JP5136268B2 - Radome - Google Patents

Description

  The present invention relates to a radome for protecting an antenna, and more particularly to a radome attached to the tip of an object that moves at a speed exceeding the speed of sound.

  In an object such as an aircraft or a rocket that flies beyond the speed of sound, an antenna such as a weather radar or a search radar is provided at the tip of the object. The radome for protecting the antenna is made into a spherical shape with a very small curvature even when the tip is pointed or not pointed in consideration of the aerodynamic characteristics when flying. For example, Non-Patent Document 1 or Non-Patent Document 2 describes such a radome shape.

Analysis of radome-enclosed antennas, D.J.Kozakoff, Artech-House, 1997, pp122 radome enginerring handbook, J.D.walton, jr, Marcel Dekker, 1970, pp502

  The radome is made of a dielectric so that the antenna inside thereof can transmit radio waves radiated or received. As an example of the dielectric, GRFP (glass fiber reinforced plastic) or ceramics is used. Furthermore, in order to broaden the frequency characteristics of the radio wave transmission of radomes, it may be effective to use a shape called a sandwich radome with thin dielectrics loaded on both sides of a low dielectric constant material such as honeycomb or foam. Are known.

In a radome made by molding a dielectric in this way, there are the following two problems when the tip is sharpened with an emphasis on the aerodynamic performance of the radome.
The first problem is that it is difficult to form a dielectric, and this difficulty is particularly remarkable in a sandwich radome.
The second problem is that due to the speed exceeding the speed of sound, the dielectric part at the tip of the radome cannot withstand the impact or thermal shock caused by air.

  Conventionally, in order to solve the problem, only the radome tip is made of metal, and improvements have been made to improve moldability and environmental resistance. For example, Non-Patent Document 1 or Non-Patent Document 2 Describes a radome with a metal tip.

  However, when a metal chip is embedded at the tip of the radome, there is a problem that the antenna radiation characteristics inside the radome deteriorate due to the influence of the metal chip. Further, due to the charging of the metal chip, a problem arises in that a discharge occurs between the radome and the antenna and the like, causing a problem of destroying the device such as the antenna.

This problem will be described in detail with reference to the drawings.
FIG. 3 is a diagram illustrating a configuration example of a conventional radome, and FIG. 4 is a diagram illustrating a charging state of the radome that passes near the thundercloud when flying.
In FIG. 3, the radome body 3 is configured by laminating a dielectric 1 and a honeycomb material 2. A metal tip 40 is provided at the tip of the radome body 3. The antenna 5 is disposed inside the radome body 3.

  Since the conventional radome body 3 has the metal chip 40 disposed at the tip, the metal chip 40 blocks radio waves transmitted and received by the antenna 5 inside the radome body 3. Due to this influence, the radio wave radiated from the antenna 5 is reflected by the metal chip 40 as indicated by arrows in the figure. The reflected wave from the metal chip 40 is reflected again by the antenna 5 and radiated in an unintended direction. As a result, there has been a problem that the antenna radiation characteristics are degraded, such as a decrease in antenna gain and an increase in sidelobe level.

  Further, as shown in FIG. 4, by passing through the vicinity of the thundercloud 6 when flying, the tip of the metal tip 40 is charged under the influence of the charge of the thundercloud 6. In this case, there is a problem that the antenna 5 is destroyed by discharging the electric charge charged on the metal chip 40 toward the antenna 5 or a device arranged in the vicinity of the antenna 5.

  SUMMARY OF THE INVENTION The present invention has been made to solve the problem, and an object of the present invention is to prevent deterioration of antenna radiation characteristics inside the radome due to a metal chip provided at the tip of the radome.

  It is another object of the present invention to suppress discharge between the radome and the antenna due to charging of the metal chip provided at the tip of the radome.

  The radome according to the present invention is formed of a dielectric material, and has a tip having a pointed shape or a shape having a very small curvature, and a radome main body in which an antenna is accommodated, and a radome main body penetrating the radome main body. And a metal chip having a pointed protrusion at a portion facing the antenna housed inside the radome body.

  According to the present invention, the shape of the metal chip on the antenna side is sharpened, and the radio waves radiated from the antenna are scattered in various directions, so that deterioration of radiation characteristics can be reduced.

  Further, the metal tip can be prevented from being charged by connecting a metal tip between the tip tip and the ground of the main device.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a radome according to Embodiment 1 of the present invention. In the figure, the radome of the first embodiment includes a radome body 3 and a metal tip 4. The first embodiment is characterized in that the metal chip 4 has a sharpened shape on the antenna 5 side. The radome body 3 has a sandwich structure in which the honeycomb material 2 constituting the honeycomb core and the dielectric 1 in contact with both surfaces of the honeycomb material 2 are laminated in three layers and bonded together. The dielectric 1 is made of GRFP. The radome body 3 has a streamline shape having a sharp tip shape or a shape having a very small curvature. A conductive metal tip 4 is embedded in the tip of the radome body 3. The antenna 5 is disposed in an internal housing space inside the radome body 3.

  FIG. 1 shows an example of a sandwich radome having a three-layer structure. In the case of a five-layer structure in which a dielectric 1, a honeycomb material 2, a dielectric 1, a honeycomb material 2, and a dielectric 1 are laminated in this order, In some cases, it may be a multilayered sandwich plate. At this time, if the tip has a pointed shape, it is difficult to make the sandwiched structure mechanically. Therefore, a metal tip 4 is provided to ensure the mechanical structure of the tip and mechanical strength. It has been devised to improve heat resistance and to withstand the thermal environment. The metal tip 4 is provided from the viewpoint of mechanical structure strength and heat strength when flying over the speed of sound. Note that the radome body 3 may be configured with a dielectric such as GFRP or ceramics as a single layer structure in accordance with the strength and radio wave characteristics to be transmitted. The metal chip 4 penetrates the dielectric 1 and is embedded in the tip of the radome body 3. The metal chip 4 has a pointed protrusion 10 at a portion facing the antenna 5. Further, the portion of the metal chip 4 exposed on the outer surface of the radome has a curved surface shape or a pointed shape according to the shape of the radome body 3.

  By configuring the radome according to the first embodiment in this way, the radio waves radiated from the antenna 5 can be scattered by the pointed protrusions 10 on the metal chip 4 in directions other than the front direction of the antenna 5. Thereby, an increase in the side lobe level in a specific direction can be suppressed, and deterioration of the antenna radiation characteristics can be reduced.

  In FIG. 1, the shape of the protrusion 10 on the antenna 5 side of the metal chip 4 is drawn as a curved shape, but this shape may be conical. In short, the shape of the protrusion 10 may be determined so that the radio wave radiated from the antenna 5 is scattered in an appropriate direction according to the geometrical positional relationship between the metal chip 4 and the antenna 5. 1 shows a configuration example of a three-layer sandwich radome, the metal chip 4 may be applied to a multilayer sandwich radome or a single-layer radome.

Embodiment 2. FIG.
FIG. 2 is a schematic configuration diagram showing a radome according to Embodiment 2 of the present invention. In the figure, a metal band 7 is a conductor provided on the outer surface of the radome body 3. The metal strip 7 has one side connected to the metal chip 4 and the other end connected to the main body ground 8. The main body ground 8 is provided in a main body device (device to which the radome is attached) to which the radome body 3 is attached.

  In FIG. 2, the metal band 7 is provided on the surface of the radome 3, but it may be inside the radome 3 and may not be a metal as long as it is a conductive material. The metal band 7 is preferably configured as a thin band and is installed so as not to affect the radio waves of the antenna 5 as much as possible. In addition, the metal chip 4 is drawn as a sharpened shape on the antenna 5 side as shown in the first embodiment of the present invention, but the antenna 5 side is drawn as in the conventional example of FIG. 3 or FIG. It may be planar.

  The second embodiment is configured in this manner, so that the electric charge charged in the metal chip 4 quickly moves to the main body ground 8 through the metal band 7 by passing through the vicinity of a huge charged body such as the thunder cloud 6. To do. For this reason, it is possible to prevent a discharge phenomenon from occurring inside the radome. In particular, as in the first embodiment, when the inner surface of the metal chip 4 on the antenna 5 side is sharpened, a discharge phenomenon is likely to occur. Therefore, it is effective to provide the metal band 7 to suppress the discharge phenomenon. is there.

It is a schematic block diagram which shows Embodiment 1 of the radome by this invention. It is a schematic block diagram which shows Embodiment 2 of the radome by this invention. It is a schematic block diagram which shows the radome which has the conventional metal tip. It is a schematic block diagram which shows the discharge phenomenon in the conventional radome.

Explanation of symbols

  1 dielectric, 2 honeycomb material, 3 radome body, 4 metal chip, 5 antenna, 6 thundercloud, 7 metal strip, 8 body ground.

Claims (1)

A radome body in which a honeycomb material and a dielectric bonded to both surfaces of the honeycomb material are laminated and formed, the tip portion has a pointed shape or a shape with a very small curvature, and an antenna is accommodated inside;
The radome main body has a pointed protrusion embedded in the radome main body and facing the antenna housed inside the radome main body, and the radio wave radiated from the antenna by the protrusion is directed toward the front of the antenna A metal tip that scatters other than
A thin metal band provided on the surface of the radome body,
Bei to give a,
The metal strip is connected to a ground provided on a device to which the radome body is attached and the metal chip, and a charge charged on the metal chip is moved to the ground .

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