JP3273402B2 - Printed antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple and highly efficient printed antenna having a bidirectional radiation pattern in a direction perpendicular to the surface of a printed circuit board. In particular, the present invention relates to a bidirectional printed antenna that is optimal as a base station antenna for a personal communication system using a microcell.

[0002]

2. Description of the Related Art PHS
(Personal Handyphone System
em, personal handyphone system) and the like, it is desired to develop a high-performance base station antenna suitable for the microcell. In particular, in a street microcell in which the cell shape is along a road, a bidirectional antenna having directivity in the length direction of a road rather than a generally used omnidirectional antenna in a horizontal plane is used as a zone. This is desirable because the length can be increased. In addition, in order to attach a large number of base station antennas to a building such as a utility pole on the side of a road, a small antenna having a simple configuration such as a printed antenna is desired.

As a typical example of a printed antenna, a microstrip antenna having a resonator shape such as a circular shape or a square shape is known (for example, IJ Bahl and and).
P. Bhartia: Microstrip Ante
nnas, Artech House, USA, 198
0). This microstrip antenna has directivity only on the other surface side because one surface of the substrate is a ground surface. Therefore, in order to have directivity on both sides of the substrate, it is necessary to superimpose the two microstrip antennas so that the back surfaces of the two microstrip antennas face each other and combine the outputs of the two microstrip antennas. However, this method has a problem that the structure becomes complicated and it is difficult to provide a bidirectional pattern with good symmetry due to a phase error at the time of synthesis.

As another example of a printed antenna, a parallel plate antenna in which patches having the same shape and the same size are printed at symmetrical positions on both surfaces of a substrate is known.

FIG. 13A is a perspective view of a configuration example of a conventional parallel plate antenna, and FIG. 13B is a plan view and a diagram showing a conductor pattern formed on the surface of the substrate. FIG. 13C is a plan view showing a conductor pattern formed on the back surface of the substrate.

In these figures, reference numerals 131 and 132 represent radiating element conductors (radiating patches) patterned on both surfaces of a substrate 133 made of a dielectric material. The radiation patch 131 on the surface of the substrate 133 includes:
The strip conductor 135 is connected via the strip conductor 134. A ground conductor 137 is connected to the patch 132 on the back surface of the substrate 133 via a strip conductor 136. The strip conductors 134 and 136 form a balanced feed line, and the strip conductor 135 forms an unbalanced feed line. Strip conductor 1
35 is connected to the center conductor of the connector 138,
37 is connected to the ground conductor of the connector 138, respectively.

According to this parallel plate antenna, FIG.
As shown in (A), the radiation directivity in the magnetic field plane (H plane) is bidirectional. However, FIG.
(B), the radiation directivity in the electric field plane (E plane) is omnidirectional or elliptical. However, the E plane is a plane parallel to the plane containing the current flowing through the two radiating element conductors 131 and 132, and in the case of FIG.
Planes perpendicular to 31 and 132 and parallel to the vertical direction of the figure,
The H plane is perpendicular to the E plane and the radiation conductor elements 131 and 132
It is a plane perpendicular to.

In the measurements shown in FIGS. 14A and 14B, the substrate 133 is a Teflon glass substrate (having a relative dielectric constant of 2.5).
5), the thickness of the substrate 133 is 1.6 mm,
Radiating element conductors 131 and 132
Is square and the measurement frequency is 2.2 GHz.

As described above, in the conventional parallel plate antenna shown in FIG. 13, the magnetic field plane (H plane) and the electric field plane (E plane)
In both planes, bidirectionality cannot be obtained.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a high-gain, high-radiation-efficiency printed antenna having a simple structure and having bidirectionality in a direction perpendicular to the surface of a printed circuit board.

[0011]

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided, in accordance with the present invention, a dielectric substrate having first and second planes substantially parallel to each other, and opposing each other on the first and second planes. At least one pair of radiating element conductors having the same shape and the same dimensions, respectively, provided at positions where the radiating element conductors are connected; and a feeding circuit connected to at least one edge of the radiating element conductors for supplying power to the radiating element conductors; A ground conductor formed at a distance from an edge of at least the second surface to which the feed circuit of the radiating element conductor is connected and an edge facing the edge; And a first strip conductor provided on the first surface and coupled to the radiating element conductor on the first surface; and a radiating element conductor provided on the second surface and coupled to the ground conductor. Second strip guide And the above-mentioned feed circuit is achieved by a printed antenna including an unbalanced feed line formed by a ground conductor and a first strip conductor, and a balanced feed line formed by first and second strip conductors. You.

As described above, in the parallel plate type printed antenna in which the radiating element conductors having the same shape and the same size are printed symmetrically on both sides of the dielectric of the printed circuit board, the radiating element printed on one side of the dielectric is provided. By forming a ground conductor in the same plane as the conductor and at a distance away from the radiating element conductor, the magnetic field surface (H
Plane) as well as the radiation directivity in the electric field plane (E plane), it is possible to obtain bidirectionality, and high gain can be achieved. Further, by providing the ground conductor, a feed distribution circuit to the radiating element conductor can be easily configured using an unbalanced feed line. That is, according to the present invention, there is provided a high-gain bidirectional antenna with a simple configuration and good symmetry, which is optimal as a base station antenna of a mobile communication system using microcells.

Preferably, the ground conductor is formed around the radiating element conductor on the second surface with a gap from the radiating element conductor. When arranging a plurality of antenna elements on a substrate, wiring of those feeder lines by microstrip lines becomes very easy.

[0014] Preferably, a plurality of pairs of the radiating element conductors are provided on the substrate in an array.

According to one embodiment of the present invention, the radiating element conductor has a square shape having four sides, and the balanced feed line is connected to the center of one of the four sides.

According to an embodiment of the present invention, the radiating element conductor has a rectangular shape having a long side and a short side shorter than the long side, and a balanced feed line is connected to one of the long sides. .
As a result, an impedance matching circuit is not required, and the circuit can be simplified and downsized. This is very effective in realizing a simple rod antenna.

The balanced feed line may be connected to a point off the center of the long side of the radiating element conductor.

According to one embodiment of the present invention, each of the radiating element conductors is provided to face each other at a predetermined distance, and includes a parasitic parasitic element conductor having substantially the same shape as the radiating element conductor. I have. Thereby, the electric field confined between the parallel plates is radiated, and the radiation efficiency can be greatly increased.

According to one embodiment of the present invention, there is provided at least one slot, and a third strip conductor provided on the first surface and intersecting the slot,
Power is supplied to the slot via an unbalanced feed line formed by the third strip conductor and the ground conductor. This makes it possible to easily realize an antenna that excites orthogonal polarization or circular polarization.

Preferably, a plurality of pairs of radiating element conductors and the same number of slots as the number of pairs are provided on the substrate.

According to one embodiment of the present invention, the line length and line width of the unbalanced feed line are adjusted to control the excitation phase and the excitation amplitude of the radiating element conductor or the radiating element conductor and the slot to desired values. It is decided. As a result, an array antenna having a desired directivity can be configured with a simple circuit configuration.

According to one embodiment of the present invention, a 90 ° hybrid is inserted between the unbalanced feed line feeding the radiating element conductor and the unbalanced feed line feeding the slot. Thereby, a circularly polarized antenna can be realized with a simple configuration.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment according to the present invention.
2 shows a configuration of an antenna according to a preferred embodiment of the present invention. FIG. 1A is a perspective view of the antenna, and FIG.
1B is a perspective view showing a conductor pattern formed on the front surface of the substrate, FIG. 1C is a perspective view showing a conductor pattern formed on the back surface of the substrate, and FIG. Figure 1
1B is a sectional view taken along line DD in FIG. 1B, and FIG. 1E is a sectional view taken along line EE in FIG.

In these figures, reference numerals 11 and 1
Reference numeral 2 denotes a radiating element conductor (radiating patch) having a rectangular shape such as a square, which is patterned on both surfaces of a substrate 13 made of a dielectric material. Patches 11 and 12
Are formed in the same shape and the same size at opposing positions (plane-symmetric positions) on both surfaces of the substrate 13.

On the surface of the substrate 13, a strip conductor 14 and a strip conductor 15 are formed in addition to the patch 11. One end of the strip conductor 15 is the strip conductor 1
4 is connected to a substantially central portion of one side of the patch 11. On the back surface of the substrate 13, a strip conductor 16 and a ground conductor 17 are provided in addition to the patch 12. As is clear from FIG. 1C, the ground conductor 17 surrounds the patch 12 and is provided around the patch 12 with a gap having a predetermined width. The patch 12 and the ground conductor 17 are connected by a strip conductor 16 provided in the gap.

The strip conductors 14 and 16 are
Are provided at positions facing each other (a position symmetrical with respect to each other), and thus constitute a balanced feed line. The strip conductor 15 is provided on the front surface at the position where the ground conductor 17 exists on the back surface, and thus constitutes an unbalanced feed line. Unbalanced feed line (strip conductor 1
The other end of 5) is connected to the center conductor of the connector 18 and to the ground conductor 17.
Are connected to the ground conductors of the connector 18, respectively.

Here, the length (resonance length) a of the patches 11 and 12 is determined according to the resonance frequency while considering the end effect. That is, in this type of antenna, it is known that the patch looks electrically long due to electric field leakage from the end of the patch, and resonates at a frequency corresponding to a length slightly longer than the actual length a. (For example,
I. J. Bahl and P.M. Bhartia: Mi
crostrip Antennas, P57, Art
ech House, USA, 1980).

In this embodiment, the patches 11 and 12 and the balanced feed lines (strip conductors 14 and 1) are used.
6), it is necessary to adjust the impedance to the same value or to provide an impedance matching circuit between them to achieve impedance matching.

Since power is supplied to the radiation patches 11 and 12 by balanced feed lines (strip conductors 14 and 16) provided on both surfaces of the dielectric substrate 13, these patches 11 and 12 are excited in opposite phases. As a result, the beam can be emitted in a direction perpendicular to the surface of the printed circuit board 13.

As described above, according to the conventional configuration shown in FIG. 13, the radiation directivity of the electric field plane (E plane) is not omnidirectional or elliptical as shown in FIG. Become. However, in this embodiment, since the grounding conductor 17 surrounds the patch 12 and is provided around the entire surface of the patch 12 with a gap of a predetermined width, the radiation directivity of the electric field surface (E surface) becomes bi-directional, and furthermore, The antenna gain is increased, and an antenna with a higher gain can be realized.

In order to make the radiation directivity of the electric field plane (E plane) bidirectional, there is no need to surround the patch 12 with the ground conductor 17 all around it. It is sufficient to provide a gap with a predetermined width (in the resonance length direction) on the side to which the power supply line is connected and the side opposite to the side.
As in the present embodiment, the ground conductor 17
Is provided to facilitate wiring of the microstrip conductor feed line. In particular, as will be described later, when a plurality of antennas are arranged on a substrate, this configuration makes wiring of the feed line very easy.

FIG. 2 shows the radiation directivity of the electric field plane (E plane) of a printed antenna actually manufactured based on this embodiment. As shown in the figure, bidirectional radiation characteristics are obtained also on the electric field surface (E surface). The measurement parameters of this characteristic are the same as those in FIG. That is, the substrate 13 is a Teflon glass substrate (relative dielectric constant 2.55),
3, the thickness is 1.6 mm, and the size of the substrate 13 is about 10 cm.
The corners and the shapes of the patches 11 and 12 are square, and the measurement frequency is 2.2 GHz.

The radiation directivity, gain, and VSWR characteristics change according to the size of the gap between the ground conductor 17 and the radiation patch 12. If this gap is infinite, that is, the ground conductor 17
The radiation directivity in the E plane when there is no radiance is almost omnidirectional as in the prior art. The smaller the gap between the radiation patch 12 and the ground conductor 17 is, the closer the radiation directivity in the E plane becomes to the bidirectionality. This spacing is determined by radiation directivity,
It is determined in consideration of gain and VSWR characteristics. Generally, it is preferable to set the length to about 1/5 or less of the length a of the patch 12 in order to obtain a desired bidirectionality.

The frequency band characteristics include the radiation patches 11 and 1
Depending on the distance between the two (the thickness of the dielectric substrate 13), a desired band characteristic can be obtained by appropriately selecting this thickness.

As described above, the antenna of the present invention
It has a structure in which a ground conductor is added to a parallel plate antenna having a structure and operation different from those of a microstrip antenna in which a ground conductor is provided on one entire surface of the substrate and a radiating element conductor is provided on the other surface. Thus, the antenna has a structure and an operation principle different from those of the conventional parallel plate antenna.

In the embodiment shown in FIG.
And 12 are square patches, but needless to say, patches of various shapes such as a circle, an ellipse, and a rectangle may be used as in the case of a normal microstrip antenna.

In addition, as in the case of a normal microstrip antenna, by feeding power to two points of the radiating element from two orthogonal directions, polarization sharing can be achieved.
It is similarly possible to excite the right-handed and left-handed circularly polarized waves using the 90 ° hybrid, and to operate as a diversity antenna using the two polarized waves.

As described above, according to the present embodiment, a printed antenna having bidirectionality can be realized with a simple configuration.

(Second Embodiment) FIG. 3 shows a second embodiment according to the present invention.
2 shows a configuration of an antenna according to a preferred embodiment of the present invention. This embodiment shows a case of an array antenna in which a plurality of (four in the example in the figure) antennas of the first embodiment are arranged.

In FIG. 3, reference numerals 31 and 32 denote rectangular radiating patches, for example, square, which are patterned on both surfaces of a dielectric substrate 33, respectively. The patches 31 and 32 are formed in the same shape and the same size at opposing positions (plane-symmetric positions) on both surfaces of the substrate 33, and constitute one antenna element.

In the antenna element portion on the surface of the substrate 33, a strip conductor 34 and a strip conductor 35 are formed in addition to the patch 31. One end of the strip conductor 35 is connected to a substantially central portion of one side of the patch 31 via the strip conductor 34. On the back surface of the substrate 33,
In addition to the patch 32, a strip conductor 36 and a ground conductor 37
Is provided. The ground conductor 37 surrounds the patch 32 and is provided around the patch 32 with a predetermined gap therebetween. The patch 32 and the ground conductor 37 are connected by a strip conductor 36 provided in the gap.

The strip conductor 34 and the strip conductor 36 provided in the gap portion on the back surface of the substrate 33
3 are provided at opposing positions (symmetrical to the plane) on both surfaces, and thus constitute a balanced feed line.
The strip conductor 35 is provided on the front surface at the position where the ground conductor 37 exists on the back surface, and thus forms an unbalanced feed line.

In this embodiment, four antenna elements having the same structure are formed in an array on the substrate 33, and the other end of the unbalanced feed line (strip conductor 35) from each antenna element is connected to a connector. The ground conductor 3
7 are connected to the ground conductors of the connector 38, respectively. The number of antenna elements is not limited to four, and may be any number as long as it is two or more.

Here, as in the first embodiment, power is supplied to the radiation patches 31 and 32 by using balanced feed lines (strip conductors 34 and 3) provided on both surfaces of the dielectric substrate 33.
6), these patches 31 and 32
Are excited in phases opposite to each other, so that the beam can be emitted in a direction perpendicular to the plane of the printed circuit board 33.

The characteristics of the antenna according to the present embodiment include:
As can be inferred from the directivity of a single antenna element in the first embodiment, the radiation directivity of the electric field plane (E plane) is:
Since the ground conductor 37 surrounds the patch 32 and is provided around the entire surface of the patch 32 with a gap of a predetermined width therebetween, the antenna becomes bidirectional, and the directional gain increases, so that an antenna with higher gain can be realized. Further, the radiation directivity in the magnetic field plane (H plane) indicates a bidirectional pattern in which the beam is narrowed down by the array effect. In addition, since the ground conductor 37 is provided on the entire surface surrounding the patch 32, a feed distribution circuit for these radiation patches can be easily configured using an unbalanced feed line.

In the second embodiment, the case where the main beam is radiated in two directions perpendicular to the surface of the printed circuit board has been described, but the magnetic field surface (H It goes without saying that the radiation directivity in the plane can be freely synthesized by changing the excitation amplitude and phase of the radiation element. Furthermore, although an array arranged one-dimensionally in the magnetic field plane (H plane) has been described here, an array arranged one-dimensionally in the electric field plane (E plane) or an array arranged two-dimensionally (planar). It is needless to say that the present invention is also effective in the case of arranging in a spherical shape or a conformal shape.

Other configurations, modifications and effects of this embodiment are the same as those of the first embodiment shown in FIG.

(Third Embodiment) FIG. 4 shows the configuration of an antenna according to a third preferred embodiment of the present invention. FIG. 4A is a perspective view of the antenna, and FIG.
(B) is a sectional view taken along line BB in (A) of FIG. 4.

In these figures, reference numerals 41 and 4
Reference numeral 2 denotes a radiating element conductor (radiating patch) having a rectangular shape such as a square, which is patterned on both surfaces of a substrate 43 made of a dielectric material. Patches 41 and 42
Are formed in the same shape and the same size at opposing positions (plane-symmetric positions) on both surfaces of the substrate 43.

On the surface of the substrate 43, in addition to the patch 41, a strip conductor 44 and a strip conductor 45 are formed. One end of the strip conductor 45 is the strip conductor 4
4 is connected to the patch 41. On the back surface of the substrate 43, a strip conductor 46 and a ground conductor 47 are provided in addition to the patch 42. The ground conductor 47 surrounds the patch 42 and is provided around the patch 42 with a gap having a predetermined width. The patch 42 and the ground conductor 47 are connected by a strip conductor 46 provided in the gap.

The strip conductors 44 and 46 are
Are provided at positions facing each other (a position symmetrical with respect to each other), and thus constitute a balanced feed line. The strip conductor 45 is provided on the back surface at the position where the ground conductor 47 exists, and thus constitutes an unbalanced feed line. Unbalanced feed line (strip conductor 4
The other end of 5) is connected to the center conductor of the connector 48 and the ground conductor 47.
Are connected to the ground conductors of the connector 48, respectively.

Since power is supplied to the radiation patches 41 and 42 by balanced feed lines (strip conductors 44 and 46) provided on both surfaces of the dielectric substrate 43, these patches 41 and 42 are excited in opposite phases. As a result, the beam can be emitted in a direction perpendicular to the surface of the printed circuit board 43.

Further, since the ground conductor 47 surrounds the patch 42 and is provided around the entire surface of the patch 42 with a gap of a predetermined width therebetween, the radiation directivity of the electric field surface (E surface) becomes bidirectional, and the directivity gain is increased. Is increased, and an antenna having a higher gain can be realized, as in the case of the first embodiment.

In order to make the radiation directivity of the electric field plane (E plane) bidirectional, it is not necessary to surround the patch 42 with the ground conductor 47 all around it. It is sufficient to provide a gap with a predetermined width (in the resonance length direction) on the side to which the power supply line is connected and the side opposite to the side.
As in the present embodiment, a ground conductor 47 is formed all around the patch 42.
Is provided to facilitate wiring of the microstrip feed line. In particular, when a plurality of antennas are arranged on a substrate, this configuration makes wiring of the feed line very easy.

The difference between the third embodiment and the first embodiment is that, in order to increase the radiation efficiency, as shown in FIG. And parasitic parasitic element conductor (parasitic patch) 4 opposed to 42
9 and 50, respectively. These parasitic patches 49 and 50 have the same shape and the same dimensions as the radiating patches 41 and 42,
2 are separated from each other by a predetermined distance (in this embodiment, a distance of about 1/10 of the wavelength).

In the conventional parallel plate antenna shown in FIG. 13, the distance between the radiating patches 131 and 132 (the thickness of the dielectric substrate, in this embodiment, the radiating patches 41 and 42).
When the distance between them is small, the electric field is confined between these parallel conductors, and there is a phenomenon that the radiation efficiency is reduced. On the other hand, if the distance is increased to a certain extent or more, a higher-order mode is created between the parallel conductors, so that the original radiation directivity cannot be obtained. Further, when the balanced power supply is lost, the radiation efficiency increases but the front-to-back ratio of the bidirectionality deteriorates.

In this embodiment, to solve this point,
Non-feeding parasitic patches 49 and 50 are arranged opposite to the radiating patches 41 and 42 and separated by a predetermined distance, respectively.
This enhances the radiation efficiency. FIG. 5 shows a change in gain with respect to the distance (h / λ) between parallel conductors by comparing the case where the parasitic patches 49 and 50 are used and the case where the parasitic patches 49 and 50 are not used in order to show the effect of increasing the radiation efficiency. It shows the calculated value of.

As shown in the figure, when the parasitic patch is not used, when the distance h between the radiating patches becomes less than about 0.02 wavelength (λ), the electric field is suddenly confined between the parallel flat plates, and Efficiency is reduced and therefore gain is reduced. On the other hand, for example, when the distance h between the radiation patches 41 and 42 is 0.01 wavelength (λ), the gain can be improved by about 8 dB by using the parasitic patches 49 and 50.

In a conventional microstrip antenna, a parasitic parasitic element conductor may be used for the purpose of widening the bandwidth (for example, Hori, Nakajima: IEICE (B), J68-B, 4, pp. 515-522, 19
85.4). However, the operation principle of the parallel plate antenna is different from that of the conventional microstrip antenna, and the parasitic patches 49 and 50 are used to increase the radiation efficiency of the antenna. When this kind of parasitic patch is used for the conventional parallel plate antenna shown in FIG. 13, the directivity of the electric field surface (E plane) of the conventional parallel plate antenna is originally omnidirectional or elliptical. Because of the directivity, even if a parasitic patch is used, a component in the substrate direction (a direction parallel to a plane perpendicular to the E-plane and the H-plane) remains and bidirectionality cannot be obtained. On the other hand, in the present embodiment, bidirectionality is obtained by the effect of the ground conductor 47 regardless of the presence or absence of the parasitic patches 49 and 50.

Although the present embodiment is an antenna having one radiating element, the present embodiment can be applied to an array antenna having a plurality of radiating elements as shown in the second embodiment. Needless to say, the configuration described above is applicable. When an array antenna is used, it is needless to say that directivity synthesis can be freely performed by changing the excitation amplitude and phase of each radiation element.

Other configurations, modifications and effects of this embodiment are the same as those of the first and second embodiments shown in FIGS. 1 and 3, respectively.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment according to the present invention.
3 shows a configuration of an antenna in a preferred embodiment of the present invention. This embodiment shows a case of an array antenna in which a plurality of (four in the example shown) are arrayed in the E plane by making the shape of the radiation patch in the antenna of the first embodiment a narrow rectangle.

In FIG. 6, reference numerals 61 and 62 denote strip-shaped (small-width rectangular) radiating patches patterned on both surfaces of a dielectric substrate 63, respectively. The patches 61 and 62 are formed in the same shape and the same size at opposing positions (symmetrical surfaces) on both surfaces of the substrate 63, and constitute one antenna element.

In the antenna element portion on the surface of the substrate 63, a strip conductor 64 and a strip conductor 65 are formed in addition to the patch 61. One end of the strip conductor 65 is connected to one point on the long side of the patch 61 via the strip conductor 64. On the back surface of the substrate 63, a strip conductor 66 and a ground conductor 67 are provided in addition to the patch 62. The ground conductor 67 is provided around the patch 62 with a predetermined width gap therebetween. Patch 6
2 and the ground conductor 67 are connected by a strip conductor 66 provided in the gap.

The strip conductor 64 and the strip conductor 66 provided in the gap on the back surface of the substrate 63
3 are provided at opposing positions (symmetrical to the plane) on both surfaces, and thus constitute a balanced feed line.
The strip conductor 65 is provided on the back surface at the position where the ground conductor 67 exists, and thus constitutes an unbalanced feed line.

In this embodiment, four antenna elements having the same structure are formed in an array on the substrate 63. The other end of the unbalanced feed line (strip conductor 65) from each antenna element is connected to a connector. Ground conductor 6
7 are connected to the ground conductors of the connector 68, respectively. The number of antenna elements is not limited to four, and may be any number as long as it is two or more.

In general, the length a (resonance length) of the radiation patch is selected to be equal to the length b. However, when the operating frequency band is narrow, the length b may be smaller than the length a. No problem. In general, power is supplied to the radiating patch from a point on a bisector of a side having a length b. This is because if the feeding point is provided at a point off the bisector of the side of the length b, the current on the radiating patch will not only flow in parallel to the side of the length a, but also This is because it also flows in a direction parallel to the side of b, and resonates at a frequency corresponding to the length b. On the other hand, if the length b of the radiation patch is selected to be shorter than the length a (resonance length), the resonance frequency corresponding to the length b is equal to the resonance frequency corresponding to the original length a of the radiation patch. Very different,
There is a characteristic that it does not affect the originally required frequency band.

The present embodiment utilizes this characteristic.
The length b of the other side is shorter than the length a of one side of the radiation patches 61 and 62 determined from the resonance length, and power is supplied from one point on the side of the length a by the balanced feed line 65. It has a structure to perform. This allows the antenna to have length a and length b
, But the resonance mode corresponding to the length b does not affect the originally required frequency band, so that it can be used as an antenna having a resonance frequency corresponding to the length a. .

Incidentally, the impedance at the center of the side of the length a of the radiation patches 61 and 62 is 0Ω, but this impedance becomes higher as approaching the end of the side.
It is about 300Ω or more at the end. In the conventional antenna, current is supplied in the direction of the arrow in FIG. 6 and power is supplied from the side of the length b in order to obtain a resonance frequency for the length a.
There is a disadvantage that the impedance at the feeding point becomes high and an impedance matching circuit is inevitably required, which complicates the circuit. In this embodiment, since the power is supplied from one point on the side excluding the end of the length a of the radiation patches 61 and 62, the feeding point can be freely selected according to the characteristic impedance of the balanced feed line. For this reason, there is an advantage that the impedance matching circuit is unnecessary and the circuit can be simplified and downsized. This is an effective technique for realizing the antenna configuration of the present invention, and has an advantage that an antenna having bidirectionality can be more easily configured.

Other configurations, modifications and effects of this embodiment are the same as those of the first and second embodiments shown in FIGS. 1 and 3, respectively.

(Fifth Embodiment) FIG. 7 shows the configuration of an antenna according to a fifth preferred embodiment of the present invention. FIG. 7A is a partially cutaway perspective view of the antenna and an enlarged perspective view of the same, and FIG. 7B is a cross-sectional view taken along the line B′-B ′ in FIG. FIG. 7C is a front view and a rear view of each radiating element.

This embodiment is a more specific example of the antenna shown in FIG. 6 provided with the parasitic patch shown in FIG. 4 and housed in a cylindrical radome.

In these figures, reference numerals 71 and 7
Reference numeral 2 denotes a narrow rectangular radiation patch patterned on both surfaces of a substrate 73 made of a dielectric material. The patches 71 and 72 are formed in the same shape and the same size at opposing positions (symmetrical surfaces) on both surfaces of the substrate 73, and constitute one antenna element.

In the antenna element portion on the surface of the substrate 73, a strip conductor 74 and a strip conductor 75 are formed in addition to the patch 71. One end of the strip conductor 75 is connected to the patch 71 via the strip conductor 74. On the back surface of the substrate 73, a strip conductor 76 and a ground conductor 77 are provided in addition to the patch 72.
The ground conductor 77 is provided around the patch 72 with a predetermined width gap therebetween. The patch 72 and the ground conductor 77 are connected to the strip conductor 76 provided in the gap.
Connected by

The strip conductor 74 and the strip conductor 76 provided in the gap portion on the back surface of the substrate 73
3 are provided at opposing positions (symmetrical to the plane) on both surfaces, and thus constitute a balanced feed line.
The strip conductor 75 is provided on the back surface where the ground conductor 77 exists, and thus constitutes an unbalanced feed line.

In order to increase the radiation efficiency, parasitic parasitic element conductors (parasitic patches) 79 and 80 are arranged opposite to the radiation patches 71 and 72 at positions away from the substrate 73, respectively. These parasitic patches 79 and 80 have the same shape and the same dimensions as the radiating patches 71 and 72, and have a predetermined distance from the radiating patches 71 and 72 (in this embodiment, a distance of about 1/10 of the wavelength). A) are located just apart. These parasitic patches 79 and 80 are formed on auxiliary substrates 81 and 82 made of a dielectric material, respectively.

A plurality of antenna elements are formed in an array on the substrate 73, and these antenna elements are accommodated in a cylindrical radome 83. The other end of the unbalanced feed line (strip conductor 75) from each antenna element is connected to the center conductor of a connector 78 projecting outside from the radome 83, and the ground conductor 77 is connected to the ground conductor of the connector 78. .

Other configurations, modifications and effects of this embodiment are the same as those of the third and fourth embodiments shown in FIGS. 4 and 6, respectively.

FIG. 8 shows the measured characteristics of the antenna of this embodiment. FIG. 8A shows the radiation directivity in the magnetic field plane (H plane), and FIG. 8B shows the radiation directivity in the electric field plane (E plane). As measurement parameters of this characteristic,
The substrate 73 is a Teflon glass substrate (relative permittivity 2.55), the thickness of the substrate 73 is 1.6 mm, the width is about 30 mm, the short side of each element is about 10 mm, and the element interval is about 10 mm. 0.9 wavelength, the distance between the radiating patches 71 and 72 and the parasitic patches 79 and 80 is about 10 mm, and the measurement frequency is 2.2 GHz.

As can be seen from the figure, since the present antenna is arranged in the electric field plane (E plane),
The radiation directivity in the plane) is reduced by the array effect,
Since the radiation directivity in the magnetic field plane (H plane) is a narrow patch, bidirectional radiation with a wide beam width is obtained.

(Sixth Embodiment) FIG. 9 shows a sixth embodiment according to the present invention.
FIG. 2 is a perspective view showing a configuration of an antenna according to a preferred embodiment of the present invention. This embodiment is an antenna having a structure in which a bidirectional narrow patch antenna and a bidirectional slot antenna are combined.

In the figure, reference numerals 91 and 92 denote strip-shaped (narrow rectangular) radiating element conductors (radiating patches) patterned on both surfaces of a substrate 93 made of a dielectric material. Patches 91 and 92
Are formed in the same shape and the same size at opposing positions (plane-symmetric positions) on both surfaces of the substrate 93.

On the surface of the substrate 93, in addition to the patch 91, a strip conductor 94, a strip conductor 95, and a strip conductor 104 are formed. One end of the strip conductor 95 is connected to the patch 91 via the strip conductor 94. On the back surface of the substrate 93, a strip conductor 96 and a ground conductor 97 are provided in addition to the patch 92.
The ground conductor 97 is provided around the patch 92 with a predetermined width gap therebetween. The patch 92 and the ground conductor 97 are connected to the strip conductor 96 provided in the gap.
Connected by

The strip conductors 94 and 96 are
Are provided at positions facing each other (a position symmetrical with respect to each other), and thus constitute a balanced feed line. The strip conductor 95 and the strip conductor 104 are provided on the front surface at the position where the ground conductor 97 exists on the back surface, and thus constitute an unbalanced power supply line. The other end of one unbalanced feed line (strip conductor 95) is connected to the center conductor of one connector 98, and the ground conductor 97 is connected to the ground conductor of this connector 98.

In order to increase the radiation efficiency, parasitic element conductors (parasitic patches) 99 and 100 are arranged at positions away from the substrate 93 so as to face the radiation patches 91 and 92, respectively. These parasitic patches 99 and 100
Has the same shape and the same dimensions as the radiation patches 91 and 92, and is a predetermined distance from the radiation patches 91 and 92, respectively (in this embodiment, about 1/10 of the wavelength).
Are only located away.

The difference between the sixth embodiment and the third embodiment is that a narrow slot 1 is formed in a substrate 93 located vertically above a radiation patch 92 in a region where a ground conductor 97 is provided.
05 on the surface of the substrate 93 for supplying power to the slot 105, and one end of the substrate
The microstrip (unbalanced type) feed line 104 is provided so as to cross the line 05. The other end of this unbalanced feed line (strip conductor 104) is connected to the center conductor of the other connector 106. Slot 1
The length of 05 is the resonance length similarly to the radiation patches 91 and 92. In this embodiment, the slot 105 is formed by opening the ground conductor 97 on the back surface of the substrate in the shape during patterning.

By providing the ground conductor 97 on the entire surface of the back surface of the substrate 93 except for the patch 92 and the gap therebetween, it is possible to arrange the slot 105 on the same plane as the radiating patches 91 and 92. Further, by providing a microstrip line 104 in a portion corresponding to the ground conductor 97 on the front surface side of the substrate 93, the slot 1
05, and the slot 105 can be operated independently of the radiating patches 91 and 92.
At this time, the radiating patches 91 and 92 radiate vertically polarized waves, and the slot 105 radiates horizontally polarized waves, so that a dual-polarized antenna can be realized. Also, diversity using both polarizations is possible.

The other configurations, modifications and effects of this embodiment are the same as those of the third and fourth embodiments shown in FIGS. 4 and 6, respectively.

(Seventh Embodiment) FIG. 10 is a perspective view showing the structure of an antenna according to a seventh preferred embodiment of the present invention. In this embodiment, a 90 ° hybrid is provided in an antenna having a structure in which the bidirectional narrow patch antenna and the bidirectional slot antenna shown in FIG. 9 are combined, and power is combined. This makes it possible to radiate right-handed and left-handed circularly polarized waves.

The structure of the antenna shown in FIG. 10 except for the 90 ° hybrid 107 is exactly the same as that of the antenna shown in FIG. However, the line length and line width of the feed lines (strip conductors 94 to 96) to the radiation patches 91 and 92 and the feed line 104 to the slot 105 are designed so that the excitation amplitudes are equal to each other and the excitation phases are equal to each other. Have been. As a result, the 90 ° hybrid 10
7, power can be supplied to each element having orthogonal polarization with a phase difference of 90 °, so that circular polarization can be excited. Note that the 90 ° hybrid 107 can also be configured on the dielectric substrate 93.

In a normal circularly polarized antenna such as a cross dipole antenna, an electric field plane (E plane) and a magnetic field plane (H plane) are used.
Since the circularly polarized antenna is configured by orthogonalizing the antennas having different directivities with respect to the plane, the elliptical polarization rate is deteriorated in directions other than the main beam direction due to the difference in directivity, and circular polarized waves are obtained. I can't. On the other hand, in the antenna of this embodiment, the directivity in the electric field plane (E plane) of the radiation patches 91 and 92 and the directivity in the magnetic field plane (H plane) of the slot 105 and the magnetic field plane of the radiation patches 91 and 92 are different. Since the directivity in the (H plane) and the directivity in the electric field plane (E plane) of the slot 105 can be made substantially equal, the circular polarization characteristics of the horizontal plane are improved over a wide angle. Note that the vertical plane is affected by the array effect because the vertical polarization element and the horizontal polarization element are separated from each other, and circular polarization characteristics are degraded in directions other than the main beam direction.

In the embodiment of FIG. 10, by selecting one of the connectors 98 and 106 as the power supply port, right-handed or left-handed circularly polarized waves can be selected. Therefore,
Just as the antenna using both vertical and horizontal polarizations is possible in the antenna of FIG. 9, the antenna of FIG. 10 is capable of diversity using both right-handed and left-handed polarizations.

The other configurations, modifications and effects of this embodiment are the same as those of the sixth embodiment shown in FIG.

(Eighth Embodiment) FIG. 11 is a perspective view showing a configuration of an antenna according to an eighth preferred embodiment of the present invention.

In this embodiment, a plurality of antennas each having a structure in which a bidirectional narrow patch antenna and a bidirectional slot antenna shown in FIG. 9 are combined are arranged on a substrate and housed in a cylindrical radome. It is a more specific example of an antenna.

As shown in the figure, a substrate 1 made of a dielectric material
13 is a narrow rectangular radiation patch (111) on both sides.
Are patterned, and the narrow slot 1 is formed in the substrate 113 in the region where the ground conductor is provided.
15 are formed. The radiation patches and the slots 115 on the back surface of the substrate are alternately arranged one by one in the length direction of the substrate 113 in this embodiment.

Further, in front of the radiation patch 111 (the substrate 1
13), a predetermined distance (in this embodiment,
Passive parasitic element conductors (parasitic patches) 119 and 120 are disposed on auxiliary substrates 121 and 122 made of a dielectric material at positions separated by a distance of about 1/10 of the wavelength). As described above, in this embodiment, the antenna having the structure in which the two sets of the bidirectional narrow patch antenna and the bidirectional slot antenna are combined is housed in the cylindrical radome 123. Note that the number of sets of the patch antenna and the slot antenna is not limited to two, and may be an arbitrary number of two or more.

The other structures, modifications and effects of this embodiment are exactly the same as those of the fifth and sixth embodiments shown in FIGS. 7 and 9, respectively.

(Ninth Embodiment) FIG. 12 is a perspective view showing a configuration of an antenna according to a ninth preferred embodiment of the present invention.

In this embodiment, as in the embodiment of FIG. 11, a plurality of antennas having a structure combining the bidirectional narrow patch antenna and the bidirectional slot antenna shown in FIG. 9 are arranged on a substrate. It is a more specific example of the antenna accommodated in a cylindrical radome.

In this embodiment, however, the radiation patch (11
1) and the slots 115 are provided for each of the plurality of radiation patches (111) and the plurality of slots 115 in the length direction of the substrate 113.
Each is separately arranged. Other configurations, modifications, and effects are completely the same as those of the eighth embodiment shown in FIG. Elements similar to those in the eighth embodiment shown in FIG. 11 are denoted by the same reference numerals.

The embodiments described above all illustrate the present invention by way of example and not by way of limitation, and the present invention can be embodied in various other modified and modified forms. Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0104]

As described above in detail, according to the present invention, the printed antenna has the same shape of the dielectric substrate and at least one pair provided at positions facing each other on the front and back surfaces of the substrate. And a radiation patch of the same size, a power supply circuit connected to at least one edge of the radiation patch for supplying power to the patches, and a power supply circuit of the radiation patch on at least the rear surface provided on the rear surface. With respect to the edge and the edge facing this edge, a ground conductor formed with a gap,
A first strip conductor provided on the front surface and coupled to the radiating patch on the front surface; and a second strip conductor provided on the back surface and coupling the radiating patch on the back surface to the ground conductor. The above-described power supply circuit includes an unbalanced power supply line formed by a ground conductor and a first strip conductor, and a balanced power supply line formed by first and second strip conductors.

As described above, in the parallel plate type printed antenna in which the radiating element conductors having the same shape and the same size are printed on both sides of the dielectric of the printed circuit board in plane symmetry, the radiating element printed on one side of the dielectric is provided. By forming a ground conductor in the same plane as the conductor and at a distance away from the radiating element conductor, the magnetic field surface (H
Plane) as well as the radiation directivity in the electric field plane (E plane), it is possible to obtain bidirectionality, and high gain can be achieved.

Further, by providing the ground conductor having such a pattern, a feed distribution circuit to the radiating element conductor can be easily configured by using an unbalanced feed line. That is, according to the present invention, there is provided a high-gain bidirectional antenna with a simple configuration and good symmetry, which is optimal as a base station antenna of a mobile communication system using microcells.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an antenna according to a first preferred embodiment of the present invention.

FIG. 2 is a diagram showing measured characteristics of an antenna in the embodiment of FIG. 1;

FIG. 3 is a diagram showing a configuration of an antenna according to a second preferred embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of an antenna according to a third preferred embodiment of the present invention.

FIG. 5 is a diagram illustrating an effect of the antenna in the embodiment of FIG. 4;

FIG. 6 is a diagram showing a configuration of an antenna according to a fourth preferred embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of an antenna according to a fifth preferred embodiment of the present invention.

8 is a diagram showing measured characteristics of the parallel plate antenna in the embodiment of FIG. 7;

FIG. 9 is a diagram showing a configuration of an antenna according to a sixth preferred embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of an antenna according to a seventh preferred embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of an antenna according to an eighth preferred embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of an antenna according to a ninth preferred embodiment of the present invention.

FIG. 13 is a diagram illustrating a configuration example of a conventional parallel plate antenna.

FIG. 14 is a diagram illustrating measured characteristics of the parallel plate antenna of FIG. 13;

[Explanation of symbols]

 11, 12 Radiation patch 13 Substrate 14, 15, 16 Strip conductor 17 Ground conductor 18 Connector

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-343915 (JP, A) JP-A-2-65529 (JP, A) JP-A-1-293704 (JP, A) 15328 (JP, U) JP-A 4-132719 (JP, U) JP-A 2-27584 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 13/08 H01Q 1 / 38 H01Q 13/10 H01Q 21/08 JICST file (JOIS)

Claims (12)

(57) [Claims] 1. A dielectric substrate having first and second surfaces that are substantially parallel to each other, and at least one pair of the same shape and at least one pair provided at opposing positions on the first and second surfaces, respectively. A radiating element conductor having the same dimensions, a power supply circuit connected to at least one edge of the radiating element conductor for supplying power to the radiating element conductor, and a power supply circuit provided on the second surface; A ground conductor formed with a gap between an edge of the radiating element conductor to which the power supply circuit is connected and an edge facing the edge of the radiating element conductor, and a ground conductor provided on the first surface; A first strip conductor coupled to the radiating element conductor on one surface; and a second strip provided on the second surface and coupling the radiating element conductor and the ground conductor on the second surface. Conductor And, printed antenna, wherein the feed circuit, characterized by comprising the said ground conductor and said first strip conductor by unbalanced feed line, and the first and second strip conductor by the balanced feed line. 2. The printed antenna according to claim 1, wherein the ground conductor is formed around the radiating element conductor on the second surface with a gap from the radiating element conductor. 3. The radiating element conductor has a square shape having four sides, and the balanced feed line is connected to a center of one of the four sides. 3. The printed antenna according to 2. 4. The radiating element conductor has a rectangular shape having a long side and a short side shorter than the long side, and one of the long sides is connected to a balanced feed line formed by the first and second strip conductors. The printed antenna according to claim 1, wherein the printed antenna is provided. 5. The printed antenna according to claim 4, wherein the balanced feed line is connected to a point off the center of the long side of the radiating element conductor. 6. A radiating element conductor comprising a parasitic element conductor which is provided opposite to each of the radiating element conductors with a predetermined distance therebetween and has substantially the same shape as the radiating element conductor. Item 6. The printed antenna according to any one of Items 1 to 5. 7. The printed antenna according to claim 1, wherein a plurality of pairs of the radiating element conductors are provided on the substrate in an array. 8. A line length and a line width of the unbalanced feed line are determined so as to control an excitation phase and an excitation amplitude of the radiating element conductor to desired values. The printed antenna according to any one of the above. 9. At least one slot, said first slot
And a third strip conductor provided on the surface of the third strip and crossing the slot, and the power is supplied to the slot via an unbalanced feed line formed by the third strip conductor and the ground conductor. The printed antenna according to any one of claims 1 to 7, wherein 10. The printed antenna according to claim 9, wherein a plurality of pairs of the radiating element conductors and the same number of slots as the number of the pairs are provided in the substrate. 11. A line length and a line width of the unbalanced feed line are determined so as to control excitation phases and excitation amplitudes of the radiating element conductor and the slot to desired values. The printed antenna according to 9 or 10. 12. The hybrid according to claim 11, wherein a 90 ° hybrid is inserted between the unbalanced feed line for feeding the radiating element conductor and the unbalanced feed line for feeding the slot. Printed antenna described.