CN112072220A - An Absorptive Broadband Bandpass Spatial Filter - Google Patents

Abstract

The absorptive broadband bandpass spatial filter disclosed in the present invention includes a plurality of square filter units arranged periodically, and each filter unit includes a loss absorption layer, an air layer and a lossless bandpass layer arranged in sequence. The absorption layer and the lossless bandpass layer are separated by an air layer, the lossy absorption layer includes a first metal layer and a first lossy dielectric layer, and the lossless bandpass layer includes a second metal layer, a second lossy dielectric layer, a third a metal layer, a third lossy dielectric layer and a fourth metal layer. The filter has bilateral broadband absorption characteristics and excellent broadband absorption capability. Its absorption bandwidth can reach 117.6% and 21.4% respectively, and the relative transmission bandwidth can reach 47%. At the same time, the filter has a wide-band passband, which can meet some scenarios that put forward broadband requirements for the working frequency band. Compared with the traditional filter structure, it has more practical application value.

Description

An Absorptive Broadband Bandpass Spatial Filter

technical field

The present invention relates to a spatial filter, in particular to an absorbing broadband bandpass spatial filter.

Background technique

With the development of science and technology, the development of electronic equipment tends to be diversified and universal, the electromagnetic environment is increasingly complex, and the communication system has higher and higher requirements for electromagnetic compatibility. In the design of traditional bandpass filters, only the low insertion loss characteristics of the working frequency band are considered, and the interference of out-of-band noise signals is often achieved only by enhancing reflection. However, the reflected stray signals in this part will affect other electronic equipment and drastically deteriorate broadband communication. System technical indicators. How to ensure the normal communication of signals in the in-band working frequency band and suppress out-of-band interference signals has become an important issue.

At the same time, in modern warfare, radar target stealth is one of the very important indicators. Among them, the radar antenna system is an important scattering source, which has a very high radar cross section (RCS) at certain frequencies. There are two main ways to reduce the radar cross section: one is to coat absorbing materials such as ferrite and magnetic materials, but this absorbing coating method will significantly reduce the radiation efficiency of the antenna and affect normal signal transmission and reception; The structure similar to the frequency selective surface is adopted to change the reflection direction of the reflected wave and reduce the forward radiation signal. This method does not affect the performance of the antenna itself, but its secondary scattered spurious signals can still interfere with communication system equipment. And with the development of multi-station radar and radar networking technology, this method cannot achieve the purpose of true stealth. How to realize the integrated design of communication and broadband absorption has also become an important topic.

In recent years, the development of electromagnetic metamaterials has achieved remarkable results. Similar to Frequency Selective Surface (FSS), a two-dimensional structure composed of a large number of periodically arranged metal resonator elements with specific shapes can realize band-stop, low-pass, high-pass, and band-pass spatial filter designs. In the traditional frequency selective surface design, the electromagnetic interference caused by its out-of-band reflection is not considered. In this context, the absorptive band-pass filter came into being, which not only ensures the free transmission and reception of pass-band signals, but also absorbs the signals outside the pass-band, so as to achieve the perfect combination of stealth/absorption and normal communication. However, it is difficult to design the structure due to taking into account both the wave-transmitting and wave-absorbing capabilities. The design method generally adopted at present can be summarized into three steps: first, load lumped resistance elements on the metal strips to achieve impedance matching in a certain frequency band. The second step is to use the metal strips loaded by lumped resistance to create some structures that can be equivalent to capacitor-like and inductive devices. These LC equivalent circuit structures are used in specific Resonance occurs in the absorbing frequency band, the impedance is close to infinity, and it cannot match the free space, so the energy cannot be absorbed, but a reflection band is formed; the third step is to use the band-pass FSS instead of the original metal grounding plate structure. The pass band matches the reflection band in the second step, and finally achieves the effect of absorption and penetration. At present, absorptive filters are still faced with the following bottlenecks: First, the existing designs are mostly low-frequency transmission/high-frequency absorption or high-frequency transmission/low-frequency absorption single-sideband absorption, which has a relatively good effect in practical applications. Second, although transmission and bilateral absorption have been reported, most of them increase the relative absorption bandwidth on the basis of sacrificing the transmission bandwidth, and it is difficult to take into account both broadband transmission and broadband absorption capabilities. Therefore, the research on spatial filters with both broadband transmission and broadband absorption capabilities has also become an important topic.

SUMMARY OF THE INVENTION

Aiming at the problems of electromagnetic compatibility and radar target stealth in a complex electromagnetic environment, the present invention proposes an absorbing broadband bandpass spatial filter. The spatial filter has bilateral broadband absorption characteristics, excellent broadband absorption capability, and can realize the detection of signals in the working frequency band. At the same time, the spatial filter has a wide-band passband, which can meet some scenarios that require broadband for the working frequency band.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: an absorbing broadband bandpass spatial filter, comprising a plurality of square filter units arranged in a periodical manner, and each of the filter units includes sequentially arranged filter units. A lossy absorption layer, an air layer and a lossless bandpass layer, the lossy absorption layer and the lossless bandpass layer are separated by the air layer, and the lossy absorption layer includes a first metal layer and a first lossy The dielectric layer, the first metal layer is attached to the front surface of the first lossy dielectric layer, the first metal layer includes two independent metal pattern structures, and the first metal layer is loaded with collectors. A total resistance element, the lossless bandpass layer includes a second metal layer, a second lossy dielectric layer, a third metal layer, a third lossy dielectric layer and a fourth metal layer stacked in sequence, the second metal layer The layer is a patch-type metal layer composed of four identical and centrally symmetrical square metal films. The third metal layer is a hollow metal layer that is complementary in shape to the second metal layer. The fourth metal layer is exactly the same as the second metal layer, and the first lossy dielectric layer, the second lossy dielectric layer and the third lossy dielectric layer are completely the same lossy dielectric layer.

The absorptive broadband bandpass spatial filter of the present invention realizes the broadband absorbing bands on the high and low frequency sides respectively by introducing two independent metal pattern structures into the first metal layer of the loss absorbing layer and loading lumped resistance elements, which absorbs The bandwidth can reach 117.6% and 21.4% respectively, and the relative transmission bandwidth can reach 47%. Compared with the traditional filter structure with only one-side absorption band, it has more practical application value; by introducing a multi-layer structure in the lossless bandpass layer , improving the impedance matching of broadband, broadening the frequency range of band-pass filtering, and providing a solution for the integrated design of broadband communication and wave absorption.

The second metal layer, the second lossy dielectric layer, the third metal layer, the third lossy dielectric layer and the fourth metal layer together constitute a lossless bandpass layer, which realizes the performance of broadband wave transmission.

The materials used in the absorptive broadband bandpass space filter of the present invention are all conventional materials, which are easy to realize and have low manufacturing cost, and can be manufactured simply by using the existing PCB processing technology. Frequency tuning can be achieved through scaling and appropriate parameter adjustment, and it can be perfectly transplanted to other frequency bands.

Preferably, in each of the filter units, the first metal layer is a center-symmetric patch metal pattern structure, and the patch metal pattern structure of the first metal layer includes a "mouth"-shaped metal pattern structure and "well" shaped metal graphic structure, the "mouth" shaped metal graphic structure is close to the outer edge of the filter unit, and the "mouth" shaped metal graphic structure is formed by connecting four first metal strips in sequence, A first resistance element is welded at the center of each of the first metal strips; the "well"-shaped metal pattern structure is located in the middle of the area enclosed by the "mouth"-shaped metal pattern structure, and the The "well"-shaped metal pattern structure is formed by four second metal strips intersecting vertically in turn, and the included angle between each of the second metal strips and any one of the first metal strips is 45°. A second resistance element is welded at the center of the second metal strip, and the resistance value of each of the second resistance elements is different from that of each of the first resistance elements. The "mouth"-shaped metal pattern structure loaded with four first resistance elements realizes the absorption of electromagnetic waves on the low-frequency side, and the "well"-shaped metal pattern structure loaded with four second resistance elements realizes the electromagnetic wave absorption on the high-frequency side. absorb.

Preferably, the periodic side length of each of the filter units is 20-22 mm; in each of the filter units, the length of each of the first metal strips is 18-20 mm, and the width is 0.5-20 mm. 1 mm, the distance between each of the first metal strips and the outer edge of the adjacent filter unit is 0.5-1 mm, the length of each of the second metal strips is 9-13 mm, and the width is 0.5-1 mm.

Preferably, the resistance value of each of the first resistance elements is 300-550Ω.

Preferably, the distance between the inner edges of each pair of the two second metal strips parallel to each other is 3 to 4 mm.

Preferably, the resistance value of each of the second resistance elements is 100-300Ω.

Preferably, in each of the filter units, each piece of the square metal film has a side length of 5-7 mm, and each piece of the square metal film is outside the adjacent filter unit in the X-axis direction. The distance of the edge and the distance from the outer edge of the adjacent filter unit in the Y-axis direction are equal to 1.5~2.5mm.

Preferably, the thicknesses of the first metal layer, the second metal layer, the third metal layer and the fourth metal layer are all 0.03 mm, the thickness of the air layer is 13.5-14.5 mm, and the first metal layer has a thickness of 13.5-14.5 mm. The thicknesses of the lossy dielectric layer, the second lossy dielectric layer and the third lossy dielectric layer are all 1.45-1.65 mm.

Preferably, the first lossy dielectric layer, the second lossy dielectric layer and the third lossy dielectric layer are all Rogers 4003C dielectric plates with a relative permittivity of 3.38 and a loss tangent value of 0.0027.

Compared with the prior art, the present invention has the following advantages:

(1) The absorptive broadband bandpass spatial filter proposed by the present invention realizes the broadband absorption on the high and low frequency sides respectively by introducing two independent metal pattern structures in the first metal layer of the loss absorbing layer and loading lumped resistance elements. Band, its absorption bandwidth can reach 117.6% and 21.4% respectively, and the relative transmission bandwidth can reach 47%, which can realize free sending and receiving of signals in the working frequency band and absorption of interference signals on both sides of the passband. At the same time, the spatial filter has a The wide-band passband can meet some scenarios that require broadband for the working frequency band. Compared with the traditional filter structure with only one-side absorption band, it has more practical application value;

(2) By introducing a multi-layer structure into the lossless bandpass layer, the impedance matching of broadband is improved, the frequency range of bandpass filtering is broadened, and a solution is provided for the integrated design of broadband communication and wave absorption;

(3) A broadband bandpass spatial filter with a double-sided wide absorption band proposed by the present invention uses conventional materials, is easy to implement, and has low manufacturing cost, and can be manufactured simply by using the existing PCB processing technology. Frequency tuning can be achieved through scaling and appropriate parameter adjustment, and it can be perfectly transplanted to other frequency bands.

Description of drawings

1 is a front view of an absorptive broadband bandpass spatial filter in an embodiment;

2 is a front view of a single filter unit in an embodiment;

Fig. 3 is the left side view corresponding to Fig. 2;

4 is a front view of a single filter unit in the embodiment after removing the first metal layer, the first lossy dielectric layer and the air layer;

5 is a front view of a single filter unit in an embodiment with the first metal layer, the first lossy dielectric layer, the second metal layer and the second lossy dielectric layer removed;

Fig. 6 is the S-parameter simulation curve diagram of the filter in the embodiment 1 when the electromagnetic wave is incident along the -Z direction;

Fig. 7 is the simulation curve diagram of the wave absorption rate of the filter in the embodiment 1 when the electromagnetic wave is incident along the -Z direction;

Fig. 8 is the S-parameter simulation curve diagram of the filter in the embodiment 2 when the electromagnetic wave is incident along the -Z direction;

FIG. 9 is a simulation curve diagram of the wave absorption rate of the filter in Example 2 when the electromagnetic wave is incident along the -Z direction.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments of the accompanying drawings.

As shown in the figure, the absorptive broadband bandpass spatial filter of Embodiment 1 includes 9 square filter units 1 arranged periodically, and each filter unit 1 includes a loss absorbing layer 2, an air Layer 3 and lossless bandpass layer 4, lossy absorption layer 2 and lossless bandpass layer 4 are separated by an air layer 3, lossy absorption layer 2 includes a first metal layer 22 and a first lossy dielectric layer 21, the first metal layer 22 is attached to the On the front side of the first lossy dielectric layer 21, the first metal layer 22 includes two independent metal pattern structures, the first metal layer 22 is loaded with a lumped resistance element, and the lossless bandpass layer 4 includes a second metal layer stacked one after the other. Layer 41 , second lossy dielectric layer 42 , third metal layer 43 , third lossy dielectric layer 44 and fourth metal layer 45 , the second metal layer 41 is composed of four identical square metal films 46 arranged symmetrically in the center The patch-type metal layer is formed, the third metal layer 43 is a hollow metal layer whose shape is complementary to the second metal layer 41, the fourth metal layer 45 is exactly the same as the second metal layer 41, the first lossy dielectric layer 21, the second metal layer 41 The lossy dielectric layer 42 and the third lossy dielectric layer 44 are completely identical lossy dielectric layers.

In each filter unit 1 of Embodiment 1, the first metal layer 22 is a center-symmetric patch metal pattern structure, and the patch metal pattern structure of the first metal layer 22 includes a "mouth"-shaped metal pattern structure 23 and a "well". "-shaped metal pattern structure 24, "mouth"-shaped metal pattern structure 23 is close to the outer edge of the filter unit 1, "mouth"-shaped metal pattern structure 23 is formed by connecting four first metal strips 25 in turn, each first metal A first resistance element 26 is welded at the center of the bar 25; the "well"-shaped metal pattern structure 24 is located in the middle of the area enclosed by the "mouth"-shaped metal pattern structure 23, and the "well"-shaped metal pattern structure 24 consists of four second The metal strips 27 are vertically crossed in sequence, and the included angle between each second metal strip 27 and any one of the first metal strips 25 is 45°, and a second resistance element 28 is welded to the center of each second metal strip 27 . The resistance value R 1 of each _{second resistance element 28 is different from the resistance value R 2 of} each first resistance element 26 .

In Example 1, the first metal layer 22, the second metal layer 41, the third metal layer 43 and the fourth metal layer 45 are metal materials of the same material, and the thickness H1 is 0.03mm; the thickness H3 of the air layer 3 is 14mm The first lossy dielectric layer 21, the second lossy dielectric layer 42 and the third lossy dielectric layer 44 are all Rogers 4003C dielectric plates, the thickness H2 is 1.524mm, the relative dielectric constant is 3.38, and the loss tangent value is 0.0027.

The periodic side length P of each filter unit 1 in Embodiment 1 is 20 mm; in each filter unit 1, the length L1 of each first metal strip 25 is 19 mm, and the width W1 is 0.5 mm. The distance W2 between the strips 25 and the adjacent outer edge of the filter unit 1 is 0.5mm, the length L2 of each second metal strip 27 is 9mm, the width W3 is 0.5mm, and each pair of two parallel second metal strips The inner side spacing W4 of 27 is 4 mm; the resistance value R ₁ of each first resistance element 26 is 500Ω, and the resistance value R ₂ of each second resistance element 28 is 150Ω.

In each filter unit 1 of Embodiment 1, the side length L3 of each square metal film 46 is 6.7 mm, and the distance W5 between each square metal film 46 and the adjacent outer edge of the filter unit 1 in the X-axis direction. And the distance W5 with the adjacent outer edge of the filter unit 1 in the Y-axis direction is equal to 1.65mm _; the third metal layer 43 is a hollow with a side length w6 of 6.5mm complementary to the shape of the second metal layer 41 metal layer.

The absorptive broadband bandpass spatial filter of Embodiment 2 has the same structure as that of Embodiment 1, and the difference is only that the values of some size parameters are different. Specifically, in Embodiment 2, L3=7mm, W5=1.5mm, W6=7mm, H3=18mm.

Fig. 6 is the S-parameter simulation curve diagram of the filter in Example 1 when the electromagnetic wave is incident along the -Z direction, in Fig. 6, S ₁₁ and S ₁₂ represent the reflection curve and the transmission curve respectively; Fig. 7 is when the electromagnetic wave is incident along the -Z direction The simulation curve diagram of the wave absorption rate of the filter in Example 1. It can be seen from Fig. 7 that when the frequency range of the simulation curve of the absorption rate on the low frequency side is 1.43-5.51 GHz, the absorption rate of the filter of Example 1 is always higher than 80%, and the relative absorption bandwidth is 117.6%; When the frequency range of the absorption rate simulation curve is 12.07-14.96 GHz, the absorption rate of the filter of Example 1 is always higher than 80%, and the relative absorption bandwidth is 21.4%.

Fig. 8 is the S-parameter simulation curve diagram of the filter in Example 2 when the electromagnetic wave is incident along the -Z direction, in Fig. 8, S ₁₁ and S ₁₂ represent the reflection curve and the transmission curve respectively; Fig. 9 is when the electromagnetic wave is incident along the -Z direction The simulation curve diagram of the wave absorption rate of the filter in Example 2. It can be seen from Fig. 9 that when the frequency range of the wave absorption rate simulation curve on the low frequency side is 1.25~4.71GHz, the wave absorption rate of the filter of Example 2 is always higher than 80%, and the relative absorption bandwidth is 116.1%; When the frequency range of the wave absorption rate simulation curve is 10.4-12.53 GHz, the absorption rate of the filter of Example 2 is always higher than 80%, and the relative absorption bandwidth is 16.7%.

Claims (9)

1. The utility model provides an absorptive broadband band-pass spatial filter, its characterized in that is including being the square filter unit of a plurality of that the cycle was arranged, every filter unit loss absorbed layer, air bed and the lossless band-pass layer that sets gradually around including, the loss absorbed layer with lossless band-pass layer by the air bed separate, the loss absorbed layer include first metal level and first loss dielectric layer, first metal level adhere to first loss dielectric layer's front, first metal level include two independent metal pattern structures, first metal level on load with lumped resistance component, lossless band-pass layer including around superpose second metal level, second loss dielectric layer, third metal level, third loss dielectric layer and the fourth metal level in proper order, the second metal level be by four pieces of complete sameness and be the paster type metal level that central symmetry arranged's square metal film constitutes, the third metal layer is a hollow metal layer with a shape complementary to that of the second metal layer, the fourth metal layer is completely the same as that of the second metal layer, and the first loss dielectric layer, the second loss dielectric layer and the third loss dielectric layer are completely the same loss dielectric layers.

2. The absorptive broadband bandpass spatial filter according to claim 1, wherein in each filter unit, the first metal layer is a centrosymmetric patch metal pattern structure, the patch metal pattern structure of the first metal layer comprises a square-shaped metal pattern structure and a square-shaped metal pattern structure, the square-shaped metal pattern structure is close to the outer edge of the filter unit, the square-shaped metal pattern structure is formed by sequentially connecting four first metal strips, and a first resistance element is welded at the center of each first metal strip; the 'well' -shaped metal pattern structure is positioned in the middle of an area defined by the 'square' -shaped metal pattern structure, the 'well' -shaped metal pattern structure is formed by sequentially and vertically crossing four second metal strips, an included angle between each second metal strip and any one first metal strip is 45 degrees, a second resistance element is welded in the center of each second metal strip, and the resistance value of each second resistance element is different from that of each first resistance element.

3. An absorptive broadband bandpass spatial filter according to claim 2, wherein each of the filter cells has a period side length of 20 to 22 mm; in each filter unit, the length of each first metal strip is 18-20 mm, the width of each first metal strip is 0.5-1 mm, the distance between each first metal strip and the outer edge of the adjacent filter unit is 0.5-1 mm, and the length of each second metal strip is 9-13 mm, and the width of each second metal strip is 0.5-1 mm.

4. An absorptive broadband bandpass spatial filter according to claim 3, wherein each of the first resistive elements has a resistance of 300 to 550 Ω.

5. An absorptive broadband bandpass spatial filter according to claim 3, wherein the inner edge distance between each pair of two parallel second metal strips is 3-4 mm.

6. An absorptive broadband bandpass spatial filter according to claim 3, wherein the resistance of each second resistive element is 100 to 300 Ω.

7. The absorptive broadband bandpass spatial filter according to claim 1, wherein each of the filter cells has a side length of 5 to 7mm, and a distance between each of the square metal films and an outer edge of the adjacent filter cell in the X-axis direction is equal to a distance between the square metal film and an outer edge of the adjacent filter cell in the Y-axis direction, and the distances between the square metal film and the outer edge of the adjacent filter cell in the Y-axis direction are equal to each other and are 1.5 to 2.5 mm.

8. The absorptive broadband bandpass spatial filter according to claim 1, wherein the thicknesses of the first metal layer, the second metal layer, the third metal layer and the fourth metal layer are all 0.03mm, the thickness of the air layer is 13.5-14.5 mm, and the thicknesses of the first loss dielectric layer, the second loss dielectric layer and the third loss dielectric layer are all 1.45-1.65 mm.

9. The absorptive broadband bandpass spatial filter according to claim 1, wherein the first, second and third lossy dielectric layers are Rogers 4003C dielectric plates having a relative dielectric constant of 3.38 and a loss tangent of 0.0027.

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