KR20070061155A - Single frequency band pass/rejection filter using frequency selective surface technique - Google Patents

Abstract

A FSS(Frequency Selective Surface) spatial filter is provided to filter a required filtering target frequency band by adjusting geometrical length and shape, material and the layer number of unit cells. A loop(12) is geometrically entangled by using a space-filling curve principle. A support(13) supports the loop. A unit cell of a single period consists of the loop and the substrate. A wanted frequency is selectively transmitted/reflected according to a geometrical shape of the loop, array and period of the unit cell, and material feature of the loop and the substrate. The length, thickness and material of the loop are adjusted to tune a filtering center frequency.

Description

Single frequency band pass / rejection filter using frequency selective surface technique

1 is a configuration diagram of an embodiment of a single frequency band transmission / blocking FSS spatial filter according to the present invention;

2 is a diagram illustrating a detailed structure of a unit cell and a parameter thereof of a single frequency band transmission / blocking FSS spatial filter according to the present invention;

3A is a diagram illustrating a detailed structure of a unit cell side cross section of a single frequency band transmission / blocking FSS spatial filter according to the present invention and parameters thereof;

FIG. 3B is a diagram illustrating a detailed structure of a unit cell side cross section and a parameter thereof when a single frequency band transmission / blocking FSS spatial filter according to the present invention operates as a band cut filter; FIG.

FIG. 3C is a diagram illustrating a detailed structure of a unit cell side cross section and a parameter thereof when a single frequency band transmission / blocking FSS spatial filter according to the present invention operates as a band pass filter; FIG.

4A is a diagram illustrating a detailed structure of a side surface of a unit cell when a single frequency band transmission / blocking FSS spatial filter having a stacked structure according to the present invention operates as a band cut filter and its related parameters;

4B is a diagram illustrating a detailed structure of a side surface of a unit cell when a single frequency band transmission / blocking FSS spatial filter having a stacked structure according to the present invention operates as a band pass filter and parameters thereof; FIG.

5 is an explanatory diagram showing a frequency characteristic of a single frequency band transmission / blocking FSS spatial filter having a structure as shown in FIG. 3B according to the present invention;

6 is a diagram illustrating an embodiment of a frequency characteristic of a single frequency band transmission / blocking FSS spatial filter having a stacked structure according to the present invention;

7A to 7C are diagrams illustrating a unit cell modification of a single frequency band transmission / blocking FSS spatial filter according to the present invention.

* Explanation of symbols for the main parts of the drawings

11: unit cell 12: loop

13 substrate 31 first conductor

32: first dielectric 33: second dielectric

34: third dielectric 35: second conductor

36: fourth dielectric 37: fifth dielectric

38: sixth dielectric 41: third conductor

42: fourth conductor 43: seventh dielectric

44: eighth dielectric 45: ninth dielectric

46: Tenth Dielectric 47: Eleventh Dielectric

48: fifth conductor 49: sixth conductor

50: 12th dielectric 51: 13th dielectric

52: 14th Dielectric 53: 15th Dielectric

54: 16th Dielectric 55: 17th Dielectric

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency selective surface (FSS) spatial filter for single frequency band transmission / blocking, and more particularly, to apply a loop structure to the FSS to reduce an area and to form geometrical lengths of loops, dielectrics, and conductors constituting the FSS. And a single frequency that allows filtering (transmission / blocking) for the desired frequency band to be filtered by adjusting the thickness, material, and number of layers of the unit cell, and has a constant frequency bandwidth around the required frequency to be filtered. A FSS spatial filter for band transmission / blocking.

FSS refers to a surface artificially manufactured to selectively transmit or reflect a desired frequency. The frequency selective characteristic of the FSS is obtained by arranging conductors or apertures at regular intervals. In this case, a structure corresponding to one period in the FSS is referred to as a unit cell.

The FSS obtains the frequency characteristics desired by the user as the frequency response characteristic varies greatly depending on the geometric shape of the structure selected as the unit cell, the arrangement type and period of the unit cell, and the material characteristics of the dielectric and conductor used. This requires a thorough understanding of the FSS, and based on this foundation, various methods for the design of the FSS have been proposed.

In the present invention, a spatial filter capable of filtering desired frequency bands is designed using FSS. Of course, in the past, various attempts have been made to filter a single frequency band using the FSS. However, in order to improve the performance of the FSS, the area of the unit cell also increases as the area occupied by the geometries constituting the unit cell increases. As a result, the total area of the FSS was increased. This increase in area of FSS is not suitable for applications that allow only a small amount of space.

The present invention has been proposed to solve the above problems, by applying a loop structure to the FSS to reduce the area, and to control the geometric length and thickness of the loop, dielectric, conductor, etc. constituting the FSS, the material, and the number of layers of the unit cell It is an object of the present invention to provide a single frequency band transmission / blocking FSS spatial filter capable of filtering the required frequency band to be filtered and having a constant frequency bandwidth around the desired frequency to be filtered.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In accordance with one aspect of the present invention, there is provided a frequency selective surface (FSS) spatial filter for single frequency band transmission / blocking, the loop being geometrically entangled using a space-filling curve principle; A substrate for supporting the loop; And a unit cell of a single cycle consisting of the loop and the substrate, and selectively transmitting a desired frequency according to the geometrical shape of the loop, the arrangement and period of the unit cell, and the material properties of the loop and the substrate. It can be reflected.

In the present invention, a loop structure is proposed to reduce the area of the FSS unit cell. Therefore, it is possible to reduce the overall manufacturing area of the FSS by using this structure, and thus effective filtering (transmission / blocking) is possible even in applications requiring a relatively small area. In addition, the FSS of the present invention has no influence on the polarization of the electromagnetic wave, and can accurately cut off the frequency at the frequency of the band requiring filtering.

The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. Could be. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an embodiment of a single frequency band transmission / blocking FSS spatial filter according to the present invention.

As shown in Fig. 1, the FSS spatial filter for single frequency band transmission / blocking according to the present invention occupies a minimum area by using a geometrically complicated loop (spare-filling curve principle). Off length) 12 is composed of an array of unit cells (11) consisting of.

2 is a diagram illustrating an embodiment of a detailed structure and parameters of a unit cell of a single frequency band transmission / blocking FSS spatial filter according to the present invention.

As shown in FIG. 2, the unit cell of the single frequency band transmission / blocking FSS spatial filter according to the present invention includes a complex intertwined loop 12 and a substrate 13 for supporting the loop 12. . In particular, the material of the loop 12 and the substrate 13 is determined according to the filtering role of the transmission / blocking FSS spatial filter. That is, when the transmission / blocking FSS spatial filter operates as a band cut filter, the loop 12 is made of a conductor and the substrate 13 is made of a dielectric. On the other hand, when the transmissive / blocking FSS spatial filter acts as a bandpass (pass) filter, the loop 12 is made of a dielectric and the substrate 13 is made of a conductor.

However, each parameter of the unit cell 11 illustrated in FIG. 2 will be described in more detail below.

FIG. 3A is a diagram illustrating a detailed structure of a unit cell side cross section of a single frequency band transmission / blocking FSS spatial filter according to the present invention and parameters thereof. FIG.

Referring to FIG. 3A, a side cross-sectional view of a unit cell of a single frequency band transmission / blocking FSS spatial filter according to the present invention includes a loop 12 and a substrate 13 supporting the same.

FIG. 3B is a diagram illustrating a detailed structure of a unit cell side cross section and a parameter thereof when a single frequency band transmission / blocking FSS spatial filter according to the present invention operates as a band cut filter. FIG. As described above, when the transmission / blocking FSS spatial filter is used as a band cut (stop) filter, the loop is composed of a conductor 31 and a part of the substrate is composed of a dielectric 33.

이고 상대유전율이

인 제1 유전체(32)와 맞닿아 있고, 타측은 두께가

이고 상대유전율이

인 제3 유전체(34)와 맞닿아 있으며, 그리고 두께가 t이고 너비가 W인 제1 도체(31)의 두께 양측면이 상대유전율이

인 제2 유전체(33)와 맞닿아 있는 형태로 이루어진다.Referring to FIG. 3B, a cross-sectional view of a unit cell of a single frequency band transmission / blocking FSS spatial filter according to the present invention when operating as a band cut filter shows a first conductor 31 having a thickness of t and a width of W. FIG. One side of the width side of the

And the relative dielectric constant

Is in contact with the first dielectric layer 32, and the other side has a thickness

And the relative dielectric constant

Contacting the third dielectric 34, and both sides of the first conductor 31 having a thickness of t and a width of W have a relative dielectric constant

The second dielectric 33 is in contact with the phosphor.

That is, in the case where the single frequency band transmission / blocking FSS spatial filter operates as a band blocking (stopping) filter as shown in FIG. 3B, the dielectric 33 of the substrate covers the entire conductor 31 corresponding to the loop. Can be designed.

3C is a diagram illustrating a detailed structure of a unit cell side cross section and a parameter thereof when a single frequency band transmission / blocking FSS spatial filter according to the present invention operates as a band pass filter. As described above, when the transmission / blocking FSS spatial filter is used as a band transmission (pass) filter, the loop is composed of the dielectric 37 and a part of the substrate is composed of the conductor 35.

이고 상대유전율이

인 제4 유전체(36)와 맞닿아 있고, 타측은 두께가

이고 상대유전율이

인 제6 유전체(38)와 맞닿아 있으며, 그리고 두께가 t인 제2 도체(35)의 두께 양측 면이 상대유전율이

이고 너비가 W인 제5 유전체(37)와 맞닿아 있는 형태로 이루어진다.Referring to FIG. 3C, a cross-sectional view of a unit cell of a single frequency band transmission / blocking FSS spatial filter according to the present invention when operating as a band pass filter shows a width side of a second conductor 35 having a thickness of t. One side is thick

And the relative dielectric constant

In contact with the fourth dielectric layer 36, the other side having a thickness

And the relative dielectric constant

Contacting the sixth dielectric layer 38 and having a thickness t on both sides of the second conductor 35 having a thickness t

And a fifth dielectric 37 having a width W.

4A is a diagram illustrating a detailed structure of a side surface of a unit cell and a parameter thereof when a single frequency band transmission / blocking FSS spatial filter having a stacked structure according to the present invention operates as a band cut filter.

이고 상대유전율이

인 제7 유전체(43)와 맞닿아 있고, 타측은 두께가

이고 상대유전율이

인 제9 유전체(45)와 맞닿아 있으며, 그리고 두께가 t이고 너비가 W인 제3 도체(41)의 두께 양측 면이 상대유전율이

인 제8 유전체(44)와 맞닿아 있다[제1 적층 구조]. 또한, 제2 적층 구조를 살펴보면, 두께가

이고 너비가 W인 제4 도체(42)의 너비 측면의 일측은 제9 유전체(45)와 맞닿아 있고, 타측은 두께가

이고 상대유전율이

인 제11 유전체(47)와 맞닿아 있으며, 두께가

이고 너비가 W인 제4 도체(42)의 두께 양측 면이 상대유전율이

인 제 10 유전체(46)와 맞닿아 있는 형태로 이루어진다. Referring to FIG. 4A, when a side cross-section of a unit cell of a single frequency band transmission / blocking FSS spatial filter according to the present invention, which is a stacked structure when operating as a band cut filter, is shown, a third having a thickness of t and a width of W is shown. One side of the width side of the conductor 41 has a thickness

And the relative dielectric constant

Is in contact with the seventh dielectric material 43, and the other side

And the relative dielectric constant

Contacting the ninth dielectric 45, and both sides of the third conductor 41 having a thickness of t and a width of W have a relative dielectric constant of

In contact with the eighth dielectric member 44 (first laminated structure). In addition, looking at the second laminated structure, the thickness is

One side of the width side of the fourth conductor 42 having a width W is in contact with the ninth dielectric 45, and the other side has a thickness.

And the relative dielectric constant

In contact with the eleventh dielectric 47

And both sides of the fourth conductor 42 having a width of W have a relative dielectric constant

In contact with the tenth dielectric member 46.

4B is a diagram illustrating a detailed structure of a unit cell side cross section and a parameter thereof when a single frequency band transmission / blocking FSS spatial filter having a stacked structure according to the present invention operates as a band pass filter.

이고 상대유전율이

인 제12 유전체(50)와 맞닿아 있고, 타측은 두께가

이고 상대유전율이

인 제 14 유전체(52)와 맞닿아 있으며, 그리고 두께가 t인 제5 도체(48)의 두께 양측 면이 상대유전율이

이고 너비가 W인 제13 유전체(51)와 맞닿아 있다[제1 적층 구조]. 또한, 제2 적층 구조를 살펴보면, 두께가

인 제6 도체(49)의 너비 측면의 일측은 두께가

이고 상대유전율이

인 제15 유전체(53)와 맞닿아 있고, 타측은 두께가

이고 상대유전율이

인 제17 유전체(55)와 맞닿아 있으며, 두께가

인 제6 도체(49)의 두께 양측 면이 상대유전율이

이고 너비가 W인 제16 유전체(54)와 맞닿아 있고, 제14 유전체(52)의 너비 측면과 제15 유전체(53)의 너비 측면이 맞닿아 있는 형태로 이루어진다.Referring to FIG. 4B, a side cross-sectional view of a unit cell of a single frequency band transmission / blocking FSS spatial filter according to the present invention, which is a stacked structure when operating as a band pass filter, has a thickness t of the fifth conductor 48. One side of the width side of the

And the relative dielectric constant

Is in contact with the twelfth dielectric member 50, and the

And the relative dielectric constant

Contacting the fourteenth dielectric 52 and having a thickness t on both sides of the fifth conductor 48 have a relative dielectric constant

And a thirteenth dielectric 51 having a width W (first laminated structure). In addition, looking at the second laminated structure, the thickness is

One side of the width side of the sixth conductor 49

And the relative dielectric constant

In contact with the fifteenth dielectric layer 53 and having a thickness

And the relative dielectric constant

In contact with the seventeenth dielectric material 55,

The surface of both sides of the sixth conductor 49 having a relative dielectric constant

And a width W of the fourteenth dielectric 52 and a width side of the fifteenth dielectric 53 are in contact with each other.

In the case of designing a single frequency band transmission / blocking FSS spatial filter according to the present invention with a stacked structure as shown in FIG. 4A and FIG. 4B, a wider bandwidth in view of the structure as shown in FIGS. 3A and 3B Can be operated as a filter having a. 4A and 4B, the stack structure of two layers has been described as an example. However, the present invention is not limited thereto, and a single cell may be arranged in a multilayer of two or more layers, and it is apparent that the single cell may be designed to have a constant bandwidth around a filtering frequency. .

FIG. 5 is an exemplary diagram illustrating frequency characteristics of a single frequency band transmission / blocking FSS spatial filter having a structure as illustrated in FIG. 3B according to the present invention. Shows the frequency characteristics of the time.

FIG. 5 shows frequency characteristics when the single frequency band FSS spatial filter according to the present invention having the structure as shown in FIG. 3B is designed to operate as a band cut filter having a center frequency of 1.8 GHz. Design parameters shown in FIGS. 2 and 3b are shown in Table 1 below.

은 상기 도 3b와 같은 구조에서 제3 유전체(34)의 상대유전율을 의미한다.In Table 1 above,

Is the relative dielectric constant of the third dielectric 34 in the structure as shown in FIG.

As shown in FIG. 5, the frequency characteristic of the single frequency band transmission / blocking FSS spatial filter according to the present invention in the case of the structure shown in FIG. 3B can be adjusted by changing the length of the entire loop. In other words, the longer the loop, the lower the cutoff frequency, and conversely, the shorter the loop, the higher the cutoff frequency. The length of such a loop can be adjusted by changing the parameters "a", "W", and the like in Table 1 above.

FIG. 6 is a diagram illustrating an exemplary frequency characteristic of a single frequency band transmission / blocking FSS spatial filter having a laminated structure according to the present invention. FIG. 6 illustrates a frequency characteristic when operating as a band cut filter in the case of a laminated structure. Shows.

6 illustrates a frequency characteristic when a single frequency band transmission / blocking FSS spatial filter according to the present invention having a structure as shown in FIG. 4A is stacked in two layers and has a predetermined cutoff bandwidth and is designed to operate as a band cutoff filter. Indicates. Design parameters shown in FIGS. 2 and 4A are shown in Table 2 below.

In Table 2, the parameter "Sc" means the scale factor of the pattern of the first conductor 31 with respect to the pattern of the third conductor 41 of FIG. 4A. That is, the size except the thickness of the pattern of the first conductor 31 is equal to the size of the pattern of the third conductor 41 multiplied by "Sc".

, 도 4b에서

,

), 그리고 전체 패턴의 길이(도 2의 루프(12)의 길이) 및 사용된 유전체의 유전율 등에 의해 결정된다. As shown in FIG. 6, the 400 MHz bandwidth corresponding to approximately 1.4 GHz to 1.9 GHz is a transmission coefficient in the frequency characteristic of a single frequency band transmission / blocking FSS spatial filter according to the present invention, which operates as a band cut filter in the case of a stacked structure. It can be seen that the filtering bandwidth is -20dB. This filtering bandwidth is called the scale factor "Sc", the thickness between the patterns (in Figure 4A

, In FIG. 4B

,

And the length of the entire pattern (the length of the loop 12 in FIG. 2) and the dielectric constant of the dielectric used.

The unit cell 11 of the single frequency band transmission / blocking FSS spatial filter may be geometrically implemented using a space-filling curve principle (see FIGS. 7A to 7C).

7A to 7C illustrate a progressively complex implementation of unit cell geometry using a spar-filling curve principle. 7C shows the same shape as the unit cell structure shown in FIG. 2.

In addition, it should be noted that it can be modified into a more complicated form than the unit cell structure of FIG. 7C to occupy a minimum area.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above, by applying a loop structure to the FSS to reduce the area, the filtering target frequency required by adjusting the geometric length and thickness of the loop, dielectric, conductor, etc. constituting the FSS, the material, and the number of layers of the unit cell It is possible to filter the band and to have a constant frequency bandwidth centering on the required filtering target frequency, and to have excellent filtering performance in a small area compared to the conventional FSS filter based on efficient space use. There is.

Claims (7)

In the frequency selective surface (FSS) spatial filter for single frequency band transmission / blocking, Geometrically entangled loops using the space-filling curve principle; A substrate for supporting the loop; And It has a unit cell of a single cycle consisting of the loop and the substrate, A single frequency band transmission / blocking FSS spatial filter, characterized in that the desired frequency can be selectively transmitted / reflected according to the geometry of the loop, the arrangement and period of the unit cell, the material characteristics of the loop and the substrate. The method of claim 1, A FSS spatial filter for single frequency band transmission / blocking, wherein the filtering center frequency is tuned by adjusting the length, thickness, and material of the loop. The method of claim 1, Single unit frequency band transmission / blocking FSS spatial filter characterized in that the unit cell is designed in a multi-layer structure to have a wider bandwidth than a single layer structure. The method of claim 3, wherein When the unit cell is designed in a multilayer structure, Single frequency band transmission / reception characterized in that the filtering bandwidth is maintained above a predetermined bandwidth by adjusting the scale factor, the thickness between the patterns, the length of the entire pattern and the dielectric constant of the dielectric used, and the number of layers of the unit cells. FSS spatial filter for blocking. The method according to any one of claims 1 to 4, In order to operate the FFS spatial filter as a band cut filter A single frequency band transmission / blocking FSS spatial filter comprising the loop as a conductor and the substrate as a dielectric. The method of claim 5, When the FFS spatial filter is operated as a band cut (jersey) filter, The cutoff frequency is lowered when the length of the loop is longer, and the cutoff frequency is increased when the length of the loop is shorter. The method according to any one of claims 1 to 4, In order to operate the FFS spatial filter as a band pass filter, A single frequency band transmission / blocking FSS spatial filter comprising the loop as a dielectric and the substrate as a conductor.

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