JP2003304101A - Band pass filter and shared transmitter/receiver using multiple mode dielectric resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a band pass filter and shared transmitter/receiver fulfilling attenuating characteristics applying deep attenuation and low insertion loss at the same time in the neighborhood of a pass band without increasing the shape of a filter. <P>SOLUTION: In this band pass filter configured of a plurality of resonators including at least one multi-mode dielectric resonator, an inter-resonator conductor wall configuring a boundary between the multi-mode dielectric resonator and the adjacent resonator therewith is formed with slits inducing electromagnetic connection, and one of those slits is configured to pass the center of the inter-resonator conductor wall as a first rectangular slit formed in parallel with another conductor wall orthogonal to the conductor wall, and the other slit is configured as a second rectangular slit formed so as to be almost orthogonal to the first rectangular slit. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bandpass filter and a duplexer using a multimode dielectric resonator used in a microwave / millimeter wave circuit such as a radio communication base station device.

[0002]

2. Description of the Related Art A band pass filter used in a wireless communication base station device or a transmission / reception duplexer, particularly a filter used in a receiver, has a deep attenuation near the pass band in order to prevent radio wave interference from other systems. Need to take.

A configuration example of a conventional bandpass filter using a multimode dielectric resonator having high selectivity will be shown. FIG. 11 shows a three-stage bandpass filter using two multimode dielectric resonators and a coupling rod for input / output matching, and FIG. 11A is a perspective view thereof, and FIG. Is B-
It is a B sectional view.

In FIG. 11A, 14 is a metal cover A, 11 is a metal housing A, 13 is a multimode dielectric resonator, 15 is a coupling rod for input / output matching, and 16 is an input / output terminal. . The metal cover A is drawn separately.

In FIG. 11B, 31 is a conventional conductor wall between resonators, and 41 is a vertically elongated slit.

In addition, two multimode dielectric resonators,
There is also an example of an eight-stage bandpass filter formed outside of it with a semi-coaxial resonator and a coupling rod for input / output matching.

Further, there is also an example of a 12-stage band pass filter constructed by using four multimode dielectric resonators through a coupling rod for input / output matching.

The conventional band-pass filter as described above is usually constructed by increasing the number of filter stages in order to deepen the attenuation amount near the pass band, thereby satisfying the attenuation characteristic.

[0009]

In a conventional bandpass filter using a multimode dielectric resonator, it is difficult to make a polarized structure having a center frequency symmetrical, and a multistage structure is adopted to make the attenuation deep. I was there. Therefore, there are drawbacks that the filter shape is large and the insertion loss is increased.

It is an object of the present invention to provide a bandpass filter which does not increase the size of the filter and can satisfy the characteristics of providing a deep attenuation in the vicinity of the passband and at the same time a low insertion loss.

[0011]

A configuration example of a conventional six-stage bandpass filter using a multimode dielectric resonator is as shown in FIG. The equivalent circuit of the filter at this time is as shown in FIG. In FIG. 12, M0
Reference numeral 1b indicates the coupling between the input / output terminal and the first-stage or sixth-stage filter.
b and C56b represent the capacitance between the stages. The portion surrounded by the alternate long and short dash line corresponds to one multimode dielectric resonator.

It is known that the polarization in which the center frequency is made symmetric in this filter can be realized by, for example, causing coupling between the second stage and the fifth stage. This will be described with reference to FIG. In FIG. 6, M11 indicates the coupling between the second and fifth stages.

Further, M01 represents the coupling between the input / output terminal and the filter of the first stage or the sixth stage, and C12, C23, C
34, C45, and C56 represent interstage capacitance. The portion surrounded by the alternate long and short dash line corresponds to one multimode dielectric resonator.

In the present invention, the conductor walls that magnetically couple the third resonances of the multimode dielectric resonator 13 are utilized, and the coupling between the first to sixth resonances and the negative coupling,
That is, the shape of the conductor wall that causes electric field coupling has been found.

More specifically, the bandpass filter of the present invention is
A bandpass filter having a plurality of resonators including at least one multimode dielectric resonator as a constituent element, wherein the resonator forms a boundary between the multimode dielectric resonator and a resonator adjacent thereto. A slit for inducing electromagnetic field coupling is provided on the conductor wall, and one of the slits passes through the center of the conductor wall between the resonators and is parallel to another conductor wall orthogonal to the conductor wall between the resonators. Is a first rectangular slit, and the other one of the slits is a second rectangular slit provided so as to be substantially orthogonal to the first rectangular slit.

The conductor wall between the resonators provided with the first and second rectangular slits has two multimode dielectrics in a six-stage bandpass filter in which two multimode dielectric resonators are symmetrically arranged. It may be a conductor wall that forms a boundary between the body resonators.

The conductor wall between the resonators provided with the first and second rectangular slits may be a conductor wall that forms a boundary between the multimode dielectric resonator and the semi-coaxial dielectric resonator.

Further, the conductor wall between the resonators provided with the first and second rectangular slits may be a conductor wall which forms a boundary between the multimode dielectric resonator and the TE _01δ mode dielectric resonator. .

The transmission / reception duplexer of the present invention can be constructed using the bandpass filter of the present invention.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) First, a dielectric block used in a multimode dielectric resonator according to the present embodiment will be described. FIG. 3 is a perspective view showing the shape of a dielectric block used in a multimode dielectric resonator. As shown in FIG. 3, the shape is a shape in which two non-parallel twill portions of a substantially rectangular parallelepiped dielectric block are cut off. With this shape, a triple-mode dielectric resonator in which three resonance modes are coupled is formed, and one dielectric block can form three
A characteristic equivalent to a stage filter is obtained.

FIG. 1 is a perspective view showing a bandpass filter according to the first embodiment. 2 is a cross-sectional view showing a conductor wall between the resonators of the first shape according to the present invention, which is taken along the line AA in FIG. In FIG. 2, the first rectangular slit 21 guides the magnetic field coupling which is the main coupling between the resonators. The second rectangular slit 22 provided with a certain width and length so as to be substantially orthogonal to the first rectangular slit 21 has a first resonance or a second resonance of each multimode dielectric resonator 13. Are bound together, and the bond induces a main bond and a negative bond.

As a result, the coupling M11 in the equivalent circuit already shown in FIG. 6 occurs. 6 is a filter equivalent circuit according to the first embodiment, and M01 indicates a coupling between the input / output terminal and the first or sixth stage filter, and C1
12, C23, C34, C45, and C56 indicate interstage capacitance. The portion surrounded by the alternate long and short dash line corresponds to one multimode dielectric resonator.

Due to such coupling M11, an attenuation pole is generated at a position of substantially the same frequency interval from the center frequency of the pass band. The position of the attenuation pole changes depending on the position of the rectangular slit 22, and also changes depending on the width d11 and the length L11.

The bandpass filter of this embodiment can be obtained by replacing the conductor wall 31 between the resonators of FIG. 11 of the conventional example with the conductor wall 12 between the resonators of the first shape according to the present invention. The filter transmission characteristic (S ₂₁ ) at this time is shown in FIG. Here, in order to clarify the characteristic comparison with the conventional example, the characteristic of the conventional example is shown by a broken line.

In FIG. 5, due to the generated attenuation pole,
It can be seen that a deeper attenuation amount is obtained in the vicinity of the pass band than in the conventional example.

(Embodiment 2) Next, a mode in which two multimode dielectric resonators and one semi-coaxial resonator are arranged outside each of them will be described. FIG. 7 is a perspective view showing a bandpass filter according to the second embodiment. 17 is a metal casing B,
18 is a semi-coaxial resonator, and 19 is a metal cover B. Further, reference numerals (numbers) common to the other drawings indicate substantially the same members.

Also in this mode, the first aspect of the present invention
By using the conductor wall 12 between the shaped resonators, it is possible to generate attenuation poles at positions having the same frequency interval from the center frequency of the pass band. The filter transmission characteristic (S ₂₁ ) is shown in FIG. Further, for comparison, FIG. 9 also includes the filter transmission characteristics when the conventional conductor wall 31 between the resonators is used instead of the conductor wall 12 between the resonators of the first shape.

It can be seen from FIG. 9 that deeper attenuation characteristics are obtained on both sides of the pass band than in the conventional example.

(Third Embodiment) Further, an example in which four multimode dielectric resonators are used will be described. FIG. 8 is a perspective view showing a bandpass filter according to the third embodiment. The reference numerals (numbers) in the figure are as described in other drawings.

Also in this embodiment, the first aspect of the present invention
By using the conductor wall 12 between the resonators having the shape described above, it is possible to generate attenuation poles at frequency positions equidistant from the center frequency of the pass band. The filter characteristic is shown in FIG. Further, for comparison, FIG. 10 also includes the filter transmission characteristics when the conductor wall 31 between the resonators of the first shape is used instead of the conductor wall 12 between the resonators of the first shape.

From FIG. 10, on both sides of the pass band,
It can be seen that a deeper damping characteristic is obtained than in the conventional example.

In the above-mentioned embodiments, the conductor wall 12 between the resonators of the first shape is used as the conductor wall between the resonators, but the same action (negative effect) can be obtained by the structure or shape shown in FIG. Can be realized.

FIG. 4A is a sectional view showing the second shape, and FIG. 4B is a sectional view showing the third shape. Also in this case, the positions of the attenuation poles are the widths d22, d33 and the length L2.
2, it can be changed by L33.

By the way, also in the conductor wall between the resonators that form the boundary between the multimode dielectric resonator and the TE _{01 δ} mode dielectric resonator in the multistage bandpass filter, the above-mentioned first, second, or third. By using the conductor wall between the resonators in the shape of, the negative coupling can be induced and the attenuation pole can be generated at the symmetrical frequency position from the center frequency. As a result, a deep attenuation amount characteristic is obtained near the pass band.

Further, by using the band pass filter having the above characteristics, a duplexer can be easily constructed.

[0037]

As described above, in the bandpass filter using the multimode dielectric resonator of the present invention,
A polar filter can be obtained without changing the basic configuration or structure.

Therefore, according to the present invention, it is possible to deepen the attenuation characteristics in the vicinity of the pass band without increasing the number of stages, and to provide a compact and low loss band pass filter and a transmission / reception duplexer using the same. can do.

[Brief description of drawings]

FIG. 1 is a perspective view showing a bandpass filter according to a first embodiment.

FIG. 2 is a sectional view showing a conductor wall between resonators of a first shape according to the present invention.

FIG. 3 is a perspective view showing the shape of a dielectric block used in a multimode dielectric resonator.

FIG. 4 is a sectional view showing the shape of a conductor wall between resonators in the present invention. 4A shows the second shape, and FIG. 4B shows the third shape.

FIG. 5 is a filter transmission characteristic according to the first embodiment.

FIG. 6 is a filter equivalent circuit according to the first embodiment.

FIG. 7 is a perspective view showing a structure of a bandpass filter according to a second embodiment.

FIG. 8 is a perspective view showing a structure of a bandpass filter according to a third embodiment.

FIG. 9 is a filter transmission characteristic according to the second embodiment.

FIG. 10 is a filter transmission characteristic according to the third embodiment.

FIG. 11 is a diagram showing a structure of a conventional 6-stage bandpass filter. 11 (a) is a perspective view thereof, and FIG. 11 (b) is a B thereof.
-B sectional view.

FIG. 12 is a conventional filter equivalent circuit.

[Explanation of symbols]

11 Metal case A 12 Conductor wall between resonators of the present invention 13 Multimode dielectric resonator 14 Metal cover A 15 Connecting rod for input / output matching 16 input / output terminals 17 Metal housing B 18 Semi-coaxial resonator 19 Metal cover B 21 First rectangular slit 22 Second rectangular slit

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Claims (5)

[Claims] 1. A bandpass filter having a plurality of resonators including at least one multimode dielectric resonator as a constituent element, wherein a resonance forming a boundary between the multimode dielectric resonator and a resonator adjacent thereto. A slit for inducing electromagnetic field coupling is provided on the conductor wall between the chambers.
One is a first rectangular slit provided through the center of the conductor wall between the resonators and parallel to another conductor wall orthogonal to this conductor wall, and another one of the slits is the first slit. 1
Band-pass filter, which is a second rectangular slit provided so as to be substantially orthogonal to the rectangular slit of. 2. The conductor wall between the resonators is a conductor wall that forms a boundary between two multimode dielectric resonators in a six-stage bandpass filter in which two multimode dielectric resonators are symmetrically arranged. The bandpass filter according to claim 1, wherein: 3. The band pass filter according to claim 1, wherein the conductor wall between the resonators is a conductor wall that forms a boundary between the multimode dielectric resonator and the semi-coaxial dielectric resonator. 4. The bandpass filter according to claim 1, wherein the conductor wall between the resonators is a conductor wall that forms a boundary between the multimode dielectric resonator and the TE _{01 δ} mode dielectric resonator. . 5. A transmission / reception duplexer using the bandpass filter according to claim 1. Description: