JPH03236603A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a desired frequency characteristic by forming plural dielectric resonators with a homogeneous and single block shaped dielectric substance and plural center conductors formed therein in parallel and providing a pattern for coupling adjustment connecting to ground so as to cause conductive impedance coupling through between the resonators. CONSTITUTION:When an electric signal of e.g. 800-880Hz is applied from an external device (not shown in figure) to dielectric resonators 15-1,15-2 via an input coupling pin 17-1, an electromagnetic field with the said frequency is generated around the resonators, and the electromagnetic field is propagated to an adjacent resonator 15-3 via a gap 14-3, a coupling quantity adjustment pattern 13-2, a gap 14-4, and a frequency adjustment pattern 12-3. The electromagnetic field is also propagated to a gap 14-5, a coupling quantity adjustment pattern 13-3, a gap 14-6, and a frequency adjustment pattern 12-4 and an output coupling pin 17-2 of an external circuit 16-4 is connected to a load (not shown in figure), then the electric signal from the pin 17-1 is led to the load via the output coupling pin 17-2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dielectric filter used in an antenna duplexer for mobile communication.

(Prior Art) Conventionally, as technologies in this field, there are those shown, for example, in Japanese Patent Application No. 63-260440 filed by the applicant of the present application and US Patent Re 32.768 of Motorola Corporation of the United States.

FIG. 2 is a perspective view of a first conventional dielectric filter. This dielectric filter is disclosed in US Patent Re 32.
This is an example of a configuration in which one stage of a notch filter having an attenuation pole is inserted on the lower or higher side of the passband using the 768 technology. As can be seen from the figure, this dielectric filter has approximately quadrangular prism-shaped dielectric bodies 51-- each having an independent height H.
Dielectric resonators 52-1 to 52 each having one cylindrical center conductor parallel to the longitudinal direction of each dielectric body.
-5 is buried, and each dielectric resonator 52-1 to 5
One end of the bottom surface side of the center conductor 2-5 is connected to the bottom surface 53 of each
In addition to the conductive metallization patterns -1 to 53-5, the bottom metallization patterns are further connected to the metallization patterns on the respective side surfaces (shaded areas).

Further, conductive wires 55-l to 5
5-5 is soldered and extends toward the board 56. Note that the side surfaces of each of the dielectrics 51-1 to 52-5 are connected and integrated by soldering as shown in the figure.

The substrate 56 is the upper surface (open surface) of the dielectrics 51-1 to 51-5.
54-1 to 54-5, the bottom and side surfaces of the substrate 56 are not metalized, but the top surface (open surface)
57 is a conductive coupling amount adjustment pattern 58- as shown in the figure.
1 to 58-5 are provided. The coupling amount adjustment patterns 58-1 to 58-5 are formed by opposing conductive lines 55-1 to 55-5, respectively.
It is soldered to 55. Furthermore, an input cover turn 591 for signal input is provided on the upper surface (open surface) 57 of the substrate 56, and an output cover turn 59 for signal output is provided between the coupling amount adjustment pattern 58-4 and the coupling amount adjustment pattern 8-5. -2 is provided. The input pin 60-1 made of a conductive wire is soldered to the input cover turn 59-1, and the output pin 60-2 made of a conductive wire is soldered to the output cover turn 59-2.

FIG. 3 shows an equivalent circuit of the first conventional dielectric filter shown in FIG. 2. In the figure, a parallel resonant circuit (fsz
-+, C5z-+), (fsz-z, C5v-z)
, (jLz-+, C52-3), (1,z-, C5
z-) and (j2sz-s, C5z-s) are the inductance and capacitance of each dielectric resonator 521 to 52-5.

c, q-+ are the capacitances between the input cover turn 59-1 and the coupling amount adjustment pattern 58-1, and CS*-Z is the output cover turn 59
-2 and the capacitance between the coupling amount adjustment pattern 58-5, C5a
-+ is the capacitance between the coupling amount adjustment pattern 58-1 and the coupling amount adjustment pattern 58-2, C, , is the capacitance between the coupling amount adjustment pattern 58-2 and the coupling amount adjustment pattern 58-3, C31 is the capacitance between the coupling amount adjustment pattern 58-3 and the coupling amount adjustment pattern 58-4, and css-a is the capacitance between the coupling amount adjustment pattern 58-4 and the output cover turn 59-2. As can be seen from the figure, the attenuation characteristics of the filter in this case tend to have a smaller amount of attenuation on the high-frequency side of the passband because the coupling between the dielectric resonators is capacitive. As you can see from the figure, the notch filter circuit part is C59-! The notch frequency of this notch filter circuit is the frequency of the series resonance of C2,4 and f5t-5.

FIG. 4 is an attenuation characteristic diagram of the dielectric filter of the first conventional configuration example when the notch frequency of FIG. 2 is on the lower side of the pass band. As can be seen from the figure, when the notch frequency is on the low side of the pass band, a large amount of attenuation can be achieved, so the number of stages of the notch filter circuit can be reduced, resulting in a relatively small size. However, when the notch frequency is set to the high side of the passband, it is difficult to obtain the required amount of attenuation with a single stage notch filter circuit due to capacitive coupling, and the number of stages of the notch filter circuit must be increased, resulting in a change in the shape of the filter. It tends to get bigger.

FIG. 5 is a perspective view of a dielectric filter of a second conventional configuration example. In FIG. 0, reference numeral 71 is a rectangular parallelepiped-shaped dielectric having a length W1 and a height H, and having an integral structure. Front (front side) 80, back (rear side) 81, left side 8 of dielectric 71
2. A conductive metallized pattern is formed on the right side surface 83 and the bottom surface 84 by plating, for example, and conductive frequency adjustment patterns 72-1 to 72-4 are formed in holes on the top surface (open surface) 85 of the dielectric 71. 73-1 to 73-3 are interposed therebetween. The dielectric body 7D has center conductors (hereinafter referred to as dielectric resonators) 74-1 to 74-1 that pass through the frequency adjustment patterns 72-1 to 72-4 and function as dielectric resonators.
74-4 is provided in a buried manner, and further a dielectric resonator 74-4 is provided.
External circuits 75-1 to 75-4 are embedded in the circuits 1 to 74-4. External circuits 75-1 and 75- as shown in the diagram
2 connects the dielectric resonator 74-1 and the dielectric resonator 74-2, and external circuits 75-3 and 75-4 connect the dielectric resonator 74-3 and the dielectric resonator 74-. 4 and constitutes a part forming an attenuation pole. input bin 7
6-1, output pin 76-2 and coupling pin 77-
A cylinder 78-1 to 77-2 made of a dielectric material such as glass epoxy, and having a radius D (>d) surrounding the cylinders 78-1 to 77-2.
78-4, input pin 76-1 and coupling pin 771
and between the output pin 76-2 and the coupling pin 77
-2 and conductive wires 79-1 that electrically connect with each other.
and a conductive wire 79-2.

The insides of the holes 73-1 to 73-3 are simply round holes with an appropriate diameter and depth, without a conductive metallized layer formed by plating, for example, and the diameter and depth of the holes can be changed. This is used to adjust the amount of coupling between dielectric resonators. Note that the hole for the dielectric resonator and the hole for adjusting the amount of coupling are formed substantially parallel to each other.

FIG. 6 is an equivalent circuit of the dielectric filter shown in FIG. Note that in this equivalent circuit, the conductive wire 79 connecting between the input bin 76-1 and the coupling pin 77-1
-1 inductance and a conductive wire 79-2 connecting between the output pin 76-2 and the coupling pin 77-2
In Figure 6, the inductance of the parallel resonant circuit Ct2-'ra-1,C? is ignored because it is small. -1), C
1qa-z, C7-2) (1,, a-+, C70
-3) and C1q4-4. Cy-4) are the inductance and capacitance of the dielectric resonators 74-1 to 74-4, respectively. C□ is the capacitance that exists between the input pin 76-1 and the dielectric resonator 74-1, Cps is the capacitance that exists between the output pin 76-2 and the dielectric resonator 74-4, l, 2 hole 7
Dielectric resonator 74- controlled by 3-■
1 and the dielectric resonator 74-2, j2'
+3 is the inductance between dielectric resonator 74-2 and dielectric resonator 74-3 controlled by hole 73-2, f? 4 is an inductance between the dielectric resonator 74-3 and the dielectric resonator 74-4 controlled by the hole 73-3. C? ? is the capacitance between the coupling pin 77-1 and the dielectric resonator 74-2, and C76 is the capacitance between the coupling pin 77-2 and the dielectric resonator 74-3. This equivalent circuit shows that there is an attenuation pole frequency f tco on the high side of the passband, and the attenuation pole frequency +tcn is 'A Z ? ? , 4-, +
yz and Aπ 711 24-4+? S
becomes.

FIG. 7 is an attenuation characteristic diagram of the second conventional dielectric filter shown in FIG. It can be seen from the figure that the attenuation pole frequency ftco exists on the high-frequency side of the passband. Such a dielectric filter has a structure in which holes are used for coupling between dielectric resonators, and therefore has problems in terms of space and ease of adjustment.

(The problem that the invention aims to solve! As shown above, a dielectric filter with a structure in which an attenuation pole frequency is provided on the high side of the passband using a conventional notch filter circuit can achieve a large amount of attenuation in one stage of the notch filter circuit. Since it is difficult to It is inherently difficult to miniaturize because it requires a hole of a certain shape or more, and it is difficult to make adjustments due to the structure in which the amount of bonding is adjusted by changing the hole position, diameter, depth, etc. There were problems such as the amount of time it took.

The present invention eliminates the problems of the prior art as described above, and provides a dielectric filter that easily achieves a large attenuation characteristic without increasing the number of stages of dielectric resonators, and that is also easy to adjust. The purpose is to obtain.

(Means for Solving the Problems) A dielectric filter of the present invention includes a block-shaped dielectric made of a homogeneous single body, and a plurality of dielectric resonances made of a plurality of center conductors formed substantially parallel within the dielectric. A coupling amount adjustment pattern is provided which passes between the dielectric resonances and is grounded.

(Function) Since the dielectric filter of the present invention has a pattern for adjusting the amount of coupling as described above, the coupling between the dielectric resonators becomes inductive impedance coupling, and the attenuation on the high-frequency side of the passband is larger than that on the low-frequency side, so even if severe attenuation is imposed on the high-frequency side, the desired frequency characteristics can be closely approximated with a small number of dielectric resonators, and at the same time,
Since inductive impedance coupling is realized by a pattern for adjusting the amount of coupling on the upper surface (open surface) of the dielectric filter, less space is required and adjustment is easy.

(Embodiment) FIG. 1 is a perspective view showing a polarized dielectric filter according to a first embodiment of the present invention. In FIG. 1, 11 is vertical W (for example, 4.
3mm), width L (e.g. 16.0mm), and height H (
For example, it is a rectangular parallelepiped dielectric body made of, for example, ceramic and having an integral structure with a diameter of, for example, 9.0 m. In the figure, a front side (front side) 21 and a back side (back side) 22 of the dielectric 11 are shown.
, the left side surface 23, the right side surface 24, and the bottom surface 25 are formed with conductive metallized layers, for example, by plating, as shown by diagonal lines.

Furthermore, conductive frequency adjustment patterns 12-1 to 12-
4 and the coupling amount adjustment patterns 13-1 to 13-3 are formed on the upper surface (open surface) 25 of the dielectric 11 with a gap 14-1-14.
-6 is interposed and formed.

Center conductors (hereinafter referred to as dielectric resonators) that penetrate the frequency adjustment patterns 12-1 to 12-4 and function as dielectric resonators (hereinafter referred to as dielectric resonators) are provided embedded in the dielectric 11, and further External circuits 16-1 to 16-4 are inserted and buried in the dielectric resonators 15-1 to 15-4.

The external circuits 816-1 to 16-4 are connected between the dielectric resonator 151 and the dielectric resonator 15-2, and between the dielectric resonators 5-3.
and the dielectric resonator 15-4 to form an attenuation pole, and the conductive manual coupling pin 17-1, the output cassop ring pin 17-2, and the compulsory pin 18-1. The radius D surrounding ~18-2 (>
d) with cylinders 19-1 to 19-4 made of dielectric material, for example glass epoxy, and manual coupling pin 17-1.
and the coupling pin 18-1, and conductive wires 20-1 to 20-2 that electrically connect the output coupling bin 17-2 and the coupling pin 18-2, respectively.

One end of the coupling amount adjustment patterns 13-1 to 13-3 is connected to the front (front side) 21 of the dielectric 11, and the other end is connected to the metallized pattern on the back (rear side) 22. -1 and 12-2, between frequency adjustment patterns 12-2 and 12-3, and between frequency adjustment patterns 12-3 and 12-4. It functions as an electrode for bond adjustment.

Next, the operation of such a polar dielectric filter will be explained. Micro frequency 800 from an external device (not shown)
~880 MH2 electrical signal input coupling pin 1
When applied to the dielectric resonators 15-1 and 15-2 via 7-1, an electromagnetic field of the above frequency is generated around the dielectric resonators 15-1 and 15-2. Dielectric resonator 15-
The electromagnetic field No. 2 is transmitted to the adjacent dielectric resonator 15-3 via the cap 14-3, the coupling amount adjustment pattern 13-2, the gap 14-4, and the frequency adjustment pattern 12-3. An electromagnetic field is generated around the resonator 15-3. This electromagnetic field is transmitted to the gap 14-5, the coupling amount adjustment pattern 13-3, the gear knob 14-6, and the frequency adjustment pattern 12-44, and further to the dielectric resonator 15-
4 to the external circuit 16-4. Also, dielectric resonator 1
The electric signal from the electromagnetic field from 5-3 is sent to the external circuit 16-3.
and is transmitted to the dielectric resonator 15-4 and the external circuit 16-4 via the conducting wire 20-2. Output power of external circuit 16-4
Since the sampling bin 17-2 is connected to a load (not shown), the electrical signal from the input coupling pin 17-1 is ultimately guided to the load via the output coupling pin 17-2.

FIG. 8 is an equivalent circuit of the polarized dielectric filter of the first embodiment of the present invention shown in FIG. In the figure, 11 is the inductance of the dielectric resonator 15-1, CI is the capacitance of the dielectric resonator 15-1, 12 is the inductance of the dielectric resonator 15-2, and C7 is the capacitance of the dielectric resonator 15-2. , l is the inductance of the dielectric resonator 15-3, C1 is the capacitance of the dielectric resonator 15-3, 14 is the inductance of the dielectric resonator 15-4, and C4 is the capacitance of the dielectric resonator.

C0 is input coupling bin 17-1 and dielectric resonator 1
CIS is the capacitance existing between the output coupling bin 17-2 and the dielectric resonator 154, jX+□ is the capacitance existing between the dielectric resonator 15-1 and the dielectric resonator 15 -2, the inductive impedance, jX
+3 is the inductive impedance coupling between the dielectric resonator 15-2 and the dielectric resonator 15-3, and j This is the inductive impedance that couples.

Cal is the coupling bin 18-1 and the dielectric resonator 15
-2, C2□ is the coupling bin 18-2
and the dielectric resonator 15-3, lzI is the inductance of the conductor 2o-1 connecting between the manual coupling bin 17-1 and the coupling bin 18-1, 12z
is the inductance of the conductor 4i 120-2 connecting between the coupling pin 18-2 and the output coupling pin 7-2.

Here, generally 1ω1−zr l < l 1/ωC2
, 1 and 1ω12□l < 11/ωC2□1.

and C□, and l1zz and C2□, so 121 and 1 can be ignored. Therefore, the equivalent circuit in such a case can be expressed as shown in FIG.

When the center frequency is fo, the attenuation pole frequency fa) of the equivalent circuit in FIG. 9 becomes fo<fl, and exists on the high-frequency side of the pass region.

In this example, f(XI I =%π” fl
l + 12 and faoz = %π-v/2□ 4+
The amount of attenuation becomes infinite at the attenuation pole frequency of .

FIG. 1O is an attenuation characteristic diagram of the polarized dielectric filter of the first embodiment of the present invention shown in FIG. In the figure, the horizontal axis shows frequency (MHz), and the vertical axis shows attenuation (dB). Further, as is clear from the figure, the polarized dielectric filter shown in FIG. 1 has an attenuation pole at a frequency higher than the passband, that is, at the high frequency side.

FIG. 11 is an equivalent circuit between the dielectric resonators 15-1 and 15-2 shown in FIG. In the figure, j in Figure 9
X+z is the portion of the equivalent circuit denoted C□, c, 2 and lI□. Cal is the frequency adjustment pattern 12-1 and the coupling amount adjustment pattern 13-1 of the dielectric resonator 15-1.
The capacitance between CO2 and CO2 is the coupling amount adjustment pattern 13-1.
and the frequency adjustment pattern 12- of the dielectric resonator 15-2.
2, 1211 is the coupling amount adjustment pattern 13
-1 is the equivalent inductance of the inductive impedance.

In Figure 1, the distance from center to center of the dielectric resonator is 4 m, length W = 4.3 mm, width L = 16 cm, and height H = 9.
．． FIG. 12 shows the experimental results of the amount of coupling between a pair of dielectric resonators when the width of the pattern for adjusting the amount of coupling was changed. As can be seen from the figure, the narrower the width of the coupling amount adjustment pattern, the smaller the coupling amount. Note that the content in parentheses between Klz and Kz3 is the difference in resonance frequency between the first and second dielectric resonators. This is mainly due to the fact that 112 in FIG. 11 becomes larger. In addition, in order to change the amount of binding, 001 and C02 in FIG.
may be changed. This applies, for example, to the distance between the frequency adjustment pattern 12-1 and the coupling amount adjustment pattern 13-1, and the distance between the frequency adjustment pattern 12-2 and the coupling amount adjustment pattern 13-1 in FIG. This corresponds to changing the interval between.

As described above, according to the present invention, in order to realize inductive impedance, by providing the coupling amount adjustment patterns 13-1 to 13-3 on the upper surface (open surface) 26 in FIG.
It can be made smaller than conventional filters with holes, and since the pattern for investigating the amount of binding is provided on the top surface (open surface), the width of the pattern can be easily changed by laser ablation, etc., making the filter more compact. characteristics can be easily adjusted.

FIG. 13 is a top view of a second embodiment of the present invention in which the pattern on the top surface of FIG. 1 is changed. The pattern on the upper surface of FIG. 1 corresponds to the case of T=O in FIG. 13. In the second embodiment, the distance between the centers of adjacent dielectric resonators is 4IIgl, the length W = 4.3cm, the width L = 16cm, and the height H = 9.0cm, and the coupling shown in FIG. Dielectric resonator 91- when changing the T interval of quantity adjustment pattern 93-1
1 and the dielectric resonator 91-2.
It is shown in Figure 5. As shown in FIG. 15, by setting T≠O, the amount of binding can be increased by about 20%.

FIG. 14 is an equivalent circuit between dielectric resonator 91-1 and dielectric resonator 91-2 in FIG. 13. FIG. 14 shows the capacitance CI! between the coupling amount adjustment pattern 93-1 and the metallized pattern on the back surface (rear side surface) 22. -1 exists, and the presence of Cl11-1 makes the combined impedance of It-It-I and Cl2-1 lower than when C1□1 does not exist, indicating that the amount of coupling increases equivalently. ing.

When a filter requires a large amount of coupling, it is necessary to widen the width of the pattern for adjusting the amount of coupling if the method shown in FIG. 12 is used, and a filter with this pattern structure has a certain limit in size. However, as shown in Figure 15,
By setting T≠0, the absolute amount of coupling can be increased by 20%, making it possible to create a smaller filter with a larger amount of coupling.

The above is an example of a polarized dielectric filter, but although not shown, a third example is characterized in that, for example, the external circuit 16-2 and the external circuit 163 in FIG. 1 are removed. There are non-polar dielectric filters. In this case, since the coupling between the dielectric resonators is dielectric impedance coupling, the amount of attenuation on the high frequency side of the passband can be made larger than that by conventional capacitive coupling.

Furthermore, although not shown, as a fourth embodiment, for example, in FIG. 1, the metallized layer on the side surface extends to a part of the upper surface of the center conductor of the dielectric resonator except around the open end of the upper surface. There is a dielectric filter that is characterized by:

(Effects of the Invention) As described above in detail, according to the present invention, the metallization, which passes between the dielectric resonators and has both ends or one end grounded, is formed on the side and bottom surfaces of the dielectric. The dielectric filter, which is characterized by having a coupling adjustment pattern connected to the pattern, can achieve the desired attenuation characteristics even if severe attenuation is imposed on the high frequency side of the passband. Furthermore, since the distance between the dielectric resonators can be reduced, miniaturization can be achieved.

Furthermore, since the coupling amount adjustment pattern is located on the surface of the dielectric filter, adjustment can be facilitated and adjustment time can be saved.

[Brief explanation of drawings]

1 is a perspective view of a polarized dielectric filter showing a first embodiment of the present invention, FIG. 2 is a perspective view of a conventional dielectric filter of the first configuration example, and FIG. 3 is a perspective view of a polarized dielectric filter showing a first embodiment of the present invention. FIG. 4 is an attenuation characteristic diagram of the dielectric filter of the first conventional configuration example shown in FIG. 2, and FIG. 5 is a diagram of the second conventional configuration 6 is an equivalent circuit of the dielectric filter of the conventional second configuration example shown in FIG. 5, and FIG. 7 is a perspective view of the dielectric filter of the conventional second configuration example shown in FIG. 5. The attenuation characteristic diagrams of the filter, FIGS. 8 and 9, are the first diagrams of the present invention.
10 is an attenuation characteristic diagram of the polarized dielectric filter according to the first embodiment of the present invention shown in FIG. Dielectric resonator 15
Equivalent circuit between -■ and dielectric resonator 15-2, Fig. 12 is a diagram of the coupling amount adjustment pattern width versus coupling amount characteristic between the first and second dielectric resonators, and Fig. 13 is the diagram of Fig. 1. FIG. 14 is a top view of the second embodiment of the present invention in which the pattern on the top surface is changed.
FIG. 15 is a characteristic diagram of the amount of coupling between the dielectric resonators 91-1 and 91-2 when the interval between T in FIG. 13 is changed. 11... Dielectric, 12-1 to 12-4 and 92-l to
92-4...Frequency, adjustment pattern, 13-1 to 1
3-3 and 93-1 to 93-3... bond amount adjustment patterns, 15-1 to 15-4 and 91-1 to 91-4...
・Dielectric resonator.

Claims (3)

[Claims] 1. A block-shaped dielectric made of a homogeneous single body, and a plurality of dielectric resonators made of a plurality of center conductors formed substantially in parallel within the dielectric, and comprising: a block-shaped dielectric made of a homogeneous single body; What is claimed is: 1. A dielectric filter characterized in that a pattern for adjusting the amount of coupling is provided to be grounded through the inductive impedance coupling pattern. 2. A plurality of dielectrics consisting of a homogeneous and single block-shaped dielectric, a grounded metallized pattern formed on the side and bottom surfaces of the dielectric, and a plurality of central conductors formed substantially parallel within the dielectric. a resonator, which passes between the dielectric resonators, has one end connected to the metallized pattern on the one side, and has the other end connected to the metallized pattern on the side opposite to the metallized pattern on the one side. A dielectric filter characterized in that a connected coupling amount adjustment pattern is provided for inductive impedance coupling. 3. 3. The dielectric filter according to claim 2, further comprising a coupling amount adjusting pattern in which one end of the coupling amount adjusting pattern of the dielectric filter is not connected to the metallized pattern on the side surface.