JPH0612842B2 - Dielectric filter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter in which at least three stages of resonators are formed in a dielectric block, and more particularly to a bandpass type dielectric filter having a pole in the attenuation region. Regarding the proposal.

Conventional technology In the bandpass filter, from the aza side,
A filter may be ordered under the condition that the amount of attenuation at a frequency away from the center frequency by a predetermined frequency is a certain value or more. In this case, it is general to increase the number of resonator stages to satisfy the above requirements.

Problems to be Solved by the Invention However, if the number of stages of the resonator is increased, the overall configuration becomes larger and the cost increases, and when a plurality of resonators are formed in the dielectric block, it is proportional to the number of stages. Then TE
There is a problem that the resonance frequency of the 11-mode becomes low, and it approaches the resonance frequency of the TEM mode which is the use mode to cause spurious.

The present invention has been made in view of such problems, and an object thereof is to provide a useful means for satisfying the above-mentioned requirements without increasing the number of resonator coupling stages.

Means for Solving the Problems To achieve the above object, the present invention provides a dielectric filter having a dielectric block having at least three stages of resonators, in which adjacent resonators are electromagnetically coupled to each other. A plurality of holes (coupling holes) are formed in the open end surface (1a) of the dielectric block so as to form an opening, and a conductor pin is planted in the opening of the plurality of coupling holes. A resin is inserted, and the conductor pins are electrically coupled to each other by a conductor line arranged on the open end face side.

Working Dielectric resin is inserted into each of two or more holes (coupling holes) for coupling resonators, and conductor pins are planted in the dielectric resin to electrically couple the conductor pins. Then, for example, as shown by the solid line in FIG. 9, poles (hereinafter, referred to as poles) P1 and P2 are generated in the attenuation region to sharpen the filter characteristic, and the filter characteristic improved in this way. Since the conductor pin is stably fixed to the resonator hole through the dielectric resin, it will always be stably exhibited without being affected by the vibration or shaking of the dielectric filter body. . To explain briefly why the poles occur, the above-mentioned configuration creates a new transmission circuit that branches from a specific point of the original filter circuit and merges at another specific point when viewed in terms of an equivalent circuit. It was done. Therefore, at the merging 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 constructed transmission circuit are shifted by 180 ° is attenuated. In this case, the position and number of poles are
It can be set depending on the position of the holes, the type (inductive or capacitive) of the component (reactance element) used when electrically connecting the holes, the value thereof, and which hole is to be connected. Therefore, by appropriately setting these, it is possible to obtain a filter having characteristics required by the user. Further, in the present invention, since the coupling holes are electrically coupled by the conductor line disposed on the open end face (1a) side of the dielectric block, the space on the open end face side is effectively used to Can be combined. Therefore, according to the present invention, it is possible to obtain the effect that the dielectric filter itself can be made compact. In FIG. 9, the broken line shows the frequency characteristic of a filter having the same number of resonator stages and no poles.

EXAMPLE FIG. 1 shows, as an example of the present invention, a dielectric filter composed of a dielectric resonance block, and 1 is a dielectric block made of a titanium oxide-based ceramic dielectric or the like. Is formed with an outer conductor 2 made of a metal film,
Through holes 3 are formed in the dielectric block 1 at appropriate intervals. An inner conductor 4 made of a metal film is formed on the inner surfaces of the through holes 3, ... And electrically connected to the outer conductor 2 by a conductive film (not shown) formed on the bottom surface of the dielectric flock 1 (hereinafter, The bottom surface of this 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 where no conductive film is formed.

The dielectric resonators A1, A2, ... (hereinafter, referred to as “inner conductors 4”, “outer conductors 2”, and the dielectric block 1 existing therebetween).
Simply called a resonator. ) Is configured. Resonator A1,
As an example of a hole for electromagnetically coupling adjacent resonators between A2 ..., Coupling holes 6a, 6b, 6c ... For obtaining a predetermined coupling between the resonators are formed, and adjacent resonances are formed. The vessels A1, A2 ... Are electromagnetically coupled. Dielectric filters having such a structure are known.

A plurality of the coupling holes 6a, 6b, 6c ... Are coupled through the reactor tank elements X1, X2, X3 and X4. The reactance elements X1, X2, ... May be composite elements including one or both of capacitors and coils, and may be distributed constant elements instead of lumped constant elements. The point is that it is possible to equivalently form the reactance. Further, which coupling hole is to be coupled by the reactance element can be appropriately determined.

FIG. 2 shows a specific configuration example in the case where the reactance element X1 is a capacitor and the coupling holes 6a and 6b existing on both sides of one resonator A2 are coupled. 21, 2 in the figure
Reference numeral 2 denotes a cylindrical body (hereinafter referred to as a resin pin) made of a dielectric resin, which is press-fitted into the two coupling holes 6a and 6b from the open end face side. Each resin pin has a metal pin 23,2
4 (hereinafter referred to as a metal pin) is inserted to an appropriate depth. These two metal pins 23 and 24 are through holes 32 and 33 formed in a dielectric substrate 31 such as Teflon glass.
It is electrically connected by an attached electrode pattern 34 (see FIG. 3). In this configuration, the reactance element is equivalently formed of components existing between the coupling holes 6a and 6b. The size of the reactance element is the metal pins 23, 2
4 can be adjusted by the insertion depth and the dielectric constant of the resin pin.
FIG. 2 shows an example in which adjacent coupling holes are coupled, but a resin pin is inserted into a desired coupling hole and the electrode pattern 34 on the dielectric substrate 31 is extended to connect all the metal pins. By doing so, the desired position and number of coupling holes can be coupled by the reactance element.

FIG. 4 shows an equivalent circuit of a dielectric filter in which four resonance groups are provided and all the coupling holes existing between them are coupled by reactance elements. In the figure, Indicates that the resonators are coupled to each other by the coupling hole. l indicates that the three holes are electrically coupled.

Further, the frequency characteristic of the dielectric filter having this equivalent circuit is as shown in FIG. 5, and it can be seen that the poles P1 and P2 are generated in the attenuation regions on the high frequency side and the low frequency side. Paul P1,
The position of P2 can be changed by adjusting the value of the reactance element.

6 to 8 are equivalent circuits each showing another embodiment of the present invention, and FIG. 6 shows an example in which the coupling holes are coupled by the reactor tank element at two positions. FIG. 7 shows an example in which two connections intersect each other. FIG. 8 shows an example in which coupling holes that are not adjacent to each other are coupled by a reactance element.

The frequency characteristics are not particularly shown in any of these examples,
A pole is generated in the attenuation range. However, since the coupling structure differs depending on the embodiment, the position, the number, etc. of the generated poles differ depending on the embodiment.

Although the connecting holes 6a, 6b ... Are square slit holes in FIG. 1, they may be circular holes and are not limited to the shape of the holes.

Further, the coupling hole may be a through hole that penetrates from the open end surface to the short circuit end surface of the dielectric block, or may be a bottomed hole that does not penetrate.

The dielectric filter used in the present invention is not limited to the examples, and any known filter such as US Pat. No. 4,523,162 and US Pat.
7, JP-A-61-22003, and JP-A-60-2003.
It may be the one disclosed in, for example, 254802.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to provide a dielectric filter using a dielectric resonator with a pole in the attenuation region, and thereby a bandpass having a frequency characteristic according to a user's request. There is an effect that the filter can be obtained without increasing the number of stages of the dielectric resonator. Further, according to the present invention, the dielectric resin is inserted into two or more holes (coupling holes) for electromagnetically coupling the resonators, each of which has an opening formed in the open end surface (1a) of the dielectric block. In addition, conductor pins are planted in the dielectric resin, and the conductor pins are electrically coupled to each other by the conductor line disposed on the open end face side to provide a new transmission circuit. Such an effect can be obtained.

That is, since the conductor pin is attached to the coupling hole by inserting the pin into the dielectric resin press-fitted into the opening, the conductor pin is firmly fixed at a predetermined position of the coupling hole. Does not cause the conductor pin to oscillate or be displaced.

Then, the oscillation or displacement of the conductor pin makes the temporal coupling state unstable between the resonators and deteriorates the frequency characteristic of the dielectric filter. However, according to the present invention, this does not occur. Further, the method of implanting the conductor pin in the dielectric resin press-fitted and press-fitted into the coupling hole has an effect of excellent manufacturing workability because the conductor pin can be positioned and fixed very easily.

Further, in the present invention, since the conductor line for electrically coupling the conductor pins to each other is arranged on the open end face side,
The so-called cut-off space on the open end face side can be utilized as a space for disposing the transmission circuit. Therefore, in the present invention, the transmission circuit does not require a new installation space, and thus the effect that the entire dielectric filter can be made compact can be obtained.

Furthermore, in the present invention, the conductor pin is inserted and fixed not in the through hole having the inner conductor formed therein but in the coupling hole provided in the middle of the adjacent resonator which does not have a conductor for operating as a resonator. Since the resonators are electromagnetically coupled with each other, a maximum of four resonators can be electromagnetically coupled with one transmission circuit. Therefore, the resonators can be efficiently coupled to each other,
Therefore, the effect that the number of constituent members is small can be obtained.
This is because the coupling hole exists in the resonance electromagnetic field between the inner conductor and the outer conductor on both sides of the coupling hole, and the conductive pin inserted into this hole simultaneously connects the resonators on both sides. is there.

As described above, according to the present invention, it is possible to provide a bandpass filter having high productivity, small size, and excellent frequency characteristics.

The present invention is directed to an apparatus combining two or more bandpass filters such as an antenna resonator and a duplexer,
It can be applied to at least one of the filter portions.

[Brief description of drawings]

FIG. 1 is a perspective view showing a dielectric filter as an embodiment of the present invention, FIG. 2 is a view showing a concrete configuration example of the essential part of the present invention, and FIG. 3 is used for the configuration of FIG. FIG. 4 is a diagram showing a conductive pattern on a substrate, FIG. 4 is an equivalent circuit diagram of a dielectric filter, FIG. 5 is a diagram showing an example of frequency characteristics of the filter of FIG. 4, and FIGS. FIG. 9 is an equivalent circuit diagram showing another embodiment of the invention, and FIG. 9 is a diagram for explaining the operation of the invention. 6a, 6b, 6c ... Coupling holes, A1, A2, ... A5 ... Resonator, X1, X2 ... Reactance element

Claims (1)

[Claims] 1. A dielectric filter having at least three stages of resonators in a dielectric block, wherein a plurality of holes (coupling holes) for electromagnetically coupling adjacent resonators to each other are provided to open the dielectric block. End face (1a)
An opening is formed in the opening, and a dielectric resin in which conductor pins are planted is inserted into the openings of the plurality of coupling holes, and the conductor pins are arranged on the open end face side. A dielectric filter characterized by being electrically coupled with.