JPS58215803A - Comb-line type band-pass filter - Google Patents

Abstract

PURPOSE:To obtain easily desired transmitting characteristics, by containing plural resonators on which metallic film forming outer conductors are coated except coupling surfaces and opening surfaces with adjacent resonators on outer surface of a dielectric in a shield case, for attaining interstage coupling by means of a magnetic field from the coupling surface. CONSTITUTION:A through-hole is formed at a center axis of a rectangular prism 11 made of a dielectric, the metallic coating film 12 being inner conductors of the resonators 61-6n is vapor-deposited on the inner wall thereof, and the length of axis is selected to 1/4 of the resonance wavelength. Further, the metallic coating film 15 is vapor-deposited on the surface of the rectangular prism 11 except the coupling and the opening surface with the adjacent resonators 61-6n, and a rod conductor 13 for component mounting is inserted into the inside of the prism 11. The resonators 61-6n constituted in this way are contained in the shield case 1 to form air gaps 81-8n-1 among the respective resonators 61-6n. Further, input/output coupling capacitive elements 101-102 are connected to coaxial input/output terminals 91, 92 respectively, the interstage coupling is performed by the magnetic field from the coupling surface, allowing to obtain the desired transmitting characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combline type bandpass filter comprising dielectric resonators. Below, the bandpass filter is B
It is abbreviated as PF.

FIG. 1 is a cross-sectional view showing an example of a groin capacitively coupled BPF consisting of a conventional dielectric resonator, in which 1 is a shield case, 2
1 to 241. Each component of a dielectric resonator has a metal coating attached to the inner wall surface of a hole that substantially coincides with the center axis of a rectangular parallelepiped made of dielectric to form an internal conductor, and each component is connected to a shield plate 31 or 33
The component 21, the shield plate 3I, and the shield case 1 constitute a first-stage resonator by closely fitting the component 21, the shield plate 3I, and the shield case 1,
2. Shield plate 3+% 3: r and shield case 1
The second stage resonator is constructed by the component 23.
．． The third and final stage resonators are constituted by the two shield plates 3Ω, 33, and the shield case 1. 41
and 42 are input/output coaxial terminals, 5(u and 54B are input/output coupling capacitance elements, 5+:r % 523 and chain are interstage coupling capacitance elements.

Figure 2 is an equivalent circuit diagram of the combline type BPF shown in Figure 1, where %Lco1, LC2, Lco] and L24 are resonant circuits, T1 and T:L are input/output terminals, co+ and C4
S is an input/output coupling capacitance, and 012, C:rz, and Ca2 are interstage coupling capacitances.

In the above-mentioned conventional groin capacitively coupled BPF, the shield case 1 and the shield plates 31 to 33 are brought into close contact with all side walls and bottom walls of a rectangular parallelepiped made of dielectric material except for the open end sides of the components 21 to 2a. is used as an external conductor, and constitutes a resonator in each stage, and capacitive elements 51;
However, the capacitance of each of these interstage coupling capacitance elements is extremely small, for example, less than 1 picofarad, so it is extremely difficult to measure the capacitance. Therefore, it is impossible to avoid variations in capacity during mass production. Therefore, the conventional BPF that uses such a capacitive element to perform groin coupling
It is extremely difficult to provide the required transmission characteristics for odor, making it extremely unsuitable for mass production.

The present invention is a combline type BPF consisting of a dielectric resonator that has a simple configuration and is extremely easy to obtain the required transmission characteristics.
The purpose is to realize the following.

FIG. 3 is a sectional view (B in FIG. 4) showing one embodiment of the present invention.
-8 sectional view), and Fig. 4 is an A-A sectional view of Fig. 3. In both figures, 1 is a shield case, and 61 to 6n are dielectric resonators, respectively. For example, Fig. 5 shows an enlarged sectional view. As shown, a rectangular parallelepiped 11 made of a dielectric material such as barium titanate
A metal coating 12 made of silver or copper or the like is formed on the inner wall surface of the through hole that substantially coincides with the central axis of the resonator to form the internal conductor of the resonator.
is attached by vapor deposition or the like, and a rod-shaped conductor 13 for attaching a component such as a resonant coupling capacitor element is firmly inserted with its axial length set to an electrical length, and a screw hole 14 for insertion of a fixing screw is bored in the bottom of the rod-shaped conductor 13. Then, on the surface of the rectangular parallelepiped 11, a metal coating 15 such as silver or copper, which forms the external conductor of the resonator, is deposited by vapor deposition or the like, except for the open upper wall surface and the coupling surface, that is, the side wall surface facing the adjacent resonator. Or, fix the shield plate.

A rod-shaped conductor 13 is directly inserted into the through-hole formed in a rectangular parallelepiped 11 made of a dielectric without attaching a metal coating to the inner wall surface of the through-hole, and the rod-shaped conductor 13 is used as an internal conductor of a resonator, a heat radiator, and the like. It may be constructed so that it also serves as a support for the component, or if the heat generation is small, the rod-shaped conductor 13 may be omitted and a part of the metal coating 12 attached to the inner wall surface of the through hole may be used as a support for the component. A connecting lead wire may be attached and a screw hole may be bored in the bottom wall of the rectangular parallelepiped 11. Further, instead of attaching a metal film to the outer surface of the dielectric rectangular parallelepiped or attaching a shield plate to the outer surface, the shield case 1 may also be used as an outer conductor.

Returning to FIGS. 3 and 4, 71 to 7n are screws for fixing the resonator 6I or TL, and the rod-shaped conductor 13 or rectangular parallelepiped 11 in the resonator is inserted through the screw insertion hole drilled in the bottom wall of the shield case. Screw hole 14 drilled in the bottom of
to secure the resonator in place. Instead of drilling screw insertion holes in the bottom wall of the shield case 1 corresponding to the fixing positions of each resonator, a common hole in the form of a long and narrow groove is bored so that the fixing position of the resonators can be freely changed. Good too. 8
I to 87L-1 are air gaps between adjacent resonators;
9+ and 9.2 are input/output coaxial terminals, 10I and 10
2 is an input/output coupling capacitive element.

In the BPF of the present invention configured as described above, when the resonator 61 is excited and resonated by the input signal introduced through the input/output coaxial terminal 9I and the input/output coupling capacitance element 101, the magnetic field generated by the resonant current is generated. , the leakage magnetic field from the coupling surface couples to the six resonators through the coupling surface of the six resonators, excites them and causes them to resonate, and in the same way, the resonators at each stage resonate, and the input/output The output signal is extracted through the coupling capacitance element 10 and the input/output coaxial terminal 9, and the magnetic field attenuation Lε of each dielectric resonator 61 to 671 as a cut-off waveguide is also as follows: The magnetic field attenuation amount b^ as a cut-off waveguide of 8yt-+ is furthermore, the magnetic field attenuation amount L^ε between the center axes of each internal conductor in adjacent and opposing resonators is LAε=Lt+L^
......(3), and from this magnetic field attenuation, the degree of magnetic field coupling between adjacent and opposing resonators, that is, the degree of magnetic field coupling between the first and second stage resonators MIJ% second stage and Third
Magnetic field coupling degree M23 between the resonators of the stage, ......th (n
−1) Magnetic coupling degree M(rL−+
)vi to M in general IK'''However, k is from 1 to n~
(up to N), LA (, iB) M, river = 10'') O... (4) However, in each of the above equations, H: consists of the dielectric material that constitutes the resonator. Side walls of a rectangular parallelepiped (
Width ε of the side wall (side wall in contact with the side wall of the shield case 1): Dielectric constant H of the dielectric forming the rectangular parallelepiped: Width of the coupling surface of the rectangular parallelepiped made of the dielectric forming the resonator Input: At the resonant wavelength of the resonator, Input ( mm) = 300/f ((lHz)
f: Resonance frequency of the resonator C^: Length of the air gap 8I or 8I -1 When calculating the degree of magnetic field coupling MK, % II:L from the above formula (1) or 4), it is shown in Fig. 6 (horizontal Axis IA2, that is, the coupling distance where the center axis spacing C of the internal conductors in adjacent resonators is standardized by the width H of the coupling surface in the resonator, and the vertical axis is the magnetic field coupling degree M,
The A curve is +1), and when the actual smoothness 1 I obtained by experiment is plotted, it becomes a curve 8. There is a gap of d″, 0.3 between curve A representing the theoretical value and curve B representing the measured value.
d (d is the outer diameter of the internal conductor in the resonator), but this is due to the fact that the theoretical value was calculated based on the central axis of the internal conductor in the resonator. In the case of actual measurements, this is an error caused by the apparent change in the center axis of the internal conductor due to disturbance of the electromagnetic field caused by the internal conductor of the resonator, and the volume of the resonator,
The experiment is repeated each time the resonance frequency etc. is changed to correct the coupling distance.

Next, when designing a distributed constant type BPF, it is common to design by finding the element values, that is, the geometric coefficients, of a reference low-pass filter (hereinafter, low-pass filter is abbreviated as LPF). For example, the element value of PFI based on the hatterworth type standard is g8 (k is 1
from n to n) is given by, and the degree of magnetic field coupling between each stage in the Hattersworth BPF is given by M'H, K<1 (k from 1 to n is expressed as 1 a BW3: 3 dB low frequency bandwidth f0 of the transmission signal
: Center frequency in the passband n: Resonance wave of the dielectric resonator of the order of the filter 1.3 dB reduction Frequency bandwidth Bws and center frequency fo are set appropriately, and each of equations (4) and (6) is Magnetic field coupling degree MK, +
By determining the widths Hε and H of the rectangular parallelepiped made of dielectric material in each resonator and determining the length of the gaps 81 to 8n-1 so that + and M's and ++ are equal for each stage, a hatter-worth shape is obtained. A comline type BPI" can be constructed, and its transmission characteristics are L (+iB) -
+olog (++X5TL) −・・−−−(
7). However, L: attenuation f: arbitrary transmission frequency Figure 7 is a curve diagram showing the transmission characteristics, where the horizontal axis is the transmission frequency f (OHz) and the vertical axis is the attenuation E, (dB).
It is.

Figure 8 is its equivalent circuit diagram, where TI and TQ are input/output terminals, C1 and C are input/output coupling capacitances, L+ or M(IL-1) is the resonant circuit, and M+2 or M(IL-1) is between the resonant circuits. is the equivalent mutual inductance.

Next, the element value of the Chebyshev type reference LPF is S: permissible voltage standing wave ratio within the passband, in this case, the resonator 61
The element value g1 related to is obtained by substituting 1 for k in equation (8),
The element value g, 2 related to the six resonators is 2 for k in equation (9).
are calculated by substituting the following resonators 63 to 6n.
The element values g3 to grL related to are respectively determined by substituting 3 to n for k in equation (9). Note that equation (8) is used only when determining gl.

Next, the degree of magnetic field coupling MK between each crotch in Chebyshev type BPF' is expressed as +1. However, M's = s4J: f.

Bwr: Bandwidth that provides an allowable ripple (allowable pass band width) Therefore, the resonance wave characteristics of the resonator, the bandwidth BW that provides an allowable ripple, and the center frequency f, are set as appropriate, and equations (4) and (10) are Add the widths Hε and H of the rectangular parallelepiped made of dielectric material in each resonator so that the degree of magnetic coupling MK+do and M''K, and niya- are equal for each stage, and also add the widths Hε and H of the rectangular parallelepiped made of dielectric material in each resonator, and the air gaps 8I to 871-1. Each length C^
By determining , it is possible to construct a combline type BPF whose passband has Chebyshev type characteristics and whose attenuation band has Wagner type characteristics, and its transmission characteristics are expressed by. However, 1<x) is Chebyshev's polynomial, and in the case of x(I, 1(x) = cos (naoe'x)X>1
If 7;, (x) = cosh (n ca day h
x) When n is an odd number, When n is an even number, In the above equation, Re means to take the real number gK, and lYL means to take the imaginary part.

FIG. 9 is a curve diagram showing the transmission characteristics of this BPF, and the horizontal and vertical axes are the same as in FIG. 7.

Among the resonators in the BPF of the present invention, a BPF having an attenuation pole in the attenuation region can be constructed by indirectly coupling two resonators separated by two or an integral multiple thereof.

FIG. 10 is a sectional view showing an example thereof (BB in FIG. 11).
1; The figure is a sectional view taken along the line A-A in FIG.
8S to 8S are air gaps, 91 and 9 are input/output coaxial terminals,
lo+ and 10 are input/output coupling capacitance elements, which have the same configuration as in Figures 3 and 4, and (4) and (6).
The configuration is such that +1 is equal to each magnetic field coupling degree M in the equation, and M and M' in each stage. Next, reference numeral 16 denotes an indirect coupling line such as a coaxial line, strip line or semi-rigid cable, and 17I and 17 denote coupling cables, which are composed of electrodes and the like that form a coupling capacitance between the loop or the internal conductor of the resonator. In Fig. 1, an example is shown in which the element 17+ is formed with a loop and the element 17.1 is formed with a capacitance forming electrode, but it is also possible to form +7° with a capacitance forming electrode and 1~ with a loop. (,17+
and 17 may be formed using loops or capacitance forming electrodes (＼.

Also in this embodiment, the input/output coaxial terminal 9. The applied signal is transmitted to the main circuit consisting of the cascaded circuit of resonators 6I to 6& and taken out from the input/output coaxial terminal 92 in the same manner as explained with reference to FIGS. 3 and 4.
Among these transmission signals, for signals with a frequency higher (lower) than the passband, the phase of the voltage and current is advanced (delayed) by 9σ in the resonators 61 to 66, and the phase is advanced by 270 m in the phase shift circuit formed between each resonator. (delayed) from resonator 62
The phase of the signal at and the phase of the signal at the resonator 65 are in phase, but if the length of the indirect coupling line 16 is made appropriate and one or both of the coupling elements 171 and 175 is formed with a loop, By adjusting the polarity of the loop appropriately, the indirect coupling line 16, the coupling element +7. and 17 circuits.
A phase difference of +ao' can be produced in the china.

Therefore, by adjusting the coupling degree of each coupling element 17+ and 172 to equalize the magnitude of the signal reaching the resonator 65 via the indirect coupling circuit and the magnitude of the signal reaching the resonator 65 via the main circuit. An attenuation pole can be generated at the frequency position of this signal, and its transmission characteristic is expressed by the following equation.

When the order n is 6 as in this example, that is, when n is an even number, when n is an odd number, f=(l−mgo) fbaj: difference between the center frequency fa and the frequency that produces the attenuation pole. Δf: Difference between the center frequency fa and the frequency of the band edge that provides the allowable voltage standing wave ratio, and the coupling element +7. When the coupling degree of 17 and 17 is lowered, the frequency position of the attenuation pole moves away from the passband, and when the coupling degree is increased, the frequency position of the attenuation pole moves closer to the passband.

When the frequency position of the attenuation pole is relatively far from the passband, the coupling characteristic is approximately equal to that of a BPF in which the passband has Chebyshev type characteristics and the attenuation area has Wakuna type characteristics.

FIG. 12 is an equivalent circuit diagram of the polarized BPF' in this embodiment, where T+ and T2 are input/output terminals, CI and C
ko is the input/output coupling capacitance, or L is the resonant circuit, M1
2 to M4A is the equivalent mutual inductance between the resonant circuits, CC is the indirect coupling line, MITI+ is the equivalent mutual inductance of the indirect coupling path, and O+y= is the indirect coupling capacitance.

FIG. 13 (horizontal and vertical axes are the same as FIG. 7) is a curve diagram showing the transmission characteristics of the polarized BPF in this example.

Instead of indirectly coupling the resonators 6Q and 65 as described above, the resonators 61 and 66 may be coupled indirectly, or
Indirect coupling between the resonators 64 and 65 and the resonator 6I
A polarized BPF can also be constructed by indirectly coupling between .

In this example, a case where six stages of resonators are provided is illustrated, but the number of stages can be increased or decreased as appropriate, and indirect coupling between two or an integral multiple of resonators can be used. The number of indirect coupling circuits can be arbitrarily selected as long as the condition is met.

The above description has been given of a case in which a BPF configured so that the passband has a Chebyshev type characteristic is polarized, but a BPF configured in a hatterworth type can also be polarized in the same manner.

FIG. 14 is also a sectional view (first embodiment) showing another embodiment of the present invention.
(C-C sectional view in Fig. 5), Fig. 15 is a sectional view taken along A-A in Fig. 14.
The sectional view, FIG. 16, is a BB sectional view of FIG.
This is similar to FIGS. 0 and 11.

In this embodiment as well, signals introduced from the input/output/power axis terminal 911 are transmitted through the main circuit consisting of the resonators 61 to 86 connected in cascade in the same manner as explained with reference to FIGS. 3 and 4. It is taken out from the terminal 92. Also, (4
) and the magnetic field coupling degree M in equation (6) or equation (10)
K, ni + writing and M'ic, + < middle l or M' ki, ni +1
The width HE -H of the rectangular parallelepiped made of dielectric material in the resonators 61 to 66 and the air gap 81 are set so that the width is the same for each stage.
By determining the dimensions of the resonators 61 to 85, it is possible to configure a combline type BPF with a hatter-worth type or a combline type BPF with a Chebyshev type passband and a Wagner type attenuation area, but in this embodiment, the resonators 61 to 66 are Since it is arranged in a U-shape, the overall size can be made smaller compared to each of the embodiments described above.

Furthermore, in this embodiment, for example, a capacitance forming electrode +9° is provided opposite the top of the internal conductor in the six resonators, and a capacitance forming electrode 19a is provided opposite the top of the internal conductor in the resonator 65, and the partition wall Hole 20 drilled in 18
Both electrodes 191 and 19 are connected by the connecting conductor 21 inserted through the
17 (horizontal and vertical axes are as shown in FIG. It is possible to construct a combline type BPF having a frame type transmission characteristic as shown in (the same).

Instead of indirectly coupling resonators 62 and 65, resonator 6I
The resonator 6 is connected by connecting the loops 23+ and 232 coupled to the resonator 6 and 66 through the connecting conductor 26 inserted through the hole 24 bored in the partition wall 18 and filled with the insulator 25.
Even if I and 66 are indirectly coupled, a polarized BPF can be formed as a groove bottom. Incidentally, instead of filling the hole 24 with the insulator 25, a connecting conductor coated with a Zesshin coating is used as the connecting conductor 26 to connect the loops 231 and 23. Of course, it is also possible to connect.

Indirect coupling between the resonators 6a and 6j and the resonator 6I
By indirectly coupling between It is possible to produce S.

FIG. 19 is its equivalent circuit diagram, in which C1qI and Ctqa
is the indirect coupling capacitance, M231 and M2JW are the equivalent mutual inductance of the indirect coupling circuit, and the other symbols are the first
It is the same as Figure 2.

As is clear from the above embodiments, in the present invention, the required transmission characteristics can be obtained by changing the width dimensions of the side surfaces and open surfaces of the resonators and by changing the length ξ of the air gap interposed between the resonators. However, the purpose of interposing the air gap between the resonators is to stabilize the operation of the resonators in addition to the above.

That is, the resonator according to the present invention is configured so that inter-stage coupling is performed by the leakage magnetic field from the coupling surface without attaching a metal film to the coupling surface, but the coupling surfaces of adjacent resonators are separated by an air gap. If the open surfaces are not completely flat, if the open surfaces are left in direct contact without intervening, the open surfaces will adhere uniformly to each other.
The areas where the open surfaces are in direct contact with each other and the areas where they face each other with air in between are irregularly distributed, and in the areas where air is present, the corrosion rate of the dielectric material making up the resonator and the air decreases. Electric dipoles are generated due to the difference, and these electric dipoles are irregularly distributed, which causes instability in operation. However, in the present invention, a gap is interposed between the coupling surfaces of the resonator, so that the coupling is prevented. The entire surface comes into uniform contact with the air, making the operation stable.

Furthermore, by interposing a gap between the resonators, it is possible to adjust the degree of coupling by inserting a coupling adjustment screw as shown in FIGS. 20 to 22. 21 is a sectional view taken along line C, FIG. 21 is a sectional view taken along line A-A in FIG. The coupling adjustment screw is inserted into the gaps 81 to 85 from the soil wall of the shield case 1 corresponding to gaps 8 to 85, and each insertion length can be changed freely, and it is formed so that it can be fixed at any insertion length. Other symbols are shown in Figures 14 to 1.
6, and the coupling operation and transmission characteristics are the same as in the embodiments shown in FIGS. 14 to 16 without the indirect coupling port, but in this embodiment, the coupling adjustment screw 27r Depending on the insertion length of the cut-off waveguide mode, the coupling adjustment screw 2
The electric field is concentrated between 7+ and 27, and the coupling electric field becomes stronger, and the coupling magnetic flux density increases accordingly, so that the degree of interstage coupling can be made denser according to the insertion length of the coupling adjustment screw. Note that instead of inserting the coupling adjustment screw from the earth wall of the shield case 1, it may be inserted from the bottom wall of the shield case 1, or it may be configured to be inserted from both the earth wall and the bottom wall. Although FIGS. 20 to 22 illustrate cases in which the resonators are arranged in a U-shaped configuration, it goes without saying that they may be arranged in a line.

FIG. 23 is an equivalent circuit diagram of this embodiment, and the reference numeral is 19th.
It is similar to the figure.

In each of the above embodiments, as shown in FIG. The present invention can also be practiced using a resonator in which a metal coating forming an external conductor is adhered to the side surfaces excluding the coupling surface and the bottom surface.

FIG. 24 is a sectional view (BB sectional view in FIG. 25) showing an embodiment using the above-mentioned cylindrical dielectric resonator, and FIG. 25 is a sectional view taken along AA in FIG. 24. In both figures, 61 to 6'6 are cylindrical dielectric resonators, and the other symbols are the 10th
It is similar to FIG.

FIG. 26 is a cross-sectional view (cc cross-sectional view in FIG. 27) showing an example of cylindrical dielectric resonators arranged in a U-shape;
The figure is an A-/L sectional view of Fig. 26, and Fig. 28 is a sectional view of Fig. 26.
In the BB cross-sectional view of the figure, 61 to 6t in each figure are cylindrical dielectric resonators, and other symbols are 14 to 1.
It is the same as Figure 6.

The coupling action and transmission characteristics of these two embodiments are exactly the same as those of the above embodiments using a resonator in which the dielectric portion is formed into a rectangular parallelepiped, and by providing an indirect coupling circuit, it can be made into a polar type. It is exactly the same as in each of the above-mentioned embodiments that the crotch magnetic field coupling degree can be made denser and the coupling degree can be changed by inserting a coupling adjustment screw into the gap.

Furthermore, as shown in FIGS. 24 and 26, by providing groove-shaped recesses with an arcuate cross section in the side walls and end walls of the shield case 1 that are in contact with the cylindrical dielectric resonator, the resonator can be held stably. When the shield case 1 is used as an external conductor without attaching a metal film to the outer surface of the cylindrical dielectric, the contact area between the shield case 1 and the side surface of the cylindrical dielectric can be increased. can be effectively used as an external conductor.

As is clear from the above explanation, in the BPF of the present invention, the interstage coupling is not performed through a microcapacitance as in the conventional case, but is performed by the leakage magnetic field from the coupling surface of the dielectric resonator. Because of this structure, it is extremely easy to obtain the required transmission characteristics and to align the characteristics, and since there is a gap between the coupling surfaces of adjacent dielectric resonators facing each other, operation can be stabilized. It has features such as being able to tighten the skin, and its effects are enormous.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a conventional band-pass wave generator;
Fig. 2 is an equivalent circuit diagram, Fig. 3, Fig. 4, Fig. 10, Fig. 11, Fig. 14 to 16, Fig. 20 to 22, and Fig. 24 to 28 are 5 is an enlarged sectional view showing an example of a resonator according to the present invention; FIG. 6 is a curve diagram showing the relationship between the coupling distance between resonators and the degree of magnetic field coupling. , Fig. 7, Fig. 9, Fig. 1
Figures 3, 17, and 18 are curve diagrams showing the transmission characteristics of the filter of the present invention, Figures 8, 12, 19, and 2.
Figure 3 is an equivalent circuit diagram of the filter of the present invention, in which 1: shield case, 2. or 2◆: component of dielectric resonator, 31
to 33: Shield plate, 41% 42.91 and 9. : Input/output coaxial terminal, 5ar 454s, IO+ and 102=input/output coupling capacitance element, 512.5 pieces 3 and 5
34: Interstage coupling capacitance element, 6I to 61 and 61 to 6t: Dielectric resonator, 7I to 7n: Fixing screw, 81 to an-7: Air gap, rectangular parallelepiped made of dielectric, 12 and 15: Metal Film, 13: Rod-shaped conductor,
14: Screw hole, 16 double junction coupling line, +77, +7
2, +91-19+, 231 and 232: coupling element,
18: Partition wall made of conductor, 20 and 24: Pore, 21
and 26: connection conductor, 22 and 25: insulator, 271
and 275 double coupling adjustment screw, LJI index, l14 and Ll to Ln = resonant circuit, TI and T-two output terminals, CoI, C4t,, C (and C input/output coupling capacitance, 012% Cja3 and C34 : Interstage coupling capacitance, M, Equivalent mutual inductance between Yu to M(FL-1)7L' resonant circuit, CC: Indirectly coupled line, MtqL
%M, 31 and M2: equivalent mutual inductance of the indirect coupling circuit, C/72, C1qt and C/91' indirect coupling capacitance. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 16 Figure 15 Figure 17 Figure 18 Figure 19

Claims (1)

[Scope of Claims] (1) The outer periphery of an inner conductor having an axial length approximately equal to that of tin at the resonant wavelength is surrounded by a dielectric material, and the outer surface of this dielectric material is provided with an external A combline type bandpass filter characterized in that a plurality of resonators each having a metal film attached thereto forming a conductor are arranged in series in a shielded case while maintaining the same polarity with an air gap interposed therebetween. (The outer periphery of an inner conductor having an axial length of approximately 4 times the resonant wavelength of 2 is surrounded by a dielectric material, and the outer surface of this dielectric material is coated with a metal coating that forms an outer conductor except for the coupling surface with the adjacent resonator and the open surface. A plurality of resonators each having the same polarity maintained in a shield case and arranged cascaded through a gap,
A combline type bandpass filter characterized in that two or an integral multiple of two or an integral multiple thereof of the plurality of resonators are indirectly coupled to each other. (3) A dielectric surrounds the outer periphery of an inner conductor having an axial length approximately equal to that of tin at the resonant wavelength, and a metal coating forms the outer conductor on the outer surface of the dielectric except for the coupling surface with the adjacent resonator and the open surface. A plurality of resonators each having the same polarity maintained in a shield case and arranged cascaded through a gap,
A combline type bandpass filter characterized in that a coupling adjustment screw whose insertion length can be changed is inserted into the gap. (4) A combline type bandpass filter according to any one of claims 1 to 3, wherein a plurality of resonators are arranged in a line. (5) A combline type bandpass filter according to any one of claims 1 to 3, in which a plurality of resonators are arranged in a U-shape. (6) The resonator includes an internal conductor that is approximately aligned with the center axis of the rectangular parallelepiped made of a dielectric material and has an axial length of approximately the tin axis of the resonant wavelength, and the resonator is adjacent to the outer surface of the rectangular parallelepiped made of the dielectric material. Claims 1 to 3, in which a metal coating forming an outer conductor is attached to the outer conductor except for the bonding surface and the open surface.
The combline type bandpass filter according to any one of paragraphs. (7) The resonator includes an internal conductor having an axial length approximately equal to the resonant wavelength approximately coincident with the central axis of the cylinder made of a dielectric, and resonates adjacent to the outer surface of the cylinder made of the dielectric. Claims 1 to 3 are formed by attaching a metal coating forming an external conductor except for the connecting surface with the container and the open surface.
The combline type bandpass filter according to any one of paragraphs. (8) Claim 1 in which the resonator is formed by surrounding the outer periphery of an inner conductor having an axial length of approximately 4 times the resonant wavelength with a dielectric material, and the shield case in which the resonator is housed also serves as the outer conductor.
The combline type bandpass filter according to any one of Items 1 to 3.