CS223237B1 - Facility limiting the transmission of the pressing force in the segment form in the construction of the vulcanization press - Google Patents

Description

The present invention relates to a method of producing attenuation material, in particular for microwave applications, which makes it possible to obtain a mass with optimum attenuation properties in a certain frequency band from the specified starting components.

In microwave technology, attenuators are very often used to design solid or sliding without reflective terminals and attenuators with constant or variable attenuation. The absorption of incident or passing RF energy of these elements occurs in a volume of attenuation material that is suitably shaped with respect to keeping a small reflection coefficient. It is placed in waveguides, coaxial or strip lines, and the optimal amount of its losses depends on the volume in which the interaction between the attenuator material and the electromagnetic field occurs.

The attenuating materials for this purpose are usually made from a mixture of pentacarbonyl iron powder and resin by casting. The casting must be sufficiently flowable during casting, and therefore a larger volume ratio of iron powder and resin as a binder than about 2 to 3: T cannot be achieved. This means that with this technology it is difficult to produce lossy materials with a specific resistance of less than the order of 10 kficm. In addition, in the relatively thin mixture, iron powder usually settles as it solidifies, so that the attenuating mass is not homogeneous throughout the volume in terms of the high-frequency properties.

These drawbacks are overcome by a microwave attenuation process which solidifies a homogenized binder mixture with a conductive or semiconductive material powder, for example a mixture of four parts by volume of pentacarbonyl iron powder and one part by volume of methyl methacrylate resin powder and four parts by volume of methyl methacrylate resin monomer according to the invention. It is based on the fact that, during solidification of the mixture, its specific resistance is measured and is maintained at a desired level, in particular in the range of 10 cm to 500 kph, by applying mechanical pressure to the solidifying mixture, for example by a punch.

The magnitude of the absorption of RF energy, which occurs mainly due to eddy currents in the material, can be characterized by a specific resistance. The method of using attenuator in microwave elements with respect to its location in the line structure and with respect to the frequency band results in the magnitude of its specific resistance. In the production of the attenuator according to the invention, this specific resistance during solidification of the binder is directly measured and its size adjusted by the pressure to which the powder-binder mixture is subjected. The press jig in which the mixture is compressed consists of at least two electrically insulated parts, for example a press mandrel and a jig bottom, which allows the electrical resistance to be measured continuously. The homogeneous powder-binder mixture need not be liquid when filled into the mold. Therefore, there are no problems with powder sedimentation and a high degree of powder binder filling can be achieved. The end result is the possibility of producing attenuation material with much lower specific resistance required by microwave applications than casting technology allows.

The production technology of the invention has been tested on mixtures of pentacarbonyl iron powder and self-setting methyl methacrylate resin. The samples were produced in a die which was heated to 100 ° C during solidification of the resin. Samples were produced with a volume ratio of iron powder to powder part of methyl methacrylate resin of up to 16: 1 with satisfactory mechanical properties. For samples having a volume ratio of iron powder to powder part of methyl methacrylate resin of 4: 1, the specific resistance of the sample in the range of 0.1 to 20 kQcm could be achieved by changing the pressure during solidification of the methyl methacrylate resin.

The manufacturing technology according to the invention has been developed for the production of a damping material, which is successfully used as part of a sliding microstrip anechoic terminal and a variable ¹ microstrip attenuator. Its advantages are the possibility to continuously influence the resulting properties of the attenuating material during its production and the production of attenuating materials with better RF energy absorption properties than the prior art casting technology. Its applicability is not limited to the production of attenuation materials for microwave applications. It can also be used to manufacture resistive materials for low frequency applications.

Claims (1)

Subject A method of producing attenuation material for microwave applications comprising solidifying a homogenized binder mixture with a conductive or semiconductive material powder, for example a mixture of four parts by volume of pentacarbonyl iron powder and one part by volume of methyl methacrylate resin powder and four parts of methyl methacrylate resin monomer. by measuring its specific resistance during solidification of the mixture and maintaining its value at a desired level, in particular in the range of 10 to 500 kDcm, by applying mechanical pressure to the solidifying mixture, for example by means of a dies of the die.