JPS59161B2 - Filter using coaxial resonator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter using a coaxial resonator, and particularly relates to a filter using a coaxial resonator having a structure that is meaningful for manufacturing.

As a prior art, Utility Model Application No. 52-125560 (Utility Model Application No. 54-50944) has been devised, but since there is no conductive film on the outer circumferential surface of the cylindrical dielectric, the coupling between adjacent coaxial resonators is due to the resonator. This is obtained by coupling the fundamental mode electromagnetic field that exists in the magnetic field with the capacitor.

Therefore, the coupling coefficient cannot be set using only the constant of the capacitor.

In addition, since the structure is such that the cylindrical dielectrics are in direct contact with each other and the case and the cylindrical dielectric, variations in the mutual positional relationship can cause large variations in the coupling coefficient.
It is difficult to set a stable coupling coefficient.

Additionally, each capacitor is formed on a ceramic plate with one
The ceramic plate is placed on the open end between adjacent cylindrical dielectrics so as to be in contact with the open end.

For this reason, the coupling coefficient and resonance frequency change depending on where the capacitor is placed, so it cannot be said that the structure is reproducible.

Also, the capacitor used in this part is 2/1000 (
However, prior art capacitor structures always require trimming due to variations in the dielectric constant, etching accuracy, etc.

In addition, the capacitance of a capacitor can usually only be measured at a low frequency such as 1 (MHz), so the U
In the HF band, the values vary depending on the inductance of the capacitor electrode, and the variation becomes large.

From these points, computer simulation is difficult, design is troublesome, and it is difficult to achieve desired characteristics due to the non-uniformity of manufacturing technology.

In other words, in order to design a filter with good reproducibility that is suitable for mass production, the structure must not affect the coupling coefficient or resonance frequency due to variations in the assembly position.

The purpose of this invention is to provide easy design and high reproducibility (
It is an object of the present invention to provide a filter that can be easily mass-produced and can reduce costs.

The gist of this invention is to
It has a 1/4 wavelength coaxial TEM resonator provided with an outer conductor, and a capacitor having capacitor electrodes on both sides of a solid dielectric, and one electrode surface of the capacitor is connected to the 1/4 wavelength coaxial T.
By attaching the capacitor to a rod-shaped terminal sufficiently protruding from the open end surface of the EM resonator, the capacitor is separated from the resonator, and when there is only one resonator, the resonator and the connector are coupled via this capacitor, When the resonators are on the edge, it is a filter that connects adjacent resonators and the first and final stage resonators and connectors.

The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

FIGS. 1 to 4 show examples of resonators used in the embodiment filter. In FIG. 1, 1 is a 1/4 wavelength coaxial TEM resonator, and between an inner conductor 2 and an outer conductor 3, For example, a dielectric material 4 such as a titanium oxide-based ceramic dielectric material is filled, and more specifically, the inner wall surface and outer peripheral surface of the thick pipe-shaped dielectric material 4 are filled with a material having excellent high frequency conductivity and The inner conductor 2 and the outer conductor 3 are made by baking a silver paste, for example, which has good adhesion to the dielectric.

The inside of the inner conductor 2 is a cavity, into which a center rod 5 made of a similar ceramic or the like and having an axial length longer than the dielectric 4 is fitted.
The rod 5 is fixed, and one end 6 of the rod 5 is connected to the open end surface 7 of the resonator 1.
It protrudes from the inner conductor 2 and is covered with an electrode film 8 formed integrally with the inner conductor 2.

FIG. 2 is a diagram showing only the essential parts of another resonator 11, and shows a case where the center rod 5 is not used. In this case, a terminal electrode 12 of an arbitrary shape is inserted into a hole surrounded by an inner conductor 2. , fixed and connected to the inner conductor 2.

On the other hand, 21 and 22 are chip capacitors, and the resonator 11
It is used when capacitively coupling to other parts, such as another resonator or connector.

That is, the upper part of the terminal electrode 12 is shaped appropriately to connect one electrode 23.24 of the capacitor 21.22, while the other electrode of the capacitor 21.22 is connected.

Connect one end of lead wire 27 and 28 to 26, and
7. The other end of 28 may be connected to, for example, another resonator or connector.

The connection structure of the capacitors 21 and 22 to the terminal electrode 12 is not limited to this, and may be as shown in FIG. 3, for example.

In this case, a terminal electrode 31 is illustrated.

In these cases, the number of connected capacitors is of course not limited to the above.

It goes without saying that when using a capacitor, the structure shown in FIG. 1 can be applied in place of the terminal electrode 12.31.

FIG. 4 shows a structure for frequency adjustment using the protruding terminals illustrated in FIGS. 1 to 3. FIG.

In this case the terminal electrode is illustrated at 41.

Reference numeral 51 denotes a male screw having a conductive component, which is screwed into a female screw formed on the terminal electrode 41, and its protrusion amount t can be adjusted.

The resonant frequency of the resonator 11 is determined by this protrusion amount t.

Of course, other parts such as capacitors 21 and 22 can be added to the terminal electrode 41.

Note that the resonance frequency can also be adjusted by cutting these terminal electrodes themselves and changing their axial lengths without using male screws.

FIG. 5 shows an embodiment of the present invention, which is a filter 61 constructed using the above-mentioned resonator, particularly the one shown in FIG.

Components that are the same as those in FIG. 2 are given the same numbers and their explanations will be omitted.

The main case 62 is a rectangular rectangular body made of a conductor such as duralumin with holes 63, 64, 65, and 66 cut out therein.

The resonators 11 are fitted into the holes 63, 64, 65, and 66, respectively, and their outer conductors 3 are fixed to the case 62 so as to be electrically conductive.

This fixing is performed, for example, by using a conductive adhesive or by screwing.

67 is an input coaxial connector, and 68 is an output coaxial connector, which are provided in the main case 62.

The center terminal of the input coaxial connector 67 and the capacitor 21 of the first stage resonator 11 are connected by a lead wire 69.

The capacitor 22 of the first stage resonator 11 and the capacitor 21 of the second stage resonator 11 are connected by a lead wire 71 through a hole 70 formed by hollowing out between the holes 63 and 64. .

The capacitor 22 of the second stage resonator 11 and the capacitor 21 of the third stage resonator 11 are connected by a lead wire 73 through a hole 72 formed by hollowing out between the holes 64 and 65. .

The capacitor 22 of the third-stage resonator 11 and the capacitor 21 of the fourth-stage resonator 11 are connected by a lead wire 15 through a hole γ4 formed by hollowing out between the holes 65 and 66. .

The capacitor 22 of the fourth stage resonator 11 and the center terminal of the output coaxial connector 68 are connected by a lead wire 76.

An upper cover 77 is attached to the opening of each hole 63, 64, 65, 66.

The shape of the terminal electrode of the resonator and the attachment of the coupling capacitor to the terminal electrode are arbitrary as long as the structure does not depart from the gist of the present invention.

If a resonator having terminal electrodes having the structure shown in FIG. 4 is used, the center frequency can be easily adjusted even after the filter is assembled.

It goes without saying that the number of resonators is arbitrary.

For example, a case where the number of resonators is one can also be considered.

At this time, one of the two capacitors attached to the terminal electrode is connected to the input coaxial connector, and the other is connected to the output coaxial connector.

As is clear from the above embodiments, according to the present invention, a conductive film is also provided on the outer peripheral surface of the solid dielectric to completely cut off external influences, and If there are multiple resonators, connect the capacitors to rod-shaped terminals that protrude sufficiently so that the capacitors are located far enough away from each other that they do not affect the electromagnetic field of the dielectric surface at the open end of the resonator. Since it is connected only with
The circuit constants of each element could be set strictly as designed values, assembly was easier, there was no non-uniformity in characteristics between products, and product costs were reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a resonator used in an embodiment of the filter of the present invention, Fig. 2 is a sectional view showing the main parts of another resonator, and Fig. 3 is a sectional view showing the main parts of another resonator. Sectional view shown, No. 4
This figure is a cross-sectional view showing the main part of another resonator, and FIG. 5 is a cross-sectional view of one embodiment of the filter of the present invention. 1.11 is a 1/4 wavelength coaxial resonator, 2 is an inner conductor, 3 is an outer conductor, 4 is a dielectric, 6 is one end side, 7 is an open end surface, 8 is an electrode film, 12, 31.41 is a terminal electrode .

Claims (1)

[Claims] 1 It has a 1/4 wavelength coaxial TEM resonator with inner and outer conductors on the inner and outer surfaces of a solid dielectric, and a capacitor with capacitor electrodes on both sides of the solid dielectric, with one electrode surface of the capacitor is attached to a sufficiently protruding rod terminal on the open end surface of the 1/4 wavelength axis TEM resonator, so that the capacitor is separated from the resonator, and when there is only one resonator, the capacitor is separated from the resonator. A filter that combines a resonator and a connector, and when the resonators are on the edge, connects adjacent resonators and the first and final stage resonators and the connector.