JPH1188006A - Dielectric filter and electronic unit having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the adjustment of the resonance frequency of a dielectric filter by providing a frequency adjusting plate so that it can freely be brought close to or be detached from a dielectric block so as to interrupt a magnetic field generated in a space between the dielectric block and a case. SOLUTION: The frame body 1 of the dielectric filter is constituted of the conductive material of aluminum (Al) and it has side walls 1a and 1b surrounding four sides. The cross section is rectangular. Relating to the dielectric block 6, the conductors 7 formed on the lower face 6b of the dielectric block 6 are fixed to a base plate 4 by soldering. The center axis of the dielectric block 6 and the coil part of the helical resonator 5 are arranged so that they are orthogonal. The frequency adjusting plate 14 constituted of the conductor material of a steel plate is inserted through plural grooves 1d in the frame body 1 and it is fixed in a desired position where a part protrudes to the inner part of the frame body 1 by solder. The frequency adjusting plate 14 can adjust the resonance frequency of the respective dielectric blocks 6 by the projecting quantity to the inner part of the frame body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter suitable for use in an electronic device such as a duplexer for transmitting and receiving signals for a cellular base station, and an electronic device having the dielectric filter.

[0002]

2. Description of the Related Art A conventional dielectric filter 31 is shown in FIG.
As shown in FIG. 11, a dielectric block 33 having a cylindrical shape and a diameter d is fixed on a bottom wall having an inner diameter D in a metal case main body 32. A case lid 32 a for confining electromagnetic field energy is provided in the opening of the main body 32.

[0003] Input connectors and output connectors 34, 34 are provided on the left and right walls of the metal case body 32, respectively.
It is attached by fixing 2b and 32b with screws. Further, input connectors, output connectors 34, 3
The tip of the center conductor 35 of No. 4 penetrates the left and right walls and projects into the metal case main body 32. And
One end of a coil-shaped coupling loop 40 is connected by soldering to the tip of each center conductor 35, and the other end of the coupling loop 40 is connected by soldering to the inner peripheral wall of the metal case body 32. I have. Thereby, it is configured to be magnetically coupled to the dielectric block 33 via the coupling loop 40. The resonance frequency of the dielectric filter 31 is determined by the inner diameter D of the bottom wall, the diameter d of the dielectric resonator 33, the dielectric constant, and the like.

[0004]

However, in the conventional dielectric filter 31, since the dielectric block 33 is made of ceramic, the diameter dimension d after firing of the dielectric block 33 and the dielectric constant of the dielectric block 33 are required. Variation occurs. Due to these variations, the resonance frequency of the dielectric filter 31 varies, so that a problem that desired filter characteristics cannot be obtained occurs, and defective products may be generated.

Further, when such a dielectric filter 31 is applied to an electronic device, there is a problem that predetermined stable electrical characteristics cannot be obtained and a defective product is generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a dielectric filter capable of easily adjusting the resonance frequency of the dielectric filter, and an electronic device using the dielectric filter. It is an object.

[0007]

A dielectric filter according to the present invention includes a conductive case and a dielectric block housed in the case. The dielectric filter blocks a magnetic field generated in a space between the dielectric block and the case. An adjusting plate is provided so as to be able to approach and separate from the block. According to the present invention, even if the diameter and the dielectric constant of the ceramic dielectric block vary, and the resonance frequency of the dielectric filter shifts, the resonance frequency can be easily adjusted by the proximity and separation of the adjustment plate. Is adjusted, and a desired filter characteristic can be obtained.

Further, the dielectric filter of the present invention uses a flat plate as the adjusting plate, and inserts it into the groove formed in the side wall of the case so that a part protruding into the case approaches and separates from the dielectric block. It is a thing. In the dielectric filter according to the present invention, the resonance frequency can be easily adjusted by adjusting the protrusion of the flat plate protruding into the case by inserting and removing the flat plate through the groove in the case side wall.

Further, the dielectric filter according to the present invention is such that one end of a flat plate having elasticity is fixed to a side wall of a case, and the other end of the flat plate is moved toward and away from the dielectric block by a biasing means. It is. In the dielectric filter of the present invention, the flat plate having elasticity is urged by the urging means so as to approach / separate from the dielectric block. Therefore, by adjusting the strength of the urging, the resonance frequency can be easily adjusted. Adjustments can be made.

In the dielectric filter according to the present invention, both ends of the elastic plate are fixed to the case, and the center of the elastic plate is moved toward and away from the dielectric block by a biasing means. In the dielectric filter of the present invention, both ends of the elastic plate are fixed to the case, and the central portion is urged by the urging means.
The stress distribution of the adjustment plate is symmetrical, and the resonance frequency can be easily and accurately adjusted.

Further, the dielectric filter of the present invention comprises a conductive case, an input terminal and an output terminal attached to the case, and a helical resonator housed in the case and connected to at least one of the input terminal and the output terminal. And a dielectric block housed in the case and magnetically coupled to the helical resonator, and an adjusting plate is provided so as to be close to and away from the dielectric block so as to block a magnetic field generated in the space between the dielectric block and the case. It is a thing. According to the present invention, a desired signal is resonated by the helical resonator, and the input terminal or the output terminal is magnetically coupled to the dielectric resonator via a magnetic field generated by the resonance. And the input terminal or the output terminal can be secured even if the resonance frequency of the dielectric filter is shifted due to the variation of the diameter and the dielectric constant of the ceramic dielectric block. The resonance frequency can be easily adjusted by approaching and separating the plates.

Further, the present invention uses these dielectric filters in electronic equipment. According to the present invention, an electronic device having stable electric characteristics can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the dielectric filter according to the present invention will be described. As shown in FIGS. 1, 2, and 3, the frame 1 of the dielectric filter is made of aluminum (Al).
Side walls 1a, 1a,
b and a rectangular cross section. Inside the frame 1, two sets of opposing partition walls 1c, 1c extending inward from the longitudinal side wall 1a are provided, and the inside of the frame 1 is first and second by the partition walls 1c, 1c. The second and third compartments 1j, 1k,
It is divided into 1m. A pair of opposing partition walls 1c, 1c
A window 1i is provided therebetween.

On one side of the side wall 1a (on the front side in FIG. 2), a plurality (for example, 6
) And a plurality (for example, two) of screw holes 1e. Two grooves 1d are provided in the side wall 1a forming the first, second and third compartments 1j, 1k and 1m. The screw holes 1e are provided in the side walls 1a of the first and third compartments 1j and 1m located on the left and right sides of the frame 1, respectively. A hole 1f penetrating therethrough and a plurality of (for example, two) screw holes (not shown) provided on both sides of the hole 1f are formed at substantially the center of the lateral side wall 1b.
A plurality of (for example, 12) screw holes 1g penetrating the side walls 1a and 1b are provided in the upper end surfaces 1h of the side walls 1a and 1b.

The input connector 2 and the output connector 3 have central conductors 2a, 3a at the center, and flange-shaped mounting plates 2b, 3b at the center. The input connector 2 and the output connector 3 are such that the center conductors 2a, 3a are inserted into the holes 1f of the side wall 1b, and a part of the input / output connectors 2, 3 protrudes outward from the side wall 1b. And is fixed to the side wall 1b with a screw 15 or the like. In this fixed state, the center conductors 2 a, 3 a are arranged so as to protrude inward of the frame 1.

The bottom plate 4 in which silver plating is applied to a steel plate is, for example, a rectangular flat plate having a thickness of about 1 mm. In the peripheral edge of the bottom plate 4, screw holes 1g provided in the side walls 1a and 1b are provided.
A plurality (for example, 12) holes (not shown) are formed at positions corresponding to. The bottom plate 4 is disposed so as to close the lower surface of the frame 1, and is fixed to the lower surface of the frame 1 by screws (not shown) to form a box with the bottom plate 4 and the frame 1.
In this state, the bottom plate 4 forms the bottom wall of the box. The bottom plate 4 is formed as a separate member from the frame body 1. However, the present invention is not limited to this. The bottom plate 4 and the frame body 1 may be integrated by die casting or the like to form a bottomed box. Of course.

The helical resonator 5 disposed in the first and third compartments 1j and 1m of the frame 1 has a coil portion 5a provided in a spiral shape. Further, the entire length of the spiral of the coil portion 5a is formed to be slightly shorter than the length of λ / 4 with respect to the wavelength: λ of the desired signal to resonate. The coil portion 5a of the helical resonator 5 has its center axis disposed substantially parallel to the lateral side wall 1b of the frame 1 and the coil portion 5a.
Are the center conductors 2 of the input / output connectors 2 and 3
So-called tap connections are made by a, 3a and solder (not shown). This tap connection is performed to match the impedance.

One end 5b of the coil portion 5a is connected to one side wall 1
The other end 5c forms an open end which is grounded to the inner wall of a by soldering (not shown) or the like. This open end faces the other side wall 1a to form a capacitor portion therebetween. Further, the other side wall 1a is located at a position facing the other end 5c constituting the open end.
And a capacity value adjusting screw 12 is screwed into the screw hole 1 e via a nut 13. By adjusting the screwing amount of the capacitance value adjusting screw 12, the distance between the tip of the capacitance value adjusting screw 12 and the other end 5c is varied, and by varying the distance, the capacitance value of the capacitor formed here is changed. Can be changed. That is, the helical resonator 5 includes a coil portion 5a and a capacitor portion formed at the other end 5c constituting an open end of the coil portion 5a and having a variable capacitance value.

The ceramic dielectric block 6 made of a dielectric material such as a BaO—TiO 2 —Nd 2 O 3 system (relative dielectric constant: εr = 90) is, for example, cylindrical and has an upper surface 6 a and a lower surface 6 b. , A columnar portion 6c sandwiched between an upper surface 6a and a lower surface 6b, and a conductive paste formed on the upper surface 6a and the lower surface 6b by applying a conductive paste or by electroless plating or the like. Are formed. The height L1 of the dielectric block 6 is
Dimension (L1) higher than the height dimension L2 of the side walls 1a and 1b of the
> L2: see FIG. 3).

The dielectric block 6 has a conductor 7 formed on the lower surface 6b of the dielectric block 6 fixed to the bottom plate 4 by soldering or the like. At this time, the upper surface 6a of the dielectric block 6 is in contact with the upper end surfaces 1a of the side walls 1a and 1b of the frame 1.
h so as to protrude outward. In this state, the center axis of the dielectric block 6 is perpendicular to the bottom plate 4. Then, the dielectric block 6 fixed to the bottom plate 4 is connected to the first, second and third compartments 1 of the frame 1.
j, 1k, and 1m are arranged at substantially the central portions, respectively. In addition, each of the dielectric blocks 6 arranged in the first, second and third compartments 1j, 1k, 1m includes a partition wall 1c,
It is electromagnetically coupled by a window 1i formed by 1c.

The center axis of the dielectric block 6 and the center axis of the coil section 5a of the helical resonator 5 are arranged so as to be orthogonal to each other. Due to the orthogonal arrangement, the magnetic field generated in the coil portion 5a crosses the center axis of the dielectric block 6, and the coupling degree of the magnetic field coupling between the dielectric block 6 and the helical resonator 5 is increased. Increases, and the signal propagation loss decreases.

The leaf spring 8 is made of a metal material such as phosphor bronze, has a thickness of about 0.1 mm, has a flat plate shape, and has a surface coated with silver plating. On the periphery of the leaf spring 8,
A plurality of (for example, 12) holes 8a are formed at positions corresponding to the screw holes 1g provided on the side walls 1a and 1b.
This leaf spring 8 is placed so as to cover the upper surface of the frame 1,
The frame 1, the bottom plate 4, and the leaf spring 8 form a conductive case.
In this state, the upper surface 6a of the dielectric block protrudes from the peripheral edge of the leaf spring 8 against the elasticity of the leaf spring 8, and the conductor 7 formed on the upper surface 6a of the dielectric block 6 and the leaf spring 8
And the lower surface of the device surely abuts.

The frame-shaped spacer 9 is made of a metal material such as phosphor bronze, has a thickness of about 0.1 to 0.5 mm, and has a flat shape. On the periphery of the spacer 9, a plurality of (for example, 1) are provided at positions corresponding to the screw holes 1g provided in the side walls 1a and 1b.
(2) holes 9a are formed. A relatively large rectangular hole 9b is formed in the center of the spacer 9. The spacer 9 is placed on the leaf spring 8. The thickness of the spacer 9 is set to be larger than the size of the dielectric block 6 protruding outward from the side walls 1a and 1b of the frame 1.

The lid 10 is made of a metal material such as aluminum (Al) or copper (Cu) and has a flat plate shape. The cover 10 is provided with three relatively large diameter screw holes 10a on the center line in the longitudinal direction, and the side walls 1a, 1b
A plurality of (for example, twelve) holes 10b are provided at positions corresponding to the screw holes 1g provided in the upper end surface 1h.
The lid 10 is placed so as to close the hole 9 b of the spacer 9.

The cap screw 11 is made of aluminum (Al)
It is made of a metal material such as copper or copper (Cu), has a disk shape, and is provided with a thread 11a at an end of a peripheral edge. The cap screw 11 is screwed into the screw hole 10 a of the lid 10. Then, the lower surface of the screwed cap screw 11 pushes down the upper surface of the leaf spring 8, and the lower surface of the leaf spring 8 contacts the conductor 7 on the upper surface 6 a of the dielectric block 6. In this state, a cap screw 11 for abutting the leaf spring 8 and the conductor 7 on the upper surface 6a of the dielectric block 6 is screwed to the lid 10, so that the leaf spring 8 including the lid 10 is formed. And the conductor 7 are reliably brought into contact with each other, so that a stable electrical connection can be obtained.

The frequency adjusting plate 14 is made of a conductive material such as a steel plate, has a thickness of about 0.8 mm, has a flat plate shape, and has a surface coated with silver plating. The height L3 of the frequency adjustment plate 14 is equal to the height L2 of the side wall 1a.
(L3 <L2), the height L of the side wall 1a is smaller than
It is formed to have a size close to 2. The frequency adjusting plate 14 is inserted into a plurality of (for example, six) grooves 1 d of the frame 1, and solder (not shown) or the like is provided at a desired position where a part protrudes inward of the frame 1. Has been fixed by.
The frequency adjustment plate 14 is a resonance frequency adjustment member for adjusting the resonance frequency f1 of each dielectric block 6 based on the amount of inward projection of the frame 1. Frequency adjustment plate 14
Is inserted and arranged in the plurality of grooves 1d, so that the band in which the resonance frequency f1 can be adjusted can be made sufficiently wide (for example, about 10 MHz).

The adjustment of the resonance frequency f1 of the dielectric block 6 is performed by adjusting the first, second and third compartments 1j, 1j
This can be performed for each of the dielectric blocks 6 of k and 1 m. Adjustment of the resonance frequency f1 of the dielectric block 6 by the frequency adjustment plate 14
The adjustment is performed by adjusting the amount of protrusion. As shown in FIG. 4, the resonance mode used in the dielectric filter of the present invention is as follows.
For example, a TM010 mode indicated by a broken line A formed concentrically around the columnar portion 6c of the dielectric block 6,
The resonance frequency f1 is adjusted by varying the amount by which the frequency adjusting plate 14 blocks this magnetic field, which is substantially equivalent to changing the volume of the compartment in which the dielectric block 6 is provided. Also, generally, TMnml (n = 0, 1, 2,
.., m = 1, 2, 3,..., L = 0, 1, 2,.
The same effect can be obtained in the case of the mode. Further, in order to secure a sufficient amount of blocking the magnetic field, it is desirable that the height L1 of the dielectric block 6 and the height L3 of the frequency adjusting plate 14 be as close as possible.

The dielectric filter of the present invention having the above-described structure is a three-stage dielectric filter having three dielectric blocks 6, and includes a frame 1, a bottom plate 4, a leaf spring 8, a spacer 9 and the lid 10 are laminated and fixed by screws (not shown) and integrated.

Next, the structure of a dielectric filter according to a second embodiment of the present invention will be described. As shown in FIG.
The frequency adjusting plate 18 is made of an elastic conductive material, has a flat plate shape, and has a surface coated with silver plating. One end 18a of the frequency adjustment plate 18 is connected to the frame 1
Is fixed to the inner peripheral wall of the side wall 1a by, for example, spot welding. The other end 18b of the frequency adjustment plate 18 is disposed as a free end so as to be movable in the direction of the central axis of the dielectric block 6.

The adjusting screw 16 is screwed into a screw hole 1n of the side wall 1a via a nut 17. This adjustment screw 1
6 is in contact with the other end 18 b of the frequency adjusting plate 18, and the other end 18 b
Of the frame 1 inwardly varies.

The adjustment of the resonance frequency f1 of the dielectric block 6 by the frequency adjusting plate 18
The adjustment is performed by adjusting the amount of protrusion. The resonance mode used in the dielectric filter of the present invention is, for example, a concentric broken line B around the columnar portion 6c of the dielectric block 6.
This is a TM010 mode in which a magnetic field shown by the following symbol is generated. The resonance frequency f1 is adjusted by changing the amount of blocking of this magnetic field by the frequency adjustment plate 18, and the dielectric block 6
This is equivalent to changing the volume of the compartment provided with. Also, generally, TMnml (n = 0, 1, 2,...,
The same effect can be obtained in the case of the m = 1, 2, 3,..., l = 0, 1, 2,.

Next, the structure of a dielectric filter according to a third embodiment of the present invention will be described with reference to FIGS. 6 and 7, the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description is omitted. As shown in FIGS. 6 and 7, one of the side walls 1a of the frame 1 (on the front side in FIG. 6) has a rectangular through hole 1p and two rectangular through holes 1p provided on both sides of the through hole 1p. A bottom screw hole 1q is formed.

The frequency adjusting plate 19 is made of a conductive material such as a steel plate having elasticity, is a band-shaped flat plate, is punched and bent, and has a surface coated with silver plating. The frequency adjusting plate 19 includes L-shaped holding portions 19a provided at both ends, and an arc-shaped curved portion 19b provided substantially at the center between the holding portions 19a, 19a.
And holes 19c, 19c respectively provided at ends of the holding portions 19a, 19a and provided at positions corresponding to the bottomed screw holes 1q, respectively. Frequency adjustment plate 19
The curved portion 19b is disposed so as to protrude into the frame 1 from the through hole 1p of the frame 1.

The mounting plate 20 is made of, for example, a molding resin material, and has a rectangular projection 20a at the center and a pair of flanges 20b provided at both ends of the projection 20a. One large-diameter screw hole 20c is formed in the center of the projection 20a, and the small-diameter hole 20c is formed in the flanges 20b, 20b at a position corresponding to the bottomed screw hole 1q.
d and 20d are provided. The mounting plate 20 is disposed so as to close the through hole 1p of the frame 1 via the frequency adjusting plate 19, and in this disposed state, the convex portion 20a and the curved portion 1
9b is opposed to the back surface.

The adjusting screw 60 is screwed into the large-diameter screw hole 20c of the mounting plate 20. In this state, the distal end portion 60a of the adjustment screw 60 is in contact with the back surface of the curved portion 19b formed in the center of the frequency adjustment plate 19 in an arc shape. The screw 61 is provided with the holes 19c, 19c of the frequency adjustment plate 19.
And the holes 20 d of the mounting plate 20, and are screwed into the screw holes 1 q of the frame 1. By screwing the screw 61 into the screw hole 1q, the frequency adjusting plate 19 and the mounting plate 20 are integrated with the frame 1.

At this time, the bending portion 19b projects and moves in the direction of the central axis of the dielectric block 6 arranged in the frame 1 depending on the screwing amount of the adjusting screw 60. Due to the protrusion and movement of the curved portion 19b of the frequency adjusting plate 19,
The resonance frequency f1 of the dielectric block 6 can be adjusted. As shown in FIG. 7, this adjustment is performed around the columnar portion 6c of the dielectric block 6 in the form of TM0 indicated by a concentric broken line C.
This is achieved by changing the amount of the frequency adjustment plate 19 blocking the 10-mode magnetic field, which is substantially equivalent to changing the volume of the compartment in which the dielectric block 6 is provided.

The adjusting screws 16 and 60 for changing the frequency adjusting plates 18 and 19 may be biasing means other than screws. In addition, the frequency adjustment plates 18, 1
Reference numeral 9 designates an adjusting member for adjusting the amount of magnetic field generated in the space between the box and the dielectric block 6 by the amount of inward projection of the box.

In the first, second, and third embodiments, the frequency adjusting plates 14, 18, and 19 are made of a conductive material. However, the present invention is not limited to this. It may be formed of a dielectric material or the like. Frequency adjustment plate 14, 1
When the conductors 8 and 19 are made of a conductive material, the magnetic field generated around the dielectric block 6 changes so as to avoid the frequency adjusting plates 14, 18 and 19. Because it is larger than 1, the compartment (1j, 1k, 1m)
Works to increase the effective magnetic permeability. This effectively changes the size of the compartment due to the shortening of the wavelength in the magnetic material. In the case of a dielectric material, since the dielectric constant of the dielectric is greater than 1, it works to increase the effective dielectric constant of the compartment (1j, 1k, 1m). This effectively changes the size of the compartment due to the shortening of the wavelength in the dielectric. That is, the effective relative dielectric constant in the medium is εe, and the effective relative magnetic permeability is μe
When the wavelength of the free space is λo, the wavelength λg in the medium has a relationship of λg = λo / (εe × μe) ^1/2 . For this reason, the effective magnetic permeability and the effective permittivity of the compartment including the dielectric block change, and the resonance frequency changes by changing the resonance wavelength in the compartment.

Next, an equivalent circuit of the above-described dielectric filter of the present invention will be described. As shown in FIG. 8, this dielectric filter is a dielectric filter having a three-stage configuration, and includes an input terminal 21, an input stage 22, an intermediate stage 23, and an output stage 2.
4 and an output terminal 25.

The input stage 22 includes the helical coil 2
Helical resonator 22c on the input side composed of 2a and variable capacitor 22b, and coils 22d and 22 connected in parallel
first dielectric resonator 2 comprising a capacitor d and a capacitor 22e
2f, the intermediate stage 23 includes a second dielectric resonator 23c including coils 23a and 23a and a capacitor 23b connected in parallel, and the output stage 24 includes a coil 24a connected in parallel, It comprises a third dielectric resonator 24c composed of a capacitor 24b and a capacitor 24b, and an output helical resonator 24f composed of a helical coil 24d and a variable capacitor 24e. In addition, the present invention provides the first, second, and third dielectric resonators 22f, 23c, and 24 by the frequency adjustment plates 14, 18, and 19.
It is possible to adjust each resonance frequency of c to a desired value.

In the dielectric filter having the above-described configuration, first, a signal input from the input terminal 21 is input to the helical resonator 22c, and a signal input to the helical resonator 22c is a desired signal selected in advance. Resonated at frequency.
At this time, by adjusting the capacitance value of the variable capacitor 22b constituting the helical resonator 22c, the resonance frequency f1 can be easily adjusted over a wide band. Further, by this adjustment, another desired resonance frequency f2 can be obtained as needed.

The helical resonator 22c on the input side that resonates at the resonance frequency f1 is magnetically coupled to the first dielectric resonator 22f. Similarly, the first dielectric resonator 22f and the second dielectric resonator 23c are magnetically coupled, the second dielectric resonator 23c and the third dielectric resonator 24c are magnetically coupled, and The third dielectric resonator 24c and the helical resonator 24f on the output side are magnetically coupled to each other, and constitute, for example, a three-stage dielectric filter that allows only a desired signal to pass therethrough.

Next, an electronic device in which the dielectric filter of the present invention is applied to a transmission signal / reception signal duplexer (Duplexer) for a cellular base station will be described. As shown in FIG. 9, the transmission signal / reception signal duplexer (Duplexer) includes at least an antenna 50, a transmission signal band-pass filter 51 including a dielectric filter, and a reception signal similarly including a dielectric filter. A band-pass filter 52, a matching circuit 53 disposed at a connection portion between the transmission signal band-pass filter 51 and the reception signal band-pass filter 52 and connected to the antenna 50, and the antenna 50 and the matching circuit 5.
3, an input terminal 54 for inputting a transmission signal to a bandpass filter 51 for a transmission signal, and an output terminal for outputting a reception signal from the bandpass filter 52 for a reception signal. Output terminal 55.

In the embodiment of the present invention, each of the bandpass filter 51 for the transmission signal and the bandpass filter 52 for the reception signal forms a three-stage bandpass filter. The transmission / reception signal duplexer configured as described above inputs the signal received by the antenna 50 to the matching circuit 53 via the low-pass filter 56, and converts the signal received from the matching circuit 53 into a band-pass signal for a reception signal. Filter 5
2, and passes only a signal of, for example, 880 to 915 MHz in a bandpass filter 52 for a reception signal, and supplies the signal from an output terminal 55 to a reception circuit (not shown).

When a transmission signal from a transmission circuit (not shown) is input to the input terminal 54, the input transmission signal is input to the transmission signal band-pass filter 51, and the transmission signal band In the pass filter 51, only a transmission signal of, for example, 925 to 960 MHz is passed, and this transmission signal is input to the matching circuit 53,
The transmission signal is supplied from the antenna 3 to the antenna 50 via the low-pass filter 56, and the transmission is performed from the antenna 50. As described above, an electronic device that switches a predetermined transmission signal and a reception signal by applying a plurality of dielectric filters in series to a transmission signal / reception signal sharing device that is an electronic device is provided.

Although the dielectric block according to the embodiment of the present invention is formed in a cylindrical shape, the present invention is not limited to this.
For example, it may be a quadrangle or a polygon, and may be a column. In the dielectric filter according to the embodiment of the present invention,
Although the description has been given of the three-stage dielectric filter, the present invention is not limited to this, and is applicable to a one-stage dielectric filter or a four-stage dielectric filter in which four or more dielectric blocks are housed in a frame. Of course.

[0047]

As described above, the dielectric filter of the present invention has a conductive case and a dielectric block housed in the case, and the dielectric filter blocks a magnetic field generated in the space between the dielectric block and the case. An adjusting plate is provided so as to be able to approach and separate from the block. According to the present invention, even if the diameter and the dielectric constant of the ceramic dielectric block vary, and the resonance frequency of the dielectric filter shifts, the resonance frequency can be easily adjusted by the proximity and separation of the adjustment plate. Is adjusted, and a desired filter characteristic can be obtained.

Also, the dielectric filter of the present invention comprises a conductive case, an input terminal and an output terminal attached to the case, and a helical resonator housed in the case and connected to at least one of the input terminal and the output terminal. And a dielectric block housed in the case and magnetically coupled to the helical resonator, and an adjusting plate is provided so as to be close to and away from the dielectric block so as to block a magnetic field generated in the space between the dielectric block and the case. It is a thing. According to the present invention, a desired signal is resonated by the helical resonator, and the input terminal or the output terminal is magnetically coupled to the dielectric resonator via a magnetic field generated by the resonance. And the input terminal or the output terminal can be secured even if the resonance frequency of the dielectric filter is shifted due to the variation of the diameter and the dielectric constant of the ceramic dielectric block. The resonance frequency can be easily adjusted by approaching and separating the plates.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a dielectric filter according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a state in which a lid, a spacer, and a leaf spring are removed from the dielectric filter shown in FIG.

FIG. 3 is a cross-sectional perspective view of a main part for describing the dielectric filter shown in FIG.

FIG. 4 is a plan view of a main part for describing adjustment of a resonance frequency of the dielectric filter shown in FIG. 1;

FIG. 5 is a plan view of a principal part for explaining a second embodiment of the dielectric filter of the present invention.

FIG. 6 is an exploded perspective view showing a main part of a dielectric filter according to a third embodiment of the present invention.

FIG. 7 is a sectional plan view of a main part of the dielectric filter shown in FIG. 6;

FIG. 8 is a circuit diagram showing an equivalent circuit of the dielectric filter according to the embodiment of the present invention.

FIG. 9 is a schematic configuration diagram for explaining an electronic device in which the dielectric filter according to the embodiment of the present invention is applied to a transmission signal / reception signal duplexer (Duplexer) for a cellular base station.

FIG. 10 is a plan view for explaining a conventional dielectric filter.

FIG. 11 is a cross-sectional side view for explaining a conventional dielectric filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frame 1a, 1b Side wall 1c Partition wall 1d Groove 1i Window 2 Input connector 3 Output connector 4 Bottom plate (bottom wall) 5 Helical resonator 6 Dielectric block 8 Leaf spring 9 Spacer 10 Lid 11 Holding screw 12 Capacity adjustment Screw 14, 18, 19 Frequency adjustment plate (adjustment member) 16, 60 Adjustment screw

Continued on the front page (72) Inventor Kenji Shimizu Inside Alps Electric Co., Ltd. 1-7 Otsuka-cho, Yukitani, Ota-ku, Tokyo

Claims (6)

[Claims] A conductive plate, and a dielectric block accommodated in the case, wherein an adjusting plate is disposed near the dielectric block so as to block a magnetic field generated in a space between the dielectric block and the case. A dielectric filter, which is provided so as to be detachable. 2. The adjusting plate is made of a flat plate, and is inserted into a groove formed in a side wall of the case, and a part of the adjusting plate protruding into the case is moved toward and away from the dielectric block. The dielectric filter according to claim 1, wherein 3. The adjusting plate is made of a flat plate having elasticity, one end of the flat plate is fixed to a side wall of the case, and the other end of the flat plate is brought into close proximity to the dielectric block by a biasing means. The dielectric filter according to claim 1, wherein the dielectric filter is separated. 4. The adjustment plate is made of an elastic plate, and both ends of the elastic plate are fixed to the case, and a central portion of the elastic plate is moved toward and away from the dielectric block by a biasing means. The dielectric filter according to claim 1, wherein: 5. A conductive case, an input terminal and an output terminal attached to the case, a helical resonator housed in the case and connected to at least one of the input terminal and the output terminal, and A dielectric block housed and magnetically coupled to the helical resonator,
A dielectric filter, wherein an adjusting plate is provided so as to be close to and away from the dielectric block so as to block a magnetic field generated in a space between the dielectric block and the case. 6. An electronic apparatus comprising the dielectric filter according to claim 1.