KR20160070459A - Synthesis structure of band stop filter with two stop bands and response characteristics variable method using the same - Google Patents

Abstract

The present invention relates to a response characteristic variable band microwave filter having two stop bands, and more particularly, to a dual band microwave filter having a new structure that minimizes the disadvantages of the conventional structure by minimizing the length of a transmission line between input and output Band suppression filter synthesis and response characteristic variable method.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band stop filter having two stop bands and a variable response method using the band stop filter.

The present invention relates to a response characteristic variable band microwave filter having two stop bands, and more particularly, to a dual band microwave filter having a new structure that minimizes the disadvantages of the conventional structure by minimizing the length of a transmission line between input and output Band synthesis filter and a variable response method using the same.

Generally, a method for designing a dual-band band-stop filter is to connect two band-stop filters having different single band-stops continuously. As a method for designing a dual band rejection filter, S. H. Han, W. L. Wang, and Y. Fan, "Analysis and design of multiple-band bandstop filters, Progress in Electromagnetics Research, vol. 70, pp. 297-306, 2007.

According to this, a band-stop filter having different characteristics is connected to constitute a filter having a double stop band. In this case, there is a disadvantage that the length of the transmission line constituting the circuit becomes inevitably longer due to the connection of two filters having different lengths.

In addition, if the combination of the transmission line and the resonance period occurs repeatedly in order to generate the stop band on the long transmission line, the characteristic impedance of the transmission line determined by the thickness of the substrate and the line width of the transmission line may have a different value from the design value .

The change in the characteristic impedance affects the reflection coefficient and / or insertion loss of the entire microwave filter and should be avoided. In the conventional method of connecting two filters continuously, it is inevitable to use a long transmission line between the input and output terminals to implement the double-stop band, but at the same time, it is an element that hinders the characteristics of the entire circuit.

FIG. 1A is a combined view of a fourth-order band-stop filter having a general double-inhibition band. 1A, a solid line 13 indicates a transmission line connecting the input terminal 11 and the output terminal 12, and a dotted line 14 indicates a coupling between the transmission line and the resonator 1, 2, 3, 4 .

As described above, two band-stop filters having different stop bands are used to implement a dual band band stop filter. A transmission line for connecting the first filter and the second filter is added to the circuit.

1B is a coupling diagram of a sixth-order band-stop filter having a general double-inhibition band. Referring to FIG. 1B, as in FIG. 1A, there exists a transmission line between the filters for connecting two 6th-band band-stop filters having different stop bands. Since the transmission line must be coupled to all the resonators 1, 2, 3, 4, 5, and 6, the length of the transmission line inside the filter increases as the degree of the filter increases.

1. Korean Patent Publication No. 10-2012-0125191 2. Korean Patent No. 10-0953408

1. Choi, Hyung-Suk, "A Study on Design Method of UWB Antenna with Two-Stage Band-stop Filter Characteristics" Kangwon National University, 2013. 2. Jonghyuk Lee et al., "Design of a New Miniature Microstrip Bandpass Filter Using Split-Ring Resonator and Spiral Resonator", Journal of Korea Electromagnetic Engineering Society, Vol. 18, No. 7 (July 2007)

The present invention has been proposed in order to solve the problem according to the above background art, and a synthesis structure of a band stop filter having two stop bands having a new combination structure different from the previous one using a combination matrix and a variable response method using the same The purpose is to provide.

It is another object of the present invention to provide a composite structure of a band-stop filter having two stop bands for realizing a variable response characteristic by adjusting a resonance frequency of a specific ground, and a variable response method using the same.

In order to achieve the above object, the present invention provides a synthesis structure of a band stop filter having two stop bands having a new combination structure different from the previous one using a combination matrix.

The composite structure of the band-

A transmission line for connecting an input end and an output end in a straight line; And

And a plurality of resonators arranged symmetrically in the vertical direction of the transmission line and directly coupled to the transmission line or coupled to each other to form two blocking bands in the vertical direction with reference to the transmission line.

The number of the resonators may be four or six.

The plurality of resonators may be microstrip line resonators.

The resonance frequency of the plurality of resonators may be adjusted to change the interval between the two stop bands.

Alternatively, the adjustment of the resonance frequency of the microstrip line resonator may be performed by adjusting the physical length.

The composite structure of the band-stop filter may further include a varactor, wherein resonance frequency adjustment of the microstrip line resonator is performed by adjusting the capacitance of the varactor.

On the other hand, another embodiment of the present invention is a response characteristic variable method using a composite structure of a band-stop filter having two stop bands, wherein a reflection zero point and a transmission zero point for frequency characteristics of the band- ; Calculating a power transfer ratio using the reflection zero and transfer zero, and calculating a transfer function from the power transfer ratio; Calculating a coupling matrix from the transfer function; And adjusting a frequency characteristic of the band-stop filter by adjusting a specific factor in the combining matrix.

The diagonal elements represent the relationship between the design center frequency of the frequency characteristic and the resonance frequency of the plurality of resonators, and the diagonal elements represent the resonance frequency of the plurality of resonators as the diagonal elements of the coupling matrix. .

Further, by adjusting the resonance frequencies of the plurality of resonators, the symmetric Butterworth response characteristic representing the same stop band bandwidth can be changed to the response characteristic exhibiting the equi-ripple characteristic.

The resonance frequency of the plurality of resonators may be adjusted to change the symmetric Butterworth response characteristic representing the same stop band bandwidth to a response characteristic of a stop band exhibiting different characteristics.

According to the present invention, it is possible to synthesize a filter having a short length of a transmission line by using a new coupling structure different from that of a general method in a dual band band low-threshold microwave filter.

Further, as another effect of the present invention, it is possible to design a response characteristic variable type dual band rejection filter due to various frequency bandwidths and / or response characteristics obtained by adjusting the resonance frequencies of the respective resonators constituting the filter .

Further, another effect of the present invention is that it is possible to suppress signals that are not desired to be received in various forms.

FIG. 1A is a combined view of a general fourth-order band-stop filter for implementing a double-stop band.
FIG. 1B is a combined view of a general 6th order band-stop filter for implementing a double-stop band.
FIG. 2A is a combined view of a fourth-order band-stop filter having a new coupling structure for implementing the double-low band according to the first embodiment of the present invention.
FIG. 2B is a combined view of a sixth-order band blocking filter having a new coupling structure implementing the double-blocking band according to the second embodiment of the present invention.
FIG. 3A is an example of a graph showing a synthesis result curve of a fourth-order band-stop filter having a Butterworth response characteristic in a dual band of the same bandwidth according to the present invention.
FIG. 3B is another example of a graph showing a synthesis result curve of a fourth-order band-stop filter having an equi-ripple response characteristic in a dual band of the same bandwidth according to the present invention.
FIG. 3C is another example of a graph showing a synthesis result curve of a quadratic dual band band-stop filter having different response characteristics in a dual band of different bandwidths according to the present invention.
FIG. 3D is another example of a graph showing a synthesis result curve of a quadratic dual band band-stop filter having a response characteristic in which an interval between two stop bands is changed (increased) according to the present invention.
4 is a conceptual diagram of a quadrature band suppression microwave filter having a dual band using a resonator of a microstrip line structure according to a third embodiment of the present invention.
5A is an example of a graph showing synthesis and simulation results of a quadratic dual band band-stop filter having a Butterworth response characteristic in the dual band of the same bandwidth according to the present invention.
FIG. 5B is another example of a graph showing a synthesis and simulation result curve of a quadratic dual band band-stop filter having an equi-ripple response characteristic in the dual band of the same bandwidth according to the present invention.
FIG. 5C is another example of a graph showing the synthesis and simulation results of a quadrature dual band band-stop filter having different response characteristics in the dual band of different bandwidth according to the present invention.
FIG. 5D is another example of a graph showing a synthesis and simulation result curve of a quadratic dual band band-stop filter having a response characteristic in which the interval between two stop bands is changed (increased) according to the present invention.
6A is an example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having a Butterworth response characteristic in a dual band of the same bandwidth according to the present invention.
FIG. 6B is another example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having an equi-ripple response characteristic in a dual band of the same bandwidth according to the present invention.
FIG. 7A is another example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having different response characteristics in a dual band of different bandwidths according to the present invention.
FIG. 7B is another example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having a response characteristic in which an interval between two stop bands is changed (increased) according to the present invention.
FIG. 8 is a flowchart illustrating a process of synthesizing a band stop filter having two stop bands according to an embodiment of the present invention and performing a variable response characteristic.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a band stop filter having two stop bands according to an embodiment of the present invention; FIG.

In one embodiment of the present invention, the microwave filter includes filters of other orders that can be applied, such as any order of filters, waveguides, and microstrip line structures. In a preferred embodiment of the present invention, as the microwave filter, a fourth-order filter using a resonator of a microstrip line structure will be described as an example. However, it should be noted that the present invention does not depend on the resonator structure of the filter and / or the order of the filter.

FIG. 2A is a combined view of a fourth-order band-stop filter having a new coupling structure for implementing the double-low band according to the first embodiment of the present invention. 2A, a solid line 233 represents a transmission line, and a dotted line 234 represents a coupling of the transmission line and the first to fourth resonators 211, 212, 213, and 214, or a combination of a resonator and a resonance period. In addition, the transmission line connects the input terminal 221 and the output terminal 222.

Since the first through fourth resonators 211, 212, 213, and 214 are coupled to two points of the transmission line, unlike the conventional structure in which the four resonators shown in FIG. 1A are combined with four transmission lines, It is short.

FIG. 2B is a combined view of a sixth-order band blocking filter having a new coupling structure implementing the double-blocking band according to the second embodiment of the present invention. 2B, unlike a general coupling structure, first to sixth resonators 211, 212, 213, 214, 215, 216 are coupled to three points on a transmission line. Therefore, it is shown that the transmission line is shorter than the structure in which the six resonators shown in FIG. 1B are combined with six transmission line positions.

In addition, FIGS. 2A and 2B explain the concept of a synthesis structure of a band-stop filter forming two stop bands.

In the following description, a method of varying the frequency response characteristic by adjusting the resonance frequency of the resonator using the composite structure of the band-stop filter shown in Figs. 2A and 2B is presented.

은 다음식과 같이 표현된다.The transmitted power ratio, which represents the frequency characteristic of the filter to which the present invention is applied,

Is expressed by the following equation.

과

은 리플상수,

와

는 각각 반사영점과 전달영점을 근으로 가지는 다항식이다. Where S is the normalized complex frequency,

and

The ripple constant,

Wow

Are polynomials having a reflection zero point and a transmission zero point, respectively.

Ripple constants and polynomials are expressed as:

은 정규화된 차단 주파수이며,

은 차단 주파수에서의 반사손실이다. 또한

와

이 필터의 주파수 응답특성을 결정하는 중요한 설계파라미터인 전달영점과 반사영점이다. here,

Is a normalized cutoff frequency,

Is the return loss at the cut-off frequency. Also

Wow

The critical design parameters that determine the frequency response of this filter are the transmission zero and the reflection zero.

를 구할 수 있다. 주파수 응답특성을 나타내는 전달함수로부터 결합행렬을 구하는 방법은 R. J. Cameron, R. Mansour, and C. M. Kudsia, Microwave Filters for Communication Systems: Fundamentals, Design and Applications, Wiley, 2007)에 공지되어 있다.From the transfer zero point and the reflection zero point, the power transfer ratio of Equation (1) can be obtained,

Can be obtained. A method for obtaining a coupling matrix from a transfer function representing a frequency response characteristic is known from RJ Cameron, R. Mansour, and CM Kudsia, Microwave Filters for Communication Systems: Fundamentals, Design and Applications, Wiley, 2007).

는 결합행렬

과 다음과 같은 관계식을 만족하며 좌우변의 계수 비교를 통해 결합행렬을 구할 수 있다.In brief, the power transfer function

Lt; RTI ID = 0.0 &

And the following relation is satisfied, and the coupling matrix can be obtained by comparing the coefficients on the left and right sides.

은 모두

차의 필터에서

행렬이며,

차라 함은 공진기와 비공진 노드(non-resonating node)의 합이

개임을 의미한다 (전술한 6차의 대역저지 필터는 6개의 공진기와 1개의 비공진 노드를 포함하므로 여기서는 7차의 필터로 간주되며,

행렬로 표현된다).

은 입출력단에 상응하는

원소가 1이며 나머지 원소는 모두 0인 행렬이다.

는 단위행렬과 유사하게 대각 원소가 1이지만, 입출력단 그리고 비공진 노드에 상응하는 원소는 0인 행렬이다.here

All

In the car's filter

Matrix,

The difference is that the sum of the resonator and the non-resonating node

(The above-mentioned sixth-order band-stop filter includes six resonators and one non-resonant node, so it is regarded as a seventh-order filter here,

Matrix).

Corresponds to the input / output stage

And the remaining elements are all 0s.

Is a matrix in which a diagonal element is 1, similarly to the unit matrix, and an element corresponding to an input / output node and a non-resonant node is 0.

FIG. 3A is an example of a graph showing a synthesis result curve of a fourth-order band-stop filter having a Butterworth response characteristic in a dual band of the same bandwidth according to the present invention. In this embodiment, there are four transfer zeroes, each with two transfer zeroes located at one frequency.

In addition, two reflection zeroes are located at the center of the two pairs of transmission zeroes, and the remaining two reflection zeroes are located at positive and negative infinite frequencies, respectively. The coupling matrix of the filter having the frequency response characteristic of FIG. 3A and having the coupling structure as shown in FIG. 2A is obtained by the above-described method.

)는 구현하는 응답특성의 설계 중심 주파수와 개별 공진기의 공진 주파수와의 관계를 나타낸다. The frequency response characteristic of FIG. 3A can be changed by adjusting the specific factor of the coupling matrix of Equation (6). The diagonal factor of the coupling matrix is a factor that determines the resonance frequency of the individual resonator, and the diagonal elements of the coupling matrix corresponding to the resonator

) Represents the relationship between the design center frequency of the response characteristic to be implemented and the resonance frequency of the individual resonator.

A zero diagonal element corresponding to the resonator means that the resonant frequency of the resonator is equal to the design center frequency of the filter. A diagonal element having a negative value means that the resonance frequency of the resonator is higher than the design center frequency of the filter, and the opposite meaning that the diagonal element has a positive value.

The quantitative relation for this is described in K. Chen, J. Lee, W. J. Chappell, and D. Peroulis, "Co-design of highly efficient power amplifier and high-Q output bandpass filter," IEEE Trans. on Micorwave Theory and Tech. vol. 61, no. 11, pp. 3940-3950, Nov. 2013. In the present invention, a method of obtaining various response characteristics through adjustment of resonance frequencies of individual resonators is presented.

The quadratic band-stop filter having a coupling matrix as shown in Equation (7) below has equal bandwidth of 15 dB equi-ripple characteristic and two band-stop filters. FIG. 3B shows the response characteristic of a filter having a coupling matrix of Equation (7). FIG. 3B is another example of a graph showing a synthesis result curve of a fourth-order band-stop filter having equi-ripple response characteristics in the dual band of the same bandwidth according to the present invention.

That is, by adjusting the resonance frequency of the resonator, it is possible to change the symmetric Butterworth response characteristic representing the same stop band bandwidth to the response characteristic exhibiting the equi-ripple characteristic.

The quadratic band-stop filter having a coupling matrix of Equation (8) has different bandwidths because the two blocking bands have different characteristics. FIG. 3C shows the response characteristic of the filter having the coupling matrix of Equation (8) Show. FIG. 3C is another example of a graph showing a synthesis result curve of a quadratic dual band band-stop filter having different response characteristics in a dual band of different bandwidths according to the present invention.

That is, FIG. 3C shows that by adjusting the resonance frequency of the resonator, the symmetric Butterworth response characteristic showing the same stop band bandwidth can be changed to a response characteristic having a stop band showing different characteristics.

The fourth-order band-stop filter having a coupling matrix of Equation (9) has a property that the interval between two blocking bands is changed (increased), and FIG. 3D shows a response characteristic Lt; / RTI > FIG. 3D is another example of a graph showing a synthesis result curve of a quadratic dual band band-stop filter having a response characteristic in which an interval between two stop bands is changed (increased) according to the present invention.

That is, FIG. 3D shows that it is possible to change the interval between the two stop bands by adjusting the resonance frequency of the resonator.

4 is a conceptual diagram of a quadrature band suppression microwave filter having a dual band using a resonator of a microstrip line structure according to a third embodiment of the present invention. 4, the band-stop microwave filter includes an input terminal 431, an output terminal 432, a microstrip line resonator 433, and the like. 4A and 4B show an embodiment of a fourth-order filter structure implemented using a microstrip line resonator based on FIG. 2A. When a filter of this structure implements the combination matrix of Equations 6 to 9 Are shown in Figs. 5A to 5D. Fig.

5A is an example of a graph showing synthesis and simulation results of a quadratic dual band band-stop filter having a Butterworth response characteristic in the dual band of the same bandwidth according to the present invention.

FIG. 5B is another example of a graph showing a synthesis and simulation result curve of a quadratic dual band band-stop filter having an equi-ripple response characteristic in the dual band of the same bandwidth according to the present invention.

FIG. 5C is another example of a graph showing the synthesis and simulation results of a quadrature dual band band-stop filter having different response characteristics in the dual band of different bandwidth according to the present invention.

FIG. 5D is another example of a graph showing a synthesis and simulation result curve of a quadratic dual band band-stop filter having a response characteristic in which the interval between two stop bands is changed (increased) according to the present invention.

In addition, the synthesis of the filter and the adjustment of the response characteristics according to an embodiment of the present invention can be extended to a higher-order filter, and a case where it is applied to a sixth-order filter is described as an example.

6A is an example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having a Butterworth response characteristic in a dual band of the same bandwidth according to the present invention. When the frequency response characteristic of FIG. 6A and the coupling matrix of the filter having the coupling structure as shown in FIG. 2B are obtained using the above-described method, the following equation (10) is obtained.

은 S. Amari, and U. Rosenberg, "New building blocks for modular design of elliptic and self-equalized microwave filter," IEEE Trans. Microwave Theory and Tech.. vol. 54, no. 2, pp. 721-736, Feb. 2004)에서 기술된 바와 같은 비공진 노드의 결합량을 의미하며 결합계수는 0을 갖는다.

을 제외한 대각원소는 그 순서대로 1, 2, 3, 4, 5, 6번 공진기의 결합량을 의미한다.Among the diagonal elements of the above equation

S. Amari, and U. Rosenberg, "New building blocks for modular design of elliptic and self-equalized microwave filters," IEEE Trans. Microwave Theory and Tech .. vol. 54, no. 2, pp. 721-736, Feb. 2004), and the coupling coefficient has zero.

And the diagonal elements except for (1), (2), (3), (4), (5) and (6) in this order.

Similar to the fourth-order filter, various response characteristics can be obtained by adjusting the resonance frequency of the resonator in the case of a higher-order filter.

FIG. 6B is another example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having an equi-ripple response characteristic in a dual band of the same bandwidth according to the present invention. In addition, the sixth-order band-stop filter having a coupling matrix as shown in Equation (11) has two equi-ripple characteristics of 20 dB and the same bandwidth, and FIG. It shows the response characteristics of a filter with a coupling matrix.

FIG. 7A is another example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having different response characteristics in a dual band of different bandwidths according to the present invention. The sixth-order band-stop filter having a coupling matrix as shown in Equation (12) has two different blocking bands having different characteristics, and thus has a different bandwidth. FIG. 7A shows a response characteristic Lt; / RTI >

FIG. 7B is another example of a graph showing a synthesis result curve of a sixth-order dual band band-stop filter having a response characteristic in which an interval between two stop bands is changed (increased) according to the present invention. The sixth-order band-stop filter having a coupling matrix as shown in the following Equation 13 has a characteristic in which the interval between two blocking bands is changed, and FIG. 7B shows a response characteristic of a filter having a coupling matrix of the following equation.

4, in the case of the fourth-order band-stop filter, the resonance frequency adjustment of the microstrip line resonator 433 for varying the diagonal coupling amount may be performed by adjusting the physical length, The resonance frequency of the resonator can be adjusted by adjusting the capacitance of the selector.

FIG. 8 is a flowchart illustrating a process of synthesizing a band stop filter having two stop bands according to an embodiment of the present invention and performing a variable response characteristic. Referring to FIG. 8, a reflection zero point and a transmission zero point for the frequency characteristic of the band stop filter are calculated (step S810).

When the reflection zero point and the transmission zero point are obtained, the power transfer ratio is calculated using these values, and the transfer function is calculated from the power transfer ratio (step S620).

When the transfer function is calculated, a coupling matrix is calculated from the transfer function (step S630).

The specific factor is adjusted from the calculated coupling matrix to change the frequency response characteristic (steps S640 and S650).

221: input stage 222: output stage
211: first resonator 212: second resonator
213: third resonator 214: fourth resonator
215: fifth resonator 216: sixth resonator
431: input terminal 432: output terminal
433: Microstrip line resonator

Claims (10)

A transmission line for connecting an input end and an output end in a straight line; And
A plurality of resonators arranged symmetrically in the vertical direction of the transmission line and directly coupled to the transmission line or coupled to each other to form two blocking bands in the vertical direction with reference to the transmission line;
And a band-stop filter having two stop bands.
The method according to claim 1,
Wherein the plurality of resonators are four or six resonators.
The method according to claim 1,
Characterized in that the plurality of resonators are microstrip line resonators. A composite structure of a band stop filter having two stop bands.
3. The method of claim 2,
And the resonance frequency of the plurality of resonators is adjusted to change the interval between the two stop bands.
The method of claim 3,
Wherein a resonance frequency of the microstrip line resonator is adjusted by adjusting a physical length of the resonator.
The method of claim 3,
Wherein a resonator frequency of the microstrip line resonator is adjusted by adjusting a capacitance of the varactor, wherein the resonance frequency of the microstrip line resonator is adjusted by adjusting a capacitance of the varactor.
A response characteristic variable method using a combined structure of a band stop filter having two stop bands according to any one of claims 1 to 6,
Calculating a reflection zero point and a transmission zero point for the frequency characteristic of the band stop filter;
Calculating a power transfer ratio using the reflection zero and transfer zero, and calculating a transfer function from the power transfer ratio;
Calculating a coupling matrix from the transfer function; And
Adjusting a frequency characteristic of the band-stop filter by adjusting a specific factor in the combining matrix;
Wherein the response characteristic is variable.
8. The method of claim 7,
Wherein the specific character is a factor for determining a resonance frequency of the plurality of resonators as a diagonal element of the coupling matrix and the diagonal elements represent a relationship between a design center frequency of the frequency characteristic and a resonance frequency of the plurality of resonators Variable response method.
8. The method of claim 7,
Wherein the symmetric Butterworth response characteristic representing the same stop band bandwidth is changed to a response characteristic exhibiting equi-ripple characteristics by adjusting the resonance frequencies of the plurality of resonators.
8. The method of claim 7,
Wherein the symmetric Butterworth response characteristic indicating the same stop band width is changed to a response characteristic having a stop band indicating different characteristics by adjusting the resonance frequencies of the plurality of resonators.

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