JP4170823B2 - Multi-frequency dipole antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-frequency shared dipole antenna suitable as a base station antenna for land mobile communications used in automobile cellular phones and the like, and in particular, obtains a horizontal plane directivity having a beam angle of about 60 degrees in each frequency band. The present invention relates to a multi-frequency dipole antenna that can be used.
[0002]
[Prior art]
FIG. 11 shows an example of a conventional dual-frequency dipole antenna. This antenna includes two radiating element portions 111a and 111b and a reflecting plate 112.
As shown in FIG. 12, the radiating element portions 111a and 111b constitute a first strip dipole 115 with radiating elements 115a and 115b formed on one and other surfaces of the dielectric substrate 114, respectively, and the dielectric substrate 114. The second strip dipole 116 is constituted by radiating elements 116a and 116b formed on one and the other surfaces of the first strip dipole 116, respectively.
[0003]
The length of the first strip dipole 115 is set so as to resonate at the first frequency f ₁ . The second strip dipole 116 is formed at a position closer to the feeding points 118a and 118b than the first strip dipole 115, and has a length so as to resonate at the second frequency f ₂ (<f ₁ ). Is set.
The dipole radiating elements 115a and 116a extend on opposite sides of the feed line 17a, and similarly, the dipole radiating elements 115b and 116b extend on the opposite sides of the feed line 117b.
[0004]
As shown in FIG. 11, the radiating element portions 111a and 111b having the above-described configuration are arranged symmetrically with a center plane 112a orthogonal to the reflecting plate 112 sandwiched so that the cross sections thereof are substantially V-shaped. At this time, the distance between the dipole radiating elements 115 of the radiating element portions 111a and 111b is about 0.5λ ₁ (λ ₁ is a wavelength based on the frequency f ₁ ), and the distance between the dipole radiating elements 116 is V. S. W. R. Considering characteristics and the like, for example, about 0.5 λ ₂ shorter than 0.5λ ₂ (λ ₂ is a wavelength based on the frequency f ₂ ).
37λ ₂ is set.
[0005]
Auxiliary reflectors 19 are suspended from the reflector 112 at symmetrical positions with respect to the center surface 112a. The height and installation position of each auxiliary reflector 119 are appropriately adjusted so that a better 60-degree beam can be obtained. Note that the entire antenna is covered with a radome 120.
[0006]
Electric power is supplied to the feeding points 118 a and 118 b of the radiating element portions 111 a and 111 b via the two distributors 113. As a result, this dual-frequency antenna radiates radio waves in two frequency bands having a horizontal plane beam angle of approximately 60 degrees. (For example, see Patent Document 1)
[0007]
[Patent Document 1]
JP-A-8-181538
[Problems to be solved by the invention]
However, since the above-mentioned conventional antenna is limited to two applicable frequency bands, it cannot sufficiently cope with the tendency to expand the frequency band of the base station antenna. In addition, since the individual dipole radiating element portions 111a and 111b are arranged so as to satisfy a predetermined geometric relationship, there is a problem that the configuration is complicated, the size is increased, and the manufacturing cost is increased.
[0009]
In view of such circumstances, the object of the present invention can be shared by more than two frequency bands, and the horizontal plane directivity with a beam angle of about 60 degrees is realized by an inexpensive, small and simple configuration. An object of the present invention is to provide a multi-frequency dipole antenna that can be used.
[0010]
[Means for Solving the Problems]
A multi-frequency dipole antenna according to the present invention includes a pair of antenna element units formed symmetrically around a feeding point on a dielectric substrate for elements, and a reflector provided to face the dielectric substrate. The antenna element unit includes a first dipole radiating element located farthest from the feeding point, and a first dipole radiating element from the middle of the feeding line from the feeding point to the first dipole radiating element. One or a plurality of second dipole radiating elements extending along the line and at least one of the first and second dipole radiating elements are separated from each other, and are formed from the feeder line to the first dipole radiating element. One or more third dipole radiating elements extending along the first, second and third dipole radiating elements, each having a different frequency It is characterized by having a length which resonates.
[0011]
A feeding dielectric substrate is provided at a right angle to the element dielectric substrate, and a feeding circuit connected to the feeding point can be formed on the feeding dielectric substrate. As a result, the power feeding circuit is integrated into one, so that the structure is further simplified.
[0012]
The arrangement interval of the dipole radiating elements corresponding to each other of the pair of antenna element units is set so as to obtain a desired horizontal plane directivity, for example, a horizontal plane directivity having a beam angle of about 60 degrees. .
[0013]
In a preferred embodiment, the first dipole radiating element and the second and third dipole radiating elements are formed so as to be capable of cross-feeding. In this way, it is possible to supply power without using a balun or the like.
Further, each of the first, second, and third dipole radiating elements can be provided with a parasitic element that resonates with them. If this parasitic element is provided, the voltage standing wave ratio can be widened.
Further, a multi-frequency dipole array antenna can be configured by arranging a pair of antenna element units in an array on the element dielectric substrate.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
1, 2 and 3 are a perspective view, a plan view and a side view, respectively, showing an embodiment of a multi-frequency shared dipole antenna according to the present invention.
The multi-frequency dipole antenna includes an element dielectric substrate 1, a power supply dielectric substrate 3 erected at right angles to the center of the back surface of the element dielectric substrate 1, and a back surface of the element dielectric substrate 1. And a reflecting plate 5 provided to face each other.
[0015]
On the element dielectric substrate 1, a pair of antenna element units 7 and 7 are formed symmetrically about the feeding point 9.
As shown in FIG. 2 and FIG. 4 when the substrate 1 is viewed from the back side, the antenna element unit 7 includes a first dipole radiating element 11 (11a, 11b), a second dipole radiating element 13 (13a, 13b), and It has the 3rd dipole radiation element 15 (15a, 15b). These dipole radiating elements 11, 13 and 15 are parallel to each other.
[0016]
The first dipole radiating element 11 is located farthest from the feeding point 9, and the second dipole radiating element 13 is located closer to the feeding point 9 than the first dipole radiating element 11. Yes. Further, the third dipole radiating element 15 is located inward of the second dipole radiating element 13.
As shown in an enlarged view in FIG. 5, the third dipole radiating elements 15a and 15b are formed by providing a notch portion 17 in the second dipole radiating elements 13a and 13b, respectively.
[0017]
The radiating elements 11a, 13a and 15a are formed on one surface of the dielectric substrate 1, respectively. The radiating element 13a and the radiating element 15a extend in the direction opposite to the radiating element 11a from the middle of the feed line 19 from the feeding point 9 to the radiating element 11a.
On the other hand, the radiating elements 11b, 13b and 15b are formed on the other surface of the dielectric substrate 1, respectively. The radiating elements 13b and 15b extend in the direction opposite to the radiating element 11b from the middle of the feed line 21 from the feeding point 9 to the radiating element 11b.
[0018]
The total length of the first dipole radiating element 11 is set to about 0.5λ ₁ (λ ₁ is a wavelength based on the frequency f ₁ ) so as to resonate at the first frequency f ₁ (800 MHz in this example). ing. Similarly, the second dipole radiating elements 13 and 15 resonate at a second frequency f ₂ (1.5 GHz in this example) and a third frequency f ₃ (2 GHz in this example), respectively. Their total length is about 0.5λ ₂ and 0.5λ ₃ (λ ₁ and λ ₂ are wavelengths based on the frequencies f ₁ and f ₂ , respectively).
[0019]
In FIG. 2, the distance between the dipole radiating elements 11, the distance between the dipole radiating elements 13, and the distance between the dipole radiating elements 15 are indicated by L ₁ , L ₂ and L ₃ , respectively. These distances L ₁ , L ₂ and L ₃ are set so as to obtain desired directivity in the horizontal plane. In this embodiment, the distance L _{1 is set} to about 0.5λ ₁ and the distance L _{2 is set} to about 0.34λ so that the beams having the frequencies f ₁ , f _2, and f ₃ have a directivity in the horizontal plane of about 60 degrees. ₂ , the distance L ₃ is set to about 0.47λ ₃ .
The distances L ₂ and L ₃ were set to about 0.34λ ₂ (<0.5λ ₂ ) and about 0.47λ ₃ (<0.5λ ₃ ), respectively. S. W. R. This is because of this. In short, the distances L ₂ , L _2, and L ₃ are approximately 60 degrees in the horizontal plane directivity and proper V.D. S. W. R. It is set so that characteristics can be obtained.
[0020]
A feeding circuit 23 connected to the feeding point 9 is formed on the feeding dielectric substrate 3.
The first dipole radiating element 11, the second dipole radiating element 13, the third dipole radiating element 15, the feed lines 19, 21 and the feed circuit 23 are each formed of a metal foil (strip conductor). .
[0021]
The frequency f ₁ (800 MHz), f ₂ (1.5 GHz) and f ₃ (2 GHz) are fed to the feeding point 9 of the multi-frequency dipole antenna according to this embodiment through the feeding circuit 23 of the dielectric substrate 3 for feeding. ) Is supplied. This power feeding is cross power feeding as shown in FIG. According to this cross feeding, feeding without using a balun or the like becomes possible.
[0022]
7, 8, and 9 show horizontal plane directivity in the 800 MHz band based on each first dipole radiating element 11, same directivity in each 1.5 GHz band based on each second dipole radiating element 13, and 3 shows the same directivity in the 2 GHz band based on three dipole radiating elements 15. As is apparent from these drawings, the dipole antenna according to this embodiment exhibits a good horizontal plane directivity with a beam angle of about 60 degrees in any frequency band of 800 MHz, 1.5 GHz, and 2 GHz.
[0023]
As shown in FIG. 3, the first, second and third dipole radiating elements 11, 13 and 15 have _first and _second lengths which resonate at frequencies f ₁ , f ₂ and f ₃ , respectively. The second and third parasitic elements 11 ′, 13 ′, and 15 ′ may be provided side by side. If these parasitic elements 11 ′, 13 ′ and 15 ′ are provided, the voltage standing wave ratio can be widened. The parasitic elements 11 ′, 13 ′, and 15 ′ can also be formed by printing a metal foil on a dielectric substrate (not shown).
[0024]
The parasitic elements 11 ′, 13 ′ and 15 ′ need not be provided to face the dipole radiating elements 11, 13 and 15. For example, the parasitic elements 11 ′, 13 ′, and 15 ′ may be provided at positions moved in the left-right direction from the positions immediately above the dipole radiating elements 11, 13, and 15 in FIG. It may be provided on the side.
[0025]
As shown in FIG. 10, a multi-frequency dipole array antenna can be configured by forming a plurality of pairs (four pairs in this example) of the pair of antenna element units 7 and 7 on the dielectric substrate 1.
A tournament-type power feeding circuit 23 for simultaneously feeding power to each pair of antenna element units 7 and 7 is formed on the dielectric substrate 3 for power feeding of the array antenna.
[0026]
Incidentally, each antenna element unit 7 shown in FIG. 2 includes one second dipole radiating element 13 and one radiating element 15 formed in the second dipole radiating element 13. However, the antenna element unit 7 is not limited to such a configuration. Below, other structural examples of the antenna element unit 7 are listed.
[0027]
(1) A third dipole radiating element corresponding to the dipole radiating element 15 can also be provided inside each of the first dipole radiating elements 11 of the pair of antenna element units 7.
In this case, the mutual distance between the third dipole radiating elements formed in the first dipole radiating element 11 is large enough to obtain a horizontal plane directivity with a beam angle of about 60 degrees (of the third dipole radiating element). About half of the wavelength based on the resonance frequency).
Since the third dipole radiating element is shorter than the length of the first dipole radiating element 11, the resonance frequency thereof is lower than that of the first dipole radiating element 11.
Thus, when the third dipole radiating element is also provided inward of the first dipole radiating element 11, the number of applicable frequency bands is four.
Of course, it is also possible to provide the third dipole radiating element only in the dipole radiating element 11, and in this case, the number of applicable frequency bands is three.
[0028]
(2) A plurality of second dipole radiating elements can be provided between the feeding point 9 and the first dipole radiating element 11 in the antenna element unit 7. In this case, the mutual distance between the corresponding second dipole radiating elements of each antenna element unit 7 is set so as to obtain a horizontal plane directivity with a beam angle of about 60 degrees.
In such a configuration, when the third dipole radiating element is not provided in any of the first dipole radiating element and the plurality of second dipole radiating elements, the number of applied frequency bands is three or more. . In addition, when the third dipole radiating element is provided in at least one of the first dipole radiating element 11 and the plurality of second dipole radiating elements, the number of applicable frequency bands is four or more.
[0029]
(3) In the example of FIG. 2, one third dipole radiating element 15 is formed in the second dipole radiating element 13, but the third dipole radiating element 13 is included in the second dipole radiating element 13. A plurality of 15 can be formed. For example, a notch corresponding to the notch 17 shown in FIG. 5 is formed in the third dipole radiating element 15 shown in FIG. 2, and a second third dipole radiating element is formed in the second dipole radiating element 13. Can be formed. Further, a notch corresponding to the notch 17 is formed in the second third dipole radiating element, and a third third dipole radiating element is formed in the second dipole radiating element 13. be able to.
When the second third dipole radiating element is formed, the number of applied frequency bands is increased by one, and when the third third dipole radiating element is formed, the applied frequency band is increased. Will be increased by one.
Of course, also in the cases (1) and (2) described above, a plurality of third dipole radiating elements can be formed in the first dipole radiating element and / or the second dipole radiating element. In this way, the number of applicable frequency bands further increases.
[0030]
【The invention's effect】
The multi-frequency dipole antenna according to the present invention can be shared by more than two frequency bands, and the horizontal plane directivity with a beam angle of about 60 ° can be realized with an inexpensive, small and simple configuration. Is possible. Therefore, it is particularly suitable as a base station antenna for land mobile communications used for automobile mobile phones and the like.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a multi-frequency dipole antenna according to the present invention.
FIG. 2 is a plan view of the antenna shown in FIG.
FIG. 3 is a side view of the antenna shown in FIG. 1;
FIG. 4 is a rear view of a dielectric substrate for an element.
FIG. 5 is an enlarged view of a third dipole radiating element formed in the second dipole radiating element.
FIG. 6 is a schematic diagram illustrating cross power feeding.
FIG. 7 is a graph showing horizontal plane directivity in a frequency band of 800 MHz.
FIG. 8 is a graph showing horizontal plane directivity in a frequency band of 1.5 GHz.
FIG. 9 is a graph showing horizontal plane directivity in a frequency band of 2 GHz.
FIG. 10 is a perspective view showing the configuration of a multi-frequency dipole array antenna according to the present invention.
FIG. 11 is a longitudinal sectional view showing a configuration of a conventional dual-frequency dipole antenna.
12 is a perspective view showing a configuration of a radiating element portion of the antenna shown in FIG. 11. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dielectric substrate for elements 3 Dielectric substrate for electric power feeding 5 Reflective plate 7 Antenna element unit 9 Feed point 11 1st dipole radiation element 13 2nd dipole radiation element 15 3rd dipole radiation element 17 Notch parts 19 and 21 Feed line 23 Feed circuit

Claims (5)

It has a length which resonates with the frequency 800 MHz (wavelength lambda _1), a pair of first dipole radiating element to parallel formed at a distance L ₁ to and symmetrically around the feeding point to the element for a dielectric substrate When,
Resonating at a frequency of 1.5 GHz (wavelength λ ₂ ), parallel to each other, formed symmetrically about the feeding point and spaced apart by an interval L ₂ (<L ₁ ) on the element dielectric substrate. A pair of second dipole radiating elements
A pair of third dipoles having a length resonating at a frequency of 2 GHz (wavelength λ ₃ ) and formed inward of the pair of second dipole radiating elements along the second dipole radiating elements. A dipole radiating element;
A feeding line that extends symmetrically about the feeding point and performs series feeding to each of the first dipole radiating elements, each of the second dipole radiating elements, and each of the third dipole radiating elements;
A reflector provided facing the dielectric substrate;
With
To about 0.5 [lambda ₁ the arrangement interval _{L 1,} the arrangement interval _{L 2} to about 0.34λ _2, multiband dipole, characterized in that respectively set the arrangement interval _{L 3} to about 0.47Ramuda ₃ antenna.   2. The multiplicity according to claim 1, wherein a power supply dielectric substrate is provided at a right angle to the element dielectric substrate, and a power supply circuit connected to the power supply point is formed on the power supply dielectric substrate. Frequency sharing dipole antenna.   3. The multi-frequency dipole antenna according to claim 1, wherein the first dipole radiating element and the second and third dipole radiating elements are formed so as to be capable of cross-feeding.   4. A multi-frequency dipole antenna according to claim 1, wherein each of the first, second, and third dipole radiating elements is provided with a parasitic element that resonates therewith. .   5. The multiplicity according to claim 1, wherein the first, second and third dipole radiating elements are arranged on the element dielectric substrate to constitute an array antenna. Frequency sharing dipole antenna.

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