JPH0555820A - Annular plane antenna - Google Patents

Abstract

PURPOSE:To easily match this annular plane antenna also with a high input impedance generated from an annular radiation element by perforating a thin gap into an area opposed to the radiation element formed on a ground conductor and exciting the annular radiation element through the thin gap. CONSTITUTION:The circular radiation element 13 is concentrically laminated on the square ground conductor 11 through a dielectric layer 12 and a circular aperture 14 is concentrically formed on the element 13. A slot 15 is perforated like an I shape in an area on the conductor 11 opposed to the element 13 in parallel with one side of the conductor and symmetrically about the center line parallel with the other side. A conductive strip 23 is arranged on the opposide side of the conductor 11 to the element 13 through a dielectric layer 22 to constitute a feeding system and the feeding system is electro-magnetically coupled with the element 13 through the slot 15. The strip 23 divides functions into a feeding system and a matching stub on the part opposed to the slot 15. Consequently the antenna can easily be matched even with a high input impedance and its constitution can be compacted as a whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annular planar antenna.

[0002]

2. Description of the Related Art Recently, it has been noted that a microstrip antenna having a ring-shaped radiating element can be made smaller than an ordinary microstrip antenna having a circular or square patch-shaped radiating element, and the present applicant Has already been proposed by Japanese Patent Application No. 3-109333.

[0003]

However, in the microstrip antenna of the ring-shaped radiating element, the inner-side feeding is performed as the inner-outer circumference ratio of the ring approaches 1, as has been made clear in the previously proposed examples. However, since the input impedance of the antenna becomes high, for example, on the order of KΩ,
Since it is necessary to provide a relatively large matching circuit including a stub on the back surface of the antenna or the like, there is a problem that the miniaturization as a whole is restricted.

In view of the above point, an object of the present invention is to provide a ring-shaped planar antenna which can be easily matched while having a ring-shaped radiating element exhibiting a high input impedance.

[0005]

The present invention is directed to a dielectric layer 1
The radiating element 13 facing the ground conductor 11 via 2 is formed with an opening 14 to form an annular shape, and a slit 15 is bored in a region of the ground conductor facing the radiating element. It is an annular planar antenna configured to excite an annular radiating element via a.

[0006]

According to this structure, it is possible to easily match the high input impedance exhibited by the ring-shaped radiating element.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the annular planar antenna according to the present invention is applied to a linearly polarized antenna will be described below with reference to FIGS.

The structure of an embodiment of the present invention is shown in FIGS. In FIGS. 1 to 3, reference numeral 10 denotes an annular planar antenna as a whole, and in each case, a circular radiation is provided on a rectangular ground conductor 11 via a low-loss dielectric layer 12 such as a glass fiber reinforced fluororesin substrate. Elements 13 are concentrically stacked, and circular apertures 14 are concentrically formed in the radiating element 13 to form a ring shape. Reference numeral 15 denotes a slot, and as shown in FIGS. 2 and 3, a center line parallel to one side of the ground conductor 11 and parallel to the other side of the ground conductor 11 in a region facing the radiating element 13. The holes are formed in an I shape symmetrically with respect to.

On the side of the ground conductor 11 opposite to the radiating element 13, a conductor strip 23 is disposed oppositely via a low-loss dielectric layer 22 to form a microstrip type power feeding system. The system and the radiating element 13 are electromagnetically coupled through the slot 15. As shown in FIGS. 2 and 3, the portion of the conductor strip 23 that faces the slot 15 functions as the feeder line 24, and the portion beyond the slot 15 functions as the matching stub 25.

When the annular planar antenna 10 of this embodiment is used in, for example, the 4 GHz band, the radiating element 13, the radius of the aperture 14, the thickness of the dielectric layer 12, and the dielectric constant are, for example, as follows. Is set. r13 = 9.7 mm, r14 = 4.5 mm t12 = 1.2 mm, εr = 2.55 Further, the width and length of the slot 15 and the offset distance from the center of the radiating element 13 are, for example, as follows. Is set. w15 = 0.8 mm, l15 = 10.0 mm, dof = 6.0
mm

The characteristic impedance of the power feeding system is 5
The thickness and the dielectric constant of the dielectric layer 22 are set so as to be 0Ω.
For example, the stub 2 is set as follows.
The length of 5 is set as follows, for example. t22 = 0.6 mm, εr = 2.55 l25 = 9.0 mm

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. In this embodiment, the feeding system and the radiating element 13 are electromagnetically coupled to each other through the slot 15, and the width of the slot 15,
By optimizing the combination of length and position, impedance matching can be achieved relatively easily.

Generally, the longer the slot length l15, the higher the impedance seen from the feeder line side, and the larger the offset distance dof, the lower the impedance. The slot width does not affect the characteristics so much, and the stub length l25 is adjusted to be optimal in combination with other parameters.

In the annular planar antenna of this embodiment, for example, in the case of the above-mentioned shape, the impedance-frequency characteristic at the time of main mode excitation is as shown in FIG. 4, which is excellent in a relatively wide frequency range. You can see that they are in alignment. Then, for example, the radiation characteristic of the E surface is as shown in FIG. Further, the radiation characteristic of the H surface is also substantially the same as that in FIG.

In this embodiment, a simple structure in which the ring-shaped radiating element and the power feeding system are electromagnetically coupled to each other through the slot provided in the ground conductor allows the ring-shaped radiating element to exhibit a high input impedance. However, matching can be easily achieved, and a more compact annular planar antenna can be obtained as a whole. When a planar array antenna is configured by connecting a plurality of planar antennas as described above, the configuration of the feeding system becomes easy.

Next, another embodiment in which the annular planar antenna according to the present invention is applied to a circularly polarized antenna will be described with reference to FIGS. 6 and 7. The configuration of another embodiment of the present invention is shown in FIG. In FIG. 6, the portions corresponding to those in FIG.

In FIG. 6, 10C shows an annular planar antenna as a whole, and in the embodiment of FIG. 6, a circular radiating element 13 is provided with a circular opening 14 concentrically, and
A pair of notches 13n are formed in the peripheral edge of the radiating element 13 symmetrically with respect to one diagonal line of the dielectric layer 12 to form a degenerate separation type. In this embodiment, the X-shaped slot 16 is provided in the region of the ground conductor 11 facing the radiating element 13 in parallel with the diagonal line of the ground conductor 11 and symmetrical with respect to the center line parallel to one side. Drilled. The rest of the configuration is the same as in FIGS.

The annular planar antenna 10C of this embodiment is
For example, when used in the 4 GHz band, the radiating element 13, the radius of the aperture 14, the thickness of the dielectric layer 12, and the dielectric constant are set as follows, for example. r13 = 10.5 mm, r14 = 2.7 mm t12 = 1.2 mm, εr = 2.55 Further, the width and length of the slot 16 and the offset distance from the center of the radiating element 13 are, for example, as follows. Is set. w16 = 0.8mm, l16 = 10.0mm, dof = 0.0
mm

The characteristic impedance of the power feeding system is 5
The thickness and the dielectric constant of the dielectric layer 22 are set so as to be 0Ω.
For example, the stub 2 is set as follows.
The length of 5 is set as follows, for example. t22 = 0.6 mm, εr = 2.55 l25 = 6.8 mm

Next, the operation of the embodiment shown in FIG. 6 will be described with reference to FIG. In the annular planar antenna of this embodiment, for example, in the case of the above-described shape, the impedance-frequency characteristics at the time of main mode excitation are as shown in FIG. 7, and a good matching state is achieved in a relatively wide frequency range. I know there is. Although not shown, a good circular polarization pattern with an axial ratio of 0.5 dB or less was obtained in the boresight direction.

The embodiment of FIG. 6 also operates and produces the same effects as the embodiments of FIGS. 1 to 3 described above. In addition, in both of the above-described embodiments, the planar antenna having the annular radiating element has been described. However, even in the case of the planar antenna 10S having the rectangular annular radiating element as shown in FIG. It operates in the same manner as and has the same effect. Further, the shape of the annular radiating element is not limited to a circular shape or a square shape, and may be any shape such as a quasi-circular shape or a quasi-square shape. And
By selecting the shape of the annular radiating element, linear polarization,
It can correspond to circularly polarized waves.

[0022]

As described above in detail, according to the present invention,
Since the ring-shaped radiating element and the feeding system are electromagnetically coupled to each other through the slot provided in the ground conductor, it is possible to easily match the high input impedance exhibited by the ring-shaped radiating element. Done, overall,
A more compact annular planar antenna is obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a conceptual configuration of an embodiment of an annular planar antenna according to the present invention.

FIG. 2 is a plan view showing the configuration of an embodiment of the present invention.

FIG. 3 is a sectional view showing the structure of an embodiment of the present invention.

FIG. 4 is a diagram showing characteristics of an embodiment of the present invention.

FIG. 5 is a diagram showing characteristics of an embodiment of the present invention.

FIG. 6 is a plan view showing the configuration of another embodiment of the present invention.

FIG. 7 is a diagram showing characteristics of another embodiment of the present invention.

FIG. 8 is an exploded perspective view showing a conceptual configuration of still another embodiment of the present invention.

[Explanation of symbols]

 10, 10C, 10S Annular planar antenna 11 Ground conductor 12, 22 Dielectric layer 13 Radiating element 14 Open hole 15, 16 Slot 24 Feed line 25 Stub

Claims (1)

[Claims] 1. A radiating element facing a ground conductor via a dielectric layer is provided with a hole to form an annular shape, and a slit is bored in a region of the ground conductor facing the radiating element. A ring-shaped planar antenna is characterized in that the ring-shaped radiating element is excited through the slit.