JPS6364403A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain BPF having frequency characteristic that meets the requirement of a user without increasing the number of steps by connecting electrically holes provided near the resonators and the resonators not adjoining to the holes. CONSTITUTION:A metalic film 2 is provided on the side face of a dielectric block 1, and a metalic film 4 inside of through holes 3 at proper interval is connected to the metalic film on the bottom face. Holes 6 are provided between resonators A1, A2... constituted between films 4, 2 to connect the resonators electromagnetically. For instance, to connect a hole 6a and A3 with a reactance element X, resin pins 21, 22 is pressed into the hole 6a and the through hole 3 and metalic pins are inserted. The upper ends of pins 23, 24 are connected by an electrode pattern 34 having through holes 32, 33 of a isolated substrate 31. The value of reactance is adjusted by selecting the amount of insertion of metalic pins and dielectric constant of resin pins, and the desired frequency characteristic can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric filter in which a plurality of resonators are formed in a dielectric block, and particularly to a bandpass type dielectric filter having a pole in the attenuation region. Regarding the proposal.

From the user side, regarding bandpass filters,
We sometimes receive orders for filters under the condition that the amount of attenuation at a frequency where a predetermined frequency is scattered from the center frequency is greater than or equal to a value. In this case, it is common to increase the number of resonator stages unless the above requirements are met.

Solution 1: IJ joints that are trying to achieve 1 However, increasing the number of resonator stages increases the size of the overall configuration and increases cost, and if multiple resonators are formed in a dielectric block, Place L in proportion to the number of stages
The resonant frequency of the mode becomes lower and the mode used is TE.
There is a problem in that it approaches the resonant frequency of the M mote and generates spurious signals.

In view of these problems, it is an object of the present invention to provide a useful means that satisfies the above requirements without increasing the number of coupling stages of resonators.

To solve the problems, the present invention provides a dielectric filter in which a plurality of resonators are formed in a dielectric block and adjacent resonators are coupled. The resonator is characterized in that a hole provided along the resonator and a resonator other than the resonator are electrically coupled.

Rule - ■ If a hole provided along a resonator is electrically coupled to a resonator other than the resonator concerned, a pole (hereinafter referred to as It's called a ball.)P
occurs, and the filter characteristics become steep. To briefly explain why poles occur, when the above configuration is adopted, when viewed from an equivalent circuit, a new transmission circuit is created that branches from a specific point in the original filter circuit and joins at another specific point. It means that it was done. Therefore, at the confluence point, the frequency component in which the phase of the output that has passed through the original filter circuit and the phase of the output that has passed through the newly configured transmission circuit is shifted by 180 degrees is attenuated. In this case, the position and number of poles P are determined by the hole position and the type (inductive (or capacitive),
It can be set depending on its value and which resonator is coupled to the hole. Therefore, by appropriately setting these, a filter with the characteristics desired by the user can be obtained. In the figure, the broken line indicates the frequency characteristics of a filter with the same number of resonator stages and no poles.

Embodiment 11 FIG. 1 shows a dielectric filter constructed of dielectric resonance blocks as an embodiment of the present invention. 1 is a dielectric block made of a titanium oxide ceramic dielectric or the like; An outer conductor 2 made of a metal film is formed on the side surface,
Inside the dielectric block 1, through holes 3 are formed at appropriate intervals.
・is formed. An inner conductor 4 made of a metal film is formed on the inner surface of the through hole 3, and is connected to the outer conductor 2 by a conductive film (not shown) formed on the bottom surface of the dielectric block 1 (hereinafter, this The bottom surface of the dielectric block is called the short-circuit end surface.) On the other hand, the upper surface 1a of the dielectric block 1 is an open end surface on which no conductive film is formed.

A dielectric resonator Al is formed by each of the inner conductors 4, the outer conductor 2, and the dielectric block 1 existing therebetween.

A2... (hereinafter simply referred to as a resonator) is configured. Coupling holes 6a, 6b, etc. are formed between the resonators AI, A2, etc. to obtain a predetermined coupling between the resonators, as examples of holes provided along the resonators. A
I, A2... are electromagnetically coupled. Dielectric filters having such a structure are known.

Among the coupling holes, for example, a coupling hole 6a between a first-stage resonator and a second-stage resonator is coupled to, for example, a third-stage resonator A3 that is not adjacent thereto via an actance element X. The reactance element X may be a composite element including either a capacitor or a coil, or both, and may also be a distributed constant element instead of a lumped constant element. In short, any material that equivalently forms reactance may be used. Further, it is possible to appropriately determine which resonator and coupling hole should be coupled, or how many resonators and coupling holes should be coupled.

FIG. 2 shows a specific example in which one coupling hole 6a and the resonator A3 are coupled by an actance element X.

In the figure, reference numerals 21 and 22 denote cylindrical bodies (hereinafter referred to as resin pins) made of dielectric resin, which are press-fitted into the coupling hole 6a and the through-hole 3 of the resonator A3 from their open ends to an appropriate depth. Metal pins 23 and 24 (hereinafter referred to as metal pins) are inserted into each resin pin 21 and 22 to an appropriate depth. The upper ends of the two metal pins 23 and 24 are electrically connected by an electrode pattern 34 (see FIG. 3) with through holes 32 and 33 formed in a dielectric substrate 31 such as Teflon glass. A reactance element X is equivalently formed by the components existing between the coupling hole 6a and the inner conductor 4 of the resonator A3. Reactance element X is capacitive. Note that since a reactance element is equivalently formed between the metal bottle 23 and the coupling hole 6a, the resin pin 22 and the metal pin 2
4, a metal cylindrical body 27 as shown in FIG. 4 may be used, and this may be inserted into the through hole 3 of the resonator A3 and directly connected to the inner door body 4. A protrusion 28 protruding toward one side from the cylindrical body 27 is used for connection to a through hole in the dielectric substrate.

FIG. 5 shows an equivalent circuit when the resonator has four stages and the reactance element X is capacitive. In the figure, "-" indicates that the resonators are coupled to each other.

Further, the frequency characteristics of the dielectric filter having this number of circuits are as shown in FIG. 6, and it can be seen that the ball P is generated in the attenuation region on the low frequency side. The position of the ball P can be changed by adjusting the value of the actance element.

7 to 11 show circuits showing other embodiments of the present invention, and FIGS. 7 and 8 show reactance element X2.
, X3, the positions and numbers of the coupling holes and the resonators that are coupled through the coupling holes are arbitrary. In the figure, 7.8 is an input/output terminal. FIG. 9 shows an example in which the coupling hole and the resonator can be coupled at two or more locations. 1st
0 and 11 show examples in which bonds at multiple locations intersect with each other. In particular, FIG. 10 shows an example in which one of the crossing bonding structures connects bonding holes.

None of these examples shows particular frequency characteristics, but
A ball is generated in the attenuation area. However, since the coupling structure differs depending on the embodiment, the position, number, etc. of the generated balls differ depending on the embodiment.

In Figure 7.8.9.11, multiple resonators are coupled via reactance elements, but when coupling such resonators to each other, the method shown in Figure 2 is used. In addition to the coupling structure using resin pins, metal pins, and dielectric substrates, the structure shown in FIG. 12 can be used. That is, the electrode pattern 42a formed on the dielectric substrate 41''
, 7I2b... are formed with capacitive glue actance elements x1, X2..., and each electrode pattern 42a,
42b... are connected to the inner conductor of the resonator via the metal cylindrical body 43... FIG. 13(a) shows an equivalent circuit having the above-mentioned coupling structure. Figure (+)) shows the equivalent circuit of the coupling structure shown in Figure 2, and Figure (c) shows Figure (a) and Figure ().
b) shows an equal number of circuits with a bonded structure made of silk. The present invention may employ any coupling structure shown by any of these circuits.

Further, although the coupling holes 6a, 6b, . . . are rectangular slit holes in FIG. 1, they may be circular holes, and are not limited to the shape of the holes.

Furthermore, the coupling hole may be a through hole penetrating the dielectric block from the open end surface to the short circuit end surface, or may be a bottom hole that does not penetrate the dielectric block. When the coupling hole is a through hole, coupling by a reactance element can also be performed using the opening on the short-circuited end surface side.

Note that the dielectric filter used in the present invention is not limited to the embodiments, and may be any known filter, such as those disclosed in U.S. Pat. No. 4,523,162 and U.S. Pat. ．． 431,9
No. 77, JP-A No. 61-52003 and JP-A No. 6
The material disclosed in Japanese Patent No. 0-254802 may also be used.

Therefore, in a dielectric filter that does not have a coupling hole, a hole is provided near the resonator and the hole is used. In this case, the resin pin 21.2 in the second embodiment
A structure in which metal pins 23 and 24 are buried directly in the dielectric block 1 without intervening the dielectric block 2 is conceivable.

Effects of the Invention As described in 4-2, according to the present invention, in a dielectric filter in which dielectric resonators are coupled through a coupling hole, a bandpass filter having a frequency characteristic according to the user's request can be combined with a dielectric resonator. This has an excellent effect that can be obtained without increasing the number of stages.

Note that the present invention provides a device in which two or more bandpass filters are combined, such as an antenna resonator or a duplexer.
This can be applied to at least one of the filter parts.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a dielectric filter as an embodiment of the present invention, FIG. 2 is a diagram showing a specific configuration example of the main part of the present invention, and FIG. Figure 4 is a diagram showing the metal cylinder connected to the inner conductor of the resonator, Figure 5 is an equivalent circuit diagram of the dielectric filter, and Figure 6 is 7 to 11 are equivalent circuit diagrams showing other embodiments of the present invention, and FIG. 12(a) is another embodiment of the main part of the present invention. A plan view showing a possible configuration, FIG. 13(b) is a side view thereof, FIGS. 13(a), (b), and (C) are equivalent circuit diagrams of a coupling structure using reactance elements, respectively, and FIG. 14 is an example of the present invention. FIG. 1...Dielectric blocks 6a, 6b, 6c...Coupling hole, AI, A2...A5...Resonator, X, XI, X2...Reactance element Patent applicant:
Murata Manufacturing Co., Ltd. Figure 1 Figure 2 Figure 1 Figure 3 Figure 4 Figure 5 Figure 13 Figure 14 O □f

Claims (1)

[Claims] (1) In a dielectric filter in which a plurality of resonators are formed in a dielectric block and adjacent resonators are coupled,
A dielectric filter characterized in that a hole provided along a resonator and a resonator not adjacent to the hole are electrically coupled.