JPH0716861A - Production of dielectric antenna element - Google Patents

Abstract

PURPOSE:To form a surface radom layer in necessary thickness within a short time without deforming the same in the foam molding of a dielectric antenna element. CONSTITUTION:A foamable material prepared by mixing a resin material, a foaming agent and a dielectric constant control agent is injected into a mold 10 and foamed to mold a dielectric lens 1. The cavities 11a, 11b of the mold 10 are composed of a metal material having good heat conductivity and held to 50-70 deg.C for 80-100sec. By this constitution, a hard radom layer 3 is thinly formed on the surface of a foamed main body part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dielectric antenna element, and more particularly to a method for manufacturing a dielectric antenna element for receiving microwaves for communication and broadcasting.

[0002]

2. Description of the Related Art Conventionally, as an antenna element for receiving microwaves of 50 GHz or more, a mixture of a resin material such as polypropylene, polyethylene, polystyrene and a foaming agent, and a ceramic powder as a dielectric constant adjusting agent is foamed into a dome shape. Molded dielectric lenses are known. In this type of dielectric lens, the surface portion is solidified during foam molding to form a radome layer. The radome layer functions as a protective layer for reinforcing the weather resistance and strength of the foam body.

However, if the radome layer is not sufficiently solidified or is taken out from the mold in a thin state, the radome layer will be deformed by the foaming pressure inside. On the other hand, if the mold is rapidly cooled or if the cooling time in the mold is set to be long, the radome layer grows thick and the lens efficiency is impaired, or the molding cycle becomes long and the production efficiency decreases.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to manufacture a dielectric antenna element which can form a radome layer in a required thickness without deformation and in a short time. To provide a method. In order to achieve the above object, a method for manufacturing a dielectric antenna element according to the present invention is such that at least a cavity portion of a molding die uses a metal material having a good thermal conductivity, and the cavity portion contains a resin as a main component. After the foam material is filled, the temperature is maintained at about 50 to 70 ° C. for about 80 to 100 seconds.

The foamed material in the molten state is usually 200 ° C.
Or the temperature is higher than that, and the mold is filled in this state, and foaming starts immediately after filling. On the other hand, the mold is about 5
Hold at 0-70 ° C for about 80-100 seconds. As a result, a radome layer is formed on the surface of the foam. This radome layer is solidified with a thickness of about 2 mm or less, has a thickness that does not impair lens efficiency in practice, and does not deform due to the foaming pressure inside even if the molded product is taken out of the mold. .

[0006]

EXAMPLES Hereinafter, the production of the dielectric antenna element according to the present invention will be described.
An example of the manufacturing method will be described with reference to the accompanying drawings. (First Embodiment, See FIG. 1) This first embodiment is a dielectric of the present invention.
An example applied to a body lens is shown. This dielectric lens 1
It has a dome shape, and its size is about 180 mm in diameter,
The height is about 76 mm. Polypropylene is used as the resin material.
98% by weight, and azodicarbonamide as a foaming agent
Of 2 wt%. Also, as a dielectric constant adjusting agent
CaTiO ₃Etc. may be mixed. Inject this foam material
Injection from the cylinder of the molding machine into the mold 10 to perform foam molding.
U The temperature of the cylinder is about 210 ° C.

The mold 10 uses copper for the cavity portion (cavity fixed side 11a and cavity movable side 11b). Copper is 0.941 cal / cm · S at 20 ℃
-Has a good thermal conductivity of ° C. A plurality of temperature adjusting holes 12 are formed in the cavity fixed side 11a and the movable side 11b, and a cooling liquid is circulated. Furthermore, the cavity fixed side 11a and the movable side 11b are made of iron outer casings 13a, 13b.
It is covered with b. In addition, A is a parting line.

When the foam material in a molten state is injected into the mold 10, it immediately starts foaming. At this time, the fixed side 11a and the movable side 11b are set to a temperature of about 60 ° C., and this temperature is held for about 89 seconds, after which the dielectric lens 1 is taken out from the mold 10 and naturally cooled in the air. After the injection, the foam material is molded as the foam main body 2 having a predetermined dielectric constant, and the solidified radome layer 3 is formed on the surface thereof.

The formation state of the radome layer 3 depends on the temperature of the cavity of the mold 10 and the holding time thereof,
Under the above conditions, it solidified to a thickness of about 1 mm. The thickness of the radome layer 3 is preferably 2 mm or less from the viewpoint of lens efficiency. In order to satisfy this condition and solidify the radome layer 3 to a required hardness, also considering shortening of the molding time,
The temperature of the mold 10 is about 50 to 70 ° C, and the holding time is about 8
0 to 100 seconds is preferable.

In the first embodiment, after the dielectric lens 1 is taken out of the mold 10, the foam main body 2 continues to foam slightly, but the radome layer 3 is solidified and therefore deformed by the foaming pressure. There is no fear. (Second Embodiment, See FIG. 2) The second embodiment shows an example in which the present invention is applied to a dielectric rod antenna. The dielectric rod antenna 20 is rod-shaped, has a diameter of 3.4 cm and a length of 300 cm. Similar to the mold 10, the mold 30 has a copper cavity fixed side 31a and a movable side 31b covered with iron outer casings 33a and 33b, and each of the fixed side 31a and the movable side 31b has a plurality of cavities. The temperature control hole 32 is formed.

In the second embodiment, the foam material and molding conditions (temperature, holding time) of the dielectric rod antenna 20 manufactured as a prototype are the same as those in the first embodiment, and the surface of the foam main body 21 is The radome layer 22 having a predetermined thickness was formed. (Other Embodiments) The manufacturing method according to the present invention is not limited to the above embodiments, but can be variously modified within the scope of the gist thereof.

In particular, polyethylene, polystyrene or the like can be used as the resin material, and p, p-oxybenzenesulfonyl hydrazide or the like can be used as the foaming agent.
Further, as a dielectric constant adjusting agent, BaTiO ₃ , CaTi
O ₃ , MgTiO ₃ or the like can be used. Further, the cavity portions 11a, 11b, 31a, 31b are made of a metal having a good thermal conductivity other than copper, such as iron (thermal conductivity at 20 ° C.,
0.125 cal / cm · S · ° C.).

Further, as the dielectric antenna element to be molded, various forms other than the dielectric lens 1 and the dielectric rod antenna 20 are conceivable, and the size thereof is also arbitrary.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, showing a state where a resin is foamed in a mold to form a radome layer.

FIG. 2 is a cross-sectional view showing a second embodiment of the present invention, showing a state in which a resin is foamed in a mold to form a radome layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Dielectric lens 2 ... Foam main body 3 ... Radome layer 20 ... Dielectric rod antenna 21 ... Foam main body 22 ... Radome layer 10, 30 ... Mold 11a, 11b, 31a, 31b ... Cavity part

Claims (1)

[Claims] 1. A method of manufacturing a dielectric antenna element, wherein a mold is filled with a foam material containing a resin as a main component, and the mold is foam-molded into a predetermined shape. At least a cavity of the mold has good thermal conductivity. A method of manufacturing a dielectric antenna element, comprising using a metal material, and holding the cavity portion at about 50 to 70 ° C. for about 80 to 100 seconds after filling the cavity portion with the resin material.