KR20030087602A - A microstrip dielectric filter - Google Patents

Abstract

PURPOSE: A microstrip dielectric filter is provided to achieve improved skirt frequency responses at both stop bands of the pass band, while eliminating higher mode harmonics. CONSTITUTION: A microstrip dielectric filter comprises an input terminal microstrip filter(30-1) coupled to an input terminal for a signal input; an output terminal microstrip filter(30-2) coupled to an output terminal for a signal output; an input terminal resonator(#1) and an output terminal resonator(#6) coupled to the input terminal microstrip filter and the output terminal microstrip filter; and coupling resonators(#2,#5) coupled to the input terminal resonator and the output terminal resonator, respectively.

Description

Microstrip dielectric filter

The present invention relates to a microstrip dielectric filter, and more particularly, to a microstrip dielectric filter capable of removing high-order mode harmonics and improving skirt frequency characteristics.

The role of a filter in a communication device is to select a signal of a desired frequency band, and the most ideal filter is a filter that passes only a signal of the desired frequency band without loss and removes all remaining signals. Therefore, the most important characteristics of the filter include both the signal pass band, that is, the in-band characteristic of passing only a signal of a frequency band without loss, and the out-band characteristic of removing the remaining frequency band. I'm satisfied.

Dielectric filters, such as those used in portable communication devices, are generally made by combining two or more dielectric resonators, for example a coaxial resonator or a re-entrant resonator, which resonates at a specific frequency. . The dielectric filter mainly determines the bandwidth, insertion loss, skirt and spurious frequency responses of the filter by the number of resonators constituting the filter and the coupling method.

However, due to the limitation of the bandwidth in the currently allocated frequency, there is a need for a sudden attenuation of frequency components other than the passband frequency. That is, when filtering, the skirt which shows the electrical characteristic of the filter is required to be steep.

Existing dielectric filter has an input stage resonator and an output stage resonator coupled to any one of an input (In) or an output (Pro) probe interpolated into a vibration hole, and an intermediate resonator coupled between the input stage resonator and the output stage resonator. The basic configuration is a three-pole filter that combines columns or rows. In order to obtain a steep skirt frequency characteristic in one or both frequency bands from the dielectric filter configured as described above, a stop band resonator (BSR) may be coupled to one or both sides of the input stage resonator or the output stage resonator. As a result, a steep skirt frequency characteristic can be obtained at either side of the passband. As described above, the cut-off frequency characteristic in the stop band band among the in-band characteristics can be greatly improved by combining the stop band resonator with the input stage resonator and the output stage resonator one by one as described above. However, there is a disadvantage that the insertion loss is increased by combining a plurality of resonators.

In order to solve this problem, the applicant of Patent Application No. 10-2001-0002523, by combining an input stage resonator and an output stage resonator and attaching an odd or even number of resonators to it, it is possible to obtain a steep skirt frequency characteristic at both sides or one side. In addition, a method to reduce insertion loss was presented. In this case, the elliptic function filter theory is applied. To apply the elliptic function theory to make an elliptic function filter, first, an array of resonators is connected so that the input stage resonator and the output stage resonator are coupled to each other. It must be correct and also find a suitable binding method for combining them. In addition, another requirement is that the elliptic coupling between the input stage resonator and the output stage resonator must be negative coupling. This can be satisfied by combining three resonators in a triangle.

In addition, in order to improve the frequency characteristics in both the in-band and the out-band, the applicant has not only been able to lower the insertion loss, which was a conventional problem in the "dielectric filter and duplexer dielectric filter" patent application No. 10-2001-0002523 In addition, the variation of the coupling characteristics between the resonator configuration of the dielectric filter and the stopband resonator also improves the skirt frequency characteristics and spurious frequency characteristics.

Then, a brief look at the prior art here.

1 is a perspective view showing an integrated dielectric filter manufactured according to the elliptic function filter theory.

As shown in FIG. 1, a dielectric filled therein is formed, and a resonance hole (H) is formed in the dielectric, and three resonance holes (H) are formed in a triangle at a predetermined interval and all in the transverse direction. Let's do it. The coupling electrode CE is patterned on the upper surface of each of the resonance hole H regions for coupling the resonance period, and all regions except the patterned portion are coated with the common electrode GE. In this case, the coupling electrode CE, the inner wall of the resonance hole H, and the common electrode GE are integrally connected. Functionally, the input stage resonator (# 1), the intermediate resonator (# 2), the output stage resonator (# 3), the intermediate resonator (# 2) between the input stage resonator (# 1) and output stage resonator (# 3) It is coupled to one side.

Meanwhile, an input terminal electrode IE and an output terminal electrode OE through which signals are input and output are formed adjacent to the coupling electrode CE. In this case, the input end electrode IE and the output end electrode OE are complementary in function, and thus the input end electrode IE may perform the function of the output end electrode OE, and is linked to the output end electrode OE. ) Serves as the input terminal electrode IE. Accordingly, the region where the coupling electrode CE adjacent to the input terminal electrode IE through which the signal is input serves as the input terminal resonator # 1, and the coupling electrode CE adjacent to the output terminal electrode OE is formed. The area serves as the output stage resonator (# 3). Like the input end electrode IE and the output end electrode OE, the input end resonator # 1 and the output end resonator # 3 have a complementary function, and the input end electrode IE and the output end electrode OE have a signal. By performing any one function in the input / output relationship of the input stage resonator (# 1) and the output stage resonator (# 3) to perform a complementary function.

Coupling electrodes CE are formed in each resonator region as described above, and these coupling electrodes CE are spaced apart from each other and patterned. At this time, the input stage resonator # 1 and the output stage resonator # 3 may be negatively coupled according to the elliptic function filter theory, that is, the input stage resonator may be weakly coupled as compared with the coupling between other resonators. The opposing distance between the coupling electrode CE formed in the region of # 1) and the output stage resonator # 3 is increased or the mutually opposing area is reduced.

2A and 2B are graphs schematically showing frequency characteristics of the dielectric filter of FIG. 1.

As shown in FIGS. 2A and 2B, the frequency characteristics of the 3-pole filter shown in FIG. 1 have an insertion loss compared to that of a filter in which a stop band resonator (BSR) is coupled to a conventional column or row type. At the same time, it shows a steep skirt frequency characteristic on one side of the transition bands on both sides of the passband and attenuation width is A. Here, A is an arbitrary value for comparison of the attenuation width described later. On the other hand, the steep skirt frequency characteristics of the high or low transition frequency band formed on the left and right sides of the passband can be adjusted by tuning the resonator shown in FIG.

On the other hand, in order to obtain steep cutoff frequency characteristics in both stopbands of the passband, the number of resonators of the elliptic function filter must be at least four. This can be confirmed through FIG. 3.

3 is a perspective view of a dielectric filter incorporating one more medium resonator for increasing attenuation width in an integrated dielectric filter manufactured according to the elliptic function filter theory.

Referring to FIG. 3, it can be seen that one more medium resonator # 4 is coupled to the dielectric filter shown in FIG. 1. The medium resonator # 4 is located in the input stage resonator # 1 region of FIG. 1. As a result, the input stage resonator # 1 is formed at one side thereof. The intermediate resonator # 4 is a resonator that mediates the input and output of signals to adjacent resonators, and serves to increase attenuation width in frequency characteristics. In addition, the intermediate resonator # 4 has negative coupling with the output stage resonator # 3 among the resonators coupled in a triangle form according to the elliptic function filter theory.

4A and 4B are graphs schematically showing frequency characteristics of the dielectric filter of FIG. 3.

4A and 4B, it can be seen that the attenuation width A1 is increased compared to the results shown in FIGS. 2A and 2B. As a result, a skirt frequency characteristic having a steeper slope in the transition band band can be obtained.

By the way, in order to obtain a steeper frequency characteristic in the transition band band, the method of increasing the above-mentioned intermediate resonator # 4 has been proposed. However, the disadvantage that the insertion loss increases due to the length of the dielectric filter is increased. In addition, as the length increases, there is a limit to the compact design design. In addition, in order to obtain a steep skirt frequency characteristic at both sides of the transition band band, a stop band resonator coupled to the input end electrode IE or the output end electrode OE simultaneously in the region of the input end resonator # 1 or the output end resonator # 3. BSR) is coupled, but when the stop band resonator (BSR) is coupled in a long length state as described above, the insertion loss increases as the resonator (# 4) is combined in a row or column form. Occurs.

The same problem occurs even when a duplexer dielectric filter in which the dielectric filter configured as described above is symmetrically coupled around the antenna electrode in the state having such a problem.

Accordingly, an object of the present invention is to vary the diameter of the resonator holes (a), the distance of the resonance period (di), the shape of the resonators in various ways so as to improve the skirt frequency characteristics on both sides of the stopband band, and also the simple tuning thereof. To provide a dielectric filter that can obtain symmetrical frequency characteristics in the stopband band.

Another object of the present invention is to provide a microstrip dielectric filter that can apply a microstrip filter to one side of the dielectric filter to improve high-order mode harmonic removal and spurious frequency characteristics while minimizing insertion loss.

The dielectric filter proposed in the present invention combines two or more elliptic function filters composed of three triangular resonators, adjusts the diameter of the resonator hole, the thickness ratio of the resonator, and the distance between adjacent resonance periods, and is formed of a coaxial resonator. By combining one or more resonators in the dielectric filter by replacing them with elliptical, concave and stepped resonators, they show sharp skirt frequency characteristics in both stopbands of the passband, and by simple and easy tuning of these resonators, The symmetrical skirt frequency characteristic can be obtained at.

In addition, a microstrip filter that attenuates the cutoff frequency at a high rate is divided into three or five sets according to a desired frequency band and applied to one side (eg, bottom or side) of the dielectric filter. Therefore, the spurious frequency characteristics can be improved by effectively eliminating the higher-order mode harmonics while compensating for the disadvantage that the insertion loss is increased.

1 is a perspective view showing an integrated dielectric filter manufactured according to the elliptic function filter theory;

2A and 2B are graphs schematically showing frequency characteristics of the dielectric filter of FIG. 1;

3 is a perspective view of a dielectric filter incorporating one more medium resonator for increasing attenuation in an integrated dielectric filter manufactured according to the elliptic function filter theory;

4A and 4B are graphs schematically showing frequency characteristics of the dielectric filter of FIG. 3;

5A and 5B are a perspective view and a plan view schematically showing an integrated 6-pole TT-block dielectric filter according to a first embodiment of the present invention;

6 is a graph showing the frequency characteristics of the TT-block dielectric filter shown in FIGS. 5A and 5B;

7a to 7d are application examples to the first embodiment of the present invention.

8 is a plan view schematically showing a TT-block dielectric filter including a resonator designed differently as a modification of the first embodiment of the present invention;

9 is a plan view schematically showing a TT-block dielectric filter including another designed resonator as another modification of the first embodiment of the present invention;

10 is a graph showing the spurious frequency characteristics of the graph of FIG. 6;

11 is a perspective view schematically showing a TT-block dielectric filter coated with a microstrip filter according to a second embodiment of the present invention;

12A and 12B show a differently designed microstrip filter as an example of application to the second embodiment of the present invention;

FIG. 13 is a graph showing the frequency characteristics of the microstrip filter shown in FIGS. 12A and 12B;

14 is a graph showing the frequency characteristics of the TT-block dielectric filter coated with the microstrip filter shown in FIG.

15 is a schematic perspective view of a TT-block dielectric filter to which a three-set microstrip filter is applied, as a modification to the second embodiment of the present invention;

16 is a schematic perspective view of a TT-block dielectric filter to which a five-set microstrip filter is applied, as another modification of the second embodiment of the present invention;

FIG. 17 is a schematic perspective view of a TT-block dielectric filter to which three- and five-set microstrip filters are applied, as another variation of the second embodiment of the present invention; FIG.

18 is a schematic perspective view of a straight-line dielectric filter to which a three-set microstrip filter is applied, as another modification of the second embodiment of the present invention;

19A to 19F illustrate a theoretical concept of a microstrip filter applied to the second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

# 1: Input stage resonator # 2, # 5: Combined resonator

# 3, # 4: intermediate resonator # 6: output stage resonator

AE: Pad electrode CE: Coupling electrode

GE: Common electrode IE: Input terminal electrode

OE: Output electrode PE: Filter electrode

H: resonance hole 10: first elliptic function filter

20: second elliptic function filter 30-1, 30-2: microstrip filter

The microstrip dielectric filter of the present invention for achieving the above object of the present invention, the input stage microstrip filter coupled to the input terminal is a signal input; An output stage microstrip filter coupled to the output stage at which the signal is output; An input / output stage resonator coupled to and coupled to the input stage and output stage microstrip filters; A coupling resonator coupled to and coupled to the input / output end resonator; Characterized in that comprises a.

When the input and output microstrip filters are integrally formed, a filter electrode is patterned on the surface of the microstrip filter to be coupled with the resonators, and a region except for the patterned portion is coated with a common electrode. The filter electrode is characterized in that the same material as the common electrode.

The microstrip filter consists of a 3-set or 5-set low pass filter; Differently designed according to a desired frequency band, the pad electrode is coupled to one side of the microstrip filter to be coupled between the filter electrode and the coupling electrode, characterized in that the coupling resonator is composed of at least two or more. .

In addition, the microstrip dielectric filter of the present invention, the input stage microstrip filter coupled to the input terminal to the signal input; An input stage resonator coupled to and coupled to the input stage microstrip filter; A coupling resonator coupled to and coupled to the input stage resonator; An output stage resonator coupled to and coupled to the coupling resonator; An output stage microstrip filter coupled to the output stage resonator and coupled to an output stage at which a signal is output; The microstrip filter is applied to the surface of the resonator dielectric, characterized in that formed integrally.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

First, in the description of the drawings of the present invention, the same reference numerals are assigned to components that perform the same function, and the same concepts will be omitted for repeated and repeated description.

5A and 5B are a perspective view and a plan view schematically showing an integrated 6-pole TT-block dielectric filter according to a first embodiment of the present invention.

As shown in FIGS. 5A and 5B, the integrated TT-block dielectric filter shown in the first embodiment includes a first elliptic function filter 10 and a second elliptic function filter 20. That is, by combining two dielectric filters of FIG. 1, each of the first elliptic function filter 10 and the second elliptic function filter 20 forms a dielectric filled therein, and the dielectric Resonant holes (H) are formed in the three resonant holes (H) in a triangle shape at a predetermined interval and all in the transverse direction. The coupling electrode CE is patterned on the upper surface of each of the resonance hole H regions for coupling the resonance period, and all regions except the patterned portion are coated with the common electrode GE. In this case, the coupling electrode CE, the inner wall of the resonance hole H, and the common electrode GE are integrally connected. Then, the first elliptic function filter 10 and the second elliptic function filter 20 are combined, but coupled to any one resonator except for the input stage resonator # 1 or the output stage resonator # 6, in which signals are input and output. It is made in one piece. An input stage resonator # 1, a first coupled resonator # 2, and a first intermediate resonator # 3 are formed in the first elliptic function filter 10, and the second elliptic function filter 20 has a second The intermediate resonator # 4, the second coupling resonator # 5, and the output stage resonator # 6 are formed. The first and second coupling resonators # 2 and # 5 are coupled electrodes protruding to one side.

Accordingly, not only the two skirt frequency characteristics caused by the first elliptic function filter 10 and the second elliptic function filter 20 are provided, but also a mediated resonator (# 3) which increases the attenuation width by integrally manufacturing. , # 4) is naturally formed. Also, it can be seen that two are formed between the input stage resonator # 1 and the output stage resonator # 6. As can be seen from the graph to be described later, not only the frequency characteristic having a steeper slope can be obtained by using the factor in which the skirt frequency characteristic appears, but also the dual effect of making the slope steeper through the increase of the attenuation width.

Meanwhile, an input terminal electrode IE and an output terminal electrode OE through which signals are input and output are formed adjacent to the coupling electrode CE. In this case, since the complementary relationship in the function of the input terminal electrode IE and the output terminal electrode OE is the same as in the related art, a detailed description thereof will be omitted. In addition, since the functions of the input stage resonator (# 1) and the output stage resonator (# 6) are also complementary interlocked accordingly, detailed description thereof will be omitted.

Coupling electrodes CE are formed in each resonator region as described above, and these coupling electrodes CE are spaced apart from each other and patterned. At this time, the input stage resonator # 1 and the first intermediate resonator # 3 of the first elliptic function filter 10 are negatively coupled according to the elliptic function filter theory, and the second elliptic function filter ( The first elliptic function filter 10 so that the second intermediate resonator # 4 and the output stage resonator # 6 of 20 may be negatively coupled, that is, weakly coupled as compared to the coupling between the other resonators. The opposing distance between the input stage resonator # 1 and the coupling electrode CE formed in the region of the first intermediate resonator # 3 is reduced or the mutually opposing area is reduced. The same applies to the output stage resonator # 6 and the second intermediate resonator # 4 of the second elliptic function filter 20.

Further, a negative elliptic coupling between the input stage resonator # 1 and the first intermediate resonator # 3, and between the second intermediate resonator # 4 and the output stage resonator # 6, -k (1,3) , -k (4,6).

FIG. 6 is a graph showing the frequency characteristics of the TT-block dielectric filter shown in FIGS. 5A and 5B.

As shown in FIG. 6, the negative elliptic coupling between the input stage resonator # 1 and the first intermediate resonator # 3, -k (1,3), and the second intermediate resonator # 4, The negative frequency coupling between the output stage resonators # 6, -k (4,6), results in a steep stopband attenuation on both sides of the high and low stopband bands, resulting in a steeper slope characteristic.

However, it should not be overlooked here, even though it has a steep skirt frequency characteristic in the stopband bands on both sides of the passband, in order to obtain a symmetric skirt frequency characteristic in which both sides are balanced in the transition band band as shown in FIG. This is necessary, which is the ratio (a / b) of the diameter (a) of the resonator hole (H) to the thickness of the resonator (b), the distance (di) of adjacent resonance periods, and the first and second coupling resonators (# 2, #). It is made by adjusting the various shapes of 5), the tuning method can be known in more detail through the patent number 0390351 filed and registered by the applicant.

7A to 7D are application examples to the first embodiment of the present invention, and show a differently designed resonator, and FIG. 7A is a coaxial resonator having a resonance hole H formed in a circular cylindrical shape. It is a cube-shaped resonator having a hole H diameter a, a resonator thickness b and a resonance hole H height D.

7B is an elliptic coaxial resonator in which the resonance hole H is formed in an elliptical cylinder shape, the diameter of the resonance hole H is a and b, the thickness of the resonator b, and the height of the resonance hole H is D. It is a cube-shaped resonator.

FIG. 7C is a reentrant coaxial resonator in which the resonance hole H is formed in a circular cylinder shape, the diameter of the resonance hole H is a, the thickness of the resonator b, and the height of the resonance hole H is high. It is a cube-shaped resonator of D '(D' <D).

FIG. 7D is a step coaxial resonator in which the resonance hole H is formed in a circular step shape. The diameter of the resonance hole H is a1, a2, the thickness of the resonator b, and the height of the resonance hole H is high. D is a cube-shaped resonator.

As shown in Figs. 7A to 7D, various modifications of the shape of the coaxial dielectric resonator make the TT-block and TTT-block dielectric filters as shown in Figs. 8 and 9 to make tuning much easier. Can be designed.

8 is a plan view schematically showing a TT-block dielectric filter including a resonator designed differently as a modification of the first embodiment of the present invention.

Referring to FIG. 8, the difference between the dielectric filter shown in the modification of the first embodiment and the dielectric filter shown in FIG. 5B is the second coupling resonator # 5 formed in the second elliptic function filter 20. Is a resonator designed differently than other resonators. That is, the second stage of the input stage resonator (# 1), the first coupled resonator (# 2), the first intermediate resonator (# 3) and the second elliptic function filter (20) of the first elliptic function filter (10) The resonator # 4 and the output stage resonator # 6 are coaxial resonators, and the second coupling resonator # 5 of the second elliptic function filter 20 is an elliptical resonator. This may be an example of applying the resonator shown in FIG.

FIG. 9 is a plan view schematically illustrating a TT-block dielectric filter including another designed resonator as another modified example of the first embodiment of the present invention.

Referring to FIG. 9, the difference between the dielectric filter shown in another modification of the first embodiment and the dielectric filter shown in FIG. 5B is that of the first coupling resonator # 2 formed in the first elliptic function filter 10. ) Is a resonator designed differently than other resonators. That is, the input stage resonator (# 1) of the first elliptic function filter (10), the first parasitic resonator (# 3) and the second parasitic resonator (# 4) of the second elliptic function filter (20), the second coupling The resonator # 5 and the output stage resonator # 6 are coaxial resonators, and the first coupling resonator # 2 of the first elliptic function filter 10 is an elliptical resonator. This is an example showing that the resonators constituting the dielectric filter can be arbitrarily combined.

In other words, the diameter of the resonator hole and the thickness ratio (a / b) of the resonator, the distance (di) of the adjacent resonant periods, and the various shapes of the coupling resonators (# 2, # 5) are selected, or by appropriate coupling methods thereof. It is possible to design a TT-block dielectric filter in which tuning to determine the characteristics of the bandwidth, the skirt frequency and the skirt frequency response, is much simpler and easier.

As shown in FIG. 6, a simple tuning according to the design of the TT-block dielectric filter described above shows that the skirt representing the electrical characteristics of the filter responds between -40 dB to 0 dB at a bandwidth of ΔW while having a steep slope. It will have a frequency characteristic.

FIG. 10 is a graph showing the spurious frequency characteristics of the graph of FIG. 6.

Referring to FIG. 10, an output having a steep skirt frequency characteristic can be obtained in a desired frequency band according to the design of the TT-block dielectric filter, but not only the desired frequency band but also unwanted unwanted frequencies in the cylindrical dielectric resonator Unnecessary frequency refers to modes other than the main operation mode, which is referred to as spurious mode, which greatly reduces filtering performance.

The spurious frequency characteristics other than the first resonant frequency fo are higher-order harmonics (2fo .....) and these higher-order high frequencies exist above the cutoff frequency (fc; CutoffFrequency). Nearly all spurious frequency characteristics are unwanted higher-order harmonics in the filter characteristics.

In order to remove the unwanted high-order mode harmonics to improve the filter characteristics, the present invention compared with the conventional common cavity cavity filter, that is, the microstrip filter coupled to the back of the filter TT-block dielectric filter of the present invention The second embodiment will be described.

In general, metal cavity filters with or without a dielectric resonator in the cavity have a higher insertion loss, skirt frequency characteristic, and higher order mode isolation response than the dielectric filter. While there is a good advantage, there is a disadvantage that the volume or cost is increased compared to the dielectric filter.

Accordingly, a method of improving the insertion loss and skirt frequency characteristics of the dielectric filter almost similar to that of the conductor cavity filter by constructing the dielectric filter as a single block of T or TT blocks has been introduced. As shown, it was still difficult to solve.

In order to solve this problem, a microstrip filter is provided on one surface (for example, the bottom surface or side surface of the dielectric filter) of the filter, that is, the one-piece (cuboid-shaped) TT-block dielectric filter presented in the first embodiment of the present invention. A second embodiment of the present invention was presented.

FIG. 11 is a perspective view schematically illustrating a TT-block dielectric filter to which a microstrip filter is applied according to a second embodiment of the present invention, wherein like reference numerals are used to designate components that perform the same function, and the same concept may overlap. And repeated description will be omitted as possible.

As shown in FIG. 11, the integrated TT-block microstrip dielectric filter shown in the second embodiment includes a first elliptic function filter 10, a second elliptic function filter 20, and a microstrip filter 30. -1) 30-2.

That is, it is formed by applying a microstrip filter to the first embodiment of the present invention shown in Figs. 5a and 5b, which is different from the filter shown in Figs. 5a and 5b, the signal in Figs. 5a and 5b It can be seen that the input terminal electrode IE and the output terminal electrode OE, to which the input and output of the input and output terminals, are used as the pad electrode AE, and thus coupling is performed to the adjacent coupling electrode CE.

A 3-set microstrip low pass filter 30-1 (hereinafter referred to as a microstrip filter) is connected to the pad electrode AE of the input stage resonator # 1 side, and is coated on the surface of the dielectric filter. On the other side of the 3-set microstrip filter 30-1, which is not connected to AE, an input terminal (IN / OUT) through which a signal is input is formed, and an output terminal resonator (# 6) side pad electrode (AE) is 5 The set microstrip filter 30-2 is connected and applied to the surface of the dielectric filter, and the signal output is output to the other side of the 5-set microstrip filter 30-2 which is not connected to the pad electrode AE. The output terminal OUT / IN which consists of is formed.

The 3- and 5-set microstrip filters 30-1 and 30-2 are patterned with a filter electrode PE on their surfaces, and all regions except the patterned portion are coated with the common electrode GE. Thus, a principle of moving and coupling from an electrode applied to the resonator dielectric surface to an electrode on the surfaces of the microstrip filters 30-1 and 30-2 is used. Such a coupling method by the electrodes on the surfaces of the microstrip filters 30-1 and 30-2 uses the microstrip filters 30-1 and 30-2 as a dielectric or similar material as in the first embodiment. (Al ₂ O ₃ ) can be used to design a single crystal. In this case, the relative permittivity of the microstrip filters 30-1 and 30-2 is ε _r = 21 or ε _r = 37.

Microstrip filters, on the other hand, are well known and can be easily designed as disclosed in "MICROWAVE Engineering" A. Das and S.K. Das, McGraw Hill 2001, Page 284-288.

12A and 12B show a differently designed microstrip filter as an application example to the second embodiment of the present invention.

Referring to FIG. 12A, a three-set low pass microstrip filter 30-1 shows that an input impedance of 50 Ω is output as an output impedance 50 through a three-step CLC filter. Referring to FIG. 12B, FIG. , A 5-set low pass microstrip filter 30-2 shows that the input impedance 50Ω is output through the 5-step CLCLC filter to the output impedance 50, and the microstrip filter 30-1 (30). The theoretical concept of -2) is shown in FIG.

19A to 19F illustrate the theoretical concept of the microstrip filter applied to the second embodiment of the present invention. FIGS. 19A to 19C are conceptual views of π-type microstrip filters, and FIGS. 19D to 19F are T-type microstripes. A conceptual diagram of a strip filter.

FIG. 13 is a graph showing the frequency characteristics of the microstrip filter shown in FIGS. 12A and 12B. Referring to FIG. 13, it can be seen that the cut-off reduction is apparent at a high rate in the transition band of one passband.

FIG. 14 is a graph showing the frequency characteristics of the TT-block dielectric filter coated with the microstrip filter shown in FIG. 11. The graphs of FIGS. 10 and 13 are combined.

Referring to FIG. 14, it can be seen that the in-band characteristics are similar to those of the graph of FIG. 6. As the out-band characteristics, the microstrip filters 30-1 and 30-2 are applied to one side of the dielectric filter. In addition to suppressing higher-order mode harmonics including the second harmonics, spurious frequency characteristics can be improved.

To compare this, the spurious frequency characteristic is shown in FIG. 10, and when comparing the graph shown in FIG. 14 with the graph shown in FIG. 10, it can be seen that the spurious frequency characteristic is greatly improved in the graph shown in FIG. 10. .

That is, it can be seen that the higher-order mode harmonics are suppressed by attenuation by -30 to -40 dB at the higher-order mode harmonics close to the second harmonic (2fo) other than the first resonance frequency fo.

FIG. 15 is a schematic perspective view of a TT-block dielectric filter coated with a three-set microstrip filter 30-1 as a modification of the second embodiment of the present invention. The microstrip dielectric filter shown in FIG. The difference is that the microstrip filter 30-1, which is coupled to the pad electrodes AE of both the input stage resonator # 1 and the output stage resonator # 6, is composed of three sets. Duplicate explanations are omitted.

FIG. 16 is a schematic perspective view of a TT-block dielectric filter incorporating a 5-set microstrip filter 30-2 as another modification of the second embodiment of the present invention. The microstrip dielectric filter shown in FIG. The difference is that the microstrip filter 30-2 coupled to the pad electrodes AE of both the input stage resonator # 1 and the output stage resonator # 6 is composed of 5-sets. , Duplicate description is omitted.

FIG. 17 is a schematic perspective view of a TT-block dielectric filter to which a three- and five-set microstrip filter is applied as a further modification of the second embodiment of the present invention, and the microstrip dielectric filter shown in FIG. The difference is that the positions of the microstrip filters 30-1 and 30-2 coupled to the pad electrode AE on the input stage resonator # 1 and the output stage resonator # 6 side are reversed. The duplicate description is omitted.

FIG. 18 is a schematic perspective view of a straight dielectric filter coated with a microstrip filter, according to another modified example of the second embodiment of the present invention, which is different from the microstrip dielectric filter shown in FIG. Since the shape of the dielectric filter constituting the water filter 10 'and the second elliptic function filter 20' is not a TT block but is a straight line, all other application examples are the same, and thus, a detailed description thereof will be omitted.

On the other hand, the present embodiment is shown as an embodiment only for the case of an integrated dielectric filter, by combining the respective resonators manufactured separately to achieve the object of the present invention as well as in this embodiment only the coaxial resonator as an example However, it is possible to configure a dielectric filter and a microstrip dielectric filter using a resonant resonator, and a combination of a coaxial resonator and a resonant resonator may be used. In addition, the coupling strength may be adjusted through the shape deformation of each resonator, the distance interval adjustment, the diameter of the resonance hole, and the like. In addition, at least one microstrip filter may be applied to improve in-band frequency characteristics as well as out-band frequency characteristics.

As described above, the microstrip dielectric filter according to the present invention is an elliptical, concave and stepped shape in which the diameter ratio of the resonator hole and the thickness ratio of the resonator, the distance of the adjacent resonance period are adjusted, and the dielectric filter formed of the coaxial resonator. Alternate coupling with a resonator improves sharp skirt frequency characteristics in both stopbands of the passband, and symmetrical skirt frequency characteristics in both stopband bands can be obtained by simple and easy tuning of these resonators. have.

In addition, by applying a microstrip filter on one side of the dielectric filter to compensate for the disadvantage that the insertion loss increases, it is possible to improve the high-order mode harmonics and spurious frequency characteristics.

The present invention is not limited to the above-described embodiment, and it will be apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (7)

An input stage microstrip filter coupled to an input stage at which a signal is input; An output stage microstrip filter coupled to the output stage at which the signal is output; An input / output stage resonator coupled to and coupled to the input stage and output stage microstrip filters; A coupling resonator coupled to and coupled to the input / output end resonator; Microstrip dielectric filter, characterized in that consisting of. The method of claim 1, The microstrip filter consists of a 3-set or 5-set low pass filter; Microstrip dielectric filter, characterized in that designed differently according to the desired frequency band. The method of claim 1, When the input and output microstrip filters are integrally formed, a filter electrode is patterned on the surface of the microstrip filter so as to be coupled with the resonators, and a region except the patterned portion is coated with a common electrode. Microstrip dielectric filter, characterized in that. The method according to claim 1 or 3, A pad electrode is coupled to one side of the microstrip filter to allow coupling between the filter electrode and the coupling electrode. The method of claim 3, wherein The filter electrode is a microstrip dielectric filter, characterized in that the same material as the common electrode. The method of claim 1, The coupling resonator microstrip dielectric filter, characterized in that consisting of at least two. An input stage microstrip filter coupled to an input stage at which a signal is input; An input stage resonator coupled to and coupled to the input stage microstrip filter; A coupling resonator coupled to and coupled to the input stage resonator; An output stage resonator coupled to and coupled to the coupling resonator; An output stage microstrip filter coupled to the output stage resonator and coupled to an output stage at which a signal is output; The microstrip filter is applied to the surface of the resonator dielectric microstrip dielectric filter, characterized in that formed integrally.