JP6100113B2 - Radome - Google Patents

Description

  Embodiments of the present invention relate to a radome.

  Conventionally, a radome is known as a cover that covers an antenna that transmits and receives radio waves and protects the antenna. Among the radomes of this type, the radome 101 covering the antenna 100 mounted on the tip of an aircraft or the like as shown in FIG. 6A has a pointed shape that tapers toward the tip in order to reduce air resistance. Has been.

  In the above-described point-shaped radome 101, for example, the incidence of radio waves in the normal direction of the surface of the radome 101 is larger than that of a spherical radome 102 that follows the shape of the antenna 100 as shown in FIG. The angle θa is large (θa> θb). In general, when the incident angles θa and θb to the radome are increased, loss due to reflection or attenuation at the radome increases, and the electrical characteristics (transmittance of radio waves) decrease.

  Here, as the structure of the radome 101 described above, a single plate structure made of a single piece of fiber reinforced plastic (FRP), an inner skin and an outer skin made of FRP, urethane provided between these two skins, or the like The thing of the sandwich structure which has the core material which consists of is generally known.

Japanese Utility Model Publication No. 6-34314 JP 2011-135223 A JP 2006-198790 A

In the radome having the single plate structure described above, if the plate thickness is about λ / 10 to λ / 16 with respect to the wavelength λ of the radio wave, the transmittance is greatly impaired even if the incident angle is increased. It is said that there is no. However, when the plate thickness is further increased to ensure the strength against wind pressure load or the like, there is a problem that the electrical characteristics are deteriorated.
On the other hand, in the radome having a sandwich structure, the thickness of the core material is about λ / 4 and the thickness of each skin is about several percent or less with respect to the wavelength λ in order to achieve both electrical characteristics and strength. It is conceivable to set it as thin as possible. However, as the incident angle on the radome increases, there is still a problem that the electrical characteristics are degraded.

  The problem to be solved by the present invention is to provide a radome capable of achieving both strength and electrical characteristics.

  The radome in the embodiment includes a dome portion that covers an antenna that transmits and receives radio waves, and the dome portion extends along the skin material, a skin material that is exposed to the outside, a core material that covers an inner surface of the skin material, and the skin material. A plurality of reinforcing members that reinforce the skin material, and an opening base for attaching the dome portion to the outside is formed at the opening end of the dome portion, and the base of the reinforcing member The portion is fixed to the mounting base.

It is sectional drawing which shows the state in which the radome in embodiment was attached to the body. It is a side view of the radome in an embodiment. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. It is a perspective view of the radome for demonstrating a reinforcement member. (A) is a schematic block diagram which shows a pointed radome, (b) is a schematic block diagram which shows a normal radome.

Next, an embodiment according to the present invention will be described with reference to the drawings.
[Radome]
As shown in FIG. 1, the radome 1 of the present embodiment protects an antenna 13 mounted on the front end portion (nose portion 12) of an airframe 11 in an airplane or the like. The dome part 21 which covers from In the following description, there is a case where the nose portion 12 side along the axial direction of the airframe 11 is referred to as the front side, and the side opposite to the nose portion 12 is referred to as the rear side.

In the illustrated example, the nose portion 12 of the airframe 11 has a cylindrical shape extending along the axial direction, and a pedestal portion 14 that supports the antenna 13 is disposed inside the nose portion 12.
An attachment flange portion 15 is formed at the front end portion of the nose portion 12 so as to project inward. The radome 1 is fixed to the nose portion 12 through the attachment flange portion 15. Note that an attachment hole 16 for attaching the radome 1 passes through the attachment flange portion 15 along the axis direction.
An antenna 13 for transmitting and receiving radio waves is installed on the pedestal portion 14. As the antenna 13, for example, a phased array antenna or the like is used, and a front end portion thereof projects forward from a front end portion (mounting flange portion 15) of the nose portion 12.

(Dome part)
As shown in FIGS. 1-3, the dome part 21 is made into the top cylinder shape in which the axis line O is arrange | positioned coaxially with an axis. Specifically, the dome portion 21 is configured to have a conical shape that tapers toward the front of the airframe 11 and is open toward the rear, and the antenna 13 is accommodated therein. . In the illustrated example, the side surface of the dome portion 21 is a curved surface that bulges outward. In FIG. 3, a reinforcing member 24 described later is indicated by a solid line, and the dome portion 21 is indicated by a chain line.

The dome portion 21 includes a skin material 22 exposed to the outside, a core material 23 that covers the inner surface of the skin material 22, a plurality of reinforcing members 24 that extend along the skin material 22 and reinforce the skin material 22, have.
The skin material 22 is made of a material excellent in radio wave permeability, such as FRP, and constitutes the appearance of the radome 1. In addition, the outer peripheral surface of the skin material 22 is smoothly connected with the outer peripheral surface of the nose part 12 mentioned above (refer FIG. 1).

An inner flange portion (mounting base) 25 is formed at the opening end (rear end portion) of the skin material 22 so as to project inward. The inner flange portion 25 is fixed to the nose portion 12 by a fastening member 26 such as a bolt (see FIG. 1) in a state of being abutted against the mounting flange portion 15 of the nose portion 12 described above. Specifically, a screw hole 27 (see FIG. 1) is formed in the inner flange portion 25 along the axis O direction (machine axis direction), and the fastening member 26 passes through the attachment hole 16 formed in the attachment flange portion 15. Is screwed. The method of attaching the radome 1 to the airframe 11 is not limited to the above-described configuration, and design changes can be made as appropriate.
Further, ribs 28 projecting inwardly are formed at intervals in the circumferential direction around the axis O at a portion of the open end of the skin material 22 located on the front side of the inner flange portion 25. The thickness of the skin material 22 is set to about several percent or less (about 0.6 mm) with respect to the wavelength λ (for example, about 30 mm). Thereby, the radio wave permeability can be maintained satisfactorily.

  The core material 23 is made of a material having a high air density, such as a foam material or a honeycomb material, and urethane is suitably used in this embodiment. The core material 23 has a conical shape formed following the inner surface shape of the skin material 22, and the outer surface is fixed to the inner surface of the skin material 22 by bonding or the like. Moreover, the core material 23 should just be formed in the thickness which can suppress the buckling of the dome part 21 (skin material 22) with respect to a wind pressure load etc., and the inner surface of the core material 23 is an inner flange in the example of FIG. It is formed with a thickness that is flush with the inner surface of the portion 25.

(Reinforcing member)
Here, as shown in FIGS. 1 to 4, each reinforcing member 24 is formed of a glass fiber reinforced plastic (GFRP) or the like in a band shape. In the present embodiment, the “strip shape” means a state extending along a predetermined direction, and the thickness (outer diameter), cross-sectional shape, and the like can be appropriately changed in design. That is, the case where the reinforcing member 24 of the present embodiment is formed in a circular shape in cross-sectional view will be described, but may be a rectangular shape or the like. Moreover, it is preferable that the fiber orientation of the glass in the reinforcing member 24 is set in a direction in accordance with the compression / tensile load acting along the extending direction of the reinforcing member 24. In FIG. 4, the above-described core material 23 is not shown.

  Each reinforcing member 24 has a plurality of first reinforcing members 24a and second reinforcing members 24b each having a different length, and the first reinforcing member 24a and the second reinforcing member 24b are grouped one by one. A plurality of sets of reinforcing member groups 33 are formed. In addition, since each 1st reinforcement member 24a and each 2nd reinforcement member 24b consist of the same structure, respectively, in the following description, 1 set of 1st reinforcement member 24a of each set and the 2nd reinforcement member 24b are set. The first reinforcing member 24a and the second reinforcing member 24b will be described as an example.

  As shown in FIG. 5, the first reinforcing member 24 a connects the side surface (the outer peripheral surface of the skin material 22) and the open end of the dome portion 21 and cuts the dome portion 21 along a plane that intersects the axis O. In FIG. 2, the arch shape extends along the curved portion of the first cut surface 50. Specifically, the first reinforcing member 24 a is inclined at an angle α with respect to the opening end of the dome portion 21 in a side view of the dome portion 21. The first reinforcing member 24a has both end portions (root portions) along the extending direction fixed to the inner flange portion 25 of the skin material (see FIGS. 2 and 3).

The second reinforcing member 24b is formed in an arch shape like the first reinforcing member 24a, and is inclined at an angle β (β> α) with respect to the opening end of the dome portion 21 in a side view of the dome portion 21. doing. Specifically, the second reinforcing member 24 b includes a portion of the side surface of the dome portion 21 that is positioned forward of the first reinforcing member 24 a (the tip end side of the dome portion 21) and an opening end of the dome portion 21. When the dome portion 21 is cut by a plane that connects the same position as the cut surface 50 and intersects the axis O, the dome portion 21 extends along the curved portion of the second cut surface 51. Accordingly, both end portions (root portions) in the extending direction of the second reinforcing member 24b are fixed to the inner flange portion 25 at the same positions as both end portions of the first reinforcing member 24a (see FIGS. 2 and 3).
As shown in FIG. 1, the reinforcing members 24 a and 24 b of the present embodiment are entirely embedded in the skin material 22 and do not protrude from the inner surface of the skin material 22.

  In the dome portion 21 of the present embodiment, the above-described reinforcing member group 33 is provided with an odd number of sets (5 sets in the example of FIG. 4) at intervals in the circumferential direction of the dome portion 21. Accordingly, in the inner flange portion 25, odd-numbered sets of support portions that support both ends of the reinforcing members 24a and 24b (reinforcing member group 33) are set in the circumferential direction.

  In this case, the reinforcing member groups 33 (reinforcing members 24a and 24b) adjacent in the circumferential direction are arranged so as to intersect at a part along the extending direction. Specifically, one end of one reinforcing member group 33 intersects the other end of another reinforcing member group 33 adjacent to one reinforcing member group 33 on one end side in the circumferential direction. The other end of one reinforcing member group 33 intersects with one end of another reinforcing member group 33 adjacent to the one other reinforcing member group 33 in the circumferential direction. Further, as shown in FIG. 4, the reinforcing members 24 a and 24 b intersect with each other so as to have an odd-numbered shape (for example, a pentagonal shape) when the radome 1 is viewed from the opening end side.

Therefore, in the dome portion 21, a plurality of reinforcing members 24 are stretched around in a mesh shape at intervals other than the front end portion.
In the present embodiment, when the frequency of radio waves transmitted and received by the antenna 13 is 10 GHz and the wire diameter φ of each reinforcing member 24 (the first reinforcing member 24a and the second reinforcing member 24b) is 1 mm, each reinforcing member 24a. , 24b is set to an average interval (average mesh size) of about several μm.

The radome 1 described above can be manufactured as follows, for example.
A prepreg impregnated with a fiber or a resin that is a precursor of the skin material 22 and a reinforcing member 24 are arranged on the outer peripheral surface of a convex mold that molds the inner surface shape of the skin material 22, and the resin impregnated in the prepreg is placed on the prepreg. By curing, the skin material 22 in which the reinforcing member 24 is embedded is formed (molding step). At this time, portions of the skin material 22 other than the inner flange portion 25 are formed. That is, the root portion of the reinforcing member 24 is exposed after the molding process.
Then, after the core material 23 is bonded to the inner surface of the skin material 22, a portion corresponding to the inner flange portion 25 of the skin material 22 is formed on the skin material 22. Thereby, the root portion of each reinforcing member 24 can be fixed to a desired position of the inner flange portion 25.
In addition, you may form the skin material 22 according to the internal peripheral surface of the concave shape shaping | molding die which shape | molds the outer surface shape of the skin material 22. FIG. Further, the skin material 22 may be formed in a state in which the reinforcing member 24 is knitted into the FRP prepreg formed in a sleeve shape.

According to the present embodiment, the strength of the dome portion 21 can be ensured by reinforcing the skin material 22 with the reinforcing member 24. In addition, since the reinforcing member 24 is formed in a band shape, radio waves transmitted and received by the antenna 13 pass between the reinforcing members 24. Therefore, the dome portion 21 can be regarded as a two-layer structure of the skin material 22 and the core material 23, and the influence on the radio wave transmission in the radome 1 can be reduced. As a result, it is possible to ensure both strength and electrical characteristics of the radome 1.
In particular, in this embodiment, since the base portion of the reinforcing member 24 is fixed to the inner flange portion 25, the reinforcing member 24 can be stably fixed to the dome portion 21, and the strength of the radome 1 can be ensured.
Moreover, by adopting the above-described configuration for the conical radome 1 that tapers toward the front of the airframe 11, deformation of the radome 1 due to wind pressure load or the like can be suppressed, and electrical characteristics due to an increase in incident angle can be suppressed. Reduction can be suppressed as much as possible.

  Further, by disposing the reinforcing member 24, which is a member different from the skin material 22, on the skin material 22, the skin material 22 and the reinforcing member are integrated, for example, a rib-like reinforcing member is integrally formed on the skin material 22, and the like. Compared with the case where it forms by, manufacture becomes easy and it can also suppress that the skin material 22 itself becomes thick. Further, the degree of freedom in design can be improved, for example, the skin material 22 and the reinforcing member 24 can be formed of optimum materials, or the reinforcing member 24 can be disposed at a desired position.

  Furthermore, in the present embodiment, since the reinforcing member group 33 including the first reinforcing member 24a and the second reinforcing member 24b is provided in an odd number, the radial direction with the axis O interposed therebetween in the plan view shown in FIG. Thus, the reinforcing members 24 facing each other extend in the direction in which they intersect. For this reason, if radio waves are reflected toward the inside of the dome portion 21 by one reinforcing member 24, it is suppressed from being reflected again by another reinforcing member 24 that is radially opposed to the one reinforcing member 24. The dome portion 21 can be quickly transmitted through the reinforcing members 24.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

For example, in the above-described embodiment, the conical radome 1 attached to the nose portion 12 of the airframe 11 has been described. However, the design of the external shape of the radome 1 can be changed as appropriate, and the location where the radome 1 is attached is the airframe 11. Not limited to this, it can be selected as appropriate.
Furthermore, in the above-described embodiment, the case where the inner flange portion 25 is formed on the mounting base attached to the nose portion 12 of the dome portion 21 has been described. Any configuration can be used. And the root part of the reinforcement member 24 may be fixed to the mounting base.

  In the above-described embodiment, the configuration in which the inside of the dome portion 21 is hollow has been described. However, the configuration is not limited thereto, and the inside of the skin material 22 may be filled with the core material 23. Even in such a case, by forming the core material from the above-described foamed material or honeycomb material, the dielectric loss tangent (tan Δ) can be suppressed to be small and equivalent to air, so that the electrical characteristics are affected. Can be suppressed.

Further, the number, shape, material, and the like of the reinforcing members 24 can be appropriately changed.
In the above-described embodiment, the configuration in which the reinforcing member 24 is embedded in the skin material 22 has been described. However, the configuration is not limited thereto, and the configuration may be such that the inner surface of the skin material 22 is fixed by bonding or the like.

  Furthermore, in the above-described embodiment, the configuration in which the skin material 22 and the reinforcing member 24 are formed as separate members has been described. However, the present invention is not limited thereto, and the skin material 22 and the reinforcing member 24 may be integrally formed. . Specifically, a rib-shaped reinforcing member may be formed on the inner peripheral surface of the skin material 22.

  In addition, in the range which does not deviate from the meaning of this invention, it is possible to replace suitably the component in the embodiment mentioned above by the known component, and you may combine the modification mentioned above suitably.

DESCRIPTION OF SYMBOLS 1 ... Radome 13 ... Antenna 21 ... Dome part 22 ... Skin material 23 ... Core material 24 ... Reinforcement member 25 ... Inner flange part (mounting base)
24 ... Reinforcing member 24a ... First reinforcing member (reinforcing member)
24b ... second reinforcing member (reinforcing member)

Claims (4)

It has a dome that covers the antenna that transmits and receives radio waves,
The dome part is
Skin material exposed to the outside,
A core material covering the inner surface of the skin material;
A strip extending along the skin material, and a plurality of reinforcing members for reinforcing the skin material,
An attachment base for attaching the dome part to the outside is formed at the opening end of the dome part,
A radome, wherein a base portion of the reinforcing member is fixed to the mounting base.   The radome according to claim 1, wherein the reinforcing member is formed of a member separate from the skin material. The reinforcing member has an arch shape, and root portions at both ends thereof are fixed to the mounting base,
3. The radome according to claim 1, wherein the reinforcing members are arranged in odd numbers at intervals in the circumferential direction of the mounting base.   The radome according to any one of claims 1 to 3, wherein the dome portion is tapered from the attachment base side toward the tip.

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