may have a configuration in which a plurality of element units including the first and second dipoles are arranged in an array, and the second antenna element section includes the third antenna element section. A plurality of element units including the dipoles can be arranged in an array.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing an embodiment of a three-frequency shared antenna according to the present invention. 2 is a cross-sectional view taken along line AA in FIG.
The antenna according to this embodiment includes a pair of antenna element portions 10 and 10, an antenna element portion 20, a main reflection plate 30, and a pair of sub reflection plates 40 and 40.
[0009]
As illustrated in FIGS. 3 and 4, the antenna element unit 10 includes a first dipole 11 that resonates at a first frequency (for example, 800 MHz) and a second dipole that resonates at a second frequency (for example, 1.5 GHz). It has a configuration in which a plurality of rows formed in an array along a cross feed type element unit U _2-1 composed of a set of dipole 12 in the longitudinal direction of the rectangular-shaped dielectric substrate 13 (the direction perpendicular to the plane of FIG. 2) . In this embodiment, four element units _U2-1 are arranged.
[0010]
The first dipole 11 and the second dipole 12 are parallel to the longitudinal axis of the dielectric substrate 13, and the line 14 connecting the center points thereof is perpendicular to the longitudinal axis of the dielectric substrate 13. Further, they are formed at a predetermined interval from each other. The interval between the dipole 11 and the second dipole 12 will be described later.
[0011]
The first dipole 11 is constituted by elements 11a and 11b formed on one and other surfaces of the dielectric substrate 13, respectively. Similarly, the second dipole 12 is formed on one and other surfaces of the dielectric substrate 11. Are formed by elements 12a and 12b formed respectively.
[0012]
The elements 11 a and 12 a extend in opposite directions with the line 14 as a center, and one end thereof is connected to a feed line 15 formed along the line 14. The feed line 15 extends to the ground conductor plate 16 formed along the edge of the dielectric substrate 13.
Similarly, the elements 11b and 12b extend in opposite directions with the line 14 as a center, and one end thereof is connected to a feed line 17 formed along the line 14.
Therefore, as shown in FIG. 5, the first dipole 11 and the second dipole 12 are fed with a power supply line 15 connecting the elements 11a and 12a and a power supply line 17 connecting the elements 11b and 12b intersecting each other. Will be.
[0013]
Note that a certain element unit U _2-1 and an element unit U _2-1 adjacent to one side of the element unit U _2-1 are connected to each other so as to be fed in parallel. A shield conductor 18 extending from the ground conductor plate 16 is formed between the element units U _2-1 arranged on the dielectric substrate 13.
[0014]
As shown in FIG. 6, the antenna element unit 20 includes an element unit U ₃ composed of a pair of dipoles 21 that resonate at a third frequency (for example, 2 GHz) in the longitudinal direction of the rectangular dielectric substrate 22 (FIG. 2). And a plurality of arrays are formed in an array along the direction perpendicular to the paper surface. In this embodiment, the sensor unit U ₃ are then eight sequences.
[0015]
Each dipole 21 constituting the sensor unit U ₃ is formed along the longitudinal axis of the dielectric substrate 22, and another of about 0.5 [lambda _{3 (lambda 3,} the wavelength of the third frequency) of The dielectric substrate 22 is positioned symmetrically about the longitudinal axis of the dielectric substrate 22 so as to form an interval. Each dipole 21 has one feed point commonly connected to the feed line 23 and the other feed point commonly connected to the feed line 24.
[0016]
The dielectric substrate 25 has a central portion of the surface on which the dipoles 21 are formed on the dielectric substrate 22 so as to be perpendicular to the surface and along the longitudinal axis of the dielectric substrate 22. Is erected. As shown in FIGS. 7 and 8, the dielectric substrate 25 has feed lines 23 ′ and 24 ′ formed on one surface and the other surface, and the feed lines 23 ′ and 24 ′ are shown in FIG. 6, respectively. It is connected to the central part of the feed lines 23 and 24.
[0017]
Incidentally, the element unit U ₃ which is adjacent to one side of a certain element unit U ₃ and the antenna element unit U ₃ is the feed line 24 corresponding to the parallel feed 'are connected in common. The feeder line 23 ′ extends to the ground conductor plate 26 formed along the edge of the dielectric substrate 25.
Each element formed on the dielectric substrates 13, 22 and 25 is formed by a strip conductor made of a metal plate or a metal foil.
[0018]
As shown in FIG. 2, each antenna element portion 10 is disposed along a longitudinal direction of the main reflector 30 and includes a longitudinal axis of the reflector 30 and a surface 31 perpendicular to the reflector 30. They are located symmetrically.
Specifically, the dipoles 11 form a space of about 0.5λ ₁ in a plane separated from the main reflector 30 by about 0.25λ ₁ (λ ₁ is the wavelength of the first frequency). And the condition that the dipoles 12 form an interval of about 0.5λ ₂ in a plane separated from the main reflector 30 by about 0.25λ ₂ (λ ₂ is the wavelength of the second frequency). Are arranged symmetrically.
Since the distance between the first dipole 11 and the second dipole 12 in each antenna element section 10 is a requirement for satisfying the above conditions, it is appropriately set so that this condition is satisfied.
[0019]
The antenna element unit 20 is positioned so that the longitudinal axis thereof is positioned in the plane 31 and so that the individual dipoles 21 are positioned in a plane separated from the main reflector 30 by a distance L described later. The main reflector 30 is disposed along the longitudinal direction.
The sub-reflection plates 40 and 40 are formed of a metal plate or a metal foil, and are provided perpendicular to the main reflection plate 30 at symmetrical positions about the surface 31 set on the main reflection plate 30.
[0020]
As shown in FIG. 2, the three-frequency shared antenna according to the above embodiment is installed so that the whole is covered with the radome 50 and the longitudinal axis of the reflector 30 is oriented in the vertical direction.
When this antenna is used as a transmitting antenna, the power of the frequencies f ₁ and f ₂ is supplied to the dipoles 11 and 12 through a two distributor (not shown), and the power of the frequency f ₃ is Power is supplied to the dipole 21.
[0021]
At this time, the horizontal plane directivity based on the dipole 11 and the horizontal plane directivity based on the dipole 12 of each antenna element unit 10 are as shown in FIGS. 9 and 10, respectively. That is, since the dipole 11 cross each antenna element portion 10 forms a gap of about 0.5 [lambda ₁ in the main reflector 30 about 0.25 [lambda ₁ away plane, 60 degrees in a band of frequencies _{f 1} A beam is obtained. Similarly, since the dipoles 12 of the antenna element portions 10 form an interval of about 0.5λ ₂ in a plane separated from the main reflector 30 by about 0.25λ ₂ , also in the band of the frequency f _2. A 60 ° beam is obtained.
[0022]
By the way, due to the voltage standing wave ratio characteristic (VSWR), the distance between the dipoles 12 of each antenna element unit 10 may be set to about 0.37λ _2, for example. A side lobe as shown by a dotted line in FIG. 10 appears. One purpose of providing the sub-reflecting plates 40 is to suppress the side lobes. That is, in this embodiment, and sets an interval of the sub-reflector 40, 40 about 0.8Ramuda _2, is set to their height of about 0.3λ _2. Accordingly, side lobes are suppressed as shown by the solid line in the figure, and good horizontal plane directivity can be obtained.
[0023]
As described above, each antenna element unit 10 has a function as a dual-frequency antenna. In this case, the ratio of the frequency f ₁ and the frequency f _{2 at} which the function as a dual-frequency antenna is obtained is 1.5 to 1.7 when the frequency f ₁ is 1. Since the ratio of the two frequency bands of 810 MHz to 960 MHz and 1429 MHz to 1501 MHz allocated to the current automobile mobile phone is about 1.65, each antenna element unit 10 is adapted to each frequency band.
[0024]
Next, the horizontal plane directivity based on each dipole 21 of the antenna element unit 20 will be described. Eggplant distance L between the main reflector 30 and the dipole 21 of the antenna element 20, inevitably larger than 0.25 [lambda ₃ from positional relationship between the dielectric substrate 13. Moreover, between each dipole 21 and the main reflector 30, a ground conductor plate 16 of the antenna element portion 10 that also functions as a reflector is interposed. Therefore, it is difficult to obtain a 60 ° beam in the band of the frequency f ₃ only with each dipole 21 of the antenna element unit 20.
[0025]
Therefore, in this embodiment, by using the subreflector 40 and 40 as a means for defining the beam angle in the band of the frequency f ₃ to approximately 60 °. That is, since the sub-reflecting plates 40 and 40 affect the main lobe of the beam in the frequency f ₃ band, the arrangement position and shape of these sub-reflecting plates 40 and 40 are set as described above, and the frequency f _The horizontal plane directivity in which the beam angle in the band ₃ is approximately 60 ° is realized (see FIG. 11).
[0026]
As a result, the distance L formed between the dipole 21 and the main reflector 30 is determined by taking into consideration the arrangement position and shape of the sub-reflectors 40 and 40, the position of the ground conductor plate 16 of the antenna element unit 10, and the like. The beam angle in the _third band is appropriately set so as to be approximately 60 °.
Incidentally, in the antenna according to the above embodiment, when it tries to actually measure the distance M between the upper edge of the dipole 21 and the ground conductor plate 16 it was about 0.25 [lambda _3.
As is apparent from the above description, according to the three-wave shared antenna of this embodiment, it is possible to realize horizontal plane directivity in which the beam angle is approximately 60 ° in each band of the frequencies f ₁ , f ₂ and f _3. it can.
[0027]
Each of the lengths 0.25λ ₁ , 0.25λ ₂ , 0.5λ ₁ , 0.5λ _2, and 0.5λ ₃ shown in FIG. 2 has an allowable range. That is, each of the values _{(0.15λ 1 ~0.35λ 1), (} 0.15λ 2 ~0.35λ 2), (0.3λ 1 ~0.7λ 1), (0.3λ 2 ~0 .7λ ₂₎ it is set to and (0.3λ ₃ ~0.7λ _3), practically sufficient horizontal directivity can be obtained.
[0028]
【The invention's effect】
According to the present invention, a pair of first antenna element portions having a dipole configuration that resonates at the first frequency f ₁ and the second frequency f ₂ (> f ₁ ) can be provided on separate dielectric substrates. And forming a second antenna element part having a two-dipole configuration that resonates at a _third frequency f ₃ (> f ₂ ), and the second antenna element part is formed between the pair of first antenna element parts. And the relative position of the dipole of the first antenna element part with respect to the main reflector and the relative position of the dipole 21 of the second antenna element part 20 with respect to the main reflector and the sub-reflector Since the directivity is set to be obtained, the three-frequency shared antenna that can obtain the horizontal directivity of the 60 ° beam can be configured in a compact and inexpensive manner.
[Brief description of the drawings]
FIG. 1 is a perspective view partially showing an embodiment of a three-frequency shared antenna according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a plan view showing the configuration of first and second frequency dipoles and a feed line formed on one surface of a dielectric substrate.
FIG. 4 is a plan view showing configurations of first and second frequency dipoles and feed lines formed on the other surface of the dielectric substrate.
FIG. 5 is an equivalent circuit diagram showing a cross feed structure.
FIG. 6 is a plan view showing a configuration of a third frequency dipole formed on a dielectric substrate.
FIG. 7 is a side view showing a configuration of a third-frequency feed line formed on one surface of the dielectric substrate.
FIG. 8 is a side view showing a configuration of a third-frequency feed line formed on the other surface of the dielectric substrate.
FIG. 9 is a characteristic diagram showing horizontal plane directivity in the 800 MHz band.
FIG. It is a characteristic view which shows the horizontal plane directivity of 5 GHz band.
FIG. 11 is a characteristic diagram showing horizontal plane directivity in the 2 GHz band.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Antenna element part 11, 12, 21 Dipole 11a, 11b, 12a, 12b Element 13, 22, 25 Dielectric board | substrate 15, 17, 23, 24, 23 ', 24' feeder line 30 Main reflector 40 Auxiliary reflector

Claims (3)

A main reflector,
A first dipole that resonates at a _first frequency f ₁ and a second dipole that resonates at a second frequency f ₂ (> f ₁ ) are formed on a dielectric substrate in parallel with each other and capable of cross-feeding. A pair of first antenna element portions;
A pair of third dipoles that resonate at the third frequency f ₃ (> f ₂ ) are formed symmetrically on the dielectric substrate at an interval of about 0.5 times the wavelength λ ₃ of the third frequency f _3. A second antenna element portion formed by:
Each of the first antenna element portions is a surface in which the first dipoles formed thereon are separated from the main reflector by a distance of about 0.25 times the wavelength λ ₁ of the first frequency f _1. Are formed at intervals of about 0.5 times the wavelength λ ₁ , and the second dipoles formed on them are separated from the main reflector by the wavelength λ ₂ of the second frequency f _2. Symmetrically arranged on both sides of the vertical plane including the center line of the main reflector so as to form an interval of about 0.5 times the wavelength λ ₂ in a plane separated by a distance of 0.25 times;
The second antenna element part is disposed between the first antenna element parts such that the third dipoles are positioned symmetrically on both sides of the vertical plane,
A three-frequency shared antenna, characterized in that auxiliary reflectors for defining a beam angle of the second antenna element portion at about 60 ° are symmetrically disposed on both sides of the vertical plane. The auxiliary reflectors are set so that the interval between them is about 0.8 times the wavelength λ ₂ of the second frequency f ₂ and the height is about 0.3 times the wavelength λ _2. The three-frequency shared antenna according to claim 1, wherein The first antenna element section has a configuration in which a plurality of element units including the first and second dipoles are arranged in an array, and the second antenna element section includes the third dipoles. The three-frequency shared antenna according to claim 1, wherein a plurality of element units including a plurality of element units are arranged in an array.

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