JP2835482B2 - Printed antenna with reflector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved printed antenna with a reflector for dual use which is suitable as a three-sector diversity base station antenna for land mobile communication used in automobile telephones and the like. Particularly, in the three-sector diversity base station, three sets (six in total) of 120-degree beam antennas in a horizontal plane are usually required, and it is required to reduce the occupied area of the antennas in consideration of installation conditions. The present invention relates to a miniaturized printed antenna with a reflector for accommodating two antennas in one radome.

[0002]

2. Description of the Related Art Conventionally, 800 MHz band frequencies are used for land mobile communication such as automobile telephones, and an omnidirectional antenna is disposed at the top of a tower as a base station antenna, or a directional antenna is provided at the side of the tower. By arranging a plurality of them and combining them, a non-directional directional characteristic is obtained.

However, land mobile communication has been developing remarkably in recent years. Particularly, in a large city, a system using an 800 MHz band is expected to be unable to cope with an increase in the number of mobile stations in the near future.
The transition to the z band is being considered.

However, the 800 MHz band and the 1500 MHz band
In the base station antenna independent for each frequency of the MHZ band,
Considering the mounting capacity of the tower, the mounting space, the mounting space for the power supply cable, and the like, it is difficult to mount the tower on the same tower. Therefore, a frequency sharing antenna is being studied.
An antenna that shares frequency (a printed antenna with a reflector) has been proposed (see Japanese Patent Application Laid-Open No. 2-57003).

However, in a three-sector diversity base station, as shown in FIG.
Six frequency sharing antennas A are required.

By the way, in order to obtain a 120-degree beam with this type of printed antenna with a reflector, which has already been proposed, a configuration as shown in FIGS. 8A and 8B is used. This printed antenna 1 with a reflector is a printed antenna 2
The first and second dipole antennas 4 and 5 formed on both surfaces of the dielectric substrate 3 and the reflector 6 are usually housed in a cylindrical radome 7 (having an outer diameter of, for example, about 160 mm). Has been put to practical use.

In this case, the first radiating elements 4a and 4b forming the first dipole antenna 4 are formed so as to resonate at a _first frequency f ₁ and the second dipole antenna 5 The second radiating element 5a,
5b is formed so as to resonate in the second frequency f _2.

The first and second radiating elements 4
a, 4b and 5a, 5b is formed so as to be respectively cross feed structure, is about a quarter of the wavelength distance in the vertical direction in each of the frequency f _1, f ₂ from the reflection plate 6 It is formed as follows. Reference numeral 8 denotes a feeding point to the dipole antennas 4 and 5.

In such a printed antenna 1 with a reflector as a dual frequency antenna, FIG.
With the arrangement of (B), almost the same directional characteristics in the horizontal plane are obtained with a 120-degree beam.

Therefore, the printed antenna 1 with a reflector
Considering the installation conditions for a three-sector diversity base, it is necessary to reduce the occupied area of the antenna 1, and it is conceivable that the two antennas 1 and 1 are housed in one radome 9. Thus, FIG.
When the antennas 1 shown in (A) and (B) are housed in the radome 9 in pairs in the direction of 120 degrees, the outer diameter of the cylindrical radome 9 becomes 260 mm as shown in FIG.

However, since the outer diameter is considerably large, a two-sided small antenna having a smaller size has been proposed in Japanese Patent Application No. 4-85958. This 2
As shown in FIGS. 10 and 11, the surface-mounted small antenna 10 includes a radiating element 1 formed on a dielectric substrate 14.
5, 16 and a first reflector 12, and these radiating elements 15, 16 have first radiating elements 15a, 15b resonating at a first frequency and second radiating elements 15a, 15b resonating at a second frequency. And the first and second radiating elements 16a and 16b.
The two dielectric substrates 14 on which the radiating elements 15 and 16 are respectively formed are symmetrically arranged with respect to the vertical center line 19 of the first reflecting plate 12 at an opening angle of about 40 degrees.
2 and a second reflector 13 is arranged along the vertical center line 19. Thus, in this case, the two printed antennas 11a, 1a are provided by arranging the second reflector 13 at the center of the symmetric printed circuit boards (printed antennas) 11a, 11b.
1b is accommodated in a cylindrical radome 20 having an opening angle of 80 degrees and an outer diameter of 200 mm. In FIGS. 10 and 11, 18a and 18b are feeding points.

[0012]

However, even with the above-described printed antenna with a reflector, the outer diameter of the cylindrical radome is still large in practice, so that the air receiving area and the strength of the cylindrical radome are increased. Increased wall thickness,
There was a problem that the cost was high economically. Therefore, the development of a printed antenna with a reflector capable of further reducing the outer diameter of the cylindrical radome has been desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems, and to make various electric characteristics, that is, a horizontal plane directivity, a voltage standing wave ratio, and a coupling amount between antennas, independent of each other. An object of the present invention is to provide a printed antenna with a reflector that can accommodate two printed antennas with a reflector in one small cylindrical radome while maintaining the used state.

[0014]

In order to achieve the above object, the present invention provides a first radiating element which resonates at a first frequency formed on a dielectric substrate and a first radiating element formed on the dielectric substrate. A second radiating element that resonates at a given second frequency;
Reflector, and the first and second radiating elements are vertically separated from the first reflector by a distance of about ４ of the wavelength at the first and second frequencies, respectively. In a printed antenna with a reflector arranged and arranged so that each of the first and second radiating elements has a cross feed structure, two dielectric substrates on which the first and second radiating elements are respectively formed. Are attached to the first reflector at an opening angle of about 32.5 degrees, respectively, symmetrically with respect to the vertical center line of the first reflector.

Further, according to the present invention, a printed antenna comprising the first radiating element formed on the dielectric substrate;
A second reflector having a width sufficiently small with respect to the wavelength of the first frequency, a second reflector at a central portion between the second antenna and the printed antenna formed by forming the second radiating element on the dielectric substrate; A third reflector having a width sufficiently smaller than the wavelength of the second frequency is provided.

Further, in the present invention, at a central portion between the two printed antennas and at a position farther than a distance from the first reflector to the second and third reflectors, A pair of directivity correcting elements for correcting the directional characteristics of the second frequency are arranged symmetrically to face each other with respect to a vertical center line of the first reflecting plate in a state where each of the directivity correcting elements is oriented in the horizontal direction. ing.

Further, according to the present invention, the first radiation element resonating at the first frequency formed on the dielectric substrate and the second radiation resonating at the second frequency formed on the dielectric substrate are provided. And a first reflector, respectively, and wherein the first and second radiating elements are vertically separated from the first reflector by about 1 of a wavelength at the first and second frequencies, respectively. In a printed antenna with a reflector arranged at a distance of / 4 and the first and second radiating elements each having a cross feed structure, the first and second radiating elements are formed respectively. Two dielectric substrates are attached to the first reflector at an opening angle of about 32.5 degrees, respectively, symmetrically with respect to a vertical center line of the first reflector, and the wavelengths of the first frequency are adjusted. The second reflector having a width sufficiently small to the front and the front A third reflector of sufficiently small width with respect to the wavelength of the second frequency and disposed along on the vertical center line, and further storing them in a single cylindrical radome.

Further, according to the present invention, the first radiating element resonating at the first frequency formed on the dielectric substrate and the second radiating element resonating at the second frequency formed on the dielectric substrate are provided. And a first reflector, respectively, and wherein the first and second radiating elements are vertically separated from the first reflector by about 1 of a wavelength at the first and second frequencies, respectively. In a printed antenna with a reflector arranged at a distance of / 4 and the first and second radiating elements each having a cross feed structure, the first and second radiating elements are formed respectively. Two dielectric substrates are attached to the first reflector at an opening angle of about 32.5 degrees, respectively, symmetrically with respect to a vertical center line of the first reflector, and the wavelengths of the first frequency are adjusted. The second reflector having a width sufficiently small to the front and the front Disposed along the third reflector sufficiently small width on the vertical center line with respect to the wavelength of the second frequency, and a plurality of stages arranged further it vertically.

[0019]

In the printed antenna with the reflector thus constructed, the two dielectric substrates on which the radiating elements are formed are arranged at an opening angle of about 32.5 degrees from the vertical center line of the first reflector. Accordingly, the outer diameter of the cylindrical radome can be reduced, for example, from about 200 mm to about 158 mm, and the printed antenna with a reflector can be further reduced in size. Further, by providing the second and third reflectors along the vertical center line, and arranging a pair of directivity correcting elements symmetrically facing each other at appropriate positions, the beam of each of the two antennas The direction can be set to 120 degrees, and the same directional characteristics as in a single antenna use state can be obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS.

FIGS. 1 and 2 show a first embodiment of a printed antenna with a reflector according to the present invention. FIG.
FIG. 2 is a perspective view of a printed antenna with a reflector, which is composed of two antennas each having a 120-degree beam and each having a directivity in the horizontal plane of 120 degrees, which is shared by two frequencies of the band and the 1500 MHz band. It is a top view.

As shown in FIGS. 1 and 2, the printed antenna 22 with a reflector mainly includes two printed antennas 23a and 23b and first, second and third reflectors 2a and 2b.
4, 25, 26 and a pair of directivity correcting elements 27a, 27
b.

The printed antenna 23a has a dielectric base.
A first strip dipole 29 is provided on both sides of the plate 28a.
The first radiating elements 29a and 29b constituting the first
Number f ₁Is formed so as to resonate with
The printed antenna 23b is provided on both sides of the dielectric substrate 28b.
In addition, the second strip dipole 30
The radiating elements 30a and 30b are connected to the second frequency f_TwoResonates with
It is formed as follows.

The first radiating elements 29a, 29b and the second
Radiating elements 30a and 30b correspond to the dielectric substrate 28
a, a feed line 31 formed at the center of each of 28b
The first radiating elements 29a and 29b are formed in opposite directions at right angles to each other with respect to the first and second dipole antennas 29a and 31b so as to form a cross feed structure.
Is formed at a position rotated by 180 degrees about the central axis of. The distance between both ends of these radiating elements 29a and 29b is set to about _{１ ／} of the wavelength λ ₁ of the first frequency f ₁ .

Also, the second radiating elements 30a and 30b
It is formed so as to have a cross feed structure as described above.
The distance between the ends is the second frequency f_Two(F_Two> F₁) Wavelength λ_Two
(Λ _Two<Λ₁) Is set to about 1/2.

When the printed antennas 23a and 23b are attached to the first reflector 14, the first radiating elements 29a and 2 are vertically arranged from the first reflector 24.
9b and the distance to the second radiating elements 30a and 30b are:
The wavelengths λ ₁ and λ at the respective resonance frequencies f ₁ and f _2
2 of about λ _1/4, is set to be about lambda _2/4. In FIGS. 1 and 2, 32a and 32b are feeding points of the print antennas 23a and 23b.

Such print antennas 23a, 23
b is set up substantially perpendicularly to both side plates 24a, 24a of the first reflection plate 24 having a reflex angle of about 245 degrees, and a vertical center line of the first reflection plate 24. 33 (symmetrical bisectors of the corners) are disposed symmetrically with an opening angle of about 32.5 degrees.

Incidentally, both side plates 24 of the first reflecting plate 24 are provided.
The end plates 24b, 24b of the print antennas 23a, 23b (the dielectric substrate 28)
a, 28b) so as to be nearly parallel to each other, and symmetrically with respect to the vertical center line 33 as a whole,
For example, as shown, it is bent in three stages.

Then, the two printed antennas 23a,
At a central location of 23b, along the vertical center line 33 from the first reflector 24, the first distance d ₁ to the second, which is about 1/6 of the frequency f ₁ of the reflector 25, the second Frequency f ₂
At a distance d ₂ which is about の of the wavelength λ ₂ of the third reflection plate 2.
Numerals 6 are arranged so that their cross sections are in the horizontal direction.

Further, a distance d ₃ along the vertical center line 33, which is about 1 / 1.7 of the wavelength λ ₂ of the second frequency f _2.
, The directivity modifying element 27a for correcting the second directional frequency f _2, 27b are symmetrical so that the cross-section is horizontal direction at a distance of each lambda _2/12 from the vertical center line 33 It is arranged.

The directivity correcting elements 27a, 27
7b is the wavelength λ _{2 of the second} frequency f _2.
Is set to about 1/3.

The second and third reflectors 25 and 26;
The directivity correcting elements 27a and 27b have the widths W ₁ and W ₂ (see FIG. 2) in the horizontal direction in the wavelength λ _{1 of the first} frequency f _1.
Of a metal plate having a thickness of 1 to 2 mm or a conductor foil formed on a dielectric substrate. .

If the first frequency f ₁ is in the 800 MHz band and the second frequency f ₂ is in the 1500 MHz band, the outer diameter of the printed antenna 22 with the reflector having the above-described configuration is 1.
It can be housed or mounted in a 58 mm cylindrical radome 34.

Accordingly, 158/200 = 0.79 compared with the conventional 200 mm outer diameter, and the receiving area can be reduced by about 21%.

FIG. 5 shows the directivity correcting element 27 as described above.
9A is a horizontal plane directional characteristic of a printed antenna with a reflector when a and 37b are not provided. In this case, the first frequency f ₁
Has obtained good directivity, but the second frequency f ₂
In the figure, the light is deflected outward from the center by the influence of the reflection plates 25 and 26. In this case, the first frequency f ₁ and the second frequency f ₂
Cannot form the same sector zone.

In the present embodiment, the directivity correcting element 27a,
The effect of 27b has, since its horizontal direction length w ₂ to set the second approximately one third of the frequency f ₂ as described above, these directional modification elements 27a, 27b of the second It operates for the frequency f ₂ as a waveguide element is to serve to return about the excursion and directivity.

FIG. 3 is a characteristic diagram showing the measured values of the return loss of the printed antennas 23a and 23b with reflectors according to the present embodiment. As is clear from the characteristic diagrams, the printed antennas 23a and 23b with reflectors are shown. According to the first frequency f
Sufficient return loss is obtained in the _first and second frequency f ₂ Prefecture.

FIG. 4 shows the directional characteristics in the horizontal plane of the printed antennas 23a and 23b with reflectors according to the present embodiment. A directional property in FIG. 4, a solid line a first frequency f _1, the dotted line indicates the second frequency f _2, the printed antenna 23a in a downward direction in the figure shows a printed antenna 23b upward. At both the first and second frequencies f ₁ and f ₂ , the radiation directions of the two printed antennas 23 a and 23 b are in the direction of 120 degrees with substantially the same 120-degree beam directivity in the horizontal plane.

FIG. 6 is a partially cutaway perspective view showing a second embodiment of the printed antenna with a reflector according to the present invention. This is because the printed antenna 22 with the reflector shown in the first embodiment is arranged so that a plurality of stages (four stages in the figure) are stacked in the vertical direction and two directivities 120 in the horizontal direction are used in two directions at 120 degrees. This is a printed antenna 25 with a reflector that can obtain a power beam.

As shown in FIG. 6, the printed antenna with reflector 35 is the same as the printed antenna 23 of the first embodiment.
a, 23b to common dielectric substrates 36a, 36, respectively.
b, the radiating elements 50 are arranged in parallel in a plurality of stages in the vertical direction according to the first embodiment, and the radiating elements 50 are connected in parallel to the feeding points 37a and 37b.

Thus, a high-gain antenna can be obtained by arranging the printed antennas with reflectors 22 in a plurality of stages in the vertical direction.

In FIG. 6, 38 is a first reflector, 39 is a second reflector, 40 is a third reflector, 41
Reference numerals a and 41b denote directional radiation elements, and reference numeral 42 denotes a cylindrical radome.

Note that the technique of the present invention is not limited to the technique in the above-described embodiment, but may be implemented by means of other modes that perform the same function. Can be changed or added.

[0044]

As described above, according to the present invention, the two dielectric substrates on which the first and second radiating elements are formed are respectively symmetrically arranged with respect to the vertical center line of the first reflector. Since the antenna is attached to the first reflector at an opening angle of 32.5 degrees, it is possible to reduce the size of the printed antenna with the reflector that is shared by two frequencies.

That is, the printed antenna with a reflector according to the present invention can reduce the diameter of the cylindrical radome that houses the antenna, for example, from 200 mm to 158 mm, which is about 21% smaller than the conventional antenna. Therefore, the air receiving area can be reduced, the radome thickness can be reduced, and an inexpensive antenna can be provided.

The second and third antennas are located at the center between two printed antennas (printed circuit boards) on which radiating elements are formed.
By arranging the reflectors of the above and a pair of directivity correcting elements symmetrically opposed to each other at a predetermined location, it is possible to maintain good electrical characteristics such as directivity characteristics. Therefore, two printed antennas with reflectors are accommodated in one small cylindrical radome while maintaining various electrical characteristics, that is, horizontal plane directivity, voltage standing wave ratio, and coupling between antennas alone. It is possible to provide a printed antenna with a reflector that can be used.

Further, the conditions for installation on a steel tower or the like can be improved, and a high-gain antenna can be obtained by arranging a plurality of such improved printed antennas with reflectors in the vertical direction.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a printed antenna with a reflector according to the present invention.
It is a perspective view showing an example.

FIG. 2 is a plan view of the printed antenna with a reflector.

FIG. 3 is a characteristic diagram showing measured values of return loss of the printed antenna with a reflector.

FIG. 4 is a directional characteristic diagram in a horizontal plane of the printed antenna with a reflector.

FIG. 5 is a diagram showing directivity characteristics in a horizontal plane of a printed antenna with a reflector when no directivity correction element is provided.

FIG. 6 shows a second example of the printed antenna with a reflector according to the present invention.
It is a perspective view showing an example.

FIG. 7 illustrates a case where a conventional printed antenna with a reflector is used.
FIG. 3 is an explanatory diagram showing a sector diversity base station.

8A and 8B show a conventional printed antenna with a reflector, wherein FIG. 8A is a perspective view thereof, and FIG. 8B is a plan view thereof.

FIG. 9 is a plan view of an antenna in which two conventional antennas with reflectors shown in FIG. 8 are housed in one cylindrical radome.

FIG. 10 is a perspective view showing a configuration which is already proposed by the present applicant and has a reduced size of an antenna having two reflector-equipped antennas housed in one cylindrical radome.

FIG. 11 is a plan view of the antenna of FIG. 10;

[Description of Signs] 22, 35 Printed antenna with reflector 23a, 23b Printed antenna 24 First reflector 25 Second reflector 26 Third reflector 27a, 27b Directivity correcting element 28a, 28b, 36a, 36b Dielectric Body substrate 29 First strip dipole 29a, 29b First radiating element 30 Second strip dipole 30a, 30b Second radiating element 33 Vertical center line (corner angle bisector) 34, 42 Cylindrical radome 50 radiating element

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Ebine 2-10-1 Toranomon, Minato-ku, Tokyo NTT Mobile Communication Network Co., Ltd. (56) References JP-A-2-57003 (JP) JP-A-5-259733 (JP, A) JP-A-6-132721 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01Q 15/18 H01Q 19/10 H01Q 19/17

Claims (5)

(57) [Claims] A first radiating element that resonates at a first frequency formed on a dielectric substrate; a second radiating element that resonates at a second frequency formed on a dielectric substrate; And the first and second radiating elements are vertically separated from the first reflecting plate by a distance of about 1/4 of a wavelength at the first and second frequencies, respectively. And the first and second radiating elements are each configured to have a cross feed structure, and the two dielectrics on which the first and second radiating elements are respectively formed. A printed antenna with a reflector, wherein a substrate is mounted on the first reflector at an opening angle of about 32.5 degrees, respectively, symmetrically with respect to a vertical center line of the first reflector. 2. A center between a printed antenna formed by forming the first radiating element on the dielectric substrate and a printed antenna formed by forming the second radiating element on the dielectric substrate. A second reflector having a sufficiently small width with respect to the wavelength of the first frequency and a third reflector having a width sufficiently small with respect to the wavelength of the second frequency. The printed antenna with a reflector according to claim 1. 3. The method according to claim 2, wherein the second printed antenna is located at a central portion between the two printed antennas and farther than a distance from the first reflector to the second and third reflectors. A pair of directivity correcting elements for correcting a directivity characteristic of a frequency are arranged symmetrically facing each other with respect to a vertical center line of the first reflector in a state where each of the directivity correcting elements is oriented in a horizontally long direction. Item 3. A printed antenna with a reflector according to Item 2. 4. A first radiating element formed on a dielectric substrate and resonating at a first frequency, a second radiating element formed on a dielectric substrate and resonating at a second frequency, And the first and second radiating elements are vertically separated from the first reflecting plate by a distance of about 1/4 of a wavelength at the first and second frequencies, respectively. And the first and second radiating elements are each configured to have a cross feed structure, and the two dielectrics on which the first and second radiating elements are respectively formed. A substrate is mounted on the first reflector at an opening angle of about 32.5 degrees each symmetrically with respect to a vertical center line of the first reflector, and is sufficiently small with respect to the wavelength of the first frequency. A second reflector of width and a wave of said second frequency A third reflector having a width sufficiently smaller than the length is disposed along the vertical center line,
Printed antenna with reflector, housed in two cylindrical radomes. 5. A first radiating element formed on a dielectric substrate and resonating at a first frequency, a second radiating element formed on a dielectric substrate and resonating at a second frequency, And the first and second radiating elements are vertically separated from the first reflecting plate by a distance of about 1/4 of a wavelength at the first and second frequencies, respectively. And the first and second radiating elements are each configured to have a cross feed structure, and the two dielectrics on which the first and second radiating elements are respectively formed. A substrate is mounted on the first reflector at an opening angle of about 32.5 degrees each symmetrically with respect to a vertical center line of the first reflector, and is sufficiently small with respect to the wavelength of the first frequency. A second reflector of width and a wave of said second frequency A printed antenna with a reflector, wherein a third reflector having a width sufficiently smaller than the length is provided along the vertical center line, and a plurality of the third reflectors are provided in the vertical direction.