JP3296617B2 - Coaxial resonator and dielectric filter using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial resonator used for a filter in a microwave band and a dielectric filter constituted by the same.

[0002]

2. Description of the Related Art With the practical use of mobile communication, further reduction in weight and size of communication equipment has been required.
This requires a reduction in the size of the duplexer, which is an essential component in such equipment.

[0003] Usually, as a filter used in a duplexer in the microwave band, a through hole is provided in a dielectric member, and an outer conductor provided on an outer peripheral surface of the dielectric member and an inner conductor provided in the through hole are provided. There is a so-called coaxial resonator composed of a conductor and a strip line type resonator using a strip line. Generally, a single-side short-circuited structure causes resonance at a quarter wavelength of f of the resonance frequency. Wavelength filters are well known. In addition, high dielectric materials (ε
_(r = 40-90) is widely used as a coaxial dielectric resonator suitable for miniaturization.

[0004] In particular, since a reception band and a transmission band are used close to each other in a mobile phone, a so-called polarization method having an attenuation pole is adopted as a filter for a duplexer. As such a polarization method, a method of obtaining an anti-resonance frequency by connecting a capacitor or an inductance in series to a coaxial dielectric resonator (see Japanese Utility Model Publication No. Sho 62-4566), or a method of connecting resonators that are not adjacent to each other is used. Some of them are coupled over the head (see JP-A-63-108801).

FIG. 19 shows a polarized filter for explaining the former method. FIG. 19 (a) is a perspective view of this filter, and FIG. 19 (b) is an equivalent circuit diagram thereof, in which three coaxial resonators are used. A polarized bandpass filter was manufactured using the above method.
In the figure, 61 is a dielectric substrate, 62, 62 and 62 are coaxial resonators, 63a, 63b and 63c are anti-resonance capacitors connected to the respective coaxial resonators, and 64a to 64d are chip capacitors. Of the chip capacitors 64a to 64d, 64b,
64c is for interstage coupling for coupling between coaxial resonators.

[0006]

However, the filter shown in FIG. 19 requires an inter-stage coupling portion, so that the dielectric substrate 61 must be formed relatively large in order to form the inter-stage coupling portion. Therefore, the size of the filter cannot be reduced. Further, in the configuration in which the resonators that are not adjacent to each other are coupled over the head, a jump coupling substrate is required, so that the size of the filter cannot be reduced.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a small-sized dielectric filter and a coaxial resonator used for the small-sized dielectric filter.

[0008]

SUMMARY OF THE INVENTION A dielectric filter according to the present invention has a dielectric block having at least four side surfaces and an inner conductor on an inner peripheral surface of the through hole of the dielectric block having a through hole substantially in the center. A quarter-wavelength coaxial resonator having an outer conductor on an outer peripheral surface of the block, one of two end surfaces perpendicular to the through hole being an open end and the other being a short-circuited end, wherein the dielectric block In a dielectric filter using a plurality of coaxial resonators provided on the outer peripheral surface and in a portion close to the open end and independent capacitive conductors so as not to electrically contact the outer conductor, All or some of the capacitive conductors were located on the same plane, the open ends and the short-circuited ends were arranged in the same direction, and the adjacent coaxial resonators were arranged on the mutual capacitive conductors. Chip components that make up reactance Therefore, it is characterized in that the combined capacity conductor of each other in the reactance.

Further, the dielectric filter according to the present invention has an inner conductor on an inner peripheral surface of the through hole of the dielectric block having at least four side surfaces and a through hole substantially at the center, and an outer peripheral surface of the dielectric block. A quarter-wavelength coaxial resonator having one open end and the other short-circuited end, two end faces perpendicular to the through-hole, the outer end face of the dielectric block. And in a portion adjacent to the short-circuit end,
A dielectric filter using a plurality of coaxial resonators provided with independent guiding conductors so as to electrically contact the inner conductor via the conductor at the short-circuited end and not to electrically contact the outer conductor. In the above, all or a part of the induction conductor formed in each coaxial resonator is located on the same plane, and the open end and the short-circuited end are arranged in the same direction, and the induction of the adjacent coaxial resonator is performed. A dielectric filter characterized in that each of the inductive conductors is coupled with a reactance by a chip component constituting a reactance disposed over the conductor for use.

[0010]

[0011]

[0012]

The above-mentioned coaxial resonator has a capacitive conductor or an inductive conductor on the outer peripheral surface of the dielectric block. The capacitive conductor or the inductive conductor is used for coupling the coaxial resonators by reactance. This provides a place for mounting chip components constituting this reactance.

Therefore, in a dielectric filter in which a plurality of the coaxial resonators are provided in a row, and the chip components constituting the reactance are mounted on the coaxial resonator and are coupled to each other, as in a conventional polarized filter, In this case, there is no need to use a dielectric substrate for mounting a chip capacitor or the like, and the size of the dielectric filter can be reduced.

[0014]

(Embodiment 1) Hereinafter, the present invention will be described with reference to the drawings showing the embodiment. 1 and 2 are perspective views of a coaxial resonator, and FIG. 3 is an equivalent circuit thereof. FIG.
FIG. 5 is a perspective view of a dielectric filter in which the above-described coaxial resonator is coupled with a chip capacitor, FIG. 5 is an equivalent circuit thereof, and FIG.
Is a graph showing the frequency characteristics. FIG. 7 is a perspective view of a dielectric filter in which the above-described coaxial resonator is coupled by a chip coil, FIG. 8 is an equivalent circuit thereof, and FIG. 9 is a graph showing a frequency characteristic thereof.

The dielectric block 1 is approximately 3 m in length and width.
m and a depth of 7 mm.
consisting iO ₂ -SnO ₂ -ZrO ₂ based ceramics made of a dielectric member (dielectric constant 38). A through hole 2 having a diameter of 1 mm is provided in the center longitudinal direction of the dielectric block 1. In addition, the inner conductor of the through hole 2 is coated with a conductive member such as silver to form the inner conductor 3.
An outer conductor 4 is also formed by coating the outer peripheral surface of the dielectric block 1 with a conductive member such as silver.

One of the two end faces perpendicular to the through hole 2 is an open end, and the other is a short-circuited end. That is, a short-circuit electrode 5 is formed on the back surface of the dielectric block 1, which is the end of the through-hole 2, and short-circuits the coaxial resonator.

A portion on the outer peripheral surface of the dielectric block 1 and close to the open end is made of a conductive material such as silver and the like, so as not to make electrical contact with the outer conductor 4. Independent capacitance conductors 6 are formed at a distance of 0.2 mm. Here, the coaxial resonator of FIG. 1 is used for input and output, and the capacitor conductor 6 is formed over two surfaces, the upper surface and the side surface. On the other hand, the coaxial resonator shown in FIG. 2 is not for input / output, and the capacitance conductor 6 is formed only on the upper surface. Note that a notch indicated by a dotted line in the figure is provided on the bottom surface of the coaxial resonator of FIG. 1 so that the outer conductor 4 formed on the bottom surface does not electrically contact the capacitor conductor 6 formed on the side surface. X1 is formed.

FIG. 3 is an equivalent circuit diagram of the above-described coaxial resonator. In FIG. 3, C ₁ denotes an electric capacitance generated between the capacitive conductor 6 and the inner conductor 3. That is, since the capacitor conductor 6 is formed on the open end side, the electric field becomes dominant, and it can be regarded as almost electrostatic coupling. Also, C ₂ and L ₁ is constituted by the inner conductor 3 and the outer conductor 4, it is obtained by equivalently express the characteristics of the coaxial transmission line with shorted side by a parallel circuit of capacitance and inductance.

FIG. 4 is a perspective view of a dielectric filter composed of three coaxial resonators. The coaxial resonators 7 and 9 on both sides are input / output coaxial resonators having the configuration shown in FIG. Is a coaxial resonator having the configuration shown in FIG. Each of them has a capacitor conductor 6 on the upper surface, but the coaxial resonators 7 and 9 on both sides.
Is a capacitor conductor 6 on each side as an input / output electrode.
Is extended. In these coaxial resonators 7, 8, and 9, all or a part of each capacitance conductor 6 is present on the upper surface, the open end and the short-circuit end face the same direction, and the outer conductor 4 on at least one side surface is formed. It is arranged so as to contact the outer conductor 4 on the side surface of the adjacent coaxial resonator. A chip capacitor 10 is mounted between the capacitance conductor 6 of the coaxial resonator 7 and the capacitance conductor 6 of the coaxial resonator 8, and the capacitance conductor 6 of the coaxial resonator 8 and the capacitance of the coaxial resonator 9 are mounted. A chip capacitor 11 is mounted between the conductor 6.

FIG. 5 is an equivalent circuit diagram of the dielectric filter. In FIG. 5, C ₃ and C ₄ indicate the capacitances of the chip capacitors 10 and 11, respectively. FIG. 6 is a frequency characteristic diagram of the dielectric filter. Graph a shows the propagation characteristics of the present filter, and graph b shows the reflection loss. As shown in this figure, it can be seen that an attenuation pole is formed in the frequency band of 1.46 GHz, suppression of about -75 dB is obtained, and a function as a polarized bandpass filter is provided.

FIG. 7 is a perspective view of a dielectric filter using chip coils 12, 13 as reactance. That is, the chip coil 12 is mounted between the capacitive conductor 6 of the coaxial resonator 7 and the capacitive conductor 6 of the coaxial resonator 8, and the capacitive conductor 6 of the coaxial resonator 8 and the capacitive conductor of the coaxial resonator 9 are mounted. 6, a chip coil 13 is mounted.

[0022] Figure 8 is an equivalent circuit diagram of the dielectric filter having the chip coil 12, figure L _2, L ₃
Indicates the capacitance of the chip coils 12 and 13. Also,
FIG. 9 is a frequency characteristic diagram of the dielectric filter. Graph a shows the propagation characteristics of the present filter, and graph b shows the reflection loss. As shown in this figure, it is understood that the device has a function as a band rejection filter.

As described above, the above-described coaxial resonator includes the capacitor conductor 6 on the outer peripheral surface of the dielectric block 1, and the capacitor conductor 6 connects the coaxial resonators to each other by the chip capacitor 10. , 11 or chip coils 12, 1
3 will provide a mounting location for this chip component.

Therefore, in a dielectric filter in which a plurality of the above-described coaxial resonators are provided, and the chip capacitors 10 and 11 or the chip coils 12 and 13 are mounted on the coaxial resonator and are coupled to each other, As described above, it is not necessary to use a dielectric substrate for mounting a chip capacitor when forming a polarized filter, and the size of the dielectric filter can be reduced. Specifically, the conventional dielectric filter of FIG. 19 has a width of 9 mm × depth 10 mm × height 3 mm, but the dielectric filter of the present embodiment has a width of 9 mm × depth 7 mm × height 3 mm. It can be seen that the depth became shorter and the volume was reduced by about 30%.

(Embodiment 2) Another embodiment of the present invention is shown in FIG.
The description will be made based on Nos. 18 to 18. For convenience of explanation, the same members as those in the first embodiment are denoted by the same reference numerals.

As in the first embodiment, the dielectric block 1 has a rectangular parallelepiped shape of about 3 mm in length and width and 7 mm in depth, and is made of, for example, a dielectric member (relative dielectric material) made of TiO ₂ —SnO ₂ —ZrO ₂ ceramics or the like. Rate 38). 1 m diameter in the central longitudinal direction of the dielectric block 1
m through holes 2 are provided. A conductive member such as silver is coated on the inner peripheral surface of the through hole 2 to form the inner conductor 3, while a conductive member such as silver is coated on the outer peripheral surface of the dielectric block 1. Thus, the outer conductor 4 is formed. One of two end faces perpendicular to the through hole 2 is an open end, and the other is a short-circuit end.

A portion on the outer peripheral surface of the dielectric block 1 and close to the open end is made of a conductive material such as silver and is electrically connected to the inner conductor 3 via the conductor at the short-circuited end. Independent guiding conductors 15 are formed at a distance of 0.2 mm so as to be in contact with each other and not to electrically contact the outer conductor 4. The width of the guiding conductor 15 is 0.2 m.
m. Here, the coaxial resonator of FIG. 10 is used for input and output, and the guiding conductor 15 is formed over two surfaces, the upper surface and the side surface. On the other hand, the coaxial resonator shown in FIG. 11 is for anything other than input and output, and its guiding conductor 15 is formed only on the upper surface. Note that the outer conductor 4 formed on the bottom surface of the coaxial resonator shown in FIG. 10 is not electrically connected to the guiding conductor 15 formed on the side surface.
A notch X2 indicated by a dotted line in the figure is formed.

FIG. 12 is an equivalent circuit diagram of the coaxial resonator. In the figure, M is a mutual inductance generated between the self-inductance L ₄ generated by the guiding conductor 15 and the inner conductor 3. That is, since the guiding conductor 15 is formed on the short-circuit end side, the magnetic field becomes dominant, and it can be regarded as almost inductive coupling. It is the conductor for guidance 1 that contributes to inductive coupling.
5 is a portion parallel to the inner conductor 3 and the inner conductor 3
Since the magnetic fields are perpendicular to each other, they do not contribute to inductive coupling. The reason for providing such a vertical part is that
This is because the coaxial resonators are mutually connected by the chip component, as described later.

FIG. 13 is a perspective view of a dielectric filter composed of three coaxial resonators.
Reference numeral 18 denotes a coaxial resonator for input and output having the configuration shown in FIG. 10, and the central coaxial resonator 17 is a coaxial resonator having the configuration shown in FIG. Both of them are provided with an induction conductor 15 on the upper surface, and the coaxial resonators 16 and 18 on both sides have the induction conductor 15 extending as an input / output electrode on each side. And
A chip capacitor 10 is mounted between the inductive conductor 15 of the coaxial resonator 16 and the inductive conductor 15 of the coaxial resonator 17, and the inductive conductor 15 of the coaxial resonator 17 and the coaxial resonator 18 are provided.
The chip capacitor 11 is mounted between the chip conductor 11 and the induction conductor 15.

FIG. 14 is an equivalent circuit diagram of the dielectric filter. In FIG. 14, C ₃ and C ₄ denote chip capacitors 10 and 11.
Shows the capacity. FIG. 15 is a frequency characteristic diagram of the dielectric filter. Graph a shows the propagation characteristics of the present filter, and graph b shows the reflection loss. As shown in this figure, it can be seen that it has a function as a polarized bandpass filter.

FIG. 16 is a perspective view of a dielectric filter using the chip coils 12 and 13 as reactance.
That is, the guiding conductor 15 of the coaxial resonator 16 and the coaxial resonator 1
7, the chip coil 12 is mounted between the inductive conductor 15 of the coaxial resonator 17 and the coaxial resonator 18.
The chip coil 13 is mounted between the guiding coil 15 and the guiding conductor 15.

FIG. 17 is an equivalent circuit diagram of a dielectric filter having the above-mentioned chip coils 12 and 13, wherein L ₂ and L ₃ are shown.
Indicates the self-inductance of the chip coils 12 and 13. FIG. 18 is a frequency characteristic diagram of the dielectric filter. Graph a shows the propagation characteristics of the present filter.
Graph b shows the reflection loss. As shown in this figure, it can be seen that it has a function as a polarized bandpass filter.

[0033]

As described above, the dielectric filter of the present invention has a capacitive conductor or an inductive conductor on the outer surface of a dielectric block of a coaxial resonator provided therewith. It is possible to provide a mounting position of the chip when the resonators are connected to each other by the chip component.

Therefore, in a dielectric filter in which a plurality of the above-described coaxial resonators are provided, the chip components are mounted on the coaxial resonator, and these are coupled, when a polarized filter is used as in a conventional filter. This eliminates the need to use a dielectric substrate for mounting chip components, and has the effect of reducing the size of the dielectric filter.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a coaxial resonator including a capacitor conductor of the present invention and used for input / output.

FIG. 2 is a perspective view showing a coaxial resonator including the capacitor conductor of the present invention and used for purposes other than input / output.

FIG. 3 is an equivalent circuit diagram of a coaxial resonator including a capacitor conductor according to the present invention.

FIG. 4 is a perspective view of a dielectric filter in which three coaxial resonators each having a capacitor conductor according to the present invention are arranged in a row, and each resonator is coupled by a chip capacitor.

5 is an equivalent circuit diagram of the dielectric filter of FIG.

6 is a frequency characteristic diagram of the dielectric filter of FIG.

FIG. 7 is a perspective view of a dielectric filter in which three coaxial resonators each including a capacitor conductor according to the present invention are arranged in a row, and each resonator is connected by a chip coil.

FIG. 8 is an equivalent circuit diagram of the dielectric filter of FIG. 7;

FIG. 9 is a frequency characteristic diagram of the dielectric filter of FIG. 7;

FIG. 10 is a perspective view showing a coaxial resonator having the guiding conductor of the present invention and used for input / output.

FIG. 11 is a perspective view showing a coaxial resonator having the guiding conductor of the present invention and used for purposes other than input / output.

FIG. 12 is an equivalent circuit diagram of a coaxial resonator including the guiding conductor of the present invention.

FIG. 13 shows three coaxial resonators each provided with the guiding conductor of the present invention.
FIG. 3 is a perspective view of a dielectric filter formed by arranging two resonators and coupling each resonator with a chip capacitor.

FIG. 14 is an equivalent circuit diagram of the dielectric filter of FIG.

FIG. 15 is a frequency characteristic diagram of the dielectric filter of FIG.

FIG. 16 shows three coaxial resonators each provided with the guiding conductor of the present invention.
FIG. 4 is a perspective view of a dielectric filter in which two resonators are arranged and connected by a chip coil.

FIG. 17 is an equivalent circuit diagram of the dielectric filter of FIG.

FIG. 18 is a frequency characteristic diagram of the dielectric filter of FIG.

FIG. 19A is a perspective view of a conventional dielectric filter, and FIG. 19B is an equivalent circuit diagram thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric block 2 Through-hole 3 Inner conductor 4 Outer conductor 5 Short-circuit electrode 6 Capacitance conductor 7-9 coaxial resonator 10, 11 chip capacitor 15 Induction conductor 16-18 coaxial resonator

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenichi Shibata 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-5-167308 (JP, A) JP-A Heisei 5-241203 (JP, A) JP-A-64-53601 (JP, A) JP-A-64-801 (JP, A) JP-A-4-150101 (JP, A) Japanese Utility Model Laid-Open No. 63-171005 (JP, A) U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01P 1/20-1/219 H01P ^7/ 00-7/10

Claims (4)

(57) [Claims] 1. At least four sides and approximately central
In the dielectric block having a through hole,
With a conductor and an outer conductor on the outer peripheral surface of the dielectric block
Having one of two end faces perpendicular to the through hole as an open end.
A quarter-wavelength coaxial resonator with the other shorted end.
The open end on the outer peripheral surface of the dielectric block.
Does not make electrical contact with the outer conductor
Multiple coaxial resonators with independent capacitance conductors
In the used dielectric filter, all or part of the capacitor conductor is positioned on the same plane.
And the open and shorted ends are oriented in the same direction.
Placed on each other's capacitance conductors of adjacent coaxial resonators.
To chip components that constitute reactance
Therefore, the capacitance conductors must be coupled by reactance.
And a dielectric filter. 2. At least four sides with a substantially central position
In the dielectric block having a through hole,
With a conductor and an outer conductor on the outer peripheral surface of the dielectric block
Having one of two end faces perpendicular to the through hole as an open end.
A quarter-wavelength coaxial resonator with the other shorted end.
The short circuit on the outer peripheral surface of the dielectric block
At the part close to the end,
Electrically contacting the conductor and electrically contacting the outer conductor.
Coaxial resonator provided with independent guiding conductor so as not to touch
In the dielectric filter using a plurality of the conductors, all or one of the induction conductors formed in the respective coaxial resonators are provided.
Parts are flush with each other, and open ends and short circuits to each other
The ends are oriented in the same direction, and the adjacent coaxial resonators are
Reactance placed over the conducting conductor
Reacting each other's guiding conductors with the chip components
A dielectric filter characterized by being coupled by a closet. 3. A chip component constituting said reactance.
3 is a chip capacitor.
Dielectric filter. 4. A chip component constituting said reactance.
Induction of but claim 1 or claim 2 is a chip coil
Electric body filter.