JPH11298232A - Tapered slot antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a tapered slot antenna (to reduce the height) and to sharpen horizontal directional characteristics at high frequencies. SOLUTION: On a disk-shaped conductive plate 21, monopole elements 22a-22f of about 1/4 wavelength are circularly and vertically raised at a central part, radiation plates 24a-24f are arranged radially to the respective elements 22a-22f, each radiation plate has a tapered power feeding terminal part, slot edge part and tapered radiation edge part from the side of the monopole element and on both the sides of the respective radiation plates 24a-24f, power non-feeding elements 31a-31f and 32a-32f respectively mutually opened outward are arranged near the outer terminal parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tapered slot antenna used as a directional antenna of a mobile station (vehicle-mounted station) in a mobile communication for high-speed data transmission or as a base station sector antenna for a wireless LAN.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional tapered slot antenna.
It is shown in FIG. In this antenna, a radiation plate 12 is formed on one surface of a dielectric substrate 11. A straight slot (cut groove) 13 is formed in the radiating plate 12, and both ends of the slot 13 are tapered so as to be gradually widened at both ends thereof.
4, the other is a radiation section 15. The feeding section 14 is short, and the radiating section 15 is about three times longer than the feeding section 14. That is, a metal layer is formed on the entire surface of the rectangular substrate 11, and the slot 13, the power supply unit 14, and the radiation unit 15 are removed from the metal layer.

A dipole element 16 is disposed close to the power supply section 14, and the dipole element 16 is located in the plane formed by the radiation plate 12 and extends in a direction perpendicular to the direction in which the slot 13 extends. 17 faces the slot 13. When power is supplied to the dipole element 16, the radio wave radiated from the dipole element 16 is spatially coupled to the power supply section 14, propagates through the slot 13, and is radiated from the radiating section 15.

As shown in FIG. 12, the antenna has relatively good directivity in the horizontal plane, that is, the antenna has a beam width of 6 mm.
There is an advantage that the angle is about 0 °, the forward gain is as large as about 8 dB, the gain frequency characteristic is wide, and the influence of the distance between the dipole element 16 and the feeding unit 15 is small.

[0005]

However, this tapered slot antenna has a problem that its height H, that is, the length of the substrate in the direction perpendicular to the radio wave radiation direction is relatively large.
An object of the present invention is to provide a tapered slot antenna having a small height, that is, a small size.

[0006]

According to the present invention, there is provided a conductive flat plate, a monopole element, and a radiation plate. The monopole element is arranged perpendicular to the conductive flat plate and has a wavelength of about 1/4 wavelength. The radiating plate substantially includes the monopole element, and is disposed in close proximity to the monopole element in a plane substantially perpendicular to the conductive flat plate, and has a parallel edge that is close to and parallel to the conductive flat plate. From the end of the parallel edge portion on the monopole element side, a tapered power supply edge portion gradually separated from the conductive flat plate, and gradually separated from the conductive flat plate from the other end of the parallel edge portion, and longer than the power supply edge portion. It is made of a conductive plate having a tapered radiation edge.

Further, a plurality of sets of the monopole element and the radiation plate are provided, and these are set to have the angle of the directional characteristic beam width in the set of the conductive flat plates centered on the monopole element. The interval is set. Two parasitic elements are provided between the radiating edges of the radiating plates, and these are formed at the conductive plate by opening them outward at an acute angle with respect to the radiating plates.

[0008]

FIG. 1 shows an embodiment of the present invention.
A monopole element 22 of about ４ wavelength is vertically arranged on a conductive flat plate 21 such as a metal plate, and a feed point 23 is provided between a terminal of the conductive flat plate 21 and the conductive flat plate 21. When the monopole element 22 and one terminal are close to each other, the radiation plate 24 is close to the conductive flat plate 21 and is disposed substantially at right angles thereto. The radiating plate 24 has a parallel edge 25 that is close to and parallel to the conductive flat plate 21,
Extending from the end of the parallel edge 25 on the monopole element 22 side,
The conductive plate 2 extends from the other end of the tapered power supply edge 26 and the parallel edge 25 gradually separated from the conductive plate 21.
And a radiating edge 27 having a tapered shape gradually separated from the radiating edge 27. The length L2 of the feeding edge 26 is equal to the length L of the radiation edge 27.
Shorter than 3. The radiation plate 24 is made, for example, as follows. That is, a metal layer is formed on one surface of the rectangular dielectric substrate 28, and the edge portions 25, 2 are formed on one side of the metal layer.
The metal layer is, for example, pattern etched away so that 6, 27 are formed. This substrate 28 is a conductive flat plate 21
Stand on top. Although not shown in the figure, the fixing member is sandwiched between dielectric fixing members from both sides, and the fixing member is fixed to the conductive flat plate 21.

The monopole element 22 and the radiation plate 24 are located on substantially the same plane. The length L1 of the parallel edge 25 is about 0.25 wavelength × M (M is an odd number).
Lengths L2 and L3 of 6,27 are respectively 0.25 to 0.5
Wavelength, approximately 0.5 wavelength × N, where N is 1, 2,
3, ... Since increasing L1 does not contribute to an increase in gain, about 0.25 wavelength is preferable. Increasing L2 decreases the gain, while increasing N increases the gain. L
3 / L2 is set to about 1.0 at the minimum. Flat plate 2 on edge 27
The angle θ2 with respect to 1 is preferably about 20 ° to 40 °, but is optimized by the antenna gain. The distance D1 between the monopole element 22 and the radiation plate 24 is about 0.02 to 0.03 wavelength, and the distance W1 between the end of the feeding edge 26 on the monopole element 22 side and the conductive flat plate 21 is 0.5. The wavelength is not more than about the wavelength, and the distance W2 between the parallel edge 25 and the conductive flat plate 21 is not more than about 0.1 wavelength.

The monopole element 22 and the flat plate 2 close thereto
1, the distance D3 between the edge of the radiating plate 28 on the side of the radiating edge 27 and the edge of the flat plate 21 close thereto, and the radiating plate 24.
It is preferable that each interval D4 between the edge and the parallel edge of the flat plate 21 is about 0.5, 0.5, 0.5 wavelength or more. The width W5 of the radiating plate 24 on the monopole element 22 side is equal to 0.
About 5 wavelengths are preferable.

The directional characteristics in the horizontal plane (plane parallel to the conductive flat plate) of this embodiment are as shown in FIG. The measurement wavelength is 8.4 GHz, the dimensions of each part are D1 = 1.0 mm, D2
= D3 = D4 = 25.6 mm, H1 = 20.9 mm, H
5 = 60.0 mm, L8 = 74.4 mm, L9 = 34.
7 mm, L10 = 9.0 mm, and W2 = 0.1 mm.

The beam width (half width) of the 3 dB reduction is about 60.
°, but sublobes occur over a wide range. However, the antenna can be used depending on the purpose of use, and the height is reduced to half of that of the conventional tapered slot antenna, which means that the antenna is considerably reduced in size. FIG. 3 shows another embodiment of the present invention. In this example, a plurality of pairs of the monopole element 22 and the radiation plate 24 shown in FIG. 1 are radially arranged on a common circular conductive flat plate 21. Each monopole element 22 is located on the center side, and the radiation plates 24 are equiangularly spaced. In this example, there are six sets, so
The intervals are 60 degrees, that is, the angular intervals are almost the same as the beam width of one set (FIG. 1).

The measurement frequency was 8.4 GHz, the diameter of the circle on which the monopole elements 22 were arranged was 1.4 wavelengths, and the other dimensions were the same as those shown in FIG. The horizontal directional characteristics at this time are as shown in FIG. 4A. Comparing this with FIG. 2, it is understood that the level of the sub lobe is lower than the characteristic of FIG. 5 and 6 show still another embodiment of the present invention. FIGS. 5 and 6 show the radiation plate 24a to 24f with respect to the embodiment shown in FIG.
Parasitic elements 31a, 32a to 31f, 32f each composed of two conductive plates are vertically arranged on and electrically connected to the conductive flat plate 21, respectively, so as to sandwich them. The parasitic elements 31a and 32a are relatively close to the end of the radiation plate 24a on the side opposite to the monopole element 22a, that is, obliquely oppose to the radiation edge 27 and far from the monopole element 22a. The distance between the radiating plate 24a and the radiating plate 24a is increased as the distance becomes smaller. The angles θ3 formed by the radiation plate 24a and the parasitic elements 31a / 32a are equal to each other, are acute, and are approximately 45 to 60 degrees. The parasitic element 31a,
The distance D5 between the radiating plate 24a and the radiating plate 24a on the extension of 32a is equal to each other, and is approximately 0.28 wavelength. The size and shape of the parasitic elements 31a and 32a are substantially equal to each other, and the height H2 and length L4 thereof are approximately 0.56 wavelength and 0.75 wavelength, respectively. H2 is the height H of the radiation plate 24a.
When it is larger than 1, HZ = H1 at the maximum because it is contrary to the object of the present invention to reduce the size (reduce the posture).
In FIG. 5B, dielectric fixing members 33 and 34 are shown on both sides of each of the radiation plates 24a to 24f. They are fixed to each other by nuts, and are fixed to the conductive flat plate 21 by bolts of fixing members 33 and 34.

When the other conditions are the same as those shown in FIGS. 1 and 3, the directional characteristics on the horizontal plane are as shown in FIG. 4B, and the beam width is slightly narrower, but the level of the sublobe is considerably reduced further. It is understood that. This is, for example, in the direction of the main beam of the radiation plate 24a, the parasitic element 31
This is probably because radio waves serving as sub lobes are concentrated at a and 32a.

FIG. 7 shows still another embodiment. 5 and 6
In the configuration shown in FIG. 7, between adjacent radiation plates, for example, between 24a and 24b, near the monopole elements 22a and 22b on substantially bisectors thereof, that is, reflection toward the monopole element side from the radiation edge 27. A plate 35a is erected on the conductive flat plate 21 while being electrically connected thereto. This radiation plate 24
a to 24f in the radial direction and each of the reflectors 35a to 35f
Is approximately 0.28 to 0.3 wavelength, and the length L6 and height H3 of the reflectors 35a to 35f are approximately 0.56 wavelength and 0.75 wavelength, respectively. Figure 5 shows other dimensions
The horizontal plane directivity characteristics at 8.4 GHz when the same as FIG. 6 was obtained, as shown in FIG. 8A.

From this figure, the beam width is about 60 °,
It can be seen that the level of the sub-lobe is further reduced, resulting in significantly better unidirectionality. This is the reflector 35a
It is thought that the direction of the radio wave is further directed to the direction of the main beam due to 干 渉 35f, and interference between the radiating elements is reduced. Next, a comparative example is shown in FIG. FIG. 9 is different from the embodiment of FIG. 3 on the bisector of each of the adjacent radiation plates 24a to 24f from the position close to the monopole elements 22a to 22f.
The reflectors 36a to 36f are extended to positions relatively close to the outer ends of the radiation plates 24a to 24f. That is, the reflection plates 35a to 35f in FIG.
It extends to near the outside of each of 1a to 31f and 32a to 32f, that is, is opposed to the radiation edge 27, and corresponds to a configuration in which the parasitic elements 31a to 31f and 32a to 32f are omitted. Height H4 and length L of these reflection plates 36a to 36f
7 are approximately 1.56 wavelengths and 1.4 wavelengths, respectively. Other dimensions are the same as those shown in FIG.
The horizontal directional characteristics at z are as shown in FIG.

As is apparent from this figure, the gain in the main beam direction is relatively large, and it is not practical. Although the radial plates are arranged radially over 360 ° in FIGS. 3, 5 and 7, at least two pairs of radial plates may be provided while holding the angles of the adjacent radial plates as shown in the drawings.

[0018]

As described above, according to the present invention, the height of the antenna can be reduced to almost half that of the conventional antenna. Moreover, the embodiment of FIG. 3 is different from the embodiment of FIG.
7 and the embodiment of FIG.
The level in the 0 ° direction can be reduced.

In particular, in the state where the characteristics of the embodiment shown in FIG. 7 are obtained, the propagation loss increases as the operating frequency increases, but a high antenna gain is obtained, and the signal propagation delay in high-speed data transmission. However, even if it is slight, a signal error occurs and communication quality deteriorates, but the horizontal plane directivity can be considerably sharpened, and required characteristics can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a horizontal plane directional characteristic diagram of the embodiment of FIG.

FIG. 3 is a perspective view showing another embodiment of the present invention.

4A is a horizontal plane directional characteristic diagram of the embodiment of FIG. 3, and FIG. 4B is a horizontal plane directional characteristic diagram of the embodiment of FIG.

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

FIG. 6 is a plan view of the embodiment of FIG. 5;

FIG. 7 is a perspective view showing still another embodiment of the present invention.

8 is a horizontal plane directional characteristic diagram of the embodiment of FIG. 7;

FIG. 9 is a plan view showing a comparative example.

FIG. 10 is a horizontal plane directional characteristic diagram of the comparative example of FIG. 9;

FIG. 11 is a front view showing a conventional tapered slot antenna.

FIG. 12 is a horizontal plane directional characteristic diagram of the antenna of FIG. 11;

Claims (4)

[Claims] 1. A conductive flat plate, a monopole element arranged perpendicularly to the conductive flat plate and having a wavelength of about 1/4 wavelength, and substantially including the monopole element, and in a plane substantially perpendicular to the conductive flat plate. A parallel edge portion disposed close to and parallel to the monopole element, and a parallel edge portion close to and parallel to the conductive flat plate, and a feeding edge portion gradually separated from the conductive flat plate from an end of the parallel edge portion on the monopole element side. A radiation plate made of a conductive flat plate having a radiation edge gradually separated from the conductive plate from the other end of the parallel edge and longer than the feeding edge. 2. A plurality of sets of the monopole element and the radiation plate are arranged at angular intervals of a directional characteristic beam width in the set of the conductive flat plates with the monopole element being substantially at the center. The tapered slot antenna according to claim 1, wherein 3. A parasitic element provided on both sides of each radiating plate at an acute angle with a radiating edge thereof and opened outward to stand on the conductive flat plate. Tapered slot antenna. 4. The method according to claim 1, wherein an angle between the adjacent radiation plates is substantially divided into two, and a reflection plate is provided on the conductive flat plate at a position near the monopole element. The tapered slot antenna according to claim 3.