KR20000020529A - Wide band ferrite radio wave absorber - Google Patents

Abstract

PURPOSE: A manufacturing method for ferrite radio wave absorber is provided to fabricate a wide band ferrite radio wave absorber economically and easily by manufacturing a tile type ferrite magnetic substance and a pillar type ferrite magnetic substance separately. CONSTITUTION: A ferrite magnetic substance of tile type is sticked to a reflection plate(M). A slot(S) is formed on the tile type ferrite magnetic substance(F1) lengthwise and crosswise of a fixed space(a), therefore a pillar type ferrite magnetic substance(F2) is inserted and established to protrude from a surface of the tile type ferrite magnetic substance(F1). When the width of the slot(S) and the pillar type ferrite magnetic substance(F2) is d, d is over zero and is under 0.9a, and the height of the pillar type ferrite magnetic substance(F2) is below a.

Description

Broadband Ferrite Wave Absorber

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband ferrite wave absorber, and more particularly, to widening of a wave absorber composed of magnetic material.

Broadband ferrite absorber is widely used as a wall material for preventing interference of TV or radar by radio wave reflection from buildings or structures such as radio darkrooms, buildings, bridges, etc. Will be.

A radio wave absorber composed of sintered ferrite, which is a conventional magnetic material, has a thin thickness of about 5-8 mm, and has an excellent characteristic of absorbing low frequency electromagnetic waves of, for example, about 30 MHz. It is widely used as a wall material for preventing reflection of radio waves by radio darkrooms for measuring radiated electromagnetic waves and buildings.

On the other hand, as a technique for widening a radio wave absorber composed of a sintered ferrite, which is a magnetic material, for example, a technique in which a tile-like ferrite magnetic material is floated in an air layer (actually from a radio wave reflector using a foamed polyurethane plate) is proposed. It is. For example of this technique, a NiZn-based ferrite tile having a height (thickness of the tile mounting surface and the vertical direction) of 7 mm is arranged by interposing an air layer of 10 mm from the reflecting plate, that is, the total height is set to 17 mm from the reflecting plate. A radio wave absorber having a reflection attenuation of 20 dB or more can be obtained for a radio wave of MHz to 800 MHz.

In general, if the reflection coefficient of the radio wave on the surface of the radio wave absorber is S, the power absorption coefficient of the radio wave absorber α _p is represented as in formula (1).

(One)

therefore, The smaller the value, the better the wave absorber. In general, it is a measure of the wave absorber characteristics evaluation.

(2)

That is, a reflection attenuation amount (-20 log S) of 20 dB or more and an absorption coefficient ≥ 0.99 are employed.

Fig. 35 is a cross-sectional view showing the structure of the most basic ferrite radio wave absorber, in which a tile-like ferrite magnetic body F is attached on the metal conductor plate M. Figs.

The characteristics of the radio wave absorber having this structure are typically as shown in FIG.

36, the horizontal axis represents frequency f and the vertical axis represents reflection coefficient. Indicates. In FIG. 36 The lower and upper frequencies of = 0.1 f _L And f _H As can be seen from the figure A frequency band B satisfying ≤ 0.1 is represented by equation (3).

B = f _H - f _L (3)

This bandwidth B has already been studied, for example,

(A) Lower limit frequency f _L When the ratio is set to 30 MHz, all of the ferrites used are sintered and NiZn or MnZn. This is usually the upper limit frequency f _H Is from 300 MHz to 400 MHz.

(B) lower limit frequency f _L When the ferrite used is 90 MHz, the ferrite used is also a sintered type of NiZn or MnZn. In this case, the upper limit frequency f _H Is 350 MHz to 520 MHz.

As an application, in the case where the radio wave absorber is applied to a wall material of a radio dark room for measuring radiated electromagnetic waves from the above-mentioned electronic device, f _L = 30 MHz, and f _H Recently f _H = 1000 MHz or more is required, so in the case of (A) above f _H Is low and insufficient. In case of (B) also the upper limit frequency f _H Is low and insufficient. In addition, in the case of wall materials to prevent reflection of TV electric wave from building f _L = 90 MHz, f _H Since 800 MHz is required, the radio absorber of (B) also has insufficient characteristics.

Thus, various attempts have been made to improve the electromagnetic wave absorber as shown in FIG. 35. As an example of the recent widening of the electromagnetic wave absorber composed of only sintered ferrite, the lattice-shaped radio wave in which ferrite F is arranged on the metal plate M in a lattice shape as shown in FIG. Absorbents have been proposed by some of the inventors in US Pat. No. 5,276,448. FIG. 37 is a perspective view of the lattice wave absorber, and FIG. 38 is an enlarged perspective view of the G-G 'line cross section of FIG. The radio wave absorber of this structure f _L = 30 MHz, f _H = 800 MHz is obtained.

As an example of widening of a radio wave absorber composed of only one sintered ferrite, a multilayer grid wave absorber as shown in FIG. 39 has been proposed as a patent application publication No. 5135 by a part of the present inventors. FIG. 39 is a perspective view of the radio wave absorber, and FIG. 40 is an enlarged perspective view of a cross section taken along the line H-H 'of FIG. 39. f _L = 30 MHz, f _H = 3000 MHz is obtained.

That is, in the radio wave absorbers of Figs. 37 and 39, the ferrite magnetic body is not a tile-like flat plate, and the sintered ferrite magnetic material F having a characteristic of having a gap portion periodically and having a height h greater than 2 _{tm in} thickness is spaced over the reflection plate M of radio waves. It is placed in b.

In the lattice or multilayer lattice wave absorber described above, the permeability and the dielectric constant are controlled to a desired value in each layer by mainly changing the thickness of the ferrite and forming voids in the absorption layer. For example, in the multilayer lattice-type radio wave absorber described in 1996 Patent Application Publication No. 5135, the initial permeability (when direct current) is used as a ferrite material. μ _r1 = 2500, relative dielectric constant ε _r1 The first layer h ₁ = 4.0 mm and the thickness t _m1 = 8.5 mm when a NiZn-based material having a thickness of 15 is employed and the thickness b = 20 mm, the equivalent dielectric constant of the layer is 13.5 and the equivalent relative permeability is 2100. . In particular, in the second layer, h ₂ = 25 mm, thickness t _{m 2} = 0.6 mm, the equivalent dielectric constant is 2.0, and the equivalent relative permeability is 151. In the third layer, h ₃ = 27 mm, thickness t _{m 3} = 0.2, equivalent dielectric constant is 1.3, and equivalent dielectric permeability is 51. Therefore, in this case, the absorption characteristics are realized in the range of 30 dB to 3000 MHz in the range of the reflection attenuation of 20 dB or more, and are very excellent as a radio wave absorber composed only of sintered ferrite.

However, in the multilayer lattice-type radio wave absorber, some ferrites may have to be manufactured to a thickness of 1 mm or less. Therefore, in the actual manufacturing, when the material is molded, the height is higher than that of the thin material. When the material is injected into the mold, it is easy to cause deformation or cracking during sintering due to poor material flow, bad mold release of the molded product, uneven molding pressure, etc. There is a disadvantage to be raised.

In particular, as interest in EMI (Electromagnetic Immunity) has recently increased, radio wave absorbers are also required to be wider, and in the future, the frequency to be used in electronic devices will be higher. f _H Is inevitably high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a broadband ferrite electromagnetic wave absorber that can be manufactured more easily and more economically while meeting the above-mentioned requirements for widening.

In order to achieve the above object, the present invention attaches a tile-type ferrite magnetic material on a reflecting plate, and forms a slot in the longitudinal direction in the longitudinal direction at a predetermined interval on the tile-type ferrite magnetic material to form a columnar ferrite magnetic material in the slot. It is characterized in that the insert is installed so as to protrude from the surface of the magnetic ferrite body.

In addition, the present invention is to form a slot along the height direction in the longitudinal direction of the tile-shaped ferrite magnetic material attached to the reflecting plate, and the column-shaped ferrite magnetic material protrudes from the surface of the tile-type ferrite magnetic material on the slot, the column ferrite magnetic material It is characterized in that the gap inserted between the slot and the slot is formed symmetrically formed.

The present invention relates to a multi-layer radio wave absorber in which a plurality of absorbing layers having different electrical constants on a reflecting plate are successively stacked in a vertical direction on a reflecting plate, and is a tile ferrite attached to a reflecting plate in an absorbing layer made of ferrite magnetic material as a means for changing the electrical constant. Slots are formed in the magnetic material, and the ferrite is formed in such a manner that the slot ferrite is formed in the same shape as the slot, and the length of the column ferrite is made smaller than the width so that the pores are formed symmetrically. The magnetic permeability and dielectric constant of the layer through the interrelationship between the tiled ferrite magnetic body and the columnar ferrite magnetic body and the air layer or the air gap in the layer are controlled to the required setting values. In other words, the width of the slot and the length and width of the ferrite ferrite are adjusted to change the permeability and permittivity of the layer.

In particular, since the slotted ferrite magnetic material is inserted into the tile-type ferrite magnetic body to insert and install, the problem of molding can be reduced, and the manufacturing is easy, and the permeability and dielectric constant can be easily adjusted, so that the absorption characteristics It can be broadband.

As a ferrite magnetic body, things, such as NiZn type and MnZn type, can be used, A sintering type is preferable.

In general, the multilayer electromagnetic wave absorber corresponds to a case in which a medium layer, that is, an absorbing layer, having different electric constants, which is stacked in multiple stages in a space, as shown in FIG. 41 is present.

Characteristic impedance of each medium layer in FIG. 41 Z _c And radio wave constant γ The specific permeability μ _r , The relative dielectric constant ε _r When expressed as, it is represented by Formula (4) and Formula (5).

(4)

(5)

only, μ _o , ε _o Are the permeability and permittivity of air, respectively, ω Is the angular frequency.

In the case of a multilayer wave absorber, the input impedance is the characteristic impedance of each medium layer. Z _c And its height d and propagation constant γ Can be displayed using.

That is, the input impedance Z _dn looking in the direction of the reflector from the incident surface a-a ′ of FIG. 41 can be expressed as shown in Equation (6) when the plane wave is incident vertically.

(6)

Where Z _dn is the input impedance of the n-th layer as the final stage, Z _dn-1 is the input impedance of the media layer to the _n-1 layer one layer before the final stage, Z _cn is the characteristic impedance of the n-th media layer, γ _n is the propagation constant of the nth stage medium layer, and d _n is the height of the nth stage layer. Equation (6) is characteristic impedance, as is known in electrical engineering. Z _c And its height d and γ It is the same as the formula in the case of connecting multiple lines of.

In general, the magnetic permeability and permittivity of a magnetic body can be expressed as a complex number as shown in Equation (7), and also has a frequency dispersion characteristic.

μ _{r =} μ _r1- j μ _r2

ε _{r =} ε _r1- j ε _r2 (7)

For example, the initial permeability of NiZn-based ferrite material itself depends on the material, μ _r Values of ₁ = 10-2500 are obtained, μ _r The value of ₂ μ _r Like ₁ , both values change with frequency. Of NiZn-based sintered ferrite materials ε _r1 The value of is about 12 to 15 depending on the material, but in this case it is almost constant for frequency. ε _r2 The value of is usually very small.

In the following description, simply referred to as the relative dielectric constant and relative permeability, respectively, the real part of equation (7), ε _r1 , μ _r1 The values are in direct current unless otherwise specified. In addition, the relative permeability and relative dielectric constant of the layer of interest is regarded as a layer occupied by a separate uniform medium equivalent to that. The relative permeability and relative dielectric constant will be referred to as "equivalent permeability" and "equivalent dielectric constant".

1 is a partially cutaway perspective view of a first to third embodiments of a radio wave absorber of the present invention;

2 is a plan view of the first to third embodiments of the electromagnetic wave absorber of the present invention;

3 is a side view of FIG. 1;

4 is a synthetic capacity model diagram of the first layer structure of the first to third embodiments of the electromagnetic wave absorber of the present invention;

5 is a synthetic inductance model diagram of the first layer structure of the first to third embodiments of the electromagnetic wave absorber of the present invention;

6 is a synthetic capacity model diagram of the second layer structure of the first to third embodiments of the electromagnetic wave absorber of the present invention;

7 is a synthetic inductance model diagram of the second layer structure of the first to third embodiments of the electromagnetic wave absorber of the present invention;

8, 9 and 10 are the absorption characteristics of Examples 1 to 3 of the radio wave absorber of the present invention,

11 is a partially cutaway perspective view of a fourth to sixth embodiments of a radio wave absorber of the present invention;

12 is a plan view of a fourth to sixth embodiments of a radio wave absorber of the present invention;

FIG. 13 is a side view of FIG. 11;

14 is a synthetic capacity model diagram of the first layer structure of the fourth to sixth embodiments of the electromagnetic wave absorber of the present invention;

Fig. 15 is a synthetic inductance model diagram of the first layer structure of the fourth to sixth embodiments of the electromagnetic wave absorber of the present invention;

16 is a synthetic capacity model diagram of a second layer structure of the fourth to sixth embodiments of the radio wave absorber of the present invention;

Fig. 17 is a synthetic inductance model diagram of the second layer structure of the fourth to sixth embodiments of the electromagnetic wave absorber of the present invention;

18 is a synthetic capacity model diagram of the third layer structure of the fourth to sixth embodiments of the radio wave absorber of the present invention;

Fig. 19 is a synthetic inductance model diagram of the third layer structure of the fourth to sixth embodiments of the electromagnetic wave absorber of the present invention;

20, 21 and 22 is an absorption characteristic diagram of Examples 4 to 6 of the radio wave absorber of the present invention,

23 is a partially cutaway perspective view of a seventh to ninth embodiment of a radio wave absorber of the present invention;

24 is a plan view of seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

25 is a side view of FIG. 23;

Fig. 26 is a synthetic capacity model diagram of the first layer structure of the seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

Fig. 27 is a synthetic inductance model diagram of the first layer structure of the seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

28 is a synthesized capacity model diagram of the second layer structure of the seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

29 is a synthetic inductance model diagram of the second layer structure of the seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

30, 31 and 32 are absorption characteristics of Examples 7 to 9 of the radio wave absorber of the present invention;

33 is a modified example of the seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

34 is still another modified example of the seventh to ninth embodiments of the electromagnetic wave absorber of the present invention;

35 is a cross-sectional structure diagram of a tile type ferrite wave absorber;

36 is an absorption characteristic diagram of the tile type ferrite wave absorber of FIG.

37 is a perspective view of a lattice type ferrite wave absorber;

38 is an enlarged perspective view of the section taken along the line G-G 'of FIG.

39 is a perspective view of a multi-layered ferrite wave absorber;

40 is an enlarged perspective view of a section taken along the line H-H 'of FIG. 39;

41 is a conceptual diagram of a multilayer electric wave absorber;

42 is a longitudinal sectional view of a strip line for conducting characteristic evaluation of an embodiment of the present invention;

FIG. 43 is a cross-sectional view of FIG. 42.

<Description of the code | symbol about the principal part of drawing>

M: reflector, F ₁ : tile type ferrite magnetic material,

F ₂ , F ₃ : column ferrite magnetic material, S: slot formed in tile ferrite magnetic material,

a: spacing between slots, d: width of slot and column ferrite magnetic material (F ₂ ),

d ': width of columnar ferrite magnetic body (F ₃ ), b: length of columnar ferrite magnetic body (F ₂ )

h ₁ , h ₂ , h ₃ : height of each layer measured in the direction of propagation ΔZ Slot thickness C: Air gap

The characteristics of the radio wave absorbers of the embodiments described below are all evaluated by measurement by plane (TEM) waves using strip lines as shown in longitudinal section and cross section in FIGS. 42 and 43, respectively.

In the embodiment, F ₁ is one layer as a tile ferrite magnetic material, F ₂ and F ₃ are two and three layers as columnar ferrite magnetic material, S and S ₁ are slots, and M is a reflecting plate.

A is the spacing between the slots, d is the width of the slot and column ferrite magnetic material F ₂ , d 'is the width of the column ferrite magnetic material F ₃ , h ₁ , h ₂ , h ₃ is measured in the direction of propagation Height of each layer, b is the length of columnar ferrite magnetic material F ₂ , ΔZ Is the thickness of the slot S measured from the surface of the tile-like ferrite magnetic body, C is the void, and is common to all drawings.

Examples 1 to 3

1 is a partially cutaway perspective view of a first to third embodiments of a radio wave absorber of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a side view of FIG. 1, and a tile-like ferrite magnetic body having a first layer on a reflecting plate M. F ₁ is attached, and the tile-type ferrite magnetic material F ₁ is formed to pass through the square slot S along the height direction in the longitudinal direction at a predetermined interval, and the square column type ferrite magnetic material F ₂ having two layers in the slot S is tiled. It will be inserted into a protrusion installed above the surface of the ferrite magnetic material F _1.

The material characteristics and dimensions of each part of Examples 1 to 3 are as follows.

Example Initial Permeability (K) Relaxation Frequency (fm) (MHz) a (mm) d (mm) h ₁ (mm) h ₂ (mm) F ₁ F ₂ F ₁ F ₂ One 2,000 ← 3.1 ← 20 15.6 6.6 10 2 2,000 ← 3.1 ← 20 15.5 6.5 10 3 2,500 2,000 2.5 3.1 20 15.2 6.4 10

Note: F ₁ and F ₂ are NiZn-based sintered ferrites with a relative dielectric constant of 14.

4 to 7 show the combined capacitance C and the synthesized inductance L of the first and second layers using the equivalent material integer calculation model for the unit structure of the radio wave absorption layers of the first to third embodiments. Can be calculated by

Synthesis capacity C and equivalent dielectric constant of the first layer structure ε _eff is each calculated | required as follows using FIG.

C _{1 =} ε _o ⋅ ε _r2 ⋅ ΔZ

(8)

(9)

Similarly, composite inductance L and equivalent permeability of the first layer structure μ _eff is each calculated | required as follows using FIG.

10

(11)

Equivalent relative dielectric constant of the second layer structure in the same way ε _eff and equivalent return on investment μ _eff is the same as Formula (12) and Formula (13), respectively.

(12)

(13)

In the above formulas 8 to 13 μ _r1 And μ _r2 Is the specific permeability of the ferrite material of the first layer and the second layer, μ _o is the vacuum (air layer) permeability ε _o Is the vacuum permittivity (hereafter, the same is true).

The absorption characteristics of Examples 1 to 3 were obtained as shown in FIGS. 8 to 10, and the frequency bands having the radio wave absorption ability of the reflection attenuation of 20 dB or more were 0.03 to 3.58 kHz and 0.03 for Examples 1 to 3, respectively. -3.69 kV and 0.03-3.97 kV were obtained.

Examples 4-6

FIG. 11 is a partially cutaway perspective view of the fourth to sixth embodiments of the radio wave absorber of the present invention, FIG. 12 is a plan view of FIG. 11, and FIG. 12 is a side view of FIG. 11, wherein the tile-type ferrite magnetic material F is a first layer on the reflecting plate M. ₁ is attached to the ferrite magnetic body F ₁ so that a square slot S penetrates along the height direction in the longitudinal and horizontal direction at a predetermined interval.

The slotted S is formed to be a second layer, a square pillar-type ferrite magnetic material F ₂ protrudes than the surface of the tile-type ferrite magnetic material F ₁ to be inserted into the installation and through a slotted S ₁ to the square pillar-type ferrite magnetic material F ₂ the The three-layered square columnar ferrite magnetic material F ₃ is provided by being protruded from the upper surface of the square columnar ferrite magnetic material F ₂ .

The material properties and the dimensions of each part of 4 to 6 of this embodiment are as follows.

Example Initial Permeability (K) Relaxation Frequency (fm) (MHz) a (mm) d (mm) d '(mm) h ₁ (mm) h ₂ (mm) h ₃ (mm) F ₁ F ₂ F ₃ F ₁ F ₂ F ₃ 4 2000 ← ← 3.1 ← ← 20 15.7 10.8 6.6 7.6 13 5 2000 ← ← 3.1 ← ← 20 15.7 10.6 6.4 7.5 9.6 6 2000 2500 3000 3.1 2.5 2.1 20 15.8 10.6 6.4 7.5 9.6

Note: F ₁ , F ₂ and F ₃ are NiZn-based sintered ferrites with a relative dielectric constant of 14.

14 to 19 show the combined capacitance C and the synthesized inductance L of the first to third layers using the equivalent material integer calculation model for the unit structure of the radio wave absorption layers of the fourth to sixth embodiments. Can be calculated by

Equivalent relative dielectric constant of single layer structure ε _eff and equivalent return on investment μ _eff is calculated | required as follows using FIG. 14 and FIG. 15 similarly to Examples 1-3.

(14)

(15)

Equivalent relative dielectric constant of the second layer structure ε _eff and equivalent return on investment μ _eff is calculated | required as follows using FIG. 16 and FIG. 17 similarly to Examples 1-3.

(16)

(17)

Equivalent dielectric constant of third layer structure ε _eff and equivalent return on investment μ _eff is calculated | required as follows using FIG. 18 and FIG. 19 similarly to Examples 1-3.

(18)

(19)

20 to 22, the absorption characteristics of the embodiments 4 to 6 were obtained, and the frequency bands having the radio wave absorbing ability of 20 dB or more with reflection amount were 0.03 to 6.68 kHz, 0.03 to 7.95 GHz and 0.03 for Examples 4 to 6, respectively. 7.92 kPa was obtained.

Examples 7-9

FIG. 23 is a partially cutaway perspective view of the seventh to ninth embodiments of the radio wave absorber of the present invention, FIG. 24 is a plan view of FIG. 23, and FIG. 25 is a side view of FIG. 23, wherein the tile-type ferrite magnetic material F ₁ is a first layer on the reflecting plate M. FIG. Is attached to the ferrite magnetic material F ₁ in the longitudinal direction along the height direction in the longitudinal direction of a certain interval through the square column S ferrite magnetic material F ₂ than the surface of the tile-like ferrite magnetic F ₁ It protrudes and is formed by inserting the cavity C symmetrically between the rectangular columnar ferrite magnetic material F ₂ and the side walls of the slot S.

The material properties and the dimensions of each part of Examples 7 to 9 are as follows.

Example Initial Permeability (K) Relaxation Frequency (fm) (MHz) a (mm) d (mm) b (mm) h ₁ (mm) h ₂ (mm) F ₁ F ₂ F ₁ F ₂ 7 2,000 ← 3.1 ← 20 15.2 12.2 7.8 11 8 2,000 ← 3.1 ← 20 14.9 12.1 7.5 10 9 2,500 3,000 2.5 2.1 20 14.9 11.9 7.5 9.9

Note: F ₁ and F ₂ are NiZn-based sintered ferrites with a relative dielectric constant of 14.

Using the equivalent material hydrometer model of the unit structure of the electromagnetic wave absorbing layer of Examples 7 to 9, the composite capacitance C and the composite inductance L of the first and second layers can be calculated from FIGS. 26 to 29. It is.

Equivalent relative dielectric constant of the first layer structure ε _eff and equivalent return on investment μ _eff is calculated | required as follows using FIGS. 24 and 25 similarly to Examples 1-3.

20

(21)

The equivalent dielectric constant is similar to that of the one-layer structure. ε _eff and equivalent return on investment μ _eff is calculated | required as follows using FIG. 28 and FIG. 29, respectively.

(22)

(23)

In Examples 7 to 9, absorption characteristics thereof were obtained as shown in Figs. 30 to 32, and the frequency bands having the radio wave absorption ability of the reflection attenuation amount of 20 dB or more were 0.03 to 6.68 kHz and 0.03 to 7.95 GHz, respectively. And 0.03 to 7.92 kPa were obtained.

In the present invention as described above, slot S is formed in the tile-type ferrite magnetic material F ₁ attached to the reflector plate M so that the slot-shaped ferrite magnetic material is protruded from the surface of the tile-type ferrite magnetic material F _{1 in} the slot S. be inserted to install or columnar ferrite magnetic material F ₂ and the slotted insert to be formed with a cavity C between S and also above the columnar ferrite magnetic material F ₂ a slotted S ₁ to columnar of the second form a ferrite magnetic material F _By inserting ₃ to protrude from the upper surface of the column ferrite magnetic material F ₂ , the permeability and permittivity of the layer through the air layer or air gap between the tile ferrite magnetic body and the column ferrite magnetic body are controlled to the required set values. As a result, the above problems in molding can be reduced, manufacturing is easy, and equivalent permeability And the equivalent dielectric constant can be easily adjusted to widen the absorption characteristics.

In Examples 7 to 9, the rectangular columnar ferrite magnetic F ₂ is inserted into the slot S such that the cavity C is formed on both sides of the columnar ferrite magnetic material, but the cross section of the columnar ferrite magnetic F ₂ is dried as shown in FIG. 33. The absorption characteristics are similar even when a plurality of symmetrical voids are formed in the shape of a model, a hexagon, or a +.

In addition, the embodiments 7 to 9 described above may be formed of only the first layer and the second layer, but may be formed of the first layer, the second layer, and the third layer as shown in FIG. 34.

As described above, the present invention is manufactured and assembled separately from the tile-type ferrite magnetic body and the columnar ferrite magnetic material, thereby making it easy to manufacture, economical, and wider than the conventional one.

Claims (5)

A tile-type ferrite magnetic material is attached to the reflecting plate, and the tile-type ferrite magnetic material is formed to have a slot along the height direction in the longitudinal direction of the predetermined interval a, so that the column-type ferrite magnetic material is inserted into the slot to protrude beyond the surface of the tile-type ferrite magnetic material. At the same time, the width of slot and column ferrite magnetic material is d, where d is 0 ≤ d ≤ 0.9a, and the height of column ferrite magnetic material is wider than the ferrite wideband ferrite absorber. 2. The broadband ferrite wave absorber according to claim 1, wherein the columnar ferrite magnetic material is formed by forming an upper layer and a lower layer, respectively, and forming an upper layer smaller than the lower layer, and forming a slot in the lower layer to insert the upper layer. The tile-type ferrite magnetic body is attached to the reflector, and the tile-type ferrite magnetic body protrudes a slot along the height direction in the longitudinal direction of the predetermined interval a, and the space is symmetrical between the columnar ferrite magnetic body and the slot. When the width of the slot and the ferrite ferrite is inserted d and d is 0 ≤ d ≤ 0.9 a, the height of the ferrite ferrite is wider than that of the broadband ferrite absorber 4. The broadband ferrite absorber according to claim 3, wherein the columnar ferrite magnetic material forms upper and lower layers, respectively, and has an upper layer smaller than the lower layer, and a slot is formed in the lower layer to insert the upper layer. 4. The broadband ferrite wave absorber according to claim 3, wherein the cross section of the columnar ferrite magnetic body is selected from square, rectangular, rhombus, hexagonal and + type.