JPH08195603A - Demultiplexing and multiplexing filter - Google Patents

Abstract

PURPOSE: To facilitate the assembling operation and lower the cost by simplifying the constitution of the branching part of the multiplexing and demultiplexing filter which connects >=2 band-pass filters in a T branch shape. CONSTITUTION: At both side parts in a thin and long metallic case 11, plural dielectric resonators 13a-13c, and 17a-17c which constitute the 1st and 2nd band- pass filters 1 and 2 are arrayed, and a strip line 21 formed of a beltlike metallic plate 20 having looped coupling parts 22 at both ends is extended to between those band-pass filters to constitute the branching part 3. This strip line 21 has the coupling parts 22 arranged nearby the initial-stage resonators 13a and 17a of the band-pass filters 1 and 2 and is electrically connected to a 1st coaxial connector 23. Further, the final-stage resonators 13c and 17c of the band-pass filters 1 and 2 are coupled with coupling rods 15 and 18, connected to 2nd and 3rd coaxial connectors 16 and 19, thorugh an electric field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demultiplexing / multiplexing filter for microwaves using different band filters, and more particularly to a demultiplexing / multiplexing filter for simplifying the configuration of a branching portion of a T-branching filter.

[0002]

2. Description of the Related Art FIG. 3 shows an equivalent circuit of an example of a demultiplexing filter composed of this type of filter. The band pass filters (BPF) 1 and 2 have different band pass characteristics, and the input ends of the band pass filters 1 and 2 are connected to the input terminal IN at the branching unit 3, respectively. The output terminals of the band pass filters 1 and 2 are connected to the output terminal O
It is configured as UT1 and OUT2. Then, signal waves of frequencies f1 and f2 are input to the input terminal IN, and the signal waves are demultiplexed by the band pass filters 1 and 2.

The bandpass filter 1 passes a signal wave of frequency f1 and reflects a signal wave of frequency f2. Similarly, the band pass filter 2 passes the signal wave of the frequency f2 and reflects the signal wave of the frequency f1. Therefore, looking at the signal wave of frequency f1, the impedance looking into the bandpass filter 2 from the branch section 3 is open, and conversely, looking at the signal wave of frequency f2, the impedance looking into the bandpass filter 1 from the branch section 3. So as to be open, the electrical lengths L from the branch point 3a of the branch unit 3 to the input ends of the band pass filters 1 and 2 are
1 and L2 are set. As a result, the signal wave of the frequency f1 passes through the band pass filter 1 in the impedance matching state, and the signal wave of the frequency f2 passes through the band pass filter 2 in the impedance matching state.

FIG. 4 is a diagram showing an example of a structure previously proposed as such a demultiplexing filter. FIG. 4A is a plan view with an upper cover removed, and FIG. 4B is a longitudinal sectional view thereof. Is. A bandpass filter 1 is formed on one side of the elongated metal case 11, and a bandpass filter 2 is formed on the other side. The band pass filter 1 is a metal case 1
Three dielectric resonators 13a to 13c are arranged in one and attached by an insulating member 14, and one side thereof has a coupling rod made of metal or the like that is field-coupled to the final-stage resonator 13c. 15 is disposed and supported by the metal case 11 in an insulated state. A central conductor 16a of a coaxial connector 16 as an output terminal OUT1 attached to the metal case 11 is connected to the coupling rod 15. In addition, the bandpass filter 1
On the other side, a coupling rod 24 that is electric-field coupled to the first-stage resonator 13a is supported in the metal case 11 in an insulated state.

Similarly, the bandpass filter 2 is also arranged in a state where three dielectric resonators 17a to 17c are insulated and supported in the metal case 11, and an electric field is applied to the final stage resonator 17c on the other side. A coupling rod 18 to be coupled is provided, and a coupling rod 25 to be coupled to the first-stage resonator 17a is provided on one side, and each is supported by the metal case 11 in an insulated state. Further, a coaxial connector 19 as an output terminal OUT2 attached to the metal case 11 is attached to the coupling rod 18 on the final stage side.
The center conductor 19a of is connected.

Further, an insulating substrate 26 is provided inside the metal case 11 between the band pass filters 1 and 2, and a strip line 27 is formed on the surface of the insulating substrate 26 by a conductor film. The center conductor 2 of the coaxial connector 23 as the input terminal IN for the strip line 27
3a is connected. Also, this strip line 27
Both ends of each are electrically soldered to the coupling rods 24 and 25 coupled to the first-stage resonators 13a and 17a of the bandpass filters 1 and 2 by using metal ribbons 28, respectively. The strip line 27 is set to have a length corresponding to the electric lengths L1 and L2 from the branch point 3a to the band pass filters 1 and 2 shown in FIG.
A filter using such a dielectric resonator is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-277201.

[0007]

In the structure of such a conventional demultiplexing filter, in order to form the branching part 3 for connecting the bandpass filters 1 and 2 to the input terminal IN with a predetermined electrical length, The band-pass filters 1 and 2 are provided with coupling rods 24 and 25, respectively, and the strip line 27 is provided between the filters 1 and 2, and then the strip line 2 is provided.
7 and the connecting rods 24 and 25 are connected by a metal ribbon 28. For this reason, in particular, the number of constituent parts of the branching part 3 increases, and the structure becomes complicated.
There is a problem that the assembly work becomes complicated and the cost becomes high.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a demultiplexing / multiplexing filter which simplifies the structure of the branching portion, simplifies the assembling work, and reduces the cost.

[0009]

A demultiplexing / multiplexing filter of the present invention is a demultiplexing / multiplexing filter having a structure in which two or more band-pass filters are connected by a T-branch, and a branch portion of the T-branch is a strip line. In this configuration, the end of the strip line is directly connected to each bandpass filter.

That is, in the strip line, a strip-shaped metal plate is extended between the band-pass filters and the ends thereof are bent to form a loop to form a coupling section, which is connected to each band-pass filter. It is configured to be magnetically coupled. Further, the bandpass filter has a plurality of dielectric resonators arrayed, and the coupling portion of the strip line is magnetically coupled to the first-stage resonator.

For example, according to the present invention, a plurality of dielectric resonators forming first and second band pass filters are arranged in both side regions in an elongated metal case, and the first and second band resonators are arranged. A strip line in which both ends of a strip-shaped metal plate are formed as loop-shaped coupling portions is extended between the pass filters, and the strip lines have the coupling portions at the first stage of the first and second band pass filters. The first and second band pass filters are arranged close to the resonator and are electrically connected to the center conductor of the first coaxial connector. In the first and second band pass filters, the final-stage resonators are the center conductors of the second and third coaxial connectors, respectively. It is preferable to have a structure in which electric field coupling is performed to a coupling rod connected to.

[0012]

In order to directly couple the ends of the branch strip lines to the band pass filter, the coupling rod for coupling with the band pass filter and the strip line constituting the branch are connected. Since a metal ribbon or the like is unnecessary, the number of components can be reduced and the number of steps for assembling these can be reduced.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a diagram showing an embodiment in which the present invention is applied to the demultiplexing filter shown in FIG. 3, (a) is a plan view with an upper cover removed, and (b) is a longitudinal sectional view thereof. The band-pass filter 1 having the pass frequency f1 is formed in the left side region of the elongated metal case 11 shown in the figure, and the pass frequency f is set in the right side region.
2 band pass filter 2 is configured, and branching section 3 is configured in the intermediate region between these band pass filters 1 and 2. An upper cover 12 is attached to the upper opening of the metal case 11 to seal the inside.

The band pass filter 1 comprises a plurality of, here three, short cylindrical dielectric resonators 13a to 13c.
Are arranged in series along the length direction of the metal case 11,
It is configured to be supported by the insulator 14. As these dielectric resonators 13a to 13c, known ones such as titanium oxide ceramics are used. A metallic coupling rod 15 is disposed close to the leftmost resonator 13c on the left side, and is insulated and supported by the inner side surface of the metal case. A central conductor 16a of a coaxial connector 16 as an output terminal OUT1 attached to the metal case 11 is connected to the coupling rod 15.

Similarly, the bandpass filter 2 has a structure in which three feeder resonators 17a to 17c are arranged and supported in series by an insulator 14 along the length direction of the metal case 11, and The coupling rod 18 is disposed close to the rightmost final stage resonator 17c and is supported in the metal case 11. The connecting rod 18 has a metal case 1
Coaxial connector 1 as output terminal OUT2 attached to 1
Nine central conductors 19a are connected.

As shown in the perspective view of the main portion of the branch portion 3, a strip line 21 formed of a long and narrow straight strip-shaped metal plate 20 extends in the length direction of the metal case 11. A coupling circuit 22 is formed by bending a metal plate into a loop shape at both ends thereof. The tip of the coupling circuit 22 is connected to the band pass filters 1 and 2 described above.
Metal case 11 near each of the first-stage resonators 13a and 17a
Is in contact with the inner bottom surface of. Further, the metal case 11
A part of the strip-shaped metal plate 20 is connected to the central conductor 23a of the coaxial connector 23 as the input terminal IN attached to the strip line 22, and the strip line 22 is electrically connected.
We are supporting it. In this case, the strip line 21
The strip line 22 may be supported on the metal case 11 by soldering or joining the tip of each coupling circuit 22 to the inner bottom surface of the metal case 11.

The connecting portion between the strip line 21 and the central conductor 23a of the coaxial connector 23 is configured as a branch point 3a. From this branch point 3a to the coupling circuit 22 for the band pass filters 1 and 2. The length of the strip line 22 and the connection position of the coaxial connector 23 are set so that the dimensions become the electric lengths L1 and L2 shown in FIG.

According to this structure, of the signal waves input to the coaxial connector 23 as the input terminal IN, the frequency f
The signal wave of 1 is passed through the band pass filter 1 and output terminal O
It is output from the coaxial connector 16 as the UT 1. The signal wave of frequency f2 passes through the band pass filter 2 and is output from the coaxial connector 19 as the output terminal OUT2. At this time, the branch point 3a connected to the input terminal IN
From the coupling circuit 2 facing the bandpass filters 1 and 2
The electrical length of the stripline 21 up to 2 is L1, L in FIG.
Since it is set to 2, the signal waves of the frequencies f1 and f2 pass through the band pass filters 1 and 2 in an impedance matching state.

Since the coupling circuit 22 provided at both ends of the strip line 21 is formed in a loop shape and its tip is grounded to the metal case 11, the band pass filters 1 and 2 are provided. The first-stage resonators (TE01 δ-mode dielectric resonators) 13a and 17a are magnetically coupled.

As described above, in this demultiplexing filter, since the branching portion 3 can be constructed by the strip line 21 of the strip-shaped metal plate 20, the number of constituent parts can be reduced. Further, both ends of the strip-shaped metal plate 20 are configured as a loop-shaped coupling circuit 22, and the tip ends thereof are the metal case 1.
Since the structure is such that the central conductor 23a of the coaxial connector 23 is simply contacted with the first conductor and the center conductor 23a is connected to a part of the middle thereof, the assembly can be carried out very easily. As a result, the demultiplexing filter can be manufactured at low cost.

In the above embodiment, an example in which the present invention is applied to a demultiplexing filter is shown, but it is also possible to construct a multiplexing filter by reversing the input terminal and the output terminal. Further, when this filter is used as a transmission / reception demultiplexing filter of a communication device, one terminal of the bandpass filter is used as an input terminal and the other terminal is used as an output terminal. It will be.

Further, although the two band-pass filters have the T-branch structure in the above-mentioned embodiment, the present invention can be similarly applied to the case where three or more band-pass filters are connected as a branch structure in some cases. You can

[0023]

As described above, according to the present invention, a branch portion connecting two or more bandpass filters with a T-branch is formed by a strip line, and the end of the strip line is directly coupled to each bandpass filter. Therefore, a coupling rod or a metal ribbon for coupling the bandpass filter and the branching part like the previously proposed filter is unnecessary, reducing the number of components and assembling these. There is an effect that the number of steps can be reduced and the manufacturing cost can be reduced.

Further, in the present invention, the strip line is formed by extending a band-shaped metal plate between the band-pass filters and bending the ends thereof into a loop to form a coupling portion, which is then passed through each band-pass filter. By magnetically coupling to the filter, the branch portion can be configured by one strip-shaped metal plate, the configuration can be extremely simplified, and the number of assembling steps can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view and a vertical sectional view showing an embodiment of the present invention with an upper cover removed.

FIG. 2 is a perspective view of a branch portion.

FIG. 3 is an equivalent circuit diagram of a branching filter having a T-branch configuration to which the present invention is applied.

FIG. 4 is a plan view and a vertical cross-sectional view showing an example of the previously proposed filter, with an upper cover removed.

[Explanation of symbols]

 1 and 2 band pass filter 3 branch part 11 metal case 13a-13c, 17a-17c dielectric resonator 15,18 coupling rod 16,19,23 coaxial connector 20 strip metal plate 21 strip line 22 coupling part

Claims (4)

[Claims] 1. A demultiplexing / multiplexing filter having a structure in which two or more band-pass filters are connected by T-branches, wherein a branch portion of the T-branch is formed by a strip line, and an end portion of the strip line is formed by each band. A demultiplexing / multiplexing filter characterized by being directly coupled to a pass filter. 2. The strip line comprises a band-shaped metal plate extending between the band-pass filters, and the ends thereof are bent to form a loop to form a coupling section. The coupling section is connected to each of the band-pass filters. 2. The demultiplexing / multiplexing filter according to claim 1, wherein the demultiplexing / multiplexing filters are magnetically coupled. 3. The demultiplexing / multiplexing filter according to claim 2, wherein the band-pass filter is formed by arranging a plurality of dielectric resonators and magnetically coupling the coupling portion of the strip line to the resonator at the first stage. 4. A plurality of dielectric resonators forming first and second band pass filters are arranged in both side regions in an elongated metal case, and between the first and second band pass filters. A strip line formed by forming both ends of a strip-shaped metal plate as loop-shaped coupling portions as branch portions, and each coupling portion of the strip line is close to each first-stage resonator of the first and second bandpass filters. Is disposed and electrically connected to the center conductor of the first coaxial connector,
And a second bandpass filter, wherein each final-stage resonator is field-coupled to a coupling rod connected to a center conductor of each of the second and third coaxial connectors.