JP4623534B2 - Planar antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a planar antenna using a radiating element.
[0002]
[Prior art]
Conventionally, there have been the following planar antennas. In this planar antenna, a substrate 2 is prepared in which one surface is a ground surface and the other surface is a pattern formation surface that can be patterned by, for example, etching, and as shown in FIG. A plurality of radiating elements 4 and a feed line 46 connecting these radiating elements 2 are formed. The radiating element 4 and the feed line 6 are combined with the ground plane to operate as a microstrip antenna and a microstrip line.
[0003]
[Problems to be solved by the invention]
In such a planar antenna, the radiating element 4 and the feed line 6 are present on the same pattern forming surface. For this reason, the radiating element 4 and the feed line 6 are likely to cause mutual interference. Further, unnecessary radiation from the feeder line 6 may affect the antenna characteristics.
[0004]
An object of the present invention is to provide a planar antenna in which a radiating element and a feed line are less likely to interfere with each other. Another object of the present invention is to provide a planar antenna that can suppress unnecessary radiation from the power supply line.
[0005]
[Means for Solving the Problems]
The planar antenna according to the present invention has a substrate. The entire surface of one side of the substrate is a ground surface, and the other side is a pattern forming surface. As long as the substrate has a flat plate shape, it can have various shapes such as a polygon and a circle. A radiating element is attached to the ground plane side while floating from the ground plane. The radiating element is conductive and has a shape selected so as to transmit and receive radio waves of a predetermined frequency. A plurality of radiating elements can be provided, or only one radiating element can be provided. A power supply line is formed on the pattern forming surface of the substrate, that is, the surface opposite to the ground surface on which the radiating element is provided. This feed line is for connecting, for example, a transmitter or receiver to the planar antenna. A power feeder connects the radiating element and the power feed line through the substrate. A conductive container having an opening having a shape corresponding to the substrate is provided, and the opening of the container is covered with the pattern forming surface of the substrate. The conductive container is coupled to the ground plane through a tab formed in the opening of the conductive container, and a shield case is configured by the conductive container and the ground plane of the substrate.
[0006]
In this planar antenna, the feed line is formed on the pattern forming surface, and the radiating element is formed on the ground surface. The pattern formation surface and the ground surface are opposite surfaces of the substrate. Therefore, the feed line and the radiating element are on opposite sides, and the radiation from the feed line hardly affects the radiating element, and the radiation from the radiating element hardly affects the feed line. . Further, the pattern forming surface is housed in a shield case formed by the conductive container and the ground surface. Therefore, radiation from the feed line can be reliably prevented from affecting the radiation element, and conversely, radiation from the radiation element can be reliably prevented from affecting the feed line in the shield case. Can do.
[0007]
Further, a connector is provided on the ground surface side of the substrate. In this case, the power supply line is connected to the connector on the pattern forming surface side.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the planar antenna according to the present invention includes a case 10 having a substantially octagonal shape as shown in FIG. The case 10 is made of, for example, a synthetic resin and has an octagonal opening.
[0010]
A conductive container, for example, a conductive short cylinder 12 is arranged inside the case 10. The short cylinder 12 is disposed in contact with the inner peripheral surface of the case 10. The short cylinder 12 is made of, for example, metal, and has a bottom wall fixed to the bosses 14 and 14 disposed on the inner surface of the case 10 by screws 16 as shown in FIG. The short cylinder 12 also has a circular opening, and this opening is located substantially on the same plane as the opening of the case 10.
[0011]
A substrate 18 is mounted on the opening so as to cover the opening of the short cylinder 12. The substrate 18 is formed in a disc shape substantially coincident with the opening of the short cylinder 12. The substrate 18 is fixed by tabs 20 formed at predetermined angles in the opening of the short cylinder 12 and screws 22 inserted through the tabs 20.
[0012]
The substrate 18 has two opposing surfaces, one of which is a pattern forming surface 24 and the other surface is a ground surface 26. The pattern formation surface 24 has a metal foil attached so that a predetermined pattern can be formed by etching, for example. The ground surface 26 is covered with a metal foil used as a ground over the entire area. The pattern forming surface 24 is disposed so as to face the inner surface side of the short cylinder 12.
[0013]
On the ground surface 26 side, as shown in FIG. 2, a plurality of, for example, five radiating elements 28 are provided in two rows at predetermined intervals. One row consists of two radiating elements 28 arranged at a predetermined distance from each other, and two rows consists of three radiating elements 28 arranged at a predetermined distance from each other. Each of the radiating elements 28 is formed in the same shape, for example, a rectangular shape. The length of each side of each radiating element 28 is selected according to the wavelength of the radio wave to be transmitted / received.
[0014]
These radiating elements 28 are attached in a state of floating from the ground surface 26.
That is, as shown in FIG. 1, the screw 30 inserted in the center of each radiating element 28 passes through the spacer 32 disposed so as to contact the lower surface of the radiating element 28 and the ground surface 26, and the pattern of the substrate 18. It protrudes toward the forming surface 24 and is fixed by a nut 34.
[0015]
A position close to a specific side of each radiating element 28 is a feeding point, and one end of a feeding tool, for example, a feeding pin 36 is soldered to each of them. The other ends of these power supply pins 36 penetrate the substrate 18 and protrude from the pattern forming surface 24.
[0016]
As shown in FIG. 3, the pattern forming surface 24 is formed with a power supply line 38 so that the other ends of the power supply pins 36 are connected to each other so as to be combined into one. In the power supply line 38, the width dimension and the length dimension in the middle are selected so that the signals received by the radiating elements 28 are in phase in the linear portion 38a. That is, each radiating element 28 is configured as a planar array antenna. As shown in FIGS. 1 and 2, a connector 40 is attached so as to correspond to the end of the linear portion 38 a of the power supply line 38.
[0017]
As shown in FIG. 1, a substantially octagonal cover 42 is attached to the opening of the case 10 so as to cover the radiation element 28 and the like.
[0018]
For example, when this planar antenna is used for reception, radio waves arrive at each radiating element, and each radiating element 28 operates as a microstrip antenna in combination with the ground plane 26 to convert the received radio waves into electrical signals. . These electric signals are supplied to the power supply line 38 via the power supply pin 36, and the power supply line 38 is combined with the ground plane 26 to operate as a microstrip line, and the electric signal is transmitted through the power supply line 38. And are output from the linear portion 38 a of the power supply line 38 via the connector 40.
[0019]
In this planar antenna, a radiating element 28 is provided on the ground surface 26 side, and a feed line 38 is provided on the pattern forming surface 24 that is the surface opposite to the ground surface 26. Therefore, the radiation from the radiating element 28 does not easily affect the signal transmitted through the feeder line 38. Conversely, radiation from a signal transmitted through the feeder line 38 is also less likely to affect the signal received by the radiating element 28. In addition, the power supply line 38 is accommodated in a shield case formed by the short cylinder 12 and the ground surface 26 of the substrate 18. Accordingly, the radiation from the feed line 38 is less likely to affect reception at the radiating element 28, and the radiation from the radiating element 28 is less likely to affect transmission at the feed line 38. Therefore, the antenna characteristics of this planar antenna are good.
[0020]
In the above embodiment, the five radiating elements 28 are used. However, the number of the radiating elements 28 can be arbitrarily changed, and at least one radiating element 28 may be provided. However, when the number of radiating elements is changed, it is necessary to change the pattern of the transmission line 28 in accordance with the change in the number. In addition, although a rectangular element is used as the radiating element 28, various known elements can be used as long as they can be used in a state of floating from the ground surface 26. Although the power supply pin 36 is used as the power supply tool, the present invention is not limited to this. For example, a metal plate formed integrally with the radiating element 28 may be used as the power supply tool. Although the disk-shaped thing was used for the board | substrate 18, it is not restricted to this, For example, it can be set as various shapes, such as a rectangle and a triangle. However, as the shape of the substrate 18 is changed, the conductive container needs to have an opening corresponding to the changed shape of the substrate instead of the short cylinder 12. Further, when the influence of radiation from the power supply line 38 and the radiating element 28 to the other can be reduced only by providing them on opposite surfaces, the short cylinder 12 is not necessary. Although the connector 40 is provided on the ground surface side, it may be provided at the tip of the linear portion 38a of the power supply line 38 on the pattern forming surface 24.
[0021]
【The invention's effect】
As described above, according to the present invention, since the mutual interference between the feed line and the radiating element can be reduced, the antenna characteristics can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a planar antenna according to an embodiment of the present invention.
2 is a partially cutaway front view of the planar antenna of FIG. 1 with a cover removed. FIG.
FIG. 3 is a rear view of a substrate used in the planar antenna of FIG. 1;
FIG. 4 is a front view of a conventional planar antenna.
[Explanation of symbols]
12 Short cylinder (conductive container)
18 Substrate 24 Pattern formation surface 26 Ground surface 28 Radiation element 36 Power supply pin (power supply tool)
38 Power supply line

Claims (1)

A single-layer substrate in which the entire area of one surface is a ground surface and the other surface is a pattern forming surface;
A radiating element attached to the ground plane side in a state of floating from the ground plane;
A power supply line formed on the pattern forming surface;
A power supply that penetrates the substrate and connects the radiation element and the power supply line;
A conductive container having an opening having a shape corresponding to the substrate, and covering the opening with the pattern forming surface of the substrate;
The conductive container is coupled to the ground plane through a tab formed in the opening of the conductive container, and a shield case is formed by the conductive container and the ground plane of the substrate; A planar antenna in which a connector is provided on the ground surface side, and the feeder line is connected to the connector on the pattern forming surface side.

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