JP3088992B2 - Rectangular waveguide resonator type bandpass filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectangular waveguide resonator type band-pass filter, and more particularly to a rectangular waveguide resonator having a good group delay time deviation characteristic and a steep attenuation characteristic within a pass band. 1. Field of the Invention The present invention relates to a bandpass filter of the type and a rectangular waveguide resonator type bandpass filter having a larger attenuation than the conventional type.

[0002]

BACKGROUND ART FIG. 29 is a sectional view for explaining the electromagnetic field of TE ₁₀ mode in the rectangular waveguide, reference numeral solid line the field (E), the dashed line represents the magnetic field (H) ing. When the height of the rectangular waveguide 1 is b and the width is a,
The cutoff wavelength (λc) of the rectangular waveguide 1 is represented by the following equation (1).

[0003]

Λc = 2a (1) FIG. 30 illustrates the resonance length (L) of the rectangular waveguide resonator. In the figure, 1 is a rectangular waveguide, 12
Is an inductive aperture (coupled iris). As shown in FIG. 30, when the guide wavelength is λg, the rectangular waveguide resonator 10
Is set to L ≒ λg / 2 (generally, around 0.95λg / 2) by the susceptance of the coupling iris determined by the resonance frequency, the pass band width, the characteristics of the pass band, and the like. .

Here, when λ is the center frequency wavelength of the rectangular waveguide resonator 10, the guide wavelength of the rectangular waveguide 1 (λ
g) is represented by the following equation (2).

[0005]

Λg = λ / (1− (λ / λc) ² ) ^1/2 (2) Further, the no-load Q (Q _u ) of the rectangular waveguide resonator 10 is expressed by the following equation (3).

[0006]

[Expression 3] Q _u ≒ 477 × b × f ^1/2 / (1+ (2b / a) × (fc / f) ² (3) where f is the center frequency of the rectangular waveguide resonator 10, fc
Is the cut-off frequency of the rectangular waveguide l. It is known that the rectangular waveguide resonator 10 has the second highest unloaded Q after the circular waveguide resonator. For this reason, when a bandpass filter is manufactured using the rectangular waveguide resonator 10, a bandpass filter having low loss and excellent electrical characteristics can be obtained. In this case, the height (b) and the width of the rectangular waveguide 1 used for the rectangular waveguide resonator 10 are generally selected as in the following equation (4).

[0007]

## EQU4 ## b ≒ λ / 4 a ≒ 3 × λ / 2 (4) FIG. 31 shows a conventional rectangular waveguide resonator. Rectangular waveguide band-pass filter (hereinafter simply referred to as BPF)
It is a figure which shows schematic structure of. In the figure, 1 is a rectangular waveguide, 10a to 10h are rectangular waveguide resonators, 12a to 1
2i is an inductive stop, and 13a and 13b are capacitive stops. In the BPF shown in FIG. 31, eight rectangular waveguide resonators (10a to 10h) are cascade-connected in a zigzag manner between an input side and an output side, and between each rectangular waveguide resonator, and ,
Inductive diaphragms (12a to 12a) are connected between the input side and the rectangular waveguide resonator 10a, and between the rectangular waveguide resonator 10h and the output side.
The main coupling is performed by the magnetic coupling circuit according to 12i), and the rectangular waveguide resonator 10a and the rectangular waveguide resonator 10d
And between the rectangular waveguide resonator 10e and the rectangular waveguide resonator 10h are sub-coupled by a capacitive coupling circuit including capacitive diaphragms (13a, 13b).

FIG. 32 is a circuit diagram showing an equivalent circuit of the conventional BPF shown in FIG. In the figure, RS1 is:
This is a resonance circuit of the rectangular waveguide resonator 10a.
S2 is a resonance circuit of the rectangular waveguide resonator 10b, RS3
Is a resonance circuit of the rectangular waveguide resonator 10c, RS4 is a resonance circuit of the rectangular waveguide resonator 10d, RS5 is a resonance circuit of the rectangular waveguide resonator 10e, and RS6 is a rectangular waveguide resonator. The resonance circuit 10f, RS7 is a rectangular waveguide resonator 10
The resonance circuit of g, RS8, is a resonance circuit of the rectangular waveguide resonator 10h. Magnetic coupling circuits (M ₀₁ , M ₁₂ , M ₂₃ ,
_{M 34, M 45, M 56} , M 67, M 78, M 89) is a magnetic coupling circuit by inductive iris (12a-12i). The magnetic coupling circuit (M ₀₁ ) magnetically couples the input side and the rectangular waveguide resonator 10a, and the magnetic coupling circuit (M ₈₉ ) circuit magnetically couples the rectangular waveguide resonator 10h and the output side. the magnetic coupling circuit _{(M 12, M 23, M} 34, M 45, M 56, M 67, M 78) , each resonator between (RS1~RS8) magnetically coupled. C _14, C
_{Reference numeral 58} denotes a capacitive coupling circuit formed by the capacitive diaphragms (13a, 13b), and the capacitive coupling circuit (C ₁₄ ) includes a resonance circuit (RS
1) and the resonance circuit (RS4) are capacitively coupled, and the capacitance coupling circuit (C ₅₈ ) is composed of the resonance circuit (RS5) and the resonance circuit (RS4).
And 8) are capacitively coupled. This magnetic coupling circuit (M ₁₂ ,
M ₂₃ , M ₃₄ , M ₄₅ , M ₅₆ , M ₆₇ , M ₇₈ ) are coupled at intervals of the inductive apertures (12 a to 12 i), and the coupling amounts of the capacitive coupling circuits (C ₁₄ , C ₅₈ ) are: Capacitive aperture (12
It can be adjusted at intervals of a to 12e).

Now, assuming that each resonator (RS1 to RS8) is tuned to a predetermined frequency, this conventional BP
The operation of F will be briefly described. Figure 31, in the conventional BPF shown in FIG. 32, the resonant circuit (RS1) → the magnetic coupling circuit (M ₁₂₎ → resonant circuit (RS2) → the magnetic coupling circuit (M ₂₃₎
→ resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → the electromagnetic field generated in the resonant circuit in the route from the resonance circuit (RS4) (RS4), the resonant circuit (RS1) → capacitive coupling circuit (C ₁₄₎ → resonance The phase of the electromagnetic field generated in the resonance circuit (RS4) in the path including the circuit (RS4) can be in opposite phase. Therefore, outside the pass band (attenuation band), an attenuation pole (attenuation pole) is generated at a pair of frequencies at which the amplitudes of both electromagnetic fields are equal to each other. Similarly, the resonance circuit (R
S5) → the magnetic coupling circuit (M ₅₆₎ → resonant circuit (RS6) →
Magnetic coupling circuit (M ₆₇₎ → resonant circuit (RS7) → the magnetic coupling circuit (M ₇₈₎ → the electromagnetic field generated in the resonant circuit in the route from the resonance circuit (RS8) (RS8), the resonant circuit (RS5)
→ Capacitive coupling circuit (C ₅₈ ) → Electromagnetic field generated in resonance circuit (RS8) can be made in the opposite phase on the path consisting of resonance circuit (RS8), so that the amplitude of both electromagnetic fields is outside the pass band. An attenuation pole is generated at a pair of frequencies equal to each other. Thus, conventional BPF, the magnetic coupling circuit _{(M 12, M 23, M} 34, M 45, M 56, M 67, M 78)
And the values of the capacitive coupling circuits (C ₁₄ , C ₅₈ ) are adjusted to provide a two-pole polarized Chebyshev type band-pass filter.

[0010]

In the conventional BPF shown in FIGS. 31 and 32, the amount of attenuation can be increased by providing three pairs of attenuation poles. There is a problem in that a band-pass filter of a polarized Chebyshev type cannot be formed. On the other hand, a digital television signal to be started has a large number of segments (13 segments) and a small segment interval (432 KHz), so that many IM waves are generated near the target signal wave. Further, depending on the modulation method, a band-pass filter to be used is required to have a small amplitude deviation and a group delay time deviation in the pass band and a frequency characteristic having a steep attenuation characteristic. However, the conventional BPF shown in FIGS. 31 and 32 is a two-pole polarized Chebyshev type band-pass filter, which is suitable for a band-pass filter that emphasizes attenuation characteristics of analog TV signals and the like. In this case, there is a problem that the amplitude deviation and the group delay time deviation are large, so that they are not suitable for bandpass filters for digital television signals requiring the above-mentioned frequency characteristics. That is, FIG.
33, the attenuation pole is limited to two pairs as shown in FIG. 33. Further, as shown in FIG. 34, the amplitude deviation in the pass band is large, and at the same time, as shown in FIG. There is a disadvantage that the group delay time (τ) within the passband has a large group delay time deviation. The present invention has been made in order to solve the problems of the prior art, and an object of the present invention is to provide a rectangular waveguide capable of reducing an amplitude deviation in a pass band and a group delay time deviation. An object of the present invention is to provide a resonator type band-pass filter. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0011]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the present invention superimposes the first to fourth rectangular waveguide resonators and the fifth to eighth rectangular waveguide resonators in the direction of the electric field in the rectangular waveguide. A rectangular waveguide resonator type band-pass filter in which the first to eighth rectangular waveguide resonators are mainly coupled by a magnetic coupling circuit. The second rectangular waveguide resonator and the sixth rectangular waveguide resonator are sub-coupled by a capacitive coupling element or an S-shaped loop element to form a second rectangular waveguide resonator and a seventh rectangular waveguide resonator. And an S-shaped loop element for sub-coupling between the first rectangular waveguide resonator and the eighth rectangular waveguide resonator. It is characterized by being sub-coupled by a U-shaped loop element. Where the S-shaped loop
The elements are arranged in the directions of electric field and magnetic field in the rectangular waveguide.
It is provided in the direction perpendicular to the direction, and the rectangular
So that the part penetrating the partition wall of the shaped waveguide resonator is located
And both ends are electrically and mechanically connected to the partition.
You. Also, the loop element is arranged in the direction of the electric field in the rectangular waveguide.
And provided in a direction perpendicular to the magnetic field direction,
Whether both ends penetrate the partition wall of the rectangular waveguide resonator
In the same direction as viewed from above, electrically and mechanically
It is connected.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In all the drawings for describing the embodiments, those having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

[First Embodiment] FIG. 1 is a front view showing the front of a group delay time compensation type rectangular waveguide resonator type band pass filter according to a first embodiment of the present invention. Also, FIG.
FIG. 3 is a main part cross-sectional view showing a cross section cut along the AA 'cutting line shown in FIG. 1, and FIG. 3 is a main part cross sectional view showing a cross section cut along the BB' cutting line shown in FIG. 1, 2 and 3, 1 is a rectangular waveguide, 3 is an input (or output) terminal,
Is an output (or input) terminal, 5a to 5h are frequency adjusting screws, 6a and 6b are U-shaped loop elements, 7a and 7b are capacitive coupling plates, 8 is an input (or output) coupling loop, and 9 is an output (or Input) coupling loops, 10a to 10h are rectangular waveguide resonators, and 12a to 12c are inductive diaphragms. The group delay time compensation type rectangular waveguide resonator type band pass filter (hereinafter, simply referred to as BPF) of the present embodiment includes first to fourth rectangular waveguide resonators (10a to 10a).
d) and the fifth to eighth rectangular waveguide resonators (1
0e to 10h) are superposed in the direction of the electric field in the rectangular waveguide 1 and arranged in a U-shape. The first to fourth rectangular waveguide resonators (10a to 10d) are connected in cascade, and the inductive apertures (12a, 12b, 12c) connect between the rectangular waveguide resonators (10a to 10d). Main coupling is performed by a magnetic coupling circuit. Similarly, the fifth to eighth rectangular waveguide resonators (10e to 10h) are cascaded, and a magnetic field generated by an inductive aperture (not shown) is provided between the rectangular waveguide resonators (10e to 10h). Main coupling is performed by a coupling circuit. In addition, a first U-shaped loop element (6) is provided between the fourth rectangular waveguide resonator (10d) and the fifth rectangular waveguide resonator (10e).
Main coupling is performed by the magnetic coupling circuit according to a).

A third rectangular waveguide resonator (10
c) and the sixth rectangular waveguide resonator (10f) are sub-coupled by a capacitive coupling circuit with a capacitive coupling plate (7a), and the second rectangular waveguide resonator (10b) and the seventh rectangular waveguide resonator (10b) are connected. The rectangular waveguide resonator (10g) is sub-coupled to the rectangular waveguide resonator (10g) by a capacitive coupling circuit using a capacitive coupling plate (7b). Furthermore, the first rectangular waveguide resonator (10a) and the eighth rectangular waveguide resonator (10a)
h) are sub-coupled by a magnetic coupling circuit using a second U-shaped loop element (6b). The capacitive coupling plate and a coupling probe described later constitute a capacitive coupling element of the present invention.

FIG. 4 is a circuit diagram showing an equivalent circuit of the group delay time compensation type BPF of the present embodiment, and FIG.
3 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 4 and 5, a magnetic coupling circuit (M ₄₅ ) is a magnetic coupling circuit using a U-shaped loop element (6a), and a magnetic coupling circuit (M ₁₈ ).
Is a magnetic coupling circuit formed by a U-shaped loop element (6b),
The capacitive coupling circuit (C ₃₆ ) is a capacitive coupling circuit using a capacitive coupling plate (7a), and the capacitive coupling circuit (C ₂₇ ) is a capacitive coupling plate (7
This is a capacitive coupling circuit according to b), and other symbols are the same as those in FIG. Conventional B shown in FIGS. 31 and 32
Similarly to the PF, also in the BPF of the present embodiment, the resonance circuit (RS3) → the magnetic coupling circuit (M ₃₄ ) → the resonance circuit (RS
4) → magnetic coupling circuit (M ₄₅ ) → resonance circuit (RS 5) → magnetic coupling circuit (M ₅₆ ) → resonance circuit (RS 6) and an electromagnetic field generated in the resonance circuit (RS 6) through the resonance circuit
S3) → capacitive coupling circuit (C ₃₆ ) → resonant circuit (RS6) can have an opposite phase to the electromagnetic field generated in resonant circuit (RS6) in the path. Therefore, in the BPF of the present embodiment, an attenuation pole (attenuation pole) is generated outside the pass band at a pair of frequencies where the amplitudes of both electromagnetic fields are equal to each other.

Further, in the BPF of the present embodiment,
Resonant circuit (RS2) → the magnetic coupling circuit (M ₂₃₎ → resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS
4) → Resonance circuit with a path consisting of → magnetic coupling circuit (M ₄₅ ) → resonance circuit (RS5) → magnetic coupling circuit (M ₅₆ ) → resonance circuit (RS6) → magnetic coupling circuit (M ₆₇ ) → resonance circuit (RS7) The phase of the voltage induced in (RS7) is the resonance circuit (R
S3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) →
Magnetic coupling circuit (M ₄₅₎ → resonant circuit (RS5) → the magnetic coupling circuit (M ₅₆₎ → differs phase and 180 ° of the voltage induced in the resonant circuit (RS6) in the route from the resonance circuit (RS6). Therefore, resonant circuits (RS2) → the magnetic coupling circuit (M ₂₃₎ → resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) → the magnetic coupling circuit (M ₄₅₎
→ resonant circuit (RS5) → the magnetic coupling circuit (M ₅₆₎ → resonant circuit (RS6) → the magnetic coupling circuit (M ₆₇₎ → resonant circuit (RS
7) and an electromagnetic field generated in the resonance circuit (RS7) through a path including the resonance circuit (RS2) → the capacitive coupling circuit (C ₂₇ ) → the resonance circuit (RS7). Are in phase with each other, so that no attenuation pole occurs at a pair of frequencies where the amplitudes of both electromagnetic fields are equal to each other. Also, the resonance circuit (RS1) →
Magnetic coupling circuit (M ₁₂ ) → resonance circuit (RS2) → capacitive coupling circuit (C ₂₇ ) → resonance circuit (RS7) → magnetic coupling circuit (M
₇₈ ) → Resonant circuit (R8)
An electromagnetic field occurring in S8), the resonant circuit (RS1) → the magnetic coupling circuit (M ₁₈₎ → The electromagnetic field generated in the resonant circuit in the route from the resonance circuit (RS8) (RS8), since opposite phases, An attenuation pole occurs at a pair of frequencies at which the amplitudes of the two electromagnetic fields are equal to each other.

On the other hand, in the pass band, the resonance circuit (RS
2) → Magnetic coupling circuit (M ₂₃ ) → Resonant circuit (RS 3) → Magnetic coupling circuit (M ₃₄ ) → Resonant circuit (RS 4) → Magnetic coupling circuit (M ₄₅ ) → Resonant circuit (RS 5) → Magnetic coupling circuit (M ₅₆ ) → Resonance circuit (RS6) → Magnetic coupling circuit ( _M67 )
→ The resonance circuit (RS7)
The electromagnetic field generated in 7) and the electromagnetic field generated in the resonance circuit (RS7) in the path of the resonance circuit (RS2) → the capacitive coupling circuit (C ₂₇ ) → the resonance circuit (RS7) are around the center frequency, They cancel each other out and tend to be added to each other near the band edge of the pass band, and the deviation of the amplitude characteristic in the pass band becomes small. Similarly, the deviation of the group delay time (τ) within the pass band also decreases.
That is, in the BPF of the present embodiment, as shown in FIG. 6, the attenuation (amplitude) characteristics are limited to two pairs of attenuation poles, but as shown in FIG. Small, and at the same time, it is possible to reduce the group delay time deviation in the pass band as shown in FIG.

[0020] In this case, the compensation amount of the group delay time can be adjusted by the value of the capacitive coupling circuit (C _27), the compensation amount of the group delay time due to the capacitive coupling circuit (C ₂₇₎ is smaller than the size of the optimal In addition, the group delay time characteristic is similar to a pan-bottom type with a small amount of compensation. FIG. 9 shows the group delay time characteristics in this state.
When the compensation amount of the group delay time by the capacitive coupling circuit (C ₂₇ ) is the optimum amount, the flat part of the group delay time characteristic becomes the widest. FIG. 10 shows the group delay time characteristics in this state. If the amount of compensation for the group delay time by the capacitive coupling circuit (C ₂₇ ) is larger than the optimal amount, the amount of compensation will be overcompensated. The graph shown in FIG. 8 shows the group delay time characteristics in this state.
If a certain allowable ripple-like group delay time characteristic can be allowed in the pass band of the group delay time compensation type BPF, the group delay time characteristic of the overcompensation type BPF becomes the widest. Thus, according to the group delay time compensation type BPF of the present embodiment, it is possible to reduce the amplitude deviation in the pass band and the group delay time deviation in the pass band.

FIGS. 11 to 14 are graphs showing frequency characteristics of an example of the group delay time compensation type BPF of the present embodiment. FIG. 11 is a graph showing the attenuation characteristic. The horizontal axis represents the frequency (MHz) and the memory interval is 2 MHz, and the vertical axis represents the attenuation (dB) and the memory interval is 10 dB. Also,
The center frequency of the group delay time compensation type BPF is 721 MHz
It is. FIG. 12 is a graph showing the graph shown in FIG. 11 in an enlarged manner, wherein the memory interval on the horizontal axis is 1 MHz and the memory interval on the vertical axis is 1 dB. As can be seen from the graph of FIG. 12, the attenuation is within 1 dB when the frequency is between 719 MHz and 723 MHz, and the BPF of the group delay time compensation type shown in FIG. ing. FIG. 13 is a graph showing the phase characteristics. The horizontal axis represents the frequency (MHz), the memory interval is 1 MHz,
The vertical axis is an angle and the memory interval is 90 °. FIG. 14 is a graph showing the group delay time characteristic, and the horizontal axis represents the frequency (MH).
In z), the memory interval is 1 MHz, and the vertical axis is the delay amount (ns), and the memory interval is 100 ns. In FIG. 14,
The group delay time between the frequencies of 719 MHz and 723 MHz is within 100 ns, and the group delay time deviation is small.

The group delay time compensation type BPF of this embodiment
, A U-shaped loop element (6b) is not provided, and a sub-coupling circuit (C ₂₇ , C
When only _C36 ) is provided, the amount of attenuation outside the pass band decreases. However, a U-shaped loop element (6b)
Is provided, a pair of attenuation poles can be generated outside the pass band, and the attenuation characteristics outside the pass band can be improved. Thus, the U-shaped loop element (6b)
Is provided to improve the attenuation characteristic outside the pass band. Therefore, in the group delay time compensation type BPF of the present embodiment, when the attenuation outside the pass band satisfies the specification condition, if, instead of providing the U-shaped loop element (6b), capacitive coupling plates (7a, 7b) subcombination circuit (C _27, C ₃₆₎ comprising only may be provided.

FIG. 15 shows the attenuation characteristics in this state. As can be understood from the graph of FIG. 15, in the group delay time compensation type BPF of the present embodiment, the U-shaped loop element (6b) is not provided, and the capacitive coupling plates (7a, 7
When only the sub-coupling circuit (C ₂₇ , C ₃₆ ) consisting of b) is provided, the U-shaped loop element (6 b) and the capacitive coupling plate in the group delay time compensation type BPF of the present embodiment. As compared with the case where the sub-coupling circuit (C ₂₇ , C ₃₆ ) composed of (7a, 7b) is provided, the attenuation outside the pass band is reduced by about 10 dB.

As described above, in the group delay time compensation type BPF of the present embodiment, the number of attenuation poles is limited to two or less, but the deviation of the amplitude characteristic and the group delay time characteristic in the pass band are both improved. be able to. In the group delay time compensation type BPF of the present embodiment, an input / output coupling probe may be used instead of the input (or output) coupling loop 8 and the output (or input) coupling loop. Alternatively, a coupling probe may be used instead of the capacitive coupling plates (7a, 7b). Further, in the group delay time compensation type BPF of the present embodiment, the number (N) of the rectangular waveguide resonators may be at least 6 (N ≧ 6).

[Second Embodiment] FIGS. 16 and 17 are sectional views showing a schematic configuration of a group delay time compensation type BPF according to a second embodiment of the present invention. FIG. 16 is a cross-sectional view of a main part at the same place as in FIG. 2, and FIG. 17 is a cross-sectional view of a main part at the same place as in FIG. B of group delay time compensation type of this embodiment
The PF is provided between the rectangular waveguide resonator (10c) and the rectangular waveguide resonator (10f) and the rectangular waveguide resonator (10f).
As a sub-coupling circuit between b) and the rectangular waveguide resonator (10g), an S-shaped loop element (16a, 16b) is used instead of the capacitive coupling plate (7a, 7b). This is different from the group delay time compensation type BPF of the first embodiment.

FIG. 18 is a circuit diagram showing an equivalent circuit of the group delay time compensation type BPF of this embodiment, and FIG.
FIG. 19 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 18. FIG.
8, in FIG. 19, a magnetic coupling circuit (M ₃₆ ) is a magnetic coupling circuit using a first S-shaped loop element (16a), and a magnetic coupling circuit (M ₂₇ ) is a second S-shaped loop element. (1
6b), and other symbols are as follows:
This is the same as FIG. 4 and FIG. When the resonance circuit (RS3) and the resonance circuit (RS6) are sub-coupled by the S-shaped loop element (16a), the resonance circuit (RS3) → the magnetic coupling circuit (M ₃₆ ) → the resonance circuit (RS6) The phase of the voltage induced in the resonance circuit (RS7) in the path consisting of the resonance circuit (RS3) and the resonance circuit (RS6) is sub-coupled by, for example, the capacitive coupling plate (7a) shown in FIG. case, the same as the phase of the resonant circuit (RS3) → capacitive coupling circuit (C ₃₆₎ → voltage induced in the resonant circuit (RS6) in the route from the resonance circuit (RS6). That is, the S-shaped loop element used as the sub-coupling circuit is equivalent to the capacitive coupling element used as the sub-coupling circuit. Therefore, also in the group delay time compensation type BPF of the present embodiment, it is possible to reduce the amplitude deviation in the pass band and the group delay time deviation in the pass band. In the present invention, the S-shaped loop element (16a, 16b)
As shown in FIG. 16, a loop element having a structure in which both ends of the loop element are electrically and mechanically connected to the rectangular waveguide 1 at different positions in the upper and lower (or left and right) directions of the rectangular waveguide 1. In general, a rectangular waveguide resonator type band-pass filter can apply a large amount of power. Therefore, the rectangular waveguide resonator type band-pass filters according to the first and the second embodiments have an output in a digital television. Most suitable as a filter or a reflection element of a power combiner (antenna duplexer).

[Third Embodiment] FIGS. 20 and 21 are sectional views showing a schematic configuration of a BPF according to a third embodiment of the present invention. FIG. 20 is a cross-sectional view of a main part at the same place as in FIG. 2, and FIG. 21 is a cross-sectional view of a main part at the same place as in FIG. The BPF of the present embodiment has a rectangular waveguide resonator (10
As a sub-coupling circuit between b) and the rectangular waveguide resonator (10g), a U-shaped loop element (6c) is used instead of the capacitive coupling plate (7b), and the rectangular waveguide resonator is used. (1
Embodiment 1 in that a capacitive coupling plate (7c) is used instead of the U-shaped loop element (6b) as a sub-coupling circuit between the rectangular waveguide resonator (10h) and the rectangular waveguide resonator (10h). Group delay time compensation type BPF.

FIG. 22 is a circuit diagram showing an equivalent circuit of the BPF of this embodiment, and FIG. 23 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 22 and 23,
The magnetic coupling circuit (M ₂₇ ) is a U-shaped loop element (6c)
The magnetic coupling circuit and the capacitive coupling circuit (C ₁₈ ) are capacitive coupling circuits with a capacitive coupling plate (7c), and the other reference numerals are the same as those in FIGS. Embodiment 1
As in the group delay time compensation type BPF of FIG.
Also in PF, the resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) → the magnetic coupling circuit (M ₄₅₎
→ Resonance circuit (RS5) → Magnetic coupling circuit (M ₅₆ ) → Electromagnetic field generated in resonance circuit (RS6) through a path composed of resonance circuit (RS6) and resonance circuit (RS3) → Capacitive coupling circuit (C ₃₆ ) → Resonance The electromagnetic field generated in the resonance circuit (RS6) in the path including the circuit (RS6) can be in an opposite phase. Therefore, outside the pass band, the amplitude of both electromagnetic fields is
At a pair of frequencies equal to each other, an attenuation pole (attenuation pole) occurs. Further, in the BPF of the present embodiment, the resonance circuit (RS2) → the magnetic coupling circuit (M ₂₃ ) →
Resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) → the magnetic coupling circuit (M ₄₅₎ → resonant circuit (RS
5) → the magnetic coupling circuit (M ₅₆₎ → resonant circuit (RS6) → the magnetic coupling circuit (M ₆₇₎ → voltage of the phase induced in the resonant circuit (RS7) in the route from the resonance circuit (RS7) is resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (R
S4) → Magnetic coupling circuit (M ₄₅ ) → Resonant circuit (RS5) →
Magnetic coupling circuit (M ₅₆₎ → the voltage induced in the resonant circuit (RS6) in the route from the resonance circuit (RS6) phase and 18
0 ° different. While only, if the resonant circuit and (RS2) of the resonant circuit (RS7) are secondary binding with magnetic coupling circuit (M _27), the resonant circuit (RS2) → the magnetic coupling circuit (M ₂₇₎ → resonant circuit (RS7 ), The phase of the voltage induced in the resonance circuit (RS7) depends on the resonance circuit (RS7).
When the 2) and resonator (RS7) and are subcombination capacitive coupling circuit (C _27), resonant at a route from the resonance circuit (RS2) → capacitive coupling circuit (C ₂₇₎ → resonant circuit (RS7) The phase of the voltage induced in the circuit (RS7) is different by 180 °. Therefore, resonant circuits (RS2) → the magnetic coupling circuit (M ₂₃₎ → resonant circuit (RS3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) → the magnetic coupling circuit (M ₄₅₎
→ resonant circuit (RS5) → the magnetic coupling circuit (M ₅₆₎ → resonant circuit (RS6) → the magnetic coupling circuit (M ₆₇₎ → resonant circuit (RS
7) and an electromagnetic field generated in the resonance circuit (RS7) through a path consisting of the resonance circuit (RS2) → the magnetic coupling circuit (M ₂₇ ) → the resonance circuit (RS7). Can be in opposite phase. for that reason,
Outside the pass band, an attenuation pole (attenuation pole) is generated at a pair of frequencies at which the amplitudes of both electromagnetic fields are equal to each other.

Further, in the BPF of this embodiment, the resonance circuit (RS1) → the magnetic coupling circuit (M ₁₂ ) → the resonance circuit (RS2) → the magnetic coupling circuit (M ₂₃ ) → the resonance circuit (RS
3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) → the magnetic coupling circuit (M ₄₅₎ → resonant circuit (RS5) → the magnetic coupling circuit (M ₅₆₎ → resonant circuit (RS6) → the magnetic coupling circuit (M ₆₇ ) → Resonance circuit (RS7) → Magnetic coupling circuit ( _M78 )
→ A resonance circuit (RS8)
8) The phase of the voltage induced in the resonance circuit (RS3) →
Magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) → the magnetic coupling circuit (M ₄₅₎ → resonant circuit (RS5) → the magnetic coupling circuit (M
₅₆ ) → Resonant circuit (R6)
The phase of the voltage induced in S6) becomes the same. Therefore, the resonance circuit (RS1) → the magnetic coupling circuit (M ₁₂ ) → the resonance circuit (RS2) → the magnetic coupling circuit (M ₂₃ ) → the resonance circuit (R
S3) → the magnetic coupling circuit (M ₃₄₎ → resonant circuit (RS4) →
Magnetic coupling circuit (M ₄₅₎ → resonant circuit (RS5) → the magnetic coupling circuit (M ₅₆₎ → resonant circuit (RS6) → the magnetic coupling circuit (M
₆₇ ) → Resonance circuit (RS7) → Magnetic coupling circuit (M ₇₈ ) → Electromagnetic field generated in resonance circuit (RS8) through a path consisting of resonance circuit (RS8) and resonance circuit (RS1) → Capacitive coupling circuit (C ₁₈ ) → The electromagnetic field generated in the resonance circuit (RS8) on the path formed by the resonance circuit (RS8) can be in opposite phase. Therefore, in the BPF of the present embodiment, an attenuation pole (attenuation pole) is generated outside the pass band at three pairs of frequencies at which the amplitudes of the two electromagnetic fields are equal to each other.

Therefore, as shown in FIG. 24, in the BPF of the present embodiment, three pairs of attenuation poles can be generated. As a result, in the BPF of the present embodiment,
The amount of attenuation can be increased by about 10 dB as compared with the BPF of the first embodiment. However, B in the present embodiment
The PF has a large amplitude deviation in the pass band and, at the same time, a large group delay time deviation in the pass band. As described above, in the BPF of the present embodiment, the amount of attenuation can be increased as compared with the conventional BPF.

[Fourth Embodiment] FIGS. 25 and 26 are sectional views showing a schematic structure of a BPF according to a third embodiment of the present invention. FIG. 25 is a cross-sectional view of a main part at the same place as in FIG. 2, and FIG. 26 is a cross-sectional view of a main part at the same place as in FIG. The BPF of the present embodiment has a rectangular waveguide resonator (10
c) and the rectangular waveguide resonator (10f), and between the rectangular waveguide resonator (10a) and the rectangular waveguide resonator (10h).
And a capacitive coupling plate (7a, 7c)
In that an S-shaped loop element (16a, 16c) is used in place of the BPF of the third embodiment.

FIG. 27 is a circuit diagram showing an equivalent circuit of the BPF of this embodiment, and FIG. 28 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 27 and 28,
The magnetic coupling circuit (M ₂₇ ) is a magnetic coupling circuit using the first S-shaped loop element (16a), and a magnetic coupling circuit (M ₁₈ ).
Is a magnetic coupling circuit formed by a second S-shaped loop element (16c).
Is the same as As described above, the S-shaped loop element used as the sub-coupling circuit is equivalent to the capacitive coupling element used as the sub-coupling circuit. Therefore, also in the BPF of the embodiment, the attenuation can be increased as compared with the conventional BPF. In the BPF of each of the above embodiments, the inductive aperture (12a
12c), an inductive coupling window formed in the partition may be used. Furthermore, by providing a coupling adjusting screw on the rectangular waveguide 1 and appropriately changing the insertion length of the coupling adjusting screw, the magnetic coupling coefficient of the inductive diaphragm (12a to 12c) can be adjusted to a required value. It is.

As described above, the invention made by the present inventor is:
Although a specific description has been given based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention.

[0034]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) According to the present invention, in a rectangular waveguide resonator type band-pass filter, an amplitude deviation within a pass band,
In addition, it is possible to reduce the group delay time deviation. (2) According to the present invention, in the rectangular waveguide resonator type band pass filter, it is possible to reduce the amplitude deviation and the group delay time deviation in the pass band and increase the attenuation.

[Brief description of the drawings]

FIG. 1 is a front view showing the front of a group delay time compensation type rectangular waveguide resonator type band-pass filter according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing a cross section cut along a line AA ′ shown in FIG. 1;

FIG. 3 is a main part cross-sectional view showing a cross section cut along a BB ′ cutting line shown in FIG. 1;

FIG. 4 is a circuit diagram showing an equivalent circuit of the group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention.

FIG. 5 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 4;

FIG. 6 is a graph showing attenuation characteristics of the group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention.

FIG. 7 is an enlarged graph showing the graph shown in FIG. 6;

FIG. 8 is a graph showing a group delay time characteristic of the group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention.

FIG. 9 shows a group delay time characteristic when the amount of group delay time compensation is smaller than an optimal amount in the group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention. It is a graph.

FIG. 10 shows the group delay time characteristics when the amount of group delay time compensation is optimal in the group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention. It is a graph.

FIG. 11 is a graph showing an attenuation characteristic of an example of a group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention.

FIG. 12 is an enlarged graph showing the graph shown in FIG. 11;

FIG. 13 is a graph showing phase characteristics of an example of a group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention.

FIG. 14 is a graph illustrating a group delay time characteristic of an example of a rectangular waveguide resonator type band-pass filter of the group delay time compensation type according to the first embodiment of the present invention.

FIG. 15 is a graph showing an attenuation characteristic when a U-shaped loop element is not provided in the group delay time compensation type rectangular waveguide resonator type band pass filter according to the first embodiment of the present invention.

FIG. 16 is a sectional view of a main part showing a schematic configuration of a rectangular waveguide resonator type band-pass filter of a group delay time compensation type according to a second embodiment of the present invention.

FIG. 17 is a sectional view of a main part showing a schematic configuration of a rectangular waveguide resonator type band-pass filter of a group delay time compensation type according to a second embodiment of the present invention.

FIG. 18 is a circuit diagram showing an equivalent circuit of a group delay time compensation type rectangular waveguide resonator type band pass filter according to the second embodiment of the present invention.

19 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG.

FIG. 20 is a sectional view of a principal part showing a schematic configuration of a rectangular waveguide resonator type band-pass filter according to a third embodiment of the present invention.

FIG. 21 is a cross-sectional view of a principal part showing a schematic configuration of a rectangular waveguide resonator type band-pass filter according to a third embodiment of the present invention.

FIG. 22 is a circuit diagram showing an equivalent circuit of a rectangular waveguide resonator type band-pass filter according to the third embodiment of the present invention.

FIG. 23 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 22;

FIG. 24 is a graph showing an attenuation characteristic of the band-pass filter of the rectangular waveguide resonator type according to the third embodiment of the present invention.

FIG. 25 is a fragmentary cross-sectional view showing a schematic configuration of a rectangular waveguide resonator type band-pass filter according to a fourth embodiment of the present invention.

FIG. 26 is a sectional view of a principal part showing a schematic configuration of a rectangular waveguide resonator type band-pass filter according to a fourth embodiment of the present invention.

FIG. 27 is a circuit diagram showing an equivalent circuit of a rectangular waveguide resonator type band-pass filter according to Embodiment 3 of the present invention.

28 is a conversion equivalent circuit diagram of the equivalent circuit shown in FIG. 27.

FIG. 29 is a cross-sectional view for explaining a TE ₁₀ mode electromagnetic field in a rectangular waveguide.

FIG. 30 is a diagram for explaining a resonance length of a rectangular waveguide resonator.

FIG. 31 is a diagram showing a schematic configuration of a rectangular waveguide band-pass filter using a conventional rectangular waveguide resonator.

32 is a circuit diagram showing an equivalent circuit of the conventional rectangular waveguide resonator type band pass filter shown in FIG. 31.

FIG. 33 is a graph showing attenuation characteristics of the conventional rectangular waveguide resonator type band-pass filter shown in FIG. 31;

34 is a graph showing the graph shown in FIG. 33 in an enlarged manner.

FIG. 35 is a graph showing group delay time characteristics of the conventional rectangular waveguide resonator type band pass filter shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rectangular waveguide, 3 ... Input (or output) terminal, 4 ... Output (or input) terminal, 5a-5h ... Frequency adjustment screw,
6a, 6b ... U-shaped loop element, 7a, 7b, 7c ...
Capacitive coupling plate, 8 ... input (or output) coupling loop, 9 ...
Output (or input) coupling loop, 10, 10a to 10h
... Rectangular waveguide resonator, 12, 12a-12c ... Inductive stop, 13a, 13b ... Capacitive stop, 16a, 16b, 1
6c: S-shaped loop element.

Continuation of the front page (56) References JP-A-3-58501 (JP, A) JP-A-61-280102 (JP, A) JP-A-64-29001 (JP, A) JP-A-11-261303 (JP, A) , A) Hatanaka et al., "Helical Resonator Type Phase Linear BPF", Technical Report of the Institute of Television Engineers of Japan, Vol. 11, No. 10, pp. 59-64, ^July 1987. (58) Field surveyed (Int. Cl. ⁷ , DB name) H01P 1/20-1/219 H01P ^7/ 00-7/10

Claims (4)

(57) [Claims] 1. A first to fourth rectangular waveguide resonators in which each resonator is mainly coupled by a magnetic coupling circuit, and a fifth waveguide resonator in which each resonator is mainly coupled by a magnetic coupling circuit. To eight rectangular waveguide resonators, the first to fourth rectangular waveguide resonators, and the fifth to eighth rectangles superimposed in the direction of the electric field in the rectangular waveguide. A U-shaped first loop element for main coupling between a fourth rectangular waveguide resonator and a fifth rectangular waveguide resonator ;
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
First loop element electrically and mechanically connected to partition
A first capacitive coupling element for sub-coupling between a third rectangular waveguide resonator and a sixth rectangular waveguide resonator, a second rectangular waveguide resonator and a seventh capacitive waveguide element, A second capacitive coupling element for sub-coupling between the rectangular waveguide resonator, and a U-shape for sub-coupling between the first rectangular waveguide resonator and the eighth rectangular waveguide resonator A second loop element ,
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
And a second loop element electrically and mechanically connected to the partition wall . 2. The first to fourth rectangular waveguide resonators in which each resonator is mainly coupled by a magnetic coupling circuit, and the fifth rectangular waveguide resonator in which each resonator is mainly coupled by a magnetic coupling circuit. To eight rectangular waveguide resonators, the first to fourth rectangular waveguide resonators, and the fifth to eighth rectangles superimposed in the direction of the electric field in the rectangular waveguide. A U-shaped first loop element for main coupling between a fourth rectangular waveguide resonator and a fifth rectangular waveguide resonator ;
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
First loop element electrically and mechanically connected to partition
When, third and capacitive coupling element for secondary coupling between the rectangular waveguide resonator and sixth rectangular waveguide resonator, a second rectangular waveguide resonator and seventh rectangular waveguide in S-shaped loop elements of the sub-coupling between the tube resonator, the rectangular guide
Provided in the direction perpendicular to the electric field direction and magnetic field direction in the waveguide
And a gap between the rectangular waveguide resonators between both ends.
Both ends are the partition walls so that the part penetrating the wall is located
An S-shaped loop element electrically and mechanically connected to the first and second U-shaped second sub-couplings between the first rectangular waveguide resonator and the eighth rectangular waveguide resonator The loop element of the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
And a second loop element electrically and mechanically connected to the partition wall . 3. A main coupling between the resonators by a magnetic coupling circuit.
The first to fourth rectangular waveguide resonators, and the fifth one in which each resonator is mainly coupled by a magnetic coupling circuit
To the eighth rectangular waveguide resonator, from the first
Up to the fourth rectangular waveguide resonator, and
Fifth to eighth rectangles superimposed in the direction of the electric field
Waveguide resonator, fourth rectangular waveguide resonator and fifth rectangular waveguide resonator
U-shaped first loop element for main coupling betweenIn the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
First loop element electrically and mechanically connected to partition
And a third rectangular waveguide resonator and a sixth rectangular waveguide resonator
-Shaped loop element sub-joining betweenIn the rectangular guide
Provided in the direction perpendicular to the electric field direction and magnetic field direction in the waveguide
And a gap between the rectangular waveguide resonators between both ends.
Both ends are the partition walls so that the part penetrating the wall is located
-Shaped loop element electrically and mechanically connected toAnd a second rectangular waveguide resonator and a seventh rectangular waveguide resonator
Capacitive coupling element for sub-coupling between the first rectangular waveguide resonator and the eighth rectangular waveguide resonator
U-shaped second loop element sub-coupled betweenIn the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
Second loop element electrically and mechanically connected to the partitionWhen
Having rectangular waveguide resonator type bandpass
filter. 4. A main coupling between the resonators by a magnetic coupling circuit.
The first to fourth rectangular waveguide resonators, and the fifth one in which each resonator is mainly coupled by a magnetic coupling circuit
To the eighth rectangular waveguide resonator, from the first
Up to the fourth rectangular waveguide resonator, and
Fifth to eighth rectangles superimposed in the direction of the electric field
Waveguide resonator, fourth rectangular waveguide resonator and fifth rectangular waveguide resonator
U-shaped first loop element for main coupling betweenIn the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
First loop element electrically and mechanically connected to partition
And a third rectangular waveguide resonator and a sixth rectangular waveguide resonator
S-shaped loop element sub-coupled betweenIn the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And the rectangular waveguide resonance between both ends.
Both ends are forward so that the part that passes through the
A first S-shaped loop electrically and mechanically connected to the partition wall
Loop elementAnd a second rectangular waveguide resonator and a seventh rectangular waveguide resonator
S-shaped loop element sub-coupled betweenIn the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And the rectangular waveguide resonance between both ends.
Both ends are forward so that the part that passes through the
A second S-shaped loop electrically and mechanically connected to the partition wall
Loop elementA first rectangular waveguide resonator and an eighth rectangular waveguide resonator
U-shaped second loop element sub-coupled betweenIn the above
Direction perpendicular to the electric and magnetic field directions in a rectangular waveguide
And both ends are the rectangular waveguide resonator.
At a position in the same direction as viewed from a portion penetrating the partition wall,
Second loop element electrically and mechanically connected to the partitionWhen
Having rectangular waveguide resonator type bandpass
filter.