JPH067077U - Sandwich structure radome - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a radome with a sandwich structure that can accommodate curved surfaces with a large buckling deflection in order to make the antenna rotation uniform. The distance between the skins is electrically maintained at 1/4 wavelength over the entire radiation surface, and is not affected by vibration. [Constitution] An outer cylinder 7 having a radiation surface having a shape along a buckling bending curve is prepared. The polyester film 9 and the outer cylinder 7
It is attached to the inner side of the radiation surface while being bent in a curved shape along the radiation surface. A low sponge 10 for keeping the distance between the outer cylinder 7 and the polyester film 9 constant is sandwiched to form a sandwich structure. Further, a vertical polarization component removing screen is printed on the surface of the polyester film 9 with silver ink.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sandwich structure radome, which is a cover for preventing mechanical stress such as snow accumulation, freezing, ingress of water drops, wind pressure, etc. of an antenna system.

[0002]

[Prior art]

 Antennas such as radar are installed outdoors. Especially when installed on ships, it is required not only to protect the antenna from adverse weather conditions such as waves and winds, but also to reduce the drive torque required to rotate the antenna and make the antenna rotation uniform. . Therefore, it has a mechanical covering that has the same characteristics as the atmosphere electrically. This canopy is called the radome. The radome has a sandwich structure radome as shown in FIG. It consists of two layers of relatively dense and strong material skin, and one layer of low density core sandwiched between the skins. Further, the distance between the skins is electrically set to 1/4 wavelength so that the reflected waves from the two layers of skins cancel each other out.

The radome outer cylinder is manufactured by extrusion molding an inexpensive and durable resin. However, in this extrusion molding, it is difficult to manufacture a radome having a desired curved surface and a radiating surface having a sandwich structure with high accuracy by integral molding. Therefore, in practice, as described in Japanese Utility Model Laid-Open No. 58-43011, the radiation surface and the other portion are separately molded, and these are assembled by adhesion or the like. Further, in the conventional radar slot aligner, the waveguide is attached to a horn-shaped flare that sandwiches the directional characteristics of the vertical plane. Furthermore, in order to prevent the deterioration of directional characteristics by removing the vertically polarized components in the radiated waves, it was necessary to provide a screen consisting of a vertical grating in front of the flare.

[0004]

In order to satisfy the above conditions, the following means are implemented. As the outer skin, an outer cylinder having a radiation surface shaped along a curve is used. A foam material or the like is used as the core. As an inner skin, a glass epoxy resin that is attached to the inner side of the radiation surface in a curved shape along the radiation surface of the outer cylinder and has a screen for removing the vertically polarized component etched. Printed circuit board (Japanese Utility Model Publication No. 64-47104).

However, this method has the following drawbacks. If the buckling deflection becomes large, the printed board cannot handle it. Due to the strong warpage of the printed board, the skin spacing cannot be electrically maintained at 1/4 wavelength over the entire radiation surface. On the contrary, the core must be made of a material that prevents vibration of the printed board. That is, it is not possible to use a strong material for preventing. The present invention has been made in view of such circumstances, and even if a large buckling flexure is caused, the spacing between the skins is electrically maintained at a quarter wavelength, and the radome is not affected by vibration. The challenge is to provide.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, in the sandwich radome of the present invention, a sponge is used as the core. As the inner skin, it is attached to the inner side of the radiation surface in a curved shape along the radiation surface of the outer cylinder, and the screen for removing the vertically polarized component is printed with silver ink. A polyester film is used.

[0007]

[Action]

 According to the sandwich structure radome thus configured, it is possible to cope with a sandwich structure radome having a large buckling deflection. Further, since the flexure can be easily formed and the pressure applied to the core is small, the distance between the skins (between the outer cylinder and the polyester film) can be electrically maintained at 1/4 wavelength. Moreover, since a flexible sponge can be used as the material of the core, vibration of the skin (polyester film) can be prevented.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a slot array antenna 2 for radar, which is characterized by the structure of a radome 1. In the figure, 3 is a slot array waveguide (hereinafter, simply referred to as “waveguide”) that radiates horizontally polarized waves. This waveguide 3 is attached to a horn-shaped flare 4 that sandwiches a vertical plane directional characteristic. ing.

The flare 4 is inserted and fixed inside the outer cylinder 7 which is the main body of the radome 1 through the support 6 made of foamed resin or the like. The outer cylinder 7 is composed of a base portion 7a for accommodating the flare 4 and a curved radiation surface 7b facing the opening of the flare 4. These respective portions are integrally molded into a cylindrical shape by extruding resin. There is. The radiating surface 7b has a cross-sectional shape that follows the bending curve when the long columns at both ends of the rotation are buckled. As shown in FIG. 2, the load is applied to the long columns under such terminal conditions. When the buckling is performed so that the maximum deflection becomes δ at the distance L, the deflection amount Y of the long column at the distance X from one end can be generally expressed by Expression 1.

Y = δ · sin (π · X / L) (1)

That is, the radiation surface 7b of the outer cylinder 7 in this embodiment is formed such that the surface shape in the vertical direction is along the above curve. Further, projections 8 are provided integrally with the outer cylinder 7 at both upper and lower ends inside the radiation surface 7b. The dielectric plate 9 is attached to the inner surface side of the radiation surface in a curved shape along the radiation surface of the outer cylinder, and the screen for removing the vertically polarized component is printed with silver ink. A polyester film 9 (hereinafter, simply referred to as “polyester film 9”) is locked to the protrusion 8 in a bent shape. The polyester film 9 has a thickness of about 200 μm, and the screen for removing the vertically polarized component is printed with silver ink, for example, with a width of 1 mm and an interval of 1 mm. Further, a resist is applied to the entire surface to protect the screen.

The vertical surface shape of the bent polyester film 9 follows the same bending curve as that of the radiation surface 7b, and the distance between the two is set as the core 10 so that the reflected waves of each are canceled. The sponge 10 has a fixed length. Moreover, the vibration of the polyester film 9 is prevented.

According to the present embodiment, the outer cylinder 7 is a cylindrical integral molding, and it is not necessary to mold the sponge 10 and the polyester film 9 into a particular curved shape. In these assembling steps, no adhesive work is required, and the polyester film 9 can be easily attached to the inner surface side of the outer cylinder 7 by bending it. Therefore, the structure and assembly are simple and the manufacturing cost can be reduced.

Further, since it is not necessary to use an adhesive agent for the sponge 10, the electrical thickness between the outer cylinder 7 and the polyester film 9 will not be equivalently increased. Further, since the outer cylinder 7 serving as the main body has a cylindrical shape that can be extruded, a radome for an antenna can be realized at a relatively low cost. Further, since the outer cylinder 7 is integrally formed in a cylindrical shape and the radiation surface 7b is a curved surface, the airtightness and watertightness with respect to the outside is high, and the wind pressure resistance of the radiation surface 7b can be secured.

In this embodiment, protrusions 8 are provided near both ends on the inner surface side of the radiation surface 7b to lock the bent polyester film 9. However, as the locking structure of the polyester film 9, a recess may be used instead of the protrusion 8.

[0016]

[Effect of device]

 As described above, the sandwich structure radome of the present invention has an outer cylinder 7 having a shape along the flexure curve, and a curved surface along the radiant surface of the outer cylinder as a dielectric plate on the inner surface side of the radiant surface. It is attached to the inner side of the radiation surface in a bent state, and is composed of a polyester film 9 on which a screen for removing vertically polarized components is printed with silver ink, and further, a core is composed of a sponge 10. did. Therefore, we were able to realize a sandwich structure radome with the following effects. With a sandwich structure, a curved radiation surface that can withstand wind pressure can be obtained with a simple structure. The radiation surface can be formed with a curved surface with large deflection, and the drive torque required to rotate the antenna can be reduced and the antenna rotation can be made uniform. The quarter wave can be electrically maintained between the outer cylinder and the polyester film, the vibration of the polyester film can be prevented, and the radiation impedance and radiation pattern are less likely to be disturbed. The manufacturing cost is low, and it is durable and has excellent environmental resistance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory view of a buckling deflection curve according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a sandwich structure.

[Explanation of symbols]

 1 radome. 7 Outer cylinder. 7b Radiant surface. 9 Polyester film. 10 Sponge.

Claims (1)

[Scope of utility model registration request] 1. An outer cylinder (7) having a radiation surface having a shape along a buckling deflection curve, a high dielectric constant dielectric plate (9) mounted inside the radiation surface of the outer cylinder, and A sandwich structure radome comprising a core (10) having a low dielectric constant for keeping a constant distance between an outer cylinder and a dielectric plate, wherein the dielectric plate has a curved shape along a radiation surface of the outer cylinder. It is attached to the inner side of the radiating surface in a bent state, and
A sandwich structure radome, characterized in that the screen for removing the vertically polarized component is made of a polyester film printed with silver ink, and the core is made of sponge.