JPH04120903A - Plane antenna - Google Patents

Abstract

PURPOSE:To adjust a half power angle uniquely decided to one array antenna by providing a wall-shaped projection for reflecting radio waves at a position symmetrical to right and left sides with the center line of the array antenna as an axis. CONSTITUTION:A wall 4 is provided with a material for reflecting radio waves at the position symmetrical to right and left sides with the center line of the array antenna as the axis, and waves 6 reflected on the wall 6 are synthesized with waves 5 to be directly radiated. When the phase of the reflected wave 6 at that time is not same as that of the radiated wave 5, electric field strength is weakened, and the distribution of the electric field is made unequal at the end of the antenna and at the center. In this case, by moving the wall-shaped projection 4 for reflecting radio waves to right and left, the phase of the reflected wave 6 is changed and as the result, the distribution of the electric field strength due to the synthesization with the radiated wave 5 is changed. By providing the wall-shaped projections 4 for reflecting radio waves at the positions symmetrical in right and left sides, the beam is made symmetrical since the same operation occurs at the positions symmetrical in the right and left sides. Thus, the beam is made symmetric and can be formed at a desired half power angle.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a planar antenna capable of shaping a radiation beam.

[Conventional technology]

Among planar antennas formed by arraying radiating elements on the same plane, as shown in FIG. In order to prevent interference between transmitting and receiving antennas, a method has been proposed in which ferrite rubber 3 is loaded between the transmitting and receiving antennas.

[Problem to be solved by the invention]

When the structure shown in Fig. 5 is adopted, the beam is deformed in the directivity characteristic of the transmitting antenna 1 as shown in Fig. 6, and the direction perpendicular to the plane and passing through the center line of the transmitting antenna l is 0゜. When this happens, it becomes asymmetrical about the 0° direction, and as a result, the half-value angle becomes small, and the desired value is not achieved. Here, when the antenna shown in Fig. 5 is used as a sensor for detecting a moving object, for example, if the sensing area becomes asymmetrical, the sensing width becomes narrower, making it impossible to obtain the desired sensing area. A planar antenna having a structure that can be molded is provided.

[Means to solve the problem]

As shown in Fig. 7, the radiation beam pattern in a planar antenna formed by arraying radiating elements on the same plane is as shown in Fig. 8, and its electric field strength distribution is as shown in Fig. 9.
As shown in the figure, from one end of the antenna through the center,
It is assumed that the distribution is equal until reaching the other end. Here, as shown in FIG. 1, walls 4 made of a material that reflects radio waves are provided at positions symmetrical about the center line of the array antenna. By rubbing G in this way, the reflected wave 6 reflected by the wall and the directly emitted radiation wave 5 are combined, as shown in Figure 2, and the phase of the reflected wave 6 and radiation wave 5 at that time is If they are not in phase, the electric field strength will be weak, and the electric field strength distribution will be non-uniform between the ends and the center of the antenna, as shown in FIG. At this time, after the reflected wave 6 is reflected by the wall-like protrusion 4, it attenuates as it moves away from the wall-like protrusion 4, so the reflected wave 6 and the emitted wave 5 are combined near the wall protrusion 4, that is, at the antenna end. This means that the electric field strength of the wave is weakened, but it is hardly weakened near the center.

As described above, when the electric field strength distribution becomes non-uniform, the gain decreases compared to when the electric field strength distribution becomes uniform, and when the gain decreases, the half-power angle inevitably becomes wider.

Here, by moving the wall-like protrusion 4 that reflects the radio waves left and right, the phase of the reflected wave 6 can be changed, and as a result, the electric field intensity distribution due to the combination with the radiated wave 5 can be changed, and the half-power angle can be adjusted. ie the beam can be shaped. Furthermore, by providing the wall-like protrusions 4 that reflect radio waves at symmetrical positions, the beams become symmetrical because the same action occurs at symmetrical positions.

[Effect]

1. Providing a wall-like protrusion made of a material that reflects radio waves on the outside of the radiating element causes reflected waves.
When the foul wave is combined with the radiated wave, the radiated electric field strength distribution over the entire antenna becomes non-uniform, changing the gain and at the same time changing the half-power angle.

2. Providing wall-like protrusions that reflect radio waves at symmetrical positions about the center of the array causes the same action on the left and right sides, resulting in a beam pattern that is symmetrical about the center line.

〔Example〕

7←已 An example of this product is shown in FIG.

The antenna applied to this example is as shown in Figure 1.
A dielectric material 8 made of foamed polyethylene with a thickness of approximately 1 mm is laminated on the ground conductor 7 as an insulating layer, and a copper foil is laminated on top of the dielectric material 8 to form a radiating element 9.
And when the object 4 is provided in the microstrinopanodi antenna formed by providing the feed line 10, the half value is '116<
Width (also, distance! 1f11112 to 4mm14.
As the diameter changes from 5 mm to 5 mm, the directivity pattern becomes 13.
．． 14. The half-power angle gradually narrows from I5. Furthermore, if the wall-like protrusions 4 are provided at symmetrical positions with respect to the center line 11, the directivity patterns 13 and 14 shown in FIG.
．． 15, if the direction of the straight line 17 passing through the center line 11 shown in FIG. 2 and perpendicular to the plane of the array antenna is O" shown in FIG. 3, then the directivity is symmetrical about 0°. It has become a sexual pattern.

The same result can be obtained even if the wall-like protrusion 4 for reflecting radio waves is a bent aluminum plate 18 having a thickness of 0.51 mm as shown in FIG.

In addition, by using a tree log, we can find the position of a wall-like protrusion that will result in an equal distribution as a result of combining reflected waves and radiated waves for antennas where the electric field strength distribution is non-uniform. By doing so, the gain can be increased, that is, the half-power angle can be narrowed.

〔Effect of the invention〕

1. Wall-like protrusions that reflect radio waves (by providing them in symmetrical positions around the center line of the array antenna, the half-power angle that was uniquely determined for one array antenna can be adjusted. be able to.

That is, it is possible to shape the beam and at the same time maintain left-right symmetry.

When applying Fart, Moe2, and Kisekai to the transmitting antenna l of the planar antenna shown in Figure 5, the ferrite rubber provided to prevent interference between the transmitting and receiving antennas and the same position symmetrical to the center line of the transmitting antenna l are applied. By providing a wall-shaped protrusion made of ferrite rubber, it is possible to create a half-power angle that is symmetrical with respect to the 0'' direction directly in front of the sensor and provides a desired sensing area.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing an embodiment of the headquarters. FIG. 7 is an electric field strength distribution diagram for explaining a second means. FIG. 5 is a perspective view for explaining the prior art. FIG. 6 shows the directivity pattern of the transmitting antenna in FIG. 7th. Figure 8.9 is a perspective view of an array antenna, directional pattern and electric field strength distribution for explaining technical means, No. 10
The figure shows an application example of this embodiment. . ;
Reflected wave 7 Ground conductor 8 Dielectric 9 Radiating element 10 Feeding line 11 Center line 12 Distance p13 Directional pattern 14 Directional pattern 15 Directional pattern
16 Directivity pattern 17 Vertical straight line
18 Bending product dimensions

Claims (1)

[Claims] 1. In a planar antenna formed by arraying radiating elements on a plane, the antenna is located on the plane, is symmetrical about one of the array center lines, and is located at the outermost edge of the array. A wall-shaped protrusion made of a material that reflects emitted radio waves and is located outside the end and has a length equal to or longer than the distance from one end of the array to the other end in the same direction as the axial direction. A flat antenna characterized by having objects placed on the same plane. 2. The planar antenna according to claim 1, wherein the wall-like protrusion is made of a metal such as aluminum or a material such as ferrite rubber containing some similar metal elements. 3. The planar antenna according to claim 1, wherein the antenna uses a frequency of 10 GHz or more. 4. The planar antenna according to any one of claims 1 to 3, wherein the antenna has a half-value angle of 35° or more in its radiation pattern.