JPH0741203Y2 - Dielectric filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a filter used in a high frequency band such as a microwave band. More specifically, the present invention relates to an input / output terminal structure of a dielectric filter in which a plurality of λ / 4 type dielectric coaxial resonators are coupled by a capacitor capacitance of a comb-shaped dielectric coupling block.

[Prior Art] A band-pass filter in which a plurality of λ / 4-type dielectric resonators having a single resonator hole are arranged in parallel and a capacitor is directly coupled between them is known. A capacitor used for coupling is generally a printed circuit board on which a predetermined conductor pattern is printed, and is configured to have a planar capacitance between adjacent conductor patterns.

[Problems to be Solved by the Invention] The capacitance obtained by the conductor pattern on the substrate is related to the pattern size, and the substrate itself becomes large to obtain a large capacitance. Further, since the size of the capacitor substrate is defined by the required capacitance, it becomes difficult to connect the dielectric resonator and the capacitor substrate when the capacitance becomes large, and the connection terminal becomes long to compensate for this. Lead wires are used to connect the capacitor substrate and the external circuit, and they are not suitable for surface mounting, resulting in poor assembly workability. These are factors that prevent miniaturization of the dielectric filter and reduction of the mounting area.

As a means for solving this problem, the inventors of the present invention first formed a plurality of grooves in a dielectric block in parallel and combined a coupling block in which a conductive film was provided in each groove, and utilized the capacitor capacitance between the grooves. The structure to combine is proposed.

An object of the present invention is to further improve the above technique and provide a dielectric filter suitable for surface mounting and easy to mount.

[Means for Solving the Problems] The present invention basically comprises a plurality of quarter-wave dielectric coaxial resonators, a plurality of grooves formed in parallel in a dielectric block, and a conductor film formed in each groove. It is a dielectric filter in which a coupling block provided with is combined. The resonators are coupled by utilizing the capacitance of the capacitor formed between the grooves of the coupling block. In order to achieve the above object, in the present invention, input / output electrodes are provided on both end surfaces of the coupling block, and lead terminals having a substantially L-shape are attached to the input / output electrodes to connect with the input / output pattern of the counterpart circuit. Is configured.

When the dielectric resonator and the coupling block are housed in the case, it is preferable to interpose an insulating plate between the coupling block and the case to fix the L-shaped lead terminal and to insulate the case.

[Operation] Capacitor capacitance is three-dimensionally formed between the grooves of the coupling block, whereby each dielectric resonator is coupled and exhibits desired filter characteristics. Like the dielectric resonator in the coupling block,
By using a material having a large dielectric constant, a large capacitor capacity can be provided. These capacities can be freely adjusted by changing the shape of the groove, that is, the groove length, depth, groove interval, and the like.

Utilizing the input / output electrodes formed on both end faces of the coupling block,
By attaching one side of the L-shaped lead terminal to it, a surface mountable terminal structure is formed, and connection with the input / output pattern of the counterpart circuit can be easily performed.

[Embodiment] FIG. 1 is an exploded perspective view showing an embodiment of a dielectric filter according to the present invention, and FIG. 2 is an assembled perspective view thereof.

The coupling block 10 has a dielectric block 11 made of a sintered body of a high dielectric constant material for microwaves. Dielectric block
Reference numeral 11 has a comb shape in which three grooves 12 having a rectangular cross section are provided in parallel on one side (upper surface in FIGS. 1 and 2) of a pair of opposed faces of a rectangular parallelepiped. The conductive film 14 is provided on the inner surface of each groove 12, that is, both wall surfaces and the bottom surface, to form the coupling block 10. Further, input / output electrodes 16 are formed on both end faces of the coupling block 10.

Three λ / 4 type dielectric coaxial resonators 20 are arranged in parallel in the vicinity of the coupling block 10 at positions corresponding to the respective grooves 12. The resonator 20 is provided with a resonator hole 22 at the center of a sintered body of a square-column high-dielectric-constant material for microwaves, and one side of the surface where the resonator hole 22 is open (in FIG. The surface) is an open surface, and the conductor film 24 is formed on the other outer surface and the inner surface of the resonator hole 22. A cylindrical metal terminal 26 is inserted into the resonator hole 22 from the open end side, and the protruding pieces 28 at the ends are soldered to the conductor films 14 on the grooves 12, respectively.

In order to make the drawings easy to understand, the portions where the conductor film and the electrode are not exposed and the base material of the dielectric is exposed are indicated by fine dots, and the shaded portions indicate the conductor films and electrodes. The resonator and the dielectric block are manufactured by a method such as press-molding powder into a predetermined shape and firing.
The conductor film and the electrodes may be formed by baking silver paste, for example.

One side of the L-shaped lead terminal 30 is attached to the input / output electrodes 16 on both ends of the coupling block 10, and the other side is connected to the input / output pattern of the counterpart circuit. As shown in FIG. 2, for example, a ground pattern 33 and an input / output pattern 34 are provided on the circuit board 32, the dielectric resonator 20 is placed on the ground pattern 33 and fixed by soldering, and the L-shaped lead terminal 30 is inserted. Solder the output pattern 34. In this way, surface mounting on the circuit board 32 becomes possible.

In the dielectric filter according to the present invention, in the coupling block 10, the input / output coupling capacitance is formed between the input / output electrode 16 and the wall conductor film of the groove near the end, and the interstage coupling is formed between the wall conductor films of the adjacent grooves. A capacity is formed. The input / output coupling capacitance and the inter-stage coupling capacitance can be adjusted by the area of the input / output electrode 16, the width of the convex portion between the grooves, the groove depth, and the like. As a result, the plurality of λ / 4 type dielectric resonators 20 are coupled by the coupling capacitance between the input / output and the stages, and the dielectric filter exhibiting the bandpass filter characteristic is obtained.

When housing the dielectric resonator and the coupling block in the case, as shown in FIG.
An insulating plate 38 is interposed between the L-shaped lead terminal 39 and the case 36 so that the L-shaped lead terminal 39 is fixed and insulated from the case 36, and the tip of the L-shaped lead terminal 39 (a connection portion with the counterpart circuit) is placed outside the case. Try to pull it out.

Another example of the input / output coupling structure is shown in FIGS. 4 and 5. FIGS. 4A to 4D are examples in which the structure of the coupling block and the L-shaped lead terminal is devised to facilitate holding and fixing. In FIG. 3A, bent portions 40a are formed on both sides of the lead terminal 40, and the ends of the coupling block 41 are sandwiched between them. In the same figure B, a bent portion 42a is formed on the upper end of the lead terminal 42, and the bent portion 42a is connected to the combined block 4
It is inserted into the lateral groove 43a formed on the end face of 3. In FIG. 6C, a vertical groove 45a is formed on the end surface of the coupling block 45, and the lead terminal 4 is formed on the vertical groove 45a.
I'm trying to fit in 4. The same figure D shows the lead terminal 46.
Further, an inverted L-shaped bent portion 46a is further formed at the upper end of the connecting block 47, and the tip thereof is inserted into the lateral groove 47a formed on the upper surface of the coupling block 47. Both are temporarily fixed as described above and soldered to the input / output electrodes. Fig. 5 shows L-shaped lead terminal 48
In this example, the board side is further bent to draw out the terminals in the lateral direction.

The present invention is also effective when incorporating another dielectric block in addition to the coupling block. An example thereof is shown in FIG. Here, in order to simplify the description, the vicinity of the combined block is mainly drawn. A coupling block 52 is attached on the insulating substrate 50. Coupling block 52 may be similar to that shown in FIGS. 1 and 2 above. A dielectric resonator (not shown) is connected to each groove 54. An L-shaped lead terminal 56 is located at the end of the coupling block 52, and another dielectric block 58 is disposed on the L-shaped lead terminal 56.
Appears. The dielectric block 58 is configured as a rejection. Coupling block 52 and dielectric block
The L-shaped lead terminal 56 is held and soldered so as to be sandwiched by the conductor films (input / output electrodes 60, 62) on the opposing surface of 58. The L-shaped lead terminal 56 serves as a common input / output terminal.

The filter circuit in this case is equivalently shown in FIG. Input / output coupling capacitances C ₁ and C ₄ are formed between the input / output electrodes in the coupling block 52 and the wall conductor films of the grooves near the ends, and inter-stage coupling capacitances C ₂ and C ₃ are between the wall conductor films of adjacent grooves. Is formed by. The parallel circuit of L ₁ , ..., L ₃ and C ₅ , ..., C ₇ is equivalent to a dielectric resonator. The series circuit of the inductance L and the capacitance C is the rejection.

When another dielectric block is attached, the lead terminal 64 may be arranged on the upper surface side of the dielectric block 58 as shown in FIG. 8. In the above-mentioned embodiments, the groove has a square cross section. ,
The cross-sectional shape of the groove may be semicircular or trapezoidal. In any case, the required capacitor capacity can be obtained by changing the groove length, depth, groove spacing, and the like. Connection between the dielectric resonator and the conductor film of the groove is made by the cylindrical metal terminal,
A strip-shaped (tongue-shaped) metal terminal or a lead wire may be used. The dielectric resonator may be cylindrical. Although three sets of grooves and resonators are provided, the number of sets (number of filter stages) may be arbitrary.

[Advantages of the Invention] Since the present invention provides L-type lead terminals by providing input / output electrodes on both end faces of the dielectric coupling block for coupling the respective dielectric resonators as described above, surface mounting becomes possible and external circuit Can be easily connected. In addition, since the coupling block has a structure in which a plurality of grooves are formed in parallel in the dielectric and a conductor film is formed,
The capacitor capacity is arranged three-dimensionally. Due to the capability of surface mounting and the three-dimensional capacitor arrangement, the entire filter can be made smaller than the conventional technique, and the mounting area can be reduced.

Further, since the capacitance portion can be downsized, the degree of freedom in connecting the dielectric resonator and the coupling block is increased, which facilitates assembly.
Since the capacitance part is integrated, it is possible to suppress the variation in capacitance by forming an accurate groove shape, which does not require high-precision screen printing technology to form the conductor film, which reduces manufacturing costs and improves reliability. Get higher

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a dielectric filter according to the present invention, FIG. 2 is an assembled perspective view thereof, FIG. 3 is a partial explanatory view showing another example of an input / output terminal structure, and FIG. 6A to 6D are partial perspective views showing another example of the input / output terminal structure, FIG. 5 is a partial perspective view showing another example of the input / output terminal structure, and FIG. 6 is a further embodiment of the present invention. FIG. 7 is an equivalent circuit diagram in that case, and FIG. 8 is still another explanatory diagram. 10 …… Coupling block, 11 …… Dielectric block, 12 ……
Groove, 14 ... Conductor film, 16 ... Input / output electrode, 20 ... Dielectric resonator, 22 ... Resonator hole, 24 ... Conductor film, 26 ... Metal terminal, 30 ... L-shaped lead terminal, 32 ... Insulation board, 33 ... Ground pattern, 34 ... Input / output pattern.

Claims (1)

[Scope of utility model registration request] 1. A plurality of grooves are formed in parallel on the upper surface of a dielectric block, a conductor film is provided in each groove, and input / output electrodes are provided on both end faces perpendicular to the groove arrangement direction of the dielectric block. As a coupling block, a plurality of 1/4 wavelength dielectric coaxial resonators each having a single resonator hole are juxtaposed in the vicinity of the coupling block, and an electrical connection is made between each resonator hole and the conductor film of the groove. In a dielectric filter in which each resonator is coupled by a capacitor capacitance formed between the grooves of the coupling block, the resonators are arranged such that the central axis of their resonator holes is the center of each groove of the coupling block. It is laid horizontally on the same plane so as to be substantially aligned with the axis, and the coupling block and each resonator are electrically and mechanically connected by a metal terminal, and the input / output electrodes formed on both end faces of the coupling block are substantially L-shaped. Attach one end of the lead terminal Surface-mount type to be connected to the output pattern of the mating circuit in the end dielectric filter.