JPS63962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter device such as a filter or a duplexer using a coaxial resonator having a dielectric between inner and outer conductors.

When constructing a filter device, such as a duplexer, using a coaxial resonator having a dielectric material between the inner and outer conductors (hereinafter simply referred to as a dielectric coaxial resonator), two main structures can be considered.

One is the structure shown schematically in FIG. 1, as disclosed in Japanese Patent Application Laid-Open No. 56-57302. The other type is disclosed in Japanese Patent Application Laid-Open No. 56-57304, and has a structure as schematically shown in FIG. 2. In the one shown in Fig. 1, the inner conductors of dielectric coaxial resonators 2 are connected so as to hang from the signal propagation path 1, and a coupling capacitor C is connected between the inner conductors of adjacent dielectric coaxial resonators 2. Therefore, it is necessary to provide a cut-off space 3 on the open end side of each dielectric coaxial resonator 2. Here, the cut-off space is defined in size and shape so that adjacent dielectric coaxial resonators 2 are not coupled by electromagnetic waves, and therefore adjacent dielectric coaxial resonators 2 are coupled by a coupling capacitor C. Ru. However, unnecessary coupling has sometimes occurred due to leakage signal components propagating along the inner surface of the case forming the cutoff space. Additionally, each dielectric coaxial resonator always requires one cutoff space, which hinders miniaturization. In the case shown in Fig. 2, the signal propagation path 1 and the dielectric coaxial resonator 2 are arranged so that their axial directions coincide, and the open ends of the 1/4 wavelength dielectric coaxial resonator 2 are coupled by a capacitor C. However, the shorted ends are magnetically coupled. Even in this structure, a cutoff space 3 is required on the open end side of the dielectric coaxial resonator 2, as in the example shown in FIG. Since the space 3 can be shared, the case can be made smaller accordingly. Also,
Unnecessary bonds are also less likely to occur. However, when configuring a filter, it is necessary to partially adopt an inductive (magnetic) coupling structure, which is structurally more complicated than capacitor coupling. must be used, which has the disadvantage of going against miniaturization.

Therefore, an object of the present invention is to provide a compact filter device that requires less cut-off space inside the case than the conventional filter device, has no unnecessary coupling, and can entirely adopt a capacitor coupling structure.

Another object of the invention is to provide a filter device having a capacitor coupling structure that is easy to manufacture.

That is, the gist of the present invention is to distribute the dielectric coaxial resonators on both sides of a signal propagation path in a filter device using at least three or more dielectric coaxial resonators having a dielectric material between the inner and outer conductors, By arranging them so that they face each other, two dielectric coaxial resonators facing each other across the signal propagation path share one cut-off space, and the dielectric coaxial resonators are coupled with each other by a capacitor. In the characteristic filter device, two dielectric coaxial resonators whose open ends face each other are coupled by a capacitor, and a dielectric coaxial resonator is connected between the dielectric coaxial resonator and another dielectric coaxial resonator arranged in parallel. This filter device has a shield wall or a shield plate, and both dielectric coaxial resonators are coupled to each other by a capacitor through an opening provided in the shield wall or shield plate.

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

FIG. 3 illustrates the basic idea of this invention. In this way, coaxial
Dielectric coaxial resonator 2 using TEM mode resonance
If the two dielectric coaxial resonators 2, 2 facing each other share one cut-off space 3, and the stages are coupled using a capacitor, which is more advantageous than inductive coupling, it will be extremely effective. A filter with a rational arrangement, small size, no unnecessary coupling, and a simple structure suitable for mass production can be obtained. Although the dielectric coaxial resonator 2 itself is well known, to explain it with reference to FIG. Body (cylinder, square tube, etc.) Body 2
The inner conductor 22 and the outer conductor 2 are coated by baking silver paste on the inner wall surface and outer peripheral surface of 1 or by electroless copper plating.
3, and an electrode 2 for short-circuiting the inner conductor 22 and the outer conductor 23 on the entire bottom surface in the figure.
4 in the same manner, and a metal rod-shaped terminal 26 having a stopper collar 25 is inserted into the center hole from the open end (top surface in the figure) in order to make contact between the inner conductor 22 and the outside. At this time, the terminal 26 and the inner conductor 22 are bonded together using a conductive adhesive. In addition, terminal 26
Although various other structures can be taken, one example is shown in FIGS. 13 to 15.
0 includes a disc-shaped part 91, a plurality of tongue-shaped contact parts 92 extending radially from the periphery of the disc-shaped part 91, and a tongue-shaped contact part 92 cut into a part of the disc-shaped part 91 toward the center. The contact portion 92 is made of a metal piece integrally formed with a connecting portion 93 and a stopper 94 extending radially from the periphery of the disc-shaped portion 91 to the necessary minimum extent.
The connection part 93 is bent to a certain degree and the whole part is bent into a "he" shape to give it springiness.
In contrast, it is bent in the opposite direction to the contact portion 92. (See FIGS. 14 and 15) When the contact portion 92 is inserted into the center hole of the dielectric coaxial resonator 2, the contact portion 9
2 is pressed against the inner conductor 22. A connection with the outside, such as a capacitor lead, is soldered to the connection portion 93, for example. contact part 92, connection part 93,
The shape and number of stoppers 94 are arbitrary.

FIG. 5 and subsequent figures show embodiments in which the present invention is applied to a duplexer.

Figure 5 shows the arrangement inside the case 4, and the right half of the figure is the part where six dielectric coaxial resonators 2 used for the first filter part are assembled in the configuration shown in Figure 3. It is. The left half shows six dielectric resonators 2 used in the second filter section.
This is the part assembled in the configuration roughly shown in FIG. However, in the illustrated embodiment, the second filter section has a configuration in which a trap consisting of a capacitor and a dielectric coaxial resonator is added to a five-stage bandpass filter. However, it goes without saying that the first and second filter portions may have any configuration as required. A common input/output connector 5 for the first and second filter portions is provided in the center of one of the longitudinal sides of the case 4, and a first filter is provided in the center of one of the two short sides of the case 4. Dedicated parts/
An output connector 6 is provided, and a dedicated input/output connector 7 for the second filter portion is provided at the center of the other shorter side of the case 4. Common use/
A strip line 8 is arranged from the output connector 5 to the center of the case 4. The stripline 8 may of course have a coaxial line structure. The coupling capacitor used in the first and second filter portions has electrodes 10 and 11 on both end surfaces of a discrete dielectric material, such as a titanium oxide ceramic disk 9 as shown in FIG. 1
2 and 13 are attached to the electrodes 10 and 11, respectively. Between the parallel dielectric coaxial resonators, a metal shield plate 1 as shown in FIG.
4 is inserted and fixed. Shield plate 14
has a length and width that crosses the cut-off space and reaches the dielectric coaxial resonator whose open ends face each other, and has a shielding function, and an opening or notch 15 is provided so that the coupling capacitor C can be positioned. The metal shield plate 14 is connected between the dedicated input/output connectors 6 and 7 and the dielectric coaxial resonators adjacent to them, and between the stripline 8 and the dielectric coaxial resonators adjacent to them, as indicated by dotted lines in FIG. It may be provided as shown. The shield plate 14 may be formed integrally with the case 4. Dielectric coaxial resonator is case 4
8, particularly as shown more clearly in FIG. That is, a recess 16 is formed in the inner bottom surface of the recess of the case 4 for each dielectric coaxial resonator, and a recess 16 whose cross section follows the circumferential surface of the dielectric coaxial resonator, and the wire mesh 1
7 exists between the surface of the recess 16 and the dielectric coaxial resonator. In other words, the recess 16 can be passed through the gap in the wire mesh 17.
After the surface and the outer conductor 23 of the dielectric coaxial resonator 2 are bonded as necessary with a non-conductive adhesive such as epoxy, the surface of the recess 16 and the outer conductor 23 of the dielectric coaxial resonator 2 are bonded via a wire mesh. Electrical continuity is established between the two. It is preferable that the wires of the wire mesh 17 are sufficiently bent in the thickness direction, since the cushioning properties will be improved and the electrical continuity will be more reliable. The length of the wire mesh 17 does not have to match the axial length of the dielectric coaxial resonator, and may be partially present near the open end of the resonator. The center conductor of the common input/output connector 5 is connected to one end of the center conductor 81 of the stripline 8, and the center conductor 81 of the stripline 8
The other end is connected via a first coupling capacitor C to a terminal 90 of the first stage dielectric coaxial resonator of the first filter section. The terminal 90 of the first-stage dielectric coaxial resonator and the terminal 90 of the second-stage dielectric coaxial resonator (the first-stage dielectric coaxial resonator and their open end faces face each other) form a second coupling capacitor C. connected via. Terminal 90 of the second stage dielectric coaxial resonator and third stage dielectric coaxial resonator (second stage dielectric coaxial TEM
A terminal 90 (located in parallel with the resonator) is connected via a third capacitor C. The third coupling capacitor C is located within an opening or cutout 15 in the metal shield plate 14. The dielectric coaxial resonators in the third and fourth stages are connected to each other in the same way as the first and second stages described above, and the dielectric coaxial resonators in the fourth and fifth stages are connected to each other in the same manner as in the second and third stages. Similarly to the case of the 6th stage, the dielectric coaxial resonators of the 5th stage and the 6th stage are connected in the same way as the case of the first stage and the 2nd stage described above, and the terminal 90 of the dielectric coaxial resonator of the 6th stage is connected. and the center conductor of the dedicated input/output connector 6 are connected by a coupling capacitor C. The second filter section is almost the same as the first filter section, but the terminal 90 of the fifth stage dielectric coaxial TEM resonator is connected to the center conductor of the dedicated input/output connector 7 via the coupling capacitor C. The sixth stage dielectric resonator in the filter part 1 is its terminal 9.
0 is connected to the center conductor of the dedicated input/output connector 7 via a capacitor Co, and functions as a trap.

After the dielectric coaxial resonator is housed and fixed in the case 4 by the means shown in FIG. 8, and the wires are connected as described above, a metal holding plate 30 as shown in FIGS. 9 and 10 is attached to the case 4. Fasten with screws. For this purpose, the case 4 is provided with female screw portions 41 to 45 at five locations, and screw holes 31 to 35 are formed in corresponding portions of the metal holding plate 30. The metal holding plate 30 has a groove section 36 extending between the dielectric coaxial resonators arranged in parallel, a strip line 8, and a groove section 37 located on the extension line of the strip line 8 and provided with a screw hole 35 in the width direction. There are cover parts 38 and 3 on both short sides that fit into the connector 6 and 7 attachment parts 46 of the case 4 and cut off the inside and outside of the case.
It has 8. Note that 39 is an opening, which has a size and shape that allows attachment and detachment of the capacitor C as much as possible. Connector 6, 7 attachment part 4 of case 4
6 protrudes somewhat from the outer circumferential side of the case 4 in the left and right direction in FIG. 5, and as shown more clearly in FIG. Female thread 41,4
2, 44, and 45 are provided. Cover part 38, 3
8 has this area processed to match its external shape. When the metal holding plate 30 itself is screwed to the case 4, it is positioned so as not to protrude above the edge 47 of the case 4. Then, the outer conductor of the dielectric coaxial resonator is electrically connected to the case via the gold steel, and the dielectric coaxial resonator is fixed within the case. and the first
A thin metal plate 50 that matches the outer shape of the case 4 as shown in FIG. 1 is attached to the edge 47 of the case 4 and the metal holding plate 30 with adhesive or tape.

In addition, multiple capacitors C and capacitors Co are
It may be configured as an integrated body in which a plurality of capacitor electrodes are provided on one dielectric substrate.

As is clear from the embodiments described above, the present invention provides dielectric coaxial resonators on both sides of a signal propagation path in a filter device using at least three or more dielectric coaxial resonators having a dielectric between the inner and outer conductors. By distributing and arranging their open ends to face each other, two dielectric coaxial resonators facing each other across the signal propagation path can share one cut-off space, and the dielectric coaxial resonators are coupled with each other using a capacitor. In the filter device, two dielectric coaxial resonators whose open ends face each other are coupled by a capacitor, and another dielectric coaxial resonator is arranged in parallel with the dielectric coaxial resonator. This is a filter device characterized by having a shield wall or a shield plate between the shield wall or the shield plate, and both dielectric coaxial resonators are coupled by a capacitor through an opening provided in the shield wall or shield plate. It is a filter that requires only the minimum cut-off space, making it more compact, less likely to cause unnecessary coupling, and achieving the above-mentioned effects with a simple coupling groove structure of capacitor coupling, which is extremely complete compared to conventional filters. A device is obtained.

[Brief explanation of the drawing]

1 and 2 are schematic explanatory diagrams of a conventional example, FIG. 3 is a schematic explanatory diagram of the present invention, FIG. 4 is a sectional view of a dielectric coaxial resonator, and FIG. 5 is a schematic diagram of an embodiment of the present invention. Internal layout diagram, Figure 6 is a perspective view of the capacitor, Figure 7 is a front view of the metal shield plate, Figure 8 is an explanatory diagram of the mounting structure of the dielectric coaxial resonator, Figure 9 is a plan view of the metal holding plate, Figure 10 is also a side view, Figure 11
12 is a side view of one embodiment, FIG. 13 is a developed view of the terminal, FIG. 14 is a plan view, and FIG. 15 is a side view. 1 is a signal propagation path, 2 is a dielectric coaxial resonator, 3 is a cut-off space, 14 is a metal shield plate, 90 is a terminal, and C is a capacitor.

Claims (1)

[Claims] 1. In a filter device using at least three or more dielectric coaxial resonators having a dielectric material between the inner and outer conductors, the dielectric coaxial resonators are distributed on both sides of the signal propagation path and arranged so that their open ends face each other. Accordingly, in a filter device characterized in that two dielectric coaxial resonators facing each other across a signal propagation path share one cutoff space, and the dielectric coaxial resonators are coupled with each other by a capacitor,
Two dielectric coaxial resonators whose open ends face each other are coupled by a capacitor, and a shield wall or shield plate is provided between the dielectric coaxial resonator and another dielectric coaxial resonator installed in parallel. A filter device characterized in that both dielectric coaxial resonators are coupled to each other by a capacitor through an opening provided in the shield wall or the shield plate.