JP2000114859A - Bidirectional circular polarizing antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna capable of simplifying a structure, facilitating miniaturization, lowering production costs, eliminating spurious radiation from a power feeder line and providing satisfactory antenna characteristics. SOLUTION: Antenna elements 14 and 15 are formed on the outer surfaces of first and second dielectric substrates 11 and 12 provided facing a group conductor plate 13 in between, and at the lower position of these antenna elements 14 and 15, a slot 16 is provided on a ground conductor plate 54. The respective antenna elements 14 and 15 are provided with degenerating/separating means (notches) 18 and 19 for generating circularly polarized waves at reverse positions as seen from respective radiating planes. Thus, bidirectional circular polarizing radiation directivity can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circularly polarized bidirectional antenna having a radiation beam and a relay function suitable for a street cell along a road used in a mobile communication system.

[0002]

2. Description of the Related Art Portable terminals such as PDC and PHS have become widespread. Accordingly, it is necessary to install a large number of mobile radio base station antennas. Therefore, the base station antenna is required to have a simple structure, small size, thin shape, and low cost.

Further, a base station antenna needs to cover a service area efficiently. For example, in an antenna installed on a road, a radiation beam along a road direction and a circularly polarized wave are very effective. is there.

Conventionally, as a radio base station for mobile communication, a "circularly polarized rod-shaped antenna having bidirectionality" reported at the 1995 IEICE General Conference B-51 shown in FIG. 9 has been proposed. As shown in FIG. 9, this circularly polarized rod-shaped antenna has a narrow patch 91, a parasitic element 92, a slot 9
3, ground plane 94, feed line 95, 3dB hybrid 9
6. Radome 97. 10 and 11
The radiation directivity in the horizontal plane and the vertical plane of the circularly polarized rod antenna is shown in FIG.

[0005] The proposed antenna requires a 3 dB hybrid 96 for generating circularly polarized waves. This 3dB
The hybrid 96 takes up area when the frequency is low,
There is a problem when miniaturizing.

Further, in this antenna, the narrow patch 91 is an antenna element for vertical polarization, the slot 93 is an antenna element for horizontal polarization, and a 3 dB hybrid 96 generates a 90-degree phase difference, which is applied to each antenna element. Circular polarization is created by feeding power. In the narrow patch 91 on the front side and the narrow patch 91 on the back side, current flows in opposite directions.
Both the front narrow patch 91 and the slot 93 emit radio waves on both sides of the ground plane 94, but cancel each other out in the direction of the ground plane 94, so that bidirectionality is obtained.

In this method, good circular polarization is obtained in the direction perpendicular to the surface of the ground plane 94, but the axial ratio deteriorates in the wide angle direction because the narrow patch 91 and the slot 93 are separated. This is apparent from the directivity of the vertical plane in FIG. The deterioration of the axial ratio cannot be improved by this method.
Further, as can be seen from FIG. 11, a null point is formed in the direction of about 30 degrees, which is also a problem. In addition, when an array is to be realized, these points are major problems.

In addition, this problem is solved by radiating a radio wave to an insensitive area by relaying the electric wave to an insensitive area through an antenna provided on the roof of a building. The antenna used in this case is required to be small and thin. Further, in order to avoid interference between the direct wave and the wave retransmitted from this antenna, the polarized wave received by this antenna and the polarized wave to be transmitted must be reverse polarized.

Conventionally, as shown in FIG. 12, antenna elements 123 and 124 formed of rectangular patches on dielectric substrates 121 and 122 sandwiching a ground conductor 120, and the antenna element 1
Microstrip line 12 for feeding 23 and 124
An array antenna has been proposed which is configured to be coupled to the ground conductor 120 via a slot 127 provided at a position deviated from the antenna elements 123 and 124. In this case, the slot 127 is the antenna element 123,
There is a problem in the arrangement when arranging them in a position deviating from 124 to take up an area. Further, this antenna generates linearly polarized waves, and does not disclose generating circularly polarized waves.

As a conventional antenna for generating circularly polarized waves, as shown in FIG. 13, a rectangular patch having degenerate separation means 135 and 136 on dielectric substrates 131 and 132 sandwiching a ground conductor 130, respectively, is used. Elements 133 and 134 made of the same, and the antenna elements 133 and 134
An array antenna configured by providing a CPW power supply line 137 for supplying power to the antenna has been proposed. However, in this antenna, the degenerate separation means 135 and 136 provided in the antenna elements 133 and 134 are used for the respective antenna elements 133 and 134.
Since they are provided at the same position as viewed from the radiation surface 34 (that is, both at the upper left and lower right), they are omnidirectional and not bidirectional.

[0011]

As described above, the conventional circularly polarized bidirectional antenna requires a 3 dB hybrid for generating circularly polarized waves, so that it becomes expensive or large in size. There is a problem to say. Further, since the patch and the antenna of the slot are at different places, there is a problem that the axial ratio, which is the circular polarization characteristic in the vertical plane, is degraded and a null point is generated. Also, this antenna configuration is not suitable for arraying. Therefore, in the base station antenna, it is necessary to increase the gain, which is a problem.

The present invention has been made in view of such problems, and does not require a 3 dB hybrid for generating circularly polarized waves, and achieves circularly polarized characteristics in a vertical plane and good radiation directivity. It is an object of the present invention to provide a circularly polarized bidirectional antenna which has an array, is easy to form an array, has a simple structure, is easy to miniaturize, has low manufacturing cost, and has little interference.

[0013]

In order to solve the above-mentioned problems, a circularly polarized bidirectional antenna according to the present invention according to claim 1 comprises a first and a second antenna which face each other at a predetermined interval.
Dielectric substrate, a ground conductor plate provided between the first and second dielectric substrates, and a ground conductor plate formed on the surface of the first and second dielectric substrates opposite to the ground conductor plate. First and second antenna elements, an opening formed in the ground conductor plate at a position below the first and second antenna elements, and a line for feeding the first antenna element. The first and second antenna elements are provided with degenerate separation means for generating circularly polarized waves so that the first and second antenna elements are at opposite positions when viewed from the respective radiation surfaces.

With such a configuration, a 3 dB hybrid for generating circularly polarized waves is not required, the circularly polarized waves in a vertical plane and good radiation directivity are provided, and the structure is simple and the miniaturization is easy. Thus, a circularly polarized bidirectional antenna having a low manufacturing cost can be realized.

According to a second aspect of the present invention, there is provided a circularly polarized bidirectional antenna according to the present invention, comprising: first and second dielectric substrates opposed to each other with a predetermined space therebetween;
And a degenerate separation for generating circularly polarized waves, respectively, formed on a surface of the first and second dielectric substrates opposite to the ground conductor plate. A first array antenna comprising a plurality of antenna elements having means, a second array antenna comprising a plurality of antenna elements having degenerate separation means for generating circularly polarized waves, and a first array antenna. An opening provided in the ground conductor plate at a position below each antenna element and each antenna element forming the second array antenna, and a first antenna element counted from one end of the first array antenna are fed. A line, a line connecting an even-numbered antenna element counted from one end to an odd-numbered antenna element that is one greater than the even number, and an odd-numbered number counted from one end of the second array antenna 1 from the antenna element and the odd
A feeder comprising a feed line connecting large even-numbered antenna elements, or a feeder comprising a feed line provided only on one of the first and second array antennas on the side of the array antenna; The degenerate separation means provided on each antenna element of the two array antennas is arranged so as to be at the opposite position when viewed from the radiation surface of each array antenna.

With such a configuration, a 3 dB hybrid for generating circularly polarized waves is not required, the circularly polarized waves in a vertical plane and good radiation directivity are obtained, and the structure is simple and the miniaturization is easy. Thus, it is possible to realize an arrayed circularly polarized bidirectional antenna having a low manufacturing cost.

According to a third aspect of the present invention, there is provided a circularly polarized bidirectional antenna according to the present invention, comprising: first and second dielectric substrates facing each other at a predetermined interval;
And a degenerate separation for generating circularly polarized waves, respectively, formed on a surface of the first and second dielectric substrates opposite to the ground conductor plate. A first array antenna in which a plurality of antenna elements having means are arranged one-dimensionally or two-dimensionally, and a plurality of antenna elements having degenerate separation means for generating a circularly polarized wave.
A second array antenna arranged two-dimensionally or two-dimensionally, and each antenna element forming the first array antenna and a lower portion of each antenna element forming the second array antenna are provided on the ground conductor plate. And an opening,
The degenerate separation means provided on each of the antenna elements of the first and second array antennas is arranged so as to be at the opposite position when viewed from the radiation surface of each of the array antennas.

[0018] With such a configuration, a circularly polarized bidirectional antenna having a simple structure, which is easy to miniaturize, has low manufacturing costs, has no interference between a received radio wave and a re-radiated radio wave, and has good characteristics. Can be realized.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following drawings, the same symbols indicate the same or corresponding parts. FIG.
BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the circularly polarized wave bidirectional antenna which concerns on this invention, and is a perspective view of the whole antenna.

The first and second dielectric substrates 11 and 12 are
A rectangular copper foil is provided on the opposite side of the ground conductor plate 13 of the first and second dielectric substrates 11 and 12, that is, on the outer surface. The first and second antenna elements 14 and 15 made of a conductive film such as those described above are respectively formed. These antenna elements 14 and 15 are
A so-called patch antenna is configured.

Each of the antenna elements 14 and 15 has a degenerate separation means (notch) 1 for generating circularly polarized waves.
8, 19 are provided at opposite positions when viewed from the respective radiation surfaces. FIGS. 2 (a) and 2 (b) show the antenna elements 14 and 15 viewed from the respective radiation surfaces. As can be seen from FIG. 2 (a), the degenerate separation means (notch) 1 having a width ΔS is provided.
8 and 19 are in opposite positions, that is, the degenerate and separate means (notch) 18 of the antenna element 14 is at the upper left and lower right, and the degenerate and separate means (notch) 19 of the antenna element 15 is at the upper right and lower left.

As shown in FIG. 1, both antenna elements 14 and 15 are placed on the ground conductor plate 13 at positions below the antenna elements 14 and 15, that is, between the antenna elements 14 and 15. A slot 16 as an opening for electromagnetically coupling the first antenna element 15 is provided, and a microstrip line 17 for feeding the first antenna element 14 is formed on the antenna element 14 side of the first dielectric substrate 11. Have been. The ground conductor plate 13 is formed on one of the first and second dielectric substrates 11 and 12,
By laminating and bonding the other dielectric substrate on the surface of the ground conductor plate 13, the circularly polarized bidirectional antenna of FIG. 1 is manufactured.

The operation of the circularly polarized bidirectional antenna will be described. Here, the widths of the first and second dielectric substrates 11, 12 W, and a length L, a relative dielectric constant epsilon _r, the thickness of the first and second dielectric substrates 11, 12 t, Antenna element 14,
The width of No. 15 is Wa and the length is La. Also, slot 1
6, length Ls, width Ws, microstrip line 1
7 is Wm. The width of the degenerate separation means (notches) 18 and 19 for generating circularly polarized waves is represented by ΔS.

As a prototype, the resonance frequency is 1.9 GHz.
An antenna in which the above parameters were determined was created so that Specifically, L = 150.0 mm, W = 70.0
mm, La = 47.3 mm, Wa = 47.3 mm, t =
1.6 mm, ε _r = 2.6, Wm = 4.0 mm, Ls =
20.0 mm, Ws = 1.0 mm, and ΔS = 4.0 mm.

FIG. 3 shows W = 70.0 m of the prototype antenna.
The input impedance at m, Ls = 20.0 mm is shown. A kink occurs at a frequency of 1.901 GHz.
FIG. 4 shows the radiation directivity in a horizontal plane (the xy plane of the coordinate axes shown in FIG. 1) at the frequency of 1.901 GHz. It can be seen that the use of the antenna having this configuration provides circularly polarized waves and bidirectional radiation directivity.

FIG. 5 shows a second embodiment of the circularly polarized bidirectional antenna according to the present invention, in which a plurality of antennas having the basic configuration shown in FIG. Show.

As shown in the figure, this array antenna has dielectric substrates 41 and 42 and a ground conductor plate 43 formed in a long length, and a degenerate separation antenna constituting a first array antenna 44 in the longitudinal direction. A plurality of antenna elements 44a to 44d having means (notches), a plurality of antenna elements 45a to 45d having degenerate separation means (notches) constituting the second array antenna 45, and microstrip lines 46a to 46d are provided. Have been. Slots 47a to 47d, which are openings, are formed in the ground conductor plate 43 at the lower positions of the antenna elements 44a to 44d and 45a to 45d.

The microslip line 46a directly feeds the antenna element 44a.
It is arranged so that each antenna element on the side may be fed alternately. That is, the microslip line 46a feeds the first antenna element 44a counted from one end of the first array antenna 44, and the microslip line 46a
c connects the second antenna element 44b and the third antenna element 44c counted from one end. The microslip line 46b is formed by connecting the first antenna element 45a and the second antenna element 45b counting from one end of the second array antenna 45 to the microslip line 46d.
Are the third antenna element 45c and the fourth antenna element 45d counted from one end of the second array antenna 45.
It is arranged to tie.

FIG. 6 shows a third embodiment of the present invention in which only one of the array antennas is fed by a microslip line.
An embodiment will be described. That is, in this embodiment, the antenna elements 44 a to 44 a on the first array antenna 44 side are used.
Only d is supplied by the microstrip lines 46a to 46d.

In the second and third embodiments shown in FIGS. 5 and 6, the microstrip lines 46a to 46d
By properly selecting the length, the radiation beam can be tilted. The advantages of the second and third embodiments are similar to those of the first embodiment.

In the first to third embodiments,
Although the shape of the antenna element is rectangular, the shape of the antenna element is not limited to this, and various modifications can be made, such as a circle, an ellipse, a triangle, and other shapes. FIG. 7 shows a case where the shape of the antenna element is circular. FIGS. 6A and 6B show the antenna elements 14 and 15 viewed from the respective radiation surfaces. The degenerate separation means (notches) 18 and 19 are in opposite positions, that is, the degenerate separation means of the antenna element 14. (Notch) 18 is at the upper left and lower right, and the degenerate separation means (notch) 19 of the antenna element 15 is at the upper right and lower left.

In the above embodiment, the slot is provided as the opening. However, the slot is not limited to the rectangular slot as described above, and may be a cross slot, a dumbbell slot, an elliptical slot, or the like. Any shape of slot may be used as long as it has the characteristics of the opening of the present invention. Further, although the microstrip line is provided as the feed line, another feed line may be used, and the positional relationship between the antenna and the feed line is not limited thereto.

Next, as a fourth embodiment of the circularly polarized bidirectional antenna according to the present invention, a plurality of antenna elements obtained by removing the feeder line from the antenna having the basic configuration of FIG. 1 are two-dimensionally arranged on a plane. FIG. 8 shows a configuration of an embodiment in which the two-dimensional relay array antenna is used.

FIG. 8 (a) shows the whole structure, and FIG. 8 (b) shows a part of the structure. In the figure, reference numeral 51 denotes a first array antenna, 52 denotes a second array antenna, and 53 denotes a slot. Also, 51a, 52
a and 53a are the first array antenna 51,
One of the second array antenna 52 and the slot 53 is an antenna element and a slot. These first and second array antennas 51 and 52 are respectively provided with dielectric substrates 55 and 5 provided to face each other with a ground conductor plate 54 interposed therebetween.
A plurality of antenna elements are two-dimensionally arranged on the side opposite to the ground conductor plate 54, that is, on the outer surface.
It should be noted that, in FIG.
Only one of the two antenna elements and the slot 53 is shown, and the others are omitted.

When a radio wave enters from the left side, it is received by the first array antenna 51, and the received radio wave is fed to the second array antenna 52 via the slot 53 below each antenna element of the first array antenna 51. Then, the light is radiated from the second array antenna 52 to the right again. It is clear from the antenna characteristics of FIG. 1 that circular polarization occurs.
In this case, if the polarizations of the first array antenna 51 and the second array antenna 52 are set to be the counter-rotating polarization, it is possible to eliminate the interference between the radio wave from the left side and the radio wave radiated again from the right side. In this embodiment, since the feed line is removed, there is an advantage that the arrangement of the antenna elements can be freely selected. In addition, unnecessary radiation from the feed line is also eliminated, so that there is no deterioration factor of the antenna characteristics.

In the fourth embodiment, a two-dimensional relay array antenna is obtained by two-dimensionally arranging a plurality of antenna elements obtained by removing the feeder line from the antenna having the basic configuration shown in FIG. A plurality of antenna elements obtained by removing the feed line from the antenna having the basic configuration may be arranged one-dimensionally to form a relay array antenna.

Also in the case of arraying as in the second to fourth embodiments, since the antenna element can be formed as a patch antenna on a dielectric substrate by photolithography or the like, the unit cost of the element is low. Instead, an array can be realized by arranging a plurality of antenna elements on the common first and second dielectric substrates, and a 3 dB hybrid is not required. Therefore, the manufacturing is simple and the manufacturing cost is low. It is easy to reduce the size.

[0038]

As described above, according to the present invention,
A circularly polarized directional antenna that is bidirectional can be realized. Here, since the antenna element can be formed as a patch antenna on the dielectric substrate by photolithography technology or the like, not only the unit cost of the element is low, but also a plurality of antenna elements can be formed on the common first and second dielectric substrates. Array formation can be realized by forming an array in
Since the B-hybrid is unnecessary, the production is simple and the production cost is low even in the case of an array, and the miniaturization is easy.

Also, in the case of a relay antenna, it can be seen that interference can be easily reduced by setting the transmission and reception polarizations to reverse polarizations. Further, the radiation directivity of the elevation angle can realize good characteristics since nulls and the like generated in the conventional antenna do not occur.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a state in which each antenna element according to the first embodiment is viewed from each radiation surface.

FIG. 3 is a diagram showing the input impedance of the antenna shown in the first embodiment.

FIG. 4 is a view showing the radiation directivity of the antenna according to the first embodiment.

FIG. 5 is a perspective view showing a second embodiment of the present invention.

FIG. 6 is a perspective view showing a third embodiment of the present invention.

FIG. 7 is a plan view showing a shape of an antenna element as a modification of the present invention.

FIG. 8 is a perspective view showing a fourth embodiment of the present invention.

FIG. 9 is a perspective view showing a configuration of a conventional example.

FIG. 10 is a diagram showing radiation directivity in a horizontal plane of a conventional antenna.

FIG. 11 is a diagram showing radiation directivity in a vertical plane of a conventional antenna.

FIG. 12 is a perspective view showing the configuration of another conventional example.

FIG. 13 is a perspective view showing a configuration of still another conventional example.

[Explanation of symbols]

 11, 41 ... first dielectric substrate 12, 42 ... second dielectric substrate 13, 43 ... ground conductor plate 14, 15 ... antenna element 16 ... slot 17 ... microstrip line 18, 19 ... degenerate separation means (cut Chipping) 44: first array antenna 45: second array antenna 44a to 44d, 45a to 45d: antenna elements 46a to 46d: microstrip lines 47a to 47d: slot 51: first array antenna 52: second Array antennas 51a, 52a Antenna elements 53, 53a Slot 54 Ground conductor plates 55, 56 Dielectric substrate 91 Narrow patch 92 Parasitic element 93 Slot 94 Ground plate 95 Feeding line 96 3dB hybrid 97 ... radome 120 ... ground conductors 121 and 122 ... dielectric substrates 123 and 124 ... antenna elements 125,126 ... microstrip line 127 ... slot 130 ... ground conductor 131, 132 ... dielectric substrate 133, 134 ... antenna elements 135, 136 ... degenerate separation unit 137 ... CPW feed line

Continued on the front page (72) Inventor Norimichi Chiba 3-1-1 Asahigaoka, Hino-shi, Tokyo F-term in Toshiba Hino Plant (reference) 5J021 AA01 AA05 AA07 AA09 AA11 AB06 CA03 GA02 GA08 HA05 JA06 JA07 5J045 AA21 AA27 AB05 AB06 CA04 DA10 EA07 FA02 GA01 HA03 LA01 MA07 NA01

Claims (3)

[Claims] A first dielectric substrate facing the first dielectric substrate at a predetermined distance; a ground conductor plate provided between the first and second dielectric substrates; First and second antenna elements respectively formed on a surface of a second dielectric substrate opposite to the ground conductor plate; and a ground conductor at a position below these first and second antenna elements. An opening formed in a plate, and a line for feeding the first antenna element, wherein the first and second antenna elements are circularly arranged so as to be in opposite positions when viewed from respective radiation surfaces. A circularly polarized bidirectional antenna, comprising degenerate separation means for generating polarized waves. 2. A first and a second dielectric substrate facing each other at a predetermined interval, a ground conductor plate provided between the first and the second dielectric substrates, A first array antenna including a plurality of antenna elements formed on a surface of a second dielectric substrate opposite to the ground conductor plate and having degenerate separation means for generating circularly polarized waves; and a circle. A second antenna comprising a plurality of antenna elements having degenerate separation means for generating polarized waves;
An opening provided in a ground conductor plate at a position below each antenna element forming the first array antenna and each antenna element forming the second array antenna; and the first array antenna. A line that feeds a first antenna element counted from one end, a line that connects an even-numbered antenna element counted from one end and an odd-numbered antenna element that is one greater than the even number, and the second array antenna Feeding means comprising a line connecting the odd-numbered antenna element and the even-numbered antenna element which is larger than the odd-numbered antenna element by one from the one end, or provided only on one of the first and second array antennas. And a feeder comprising a feeder line provided in the first and second array antennas. Means, circularly polarized bidirectional antenna, characterized in that it is arranged to have opposite positions as viewed from the emitting surface of the respective array antenna. 3. A first and a second dielectric substrate facing each other with a predetermined space therebetween, a ground conductor plate provided between the first and the second dielectric substrates, A plurality of antenna elements having degenerate separation means for generating circularly polarized waves, which are formed on the surface of the second dielectric substrate opposite to the ground conductor plate, are arranged one-dimensionally or two-dimensionally. A first array antenna, a second array antenna in which a plurality of antenna elements having degenerate separation means for generating circularly polarized waves are arranged one-dimensionally or two-dimensionally, and the first array antenna An opening provided in the ground conductor plate at a position below each of the antenna elements to be formed and each of the antenna elements to form the second array antenna, wherein each of the first and second array antennas has Establishment The degenerate separation means is arranged so as to be at an opposite position when viewed from the radiation surface of each array antenna.