KR20010096998A - A wide band electromagnetic wave absorption frame used complex material of ferrite and binder - Google Patents

Abstract

The present invention uses ferrite powder (Ni-Zn ferrite, hexagonal ferrite containing Co ₂ Z) and pure iron powder having high magnetic loss as an absorption filler, and the powder is incorporated into a binder or a plastic support having excellent moldability. By using a composite material as a pyramid-shaped wide band absorber suitable for small or simple radio darkrooms, the thickness can be reduced compared to the absorbers used in conventional radio darkrooms. By solving the problem, there is a characteristic of providing a broadband wave absorber using a composite material of a ferrite and a binder to maximize the use reliability for the user while forming an efficient broadband wave absorber.

Description

Wideband radio wave absorber using composite material of ferrite and binder {A WIDE BAND ELECTROMAGNETIC WAVE ABSORPTION FRAME USED COMPLEX MATERIAL OF FERRITE AND BINDER}

The present invention relates to a broadband wave absorber using a composite material of ferrite and binder,

More specifically, ferrite powder (Ni-Zn ferrite, hexagonal ferrite containing Co ₂ Z) and pure iron powder having high magnetic loss are used as an absorption filler, and the powder is used as a binder or a plastic support having excellent moldability. By using mixed composite material as a pyramid-shaped broadband radio absorber suitable for small or simple radio darkroom, the thickness can be reduced compared to the absorbers used in conventional radio darkroom, and the difficulty in processing in controlling sintering shape The present invention relates to a broadband wave absorber using a composite material of ferrite and a binder to maximize the use reliability for a user while at the same time forming an efficient broadband wave absorber.

In general, it is essential to perform in the radio dark room as a facility for measuring the electromagnetic interference and electromagnetic resistance of various electronic and communication equipment.

As a radio wave absorber used in the radio dark room, a hybrid wave absorber combining a pyramidal absorber (made of a foamed urethane or polystyrene foam impregnated with carbon powder) on a ferrite tile to obtain broadband characteristics is widely used. to be.

However, the pyramid-type absorber shows a very good broadband radio wave absorption characteristics in the GHz band, but because the height of the absorber is 30 cm or more, the effective space inside the radio darkroom is reduced, which is difficult to install the radio darkroom because of the demand In the case of a small or simple radio darkroom where the size is increasing, there is a problem that the use of the pyramid absorber is further limited.

Therefore, in the conventional method as described above, the pyramidal absorber made of urethane or polystyrene foam material in which carbon powder is mixed is used so that the height of the absorber is so large that the effective space inside the radio darkroom is reduced, and the ferrite sintered body As a base material, it has been proposed to reduce the thickness while maintaining broadband absorption characteristics by processing into pyramid shape or similar cross slot or tapered shape, but it is difficult to form ferrite due to complex phenomena and control the dimension by volume shrinkage during sintering. There is a problem.

In addition, in the case of the sintered ferrite, since the loss coefficient is small in the ultra-high frequency band of GHz or more, there is a material problem that is difficult to extend the radio wave absorption function to these high-frequency bands.

As a result, there is always a problem that the above method is deteriorated in efficiency, minimized in the reliability of the use to the user, or inferior in productivity and economy.

The present invention has been made to solve the problems occurring in the related art as described above, and has the following objects.

The present invention uses ferrite powder (Ni-Zn ferrite, hexagonal ferrite containing Co ₂ Z) and pure iron powder having high magnetic loss as an absorption filler, and the powder is incorporated into a binder or a plastic support having excellent moldability. By using a composite material as a pyramid-shaped wideband radio absorber suitable for small or simple radio darkrooms, the thickness of the absorber can be reduced compared to the conventional pyramid absorber and efficiency is solved by solving the processing difficulties generated in sintered ferrite. It is an object of the present invention to provide a broadband wave absorber using a composite material of ferrite and binder to maximize the use reliability for the user while forming a broadband wave absorber.

1 is a schematic diagram of a pyramidal wave absorber shown by the present invention,

2 is an approximate schematic of a transmission line of a pyramidal absorber for explaining the present invention;

3 is a graph showing the complex dielectric constant and complex permeability of the Ni-Zn ferrite composite according to the present invention,

Figure 4 is a graph of propagation absorption characteristics of Ni-Zn ferrite composite according to the present invention,

5 is a graph showing the complex dielectric constant and complex permeability of a composite material composed of Ni-Zn ferrite and pure iron mixed powder according to the present invention;

6 is a graph showing propagation absorption characteristics of a composite material composed of Ni-Zn ferrite and pure iron mixed powder according to the present invention;

7 is a graph showing the complex dielectric constant and complex permeability of the Co ₂ Z hexagonal ferrite composite according to the present invention,

8 is a graph of propagation absorption characteristics of Co ₂ Z hexagonal ferrite composite according to the present invention,

9 is a schematic diagram of a hybrid wave absorber (pyramid-type ferrite composite / ferrite tile) shown by the present invention,

10 is a graph of propagation absorption characteristics of the hybrid absorber {(Ni-Zn ferrite + pure iron powder) composite material / ferrite tile} according to the present invention,

11 is a graph of propagation absorption characteristics of the hybrid absorber (Co ₂ Z hexagonal ferrite composite material / ferrite tile) according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: metal conductor plate

2: flat plate part of ferrite-binder composite material

2a: sintered ferrite tile

3: pyramid part of ferrite-binder composite material

In order to achieve the above object, it will be described in detail with reference to the accompanying drawings which is a preferred embodiment of the present invention.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The following terms are terms set in consideration of functions in the present invention, which may vary depending on the intention or custom of the producer, and the definitions should be made based on the contents throughout the present specification.

First, the present invention is shown in Figures 1 to 11, Figure 1 is a schematic diagram of the pyramidal wave absorber shown by the present invention, Figure 2 is an approximate schematic of the transmission line of the pyramid-shaped absorber for explaining the present invention 3 is a graph showing the complex dielectric constant and the complex permeability of the Ni-Zn ferrite composite according to the present invention, FIG. 4 is a graph showing the propagation absorption characteristics of the Ni-Zn ferrite composite according to the present invention, and FIG. Fig. 6 is a graph showing the complex dielectric constant and complex permeability of a composite material composed of Ni-Zn ferrite and pure iron mixed powder. FIG. 6 is a graph of propagation absorption characteristics of a composite material composed of Ni-Zn ferrite and pure iron mixed powder according to the present invention. is a graph showing the complex dielectric constant and the complex magnetic permeability of the Co ₂ Z hexagonal ferrite composite material according to the present invention, Figure 8 is according to the invention Co ₂ Z hexagonal ferrite It is a graph of the radio wave absorption characteristics of the mixture, Figure 9 is a schematic diagram of the hybrid wave absorber (pyramid composite / ferrite tile) shown by the present invention, Figure 10 is a hybrid absorber according to the present invention ((Ni-Zn ferrite + pure iron powder) Composite wave / absorption characteristic graph of the composite material / ferrite tile}, Figure 11 shows a wave absorption characteristic graph of the hybrid absorber (Co ₂ Z hexagonal ferrite composite material / ferrite tile) according to the present invention.

That is, the present invention forms a broadband radio wave absorber having a reflection loss of -20 dB or less from the MHz band to the 18 GHz band by laminating a pyramidal-shaped ferrite-binder composite material and a sintered ferrite layer to be easily applied to a small and simple radio darkroom. It is achieved by reducing the thickness of the radio wave absorber to 70mm.

In addition, a hexagonal ferrite containing Ni-Zn-based spinel ferrite and Co ₂ Z, which is a ferrite powder having a wide frequency dispersion characteristic of magnetic loss, is easily used as an absorbent filler to easily apply to the small and simple radio darkroom. Mixing two or more kinds of ferrite powder for wide area or using pure iron powder as the absorbent filler in the ferrite powder.

It is composed of a hybrid absorber having broadband characteristics by thermally combining a sintered ferrite tile and a pyramidal ferrite-binder composite material which extend the lower limit frequency band to the MHz band for easy application to the small and simple radio darkrooms.

That is, the present invention may be variously modified in various ways in reducing the pyramid shape.

It is to be understood, however, that the present invention is not limited to the specific forms referred to in the above description, but rather includes all modifications, equivalents and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood to do.

On the other hand, as shown in Fig. 1, in the pyramid absorber, a metal conductor plate 1 is formed on the rear surface, and the flat plate portion 2 of the ferrite-binder composite material and the pyramid portion 3 of the ferrite-binder composite material. ) Has a laminated structure.

The layer consisting of the flat plate portion 2 of the ferrite-binder composite material and the pyramid portion 3 of the ferrite-binder composite material is made of the same composite material, and is integrally manufactured by a conventional pressurized plastic molding process or bonding by a binder. do.

In addition, by applying the transmission line approximation method by dividing the absorber of the pyramid into a plurality of layers, it can be approximated with a density gradient composite material of a plurality of planar multilayer structure composed of a ferrite composite and an air portion as shown in the accompanying drawings. .

In this structure, each layer has an equivalent complex dielectric constant and an equivalent complex permeability corrected by the insertion of the air part, and the absorber surface has an equivalent dielectric constant and equivalent permeability similar to that of the air, thereby minimizing radio wave reflections and simultaneously entering the interior of the ferrite composite. As the density increases linearly, the progressive increase in the loss factor enables the design of broadband absorbers.

In the composite material having the above structure, the radio wave absorption function is due to the loss characteristics of the medium, so that the magnetic filler has a large magnetic loss over a wide band, and the period (a ₁ ), which is the dimension of the absorber shape, and the thickness of the flat plate part 2. The broadband absorber can be designed by adjusting (d ₁ ) and the lower length (a ₂ ) and height (d ₂ ) of the pyramid square pyramid.

EXAMPLE

The complex dielectric constant (ε _r = ε _r '-jε _r '') and the complex permeability of the composite material using the Ni-Zn ferrite powder as the absorbent filler and the binder as the support material (weight ratio of ferrite and the binder = 4: 1) (μ _r = μ _r '-jμ _r '') is shown (see FIG. 3).

The propagation absorption graph of the pyramid absorber designed with the complex permeability and the complex dielectric constant of the Ni-Zn ferrite composite (see FIG. 4), wherein the period (a ₁ ) is ## mm, the length (a ₂ ) is # When designed to be #mm, thickness (d ₁ ) is 40mm, and height (d ₂ ) is 60mm, return loss is less than -20dB in the range of 0.8 GHz to 13.7 GHz. This drop is due to the low magnetic loss (μ _r '') of the ferrite composite.

In addition, the complex dielectric constant (ε _r = ε _r '-jε _{r of} the composite material (mixing weight ratio = 2: 1) of the mixed powder (mixed weight ratio = 2: 1) of the Ni-Zn ferrite and pure iron in the binder can expand to jμ _r 'will showing a') (see Fig. 5), was added 50MHz ~ 18GHz range of the frequency distribution range of the magnetic loss by the pure iron powder - '') and the complex magnetic permeability (μ _r = μ _r ' .

The propagation absorption graph of the pyramidal absorber designed with the complex dielectric constant and complex permeability of the Ni-Zn ferrite and the pure iron mixed powder composite material (see FIG. 6), wherein the period (a ₁ ) is $$ mm, the length (a ₂ ) is $$ mm, thickness (d ₁ ) is 40mm, height (d ₂ ) is 60mm, the return loss of less than -20dB in the range of 1.0GHz ~ 18GHz, the Ni-Zn ferrite and pure iron By using the mixed powder as the absorption filler, it is possible to design a broadband absorber in the GHz band, which is due to the frequency dispersion characteristic of the magnetic loss widened by the combination of the Ni-Zn ferrite and pure iron powder.

In addition, the complex dielectric constant (ε) of the composite material (weight ratio of ferrite and the binder = 4: 1) using the Co ₂ Z hexagonal ferrite (Formula: Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ) as the absorption filler and the binder as a support material _r = ε _r '- jε _r' ') and the complex magnetic permeability (μ _r = μ _r' - jμ _r 'will showing a') (see Fig. 7), the magnetic loss of the composite material also shows a relatively large frequency dispersion characteristics .

Propagation characteristics graph (see Fig. 8) of the Co ₂ Z hexagonal ferrite composite having the pyramid shape, wherein period (a ₁ ) is ** mm, length (a ₂ ) is ** mm, thickness (d ₁ ) is 40mm and height (d ₂ ) is 60mm when the return loss of less than -20dB in the range of 1.2GHz ~ 18GHz can be seen that.

In order to investigate the applicability of the ferrite composite to the absorber for the radio dark room in the GHz band as described above, a hybrid wave absorber was designed as shown in FIG. In order to widen the plate-like sintered ferrite tile 2a, a structure is inserted between the metal conductor plate 1 and the plate portion 2 of the pyramid-binder composite material.

Illustrates the Ni-Zn-based electric wave absorption characteristics of a mixed-absorber combination of the pyramid absorber having a ferrite with the accompanying drawings wave absorption characteristics of Fig. 6 graph (see Fig. 10), in which the drawing period in Fig. 9 (a ₁₎ Is && mm, length (a ₂ ) is && mm, thickness (d ₁ ) is 4mm, thickness (D ₂ ) is 10mm, height (d ₃ ) is 60mm It can be seen.

In addition, the graph shows the wave absorption characteristic graph (see FIG. 11) of the hybrid absorber combining the Ni-Zn-based sintered ferrite and the pyramidal absorber having the wave absorption characteristic of FIG. 8. ₁ ) is && mm, length (a ₂ ) is && mm, thickness (d ₁ ) is 3mm, thickness (D ₂ ) is 10mm, height (d ₃ ) is 90mm Loss is shown.

As described above, a hybrid absorber is formed by combining a pyramidal-shaped ferrite composite having a broadband absorption characteristic in the GHz band with a flat plate sintered ferrite to form a hybrid absorber, thereby reducing the total thickness to 100 mm or less while reducing the return loss of -20 dB or less in the range of 100 MHz to 18 GHz. While it is possible to design an ultra-wide band absorber having the above characteristics, the absorber having such characteristics satisfies the requirements of the radio wave chamber absorber and it can be seen that the performance is much improved in terms of thickness than the absorber using the conventional pyramid absorber.

As described in detail above, the present invention uses ferrite (Ni-Zn ferrite, hexagonal ferrite containing Co ₂ Z) powder and pure iron powder having high magnetic loss as an absorption filler, and the powder is used as a binder having excellent moldability or By using the composite material mixed in the plastic support material, it can be used as a pyramid-shaped wideband radio absorber suitable for small or simple radio darkroom, and it is possible to reduce the thickness of the absorber as compared to the conventional pyramid absorber, and to produce the sintered ferrite. It is obvious that the invention is a very useful invention that can simultaneously produce various effects such as creating an efficient broadband radio absorber and maximizing the reliability of the user.

Claims (3)

Layered combination of pyramidal-shaped ferrite-binder composite material and sintered ferrite for easy application in small and simple radio darkrooms forms a broadband wave absorber having a return loss of -20 dB or less from the MHz band to the 18 GHz band, and the thickness of the wave absorber Broadband radio absorber using a composite material of ferrite and the binder, characterized in that by reducing to 70mm. The method of claim 1, Ni-Zn-based spinel ferrite, which is a ferrite powder having a wide frequency dispersion characteristic of magnetic loss, and a hexagonal ferrite including Co ₂ Z as an absorption filler to easily apply to the small and simple radio darkrooms, In order to mix two or more types of ferrite powder or to use the ferrite powder pure iron powder as an absorption filler, broadband radio absorber using a composite material of ferrite and the binder. The method of claim 1, A composite of ferrite and binder comprising a hybrid absorber having broadband characteristics by layer-combining a sintered ferrite tile and a pyramid-type ferrite-binder composite which layer the lower limit frequency band to the MHz band for easy application to the small and simple radio darkrooms. Broadband wave absorber using materials.