JPH0548415U - Planar antenna - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To reduce the size of the antenna, make the antenna board small, that is, even if the grounding conductor is made narrow, to prevent radio waves from leaking as much as possible, and to keep the antenna in a matched state. (EN) Provided is a flat antenna having a structure that does not have a bad influence and does not widen the radiation directivity. [Structure] The lower lid 8 is made of metal, and a flat antenna part is attached to the box-shaped case 10 so that there is no gap between the lower lid 8 and the box-shaped case 10. When the box-shaped case 10 is made of metal, the flange portion 9 has a choke flange structure in order to improve the adhesion with the case 10.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a microwave band planar antenna for mobile communication and various sensors.

[0002]

[Prior Art]

 As shown in FIG. 2, the structure of a planar antenna in which a planar antenna part is housed and fixed in a box-shaped case is formed of a planar antenna substrate 1 and a resin foam provided thereon. The spacer 2 is sandwiched between a radome 3 made of resin and a lower lid 4 made of resin, which has almost the same shape as that of the spacer 2, to form a planar antenna part, which is screwed, nuts 7 or an adhesive or the like. A structure for fixing to the box-shaped case 5 has been proposed.

[0003]

[Problems to be solved by the device]

 In the case of the structure shown in Fig. 2, when the antenna substrate to be housed is large, that is, when the ground conductor is relatively wide, as shown in Fig. 3, most of the radio waves are radiated in the front direction, but the size of the antenna is reduced. If the antenna board is made smaller in order to achieve this, that is, the ground conductor is made narrower, part of the radio wave leaks inside the box-shaped case made of metal, as shown in Fig. 4, and is reflected inside the case. In addition to adversely affecting the matching state of, the amount of leakage in the case reduces the radiation in the front direction and widens the radiation directivity. The present invention reduces the size of the antenna board in order to miniaturize the antenna, that is, even if the ground conductor is narrowed, it prevents radio waves from leaking as much as possible, does not adversely affect the matching state of the antenna, and directs radiation. The purpose of the present invention is to provide a planar antenna having a structure that does not widen the property.

[0004]

[Means for Solving the Problems]

 As shown in FIG. 5, the lower lid 8 is formed of metal, and the planar antenna portion is attached so as to be in close contact with the box-shaped case 10 so that there is no gap. Further, the flange portion 9 shown in FIG. 5 is provided on the four circumferences of the lower lid 8 to improve the adhesion with the box-shaped case 10. Further, when the box-shaped case is made of metal, the flange portion 9 has a choke flange 20 structure as shown in FIG.

[0005]

[Action]

 1. It is necessary to cover the planar antenna part with a lower lid made of metal so that it closely adheres to a box-shaped case also made of metal, etc., because the lower lid made of metal prevents radio waves from leaking inside the box-shaped case. Since it is shielded to some extent, the leakage of radio waves inside the box-shaped case is reduced. 2. Providing flanges on the four sides of the lower lid made of metal improves the tightness of adhesion with the box-shaped case. 3. When the box-shaped case is made of metal, it is relatively unaffected by the close contact state between the lower lid and the box-shaped case that the four-circumferential flange part made of metal has a choke flange structure. Reduce leakage of radio waves.

[0006]

【Example】

As shown in FIG. 5, one embodiment of the present invention is that the antenna element 11 and the feed line are a flat antenna substrate 12 provided by etching the substrate, and the distance is set as far as possible so as not to affect radio wave radiation. In order to hold the radome 13 formed of resin or the like, the spacer 14 formed of foam such as resin is provided on the planar antenna substrate 12, and the radome 13 having a shape as shown in FIG. The planar antenna unit is configured so as to be sandwiched by the lower lid 8 formed of a metal having the shape shown in FIG. At this time, the lower cover 8 has a structure in which the flange portion 9 is provided on the four circumferences. The planar antenna part configured as described above is housed in a box-shaped case 10 made of metal as shown in FIG. At this time, the box-shaped case 10 is preliminarily provided with a hole into which the radome 13 just fits, as shown in FIG. Here, when accommodating the planar antenna part in the box-shaped case 10, as shown in FIG. 5, the planar antenna part is inserted into the hole provided in the box-shaped case 10 from the inside of the case so that the reddom 13 is in the box-shaped case. Of the box 16 and the flange 9 of the lower lid 8 with a screw 16 and a nut 17 or an adhesive agent so that there is no gap between the box 16 and the flange 9. Further, as shown in FIG. 6, the choke flange 20 can be obtained by setting the length l ₁ 18 and the length l ₂ 19 of the flange portion 9 to about 1/4 wavelength. In this way, the antenna portion is fixed to the side surface 21 of the box-shaped case as shown in FIG. 7 to form the planar antenna as shown in FIG. By doing so, it is possible to reduce radio waves leaking to the inside of the box-shaped case 10 as shown in FIG. The substrate is made smaller in order to reduce the size of the antenna as described below. That is, even if the ground conductor is made narrow, the radiation directivity does not become wide, and a planar antenna that does not adversely affect the matching state of the antenna can be constructed. In the present invention, the same effect can be obtained to some extent even without the flange portion 9 of the lower lid 8.

[0007]

[Effect of the device]

 1. Covering the flat antenna part with a lower lid made of metal and closely contacting it with a box-shaped case made of metal, etc. It is possible to reduce the leakage of radio waves inside, and the unnecessary matching inside the box-shaped case is reduced, so that the matching state of the antenna does not deteriorate and the radio waves leak inside the box-shaped case. As the amount of radiation decreases, radiation is emitted in the front direction, so radiation directivity does not need to be widened. 2. Providing flanges on the four circumferences of the lower lid can improve the adhesion to the box-shaped case and further reduce the leakage of radio waves into the box-shaped case. 3. Especially when the box-shaped case is made of metal, the choke flange structure of the flange can reduce the leakage of electric waves without being affected by the adhesion to the box-shaped case. 4. Since the ground conductor can be made narrower, the planar antenna can be made smaller.

[Brief description of drawings]

FIG. 1 is a plan view, a side view, and a top view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional technique.

FIG. 3 is a cross-sectional view for explaining the principle of the present invention.

FIG. 4 is a cross-sectional view for explaining the principle of the present invention.

FIG. 5 is a sectional view showing an embodiment of the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the present invention.

FIG. 7 is a perspective view showing a mounting state of an embodiment of the present invention.

[Explanation of symbols]

1 planar antenna substrate 2 spacer 3 radome 4 lower lid 5 box-shaped case 6 screw 7 nut 8 lower lid 9 flange part 10 box-shaped case 11 antenna element 12 planar antenna substrate 13 radome 14 spacer 16 screw 17 nut 18 length l ₁ 19 Length l ₂ 20 Choke flange 21 Side of box case

Claims (3)

[Scope of utility model registration request] 1. A flat antenna part in which an antenna element and a feed line are provided on the same substrate, and a radio wave radiation surface of the substrate is covered with a radome formed of resin or the like, and the radome surface of the flat antenna part is previously formed. In a box-shaped case formed of metal or the like in which a hole having a shape that exactly fits is provided, the radome surface of the planar antenna part is projected from the inside of the box-shaped case from the inside of the box-shaped case. In a planar antenna that is fitted and fixed through a hole in a box-shaped case, a portion of the planar antenna portion projecting inside the box-shaped case is covered with a lid formed of metal, and the lid and the box-shaped case are A planar antenna characterized in that the two are in close contact with each other so that no gap is created between the two. 2. The planar antenna according to claim 1, wherein the lid formed of the metal has a flange structure on four sides. 3. The planar antenna according to claim 1, wherein the flange has a choke flange structure.