JPS6178201A - Notch filter - Google Patents

Abstract

PURPOSE:To attain easy and simple constitution, manufacture and adjustment and excellent electric characteristic by providing a coupling loop to one short- circuit wall and providing an element respectively adjusting each resonance frequency of the H and V modes with different frequency to a cylindrical side wall. CONSTITUTION:One coupling loop 3 is provided to one short-circuit wall 2, and elements 5, 6 adjusting respectively each resonance frequency of the H and V mode having different frequency are provided to the cylindrical side wall 1. A circular waveguide cavity resonator is formed so that the in-tude inserting directions of the elements 5, 6 are at a right angle together and an angular difference of 45 deg. or 135 deg. is provided respectively with the loop face of the coupling loop 3. In exciting the circular waveguide cavity resonator with two waves having different frequency via a coaxial terminal 4 and the coupling loop 3, the electric fields EH and EV are made orthogonal together and also the magnetic fields are orthogonal together, then the H and V modes are resonated at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a constant impedance diplexer (hereinafter abbreviated as CIN diplexer) used for combining a video signal carrier wave and an audio signal carrier wave, for example, in a television broadcasting device. The present invention relates to a 7-touch filter suitable as a component such as the following.

BACKGROUND ART FIG. 15 is a diagram showing an example of a CIN diplexer conventionally used to synthesize a video signal carrier wave and an audio signal carrier wave in a television broadcasting device.
I and 122 are hybrid circuits, 161 and 16- are color beat frequencies, i.e. fv-3, 58 (MH2)
(fV is the frequency of the video signal carrier wave), 17+ and 17 are resonators that resonate with the audio signal carrier wave f^ (MH2), and the video signal carrier fv is connected to the input terminal 12++ of the hyper-end circuit 12+. When the color beat fV-3,53 generated in the video signal transmitter is added, the color beat fV-3,58 is absorbed by the non-reflection terminator 14 connected to the isolation terminal 121. When audio signal carrier wave fA is applied to input terminals 12 + of 12 hybrid circuits, video signal carrier wave fv and audio signal carrier wave f are output from 12 isolation terminals.
^ is sent. And the resonators 16u, ``''l6'' in the CIN guiplexer shown in Fig. 15,
As 17+ and 17, for example, a semi-coaxial cavity resonator whose cross section is schematically shown in FIG. 16 or a rectangular waveguide cavity resonator whose cross section is schematically shown in FIG. 17 is used. Four cavity resonators are required, and the number of connectors between the resonators is also relatively large.As a result, the overall structure is complicated and large, and the cost is high.

The present inventor has previously proposed an IS notch filter consisting of a dual-mode circular waveguide cavity resonator that is suitable as a component of a CIN diplexer and can eliminate the drawbacks of the CIN diplexer shown in FIG.

(Japanese Patent Application No. 51-019121) FIG. 18 is a sectional view showing the structure, and FIG. 19 is a sectional view taken along line A-A in FIG. 18.
In both figures, 18 is a circular waveguide cavity resonator, 19 is a coupling hole drilled in the short-circuit wall, 20 is a coupling #11i1 path, and 21 is a main line, which forms a T-branch circuit together with the coupling line 20.

22 and 23 are coaxial terminals, and each internal conductor is connected to the main line 21.
Connect to the end of the FIG. 20 is a diagram showing a CIN guiplexer using the above-mentioned notch filter.
and 24 are the nonoji filters shown in FIGS. 18 and 19, and the /border filter 24. The coaxial terminal 22 of the hybrid circuit 12- is connected to the coupling terminal 12-3 of the coaxial terminal 23
Connect to the coupling terminals 12 and 3 of the 12 hybrid circuits, respectively, and connect the coupling terminals 12+11 of the hybrid circuit 3812+ to the coaxial terminals 22 and 23 of the 24 border filters.
and the 12 coupling terminals of the 12 hybrid circuits.

When the fV wave and the fv -3,58- wave are applied to the input terminal 12++ of the high precision circuit 121, the notch filter 2
Due to the magnetic coupling between the 41 and 24 coupling lines 20 and the coupling hole 19, an electric field corresponding to the fV wave having an angular difference of 45° with the coupling line 20 is generated, and an angular difference between the coupling line 20 and 45' is generated. and perpendicular to the electric field Ev fv 3.58
The electric fields My-O and corresponding to the waves coexist and resonate in the cavity resonator, and the fC 3.58 wave is reflected by the edge filters 24- and 242 and connected to the isolation terminal 12+. The fV wave is absorbed by the non-reflection terminator 14 and appears at the isolation terminal 125 of the hybrid circuit 12. Further, the fA wave applied to the input terminal 12 of the hybrid circuit &8+2:t is reflected by the notch filters 24+ and 24, appears at the isolation terminal 12, and is combined with the fV wave.

In this CIN guiplexer, since only two cavity resonators are required, the entire configuration can be made simpler and smaller, and each of the two waves of different frequencies that co-resonate in the cavity resonator can be Although it has the advantage that the loads Q are equal to each other, the structure of the coupling part in the cavity resonator is complicated, and there are relatively many parts that require adjustment, such as coupling holes and coupling lines, so it is difficult to manufacture a notch filter. However, it cannot avoid the drawbacks of being difficult to implement and high cost.

Problems to be Solved by the Present Invention The present invention solves the above-mentioned conventional drawbacks, namely, when constructing a diplexer etc., generally a relatively large number of 7-touch filters are required, and a notch filter constructed so that a relatively small number is sufficient. However, the structure and manufacturing adjustment are simple and easy, and the cost is low, except for the disadvantage that the structure is complicated and difficult to manufacture, resulting in high cost.We have realized a non-nji filter that is suitable as a component of Guiplexer, etc. The purpose is to

Biomembrane for Solving Problems (Example 1) Fig. 1 is a sectional view showing one embodiment of the present invention, and Fig. 2 is a cross-sectional view showing an example of the present invention.
A sectional view and Figure 3 are front views, and in each figure, 1 is the cylindrical side wall of the circular waveguide cavity, and its axial length, that is, the resonance length, is the wavelength within the tube. It is formed in Z. 2 is the short circuit wall, 3 is the coupling loop,
It is installed on either one of the shorting walls. 4 is a coaxial terminal, and 5 is an H-mode resonant frequency fine adjustment element, which is made of a rod-shaped conductor inserted into the tube from the cylindrical side wall 1, and can minutely change the length of insertion into the tube, and whose insertion direction is the same as that of the coupling loop. 3 and the center of the short-circuiting wall 2, and have an angle difference of 45° and 135° (or approximately 45° and approximately 135°). 6 is a ■ mode resonant frequency fine adjustment element whose insertion direction into the pipe is perpendicular to element 5 (
The configuration is the same as that of element 5 except that it is formed to form a substantially right angle). 7 is a moat-coupled fine V @ adjustment element, which has the same configuration as elements 5 and 6 except that its insertion direction into the tube has an angular difference of 45° (or approximately 45°) from that of elements 5 and 6, respectively. It is. It should be noted that the adjustment effect can be maximized when the elements 5 to 7 are provided at four fixed points approximately %t of the axial length of the cylindrical side wall 1; You can do it like this. Further, although the figure shows an example in which two elements 5 are provided at side wall locations symmetrical about the central axis, one of them may be omitted, and one of the elements 6 may be similarly omitted. Furthermore, instead of providing four elements 7 as shown in the figure, two of the four elements whose insertion directions into the tube are orthogonal to each other and have an angular difference of 45'' or +35° with elements 5 and 6 are used. A mode coupling fine adjustment element may be formed using the elements.

Actions and Effects When the circular waveguide cavity resonator is excited by two waves with different frequencies through the coaxial terminal 4 and the coupling loop 3, the second
As shown in the figure, the electric fields Es and White are orthogonal to each other, and the magnetic fields are also orthogonal to each other, H mode and V mode, which resonate simultaneously. Notch filter shown in Figures 18 and 19 However, as is clear from FIGS. 1 to 3, the structure of the connecting portion of the notch filter of the present invention is different from that of the notch filter shown in FIGS. 18 and 19. Since the structure is simple and easy to manufacture, the cost can be reduced, and it has the following features.

That is, the distance between the center of the coupling loop 3 (the position of the internal conductor of the coaxial terminal 4) and the center 9 of the shorting wall 2 is set as r1 in the shorting wall 2.
, Hr+ and the center of the coupling loop 3, and the angle formed between the loop surface and the radial direction is θL. By changing θL, the resonator load Q (QLH) and V in the H mode can be changed.
The ratio to the load Q (QLV) in the mode can be arbitrarily changed. If the area of the coupling loop 3 is Ae, the load Q of the resonator is inversely proportional to Ae and proportional to 90r (--) (including r=O), so at r・r=o, H The isolateral area AeH of the coupling loop that intersects with the magnetic field of the mode is approximately expressed by equation (1), and the isolateral area Aev of the coupling loop that intersects with the magnetic field of mode is approximately expressed as equation (2). The load Q (
QLN) is inversely proportional to Ae)I, and the load Q (QLV) in mode ■ is inversely proportional to AeV. By changing +31 on the right-hand sides of equations (1) and (2), Aes and Aev are related. θL
By changing , the ratio of Qin and Qtv can be changed.

Ae++ King Ae sin (45°±θL)
・・・・・・ (1) Aev #Ae Bin (45
° hand C1t) ・・・・・・(2) Also, short circuit wall 2
When the distance r from the center r of and is inversely proportional to the isolateral areas AeNr and Acvt of the coupling loop 3 expressed by equation (4).

Generally, the no-load Q (Qu) of a circular waveguide cavity resonator in H1+ mode is determined by the following equation.

D: diameter of circular waveguide cavity (am) f: arbitrary frequency (GHz) f(: cutoff frequency (GH2)) Also, the attenuation amount Lo in the damping ball is the load Q (QL)
The theoretical value can be determined by the following equation.

The attenuation amount L in the H mode attenuation ball (the attenuation amount L6V in the IN and V mode attenuation balls) of the notch filter of the present invention can be theoretically determined by equations (7) and (8).

The notch filter of the present invention operates as an independent resonant circuit for the H mode and the V mode, as shown in FIG. 4, and has an admittance YH for the H mode and an admittance 'fv teeth(
It is obtained using equations (9) and (10).

In equation (9), foH: resonant frequency in H mode BwH: dB attenuation frequency bandwidth in H mode (
In equation 10), fav: Resonance frequency in V mode Bwy: AdB attenuation frequency bandwidth in V mode Basic matrix of the circuit shown in Figure 4...
(11) From equations (9), (10), and (11), the transmission characteristic LH
The measured value obtained by the present inventor for the prototype product is in extremely good agreement with the theoretical value obtained from equation (12), and the transmission characteristic of v is shown in Figure 5 (the horizontal axis is the frequency fMHz, the vertical axis is is the damping I
ATTdB).

Means for solving the gap point (Embodiment 2) FIG. 6 is a diagram showing another embodiment of the present invention, and 8 is a diagram showing another embodiment of the present invention. It is connected to a coaxial terminal 4 via a cross-shaped branch circuit 10 consisting of a coaxial line.

Actions and Effects FIG. 7 is an equivalent circuit diagram thereof, and 9L is the admittance of the compensation circuit 9. The basic matrix transmission characteristics of this circuit are the same as in Figure 5. ), and as is clear from the figure, by adding an inductive compensation circuit, NTSC
A suitable notch filter can be formed when there is a relationship such as fv (f^) between the video signal carrier wave fv and the audio signal carrier wave f^, such as in a television system. fv+4
．． 18MH2 (color subcarrier fs: fv + 3
-58MHz included. ) can form a notch filter with good transmission characteristics and group delay time characteristics.

Means for Solving the Problem (Embodiment 3) FIG. 9 also shows another embodiment of the present invention, consisting of 11 curved coaxial stubs. Other symbols are the same as in FIG.

Actions and Effects FIG. 10 is an equivalent circuit diagram thereof, where Yc is the admittance of the capacitive compensation circuit. This is the basis of this equivalent circuit,
The transmission characteristics are as follows.

FIG. 11 (horizontal and vertical axes are the same as FIG. 5) is a curve diagram showing the transmission time 11 of the notch filter of the present invention shown in FIG. By adding , it is possible to form a notch filter suitable for television systems and the like having the frequency relationship fv>f^.

FIG. 12 is a diagram illustrating the relationship between the transmission characteristics of the notch filter of the present invention to which an inductive or capacitive compensation circuit is added and the voltage reflection coefficient r (f) at frequency f. r) tPm (r), output power P. LIT (f), the admittance f! of the resonant circuit and the compensation circuit at the frequency f! -YH(f),
Assuming Yv (f), YL(f), and Yc(f),
If the compensation circuit is inductive, then...(17) The return loss br(r) at frequency f is...
(18) When the compensation circuit is capacitive, ... (19) ... (20) A hybrid circuit can be constructed by combining the notch filter of the present invention with a circulator, etc.; FIG. 13 is a diagram showing a CIN multiplexer constructed by combining the notch filter of the present invention with a hybrid circuit, in which 81 and 8- are the notch filters of the present invention explained with reference to FIGS. 1 to '3, and 12I and 12 are hybrid circuits. Times 88.12u and 123. is the input terminal, 1
2 saw and 12= are isolation terminals, 12rs,
12+II+, 12coj and 12coq are coupling terminals, +3
1 and 13 are branch circuits, for example, made of coaxial lines, and each branch terminal is connected to a hyper-end circuit +2. and 12 coupling terminals +213, +2 3 and +211.12 2V
In addition, 7 filters 8I and 8 coaxial terminals 41 and 4
2 (4 in FIGS. 1 and 3).

14 is a non-reflection terminator.

The coupling coefficient of the hybrid circuit 12+ is 01, the electrical angle of the coupling line is θ, and the characteristic impedance is Zo1 coupling terminal +21
The load impedance connected to 3 and 12+Q is Zt
When zL=Zo-1, when input voltage Em is applied to input terminal 1211, coupling terminals 12rr, 12+
v and isolation terminal +2. Each output voltage En
, Et* and Elko are 屹MI0 ......(23
) Terminals 12+3.12+9 and 12.) when a load of voltage reflection coefficient is connected to the coupling terminals 12.3 and 12J9. Each output voltage sieve, E: @ and F, ra are,
... (26) Reflected voltage Ellr to input terminal 12II and input terminal 1
2I.

The voltage reflection coefficient S+s at is ...(27) It is expressed as

FIG. 14 is a diagram showing a guiplexer constructed by combining the notch filter of the present invention shown in FIG. 7 with a hybrid circuit, and 8'1 and 8') are the notch filters of the present invention shown in FIG. 15 is a cross-shaped branch circuit, and the other symbols are the same as in FIG.

The input voltage and power at the frequency of the input terminal 12s1 in the hybrid circuit 121 are E++II(f) and puy(r), and the input voltage and input power at the input terminal l2)l in the hybrid circuit 122 are EvI+/
(f) and P2Is (f), hybrid circuit 1
The output voltage and output power of 122 isolation terminals in 2 terminals are E+ouy (f), Ezauy (
f) and P1611T (f) % P2out (f)
Then, input terminal 12u of hybrid time S name 121
and the isolation terminal 12 of the hybrid circuit 122
The voltage transmission characteristics and power transmission characteristics between the hybrid circuit 122 and the hybrid circuit ff812+ are as follows: (29) (30) The voltage between the input terminal 1221 of the hybrid circuit 122 and the isolation terminal 122 of the hybrid circuit ff812+ The transmission characteristics and the power transmission characteristics are as follows: In equations (29) and (31), θj: Electrical angle high print circuit of the coupled line of the hybrid circuit at frequency f. and 12. Input terminal 1 in
211.12p+- isolation terminal 12/co, 1
Assuming that each of the two reflected voltages is Er(f) and the input voltages of each terminal are M and (r), the reflected voltage ratio at each terminal can be determined by the following equation.

...... (33) The voltage reflection coefficient S of each terminal above is: 1 + R (f) In equations (33) and (34), k is each terminal!2u
−122+ % 11 , 21 , +2 and 22 corresponding to the subscripts of 1212 and 1222.

The notch filter shown in FIG. 9, that is, the capacitive compensation Do
When a notch filter with B + + added is combined with a hybrid circuit, Fig. 14, equation (29),
Each YL(f) in equations (31) and (33) is replaced by Yc(f
), the voltage and power transmission characteristics between the input terminal and isolation terminal of the hybrid circuit, the reflected voltage ratio and voltage reflection coefficient at each terminal, etc. can be determined in the same manner as above.

The present inventor determined the transmission characteristics of a prototype of the Guiplexer, but when a notch filter with an inductive compensation circuit is incorporated, the characteristic curve shown in Figure 8 and that of a notch filter with a capacitive compensation circuit are obtained. In the case of incorporating t, we were able to obtain results that closely matched the characteristic curves shown in FIG. 11.

Summary of the effects of the present invention As is clear from the above explanation, the notch filter of the present invention is simple and easy to configure and manufacture and adjust, has good electrical characteristics, and is of dual mode type, so it can be used in hybrid circuits or circulators. When a guiplexer is formed in combination with It can constitute a C1IN diplexer suitable for combining video and audio signal carrier waves, and its effects are enormous.

[Brief explanation of drawings]

1 to 3 are diagrams showing one embodiment of the present invention, FIG. 4 is an equivalent circuit diagram thereof, FIG. 5 is a transmission characteristic curve diagram thereof, and FIGS. 6 and 9 are diagrams of the present invention. Figures 7 and 10 are equivalent circuit diagrams showing other embodiments of the invention, Figures 8 and 11 are curve diagrams showing its transmission characteristics, and Figure 12 is its transmission characteristics. Figure 13 explaining the relationship between and voltage reflection coefficient
14 and 14 show a guiplexer using the notch filter of the present invention, FIGS. 15 and 20 show a conventional guiplexer, and FIGS. 16 to 19 show a conventional 7-touch filter. In the figure, l: cylindrical side wall, 2: shorting wall, 3: coupling loop, 4.4I and 42: coaxial terminal,
5 and 6: joint frequency fine adjustment element, 7: mode coupling fine adjustment element, 8.8+. a>, a: and 8゛coni invention notch filter, 9 and 1
1: Compensation circuit, 10.13+, 13th, 15- and 1
52: Branch circuit, 12) and 122: Hybrid circuit, 12u and +2)l: Input terminal, +2I) and 12
n: Isolation terminal, 12z3・12z11,1
2 pieces J and 122 pieces; coupling terminal; 14: non-reflection terminator;
l+! u, 162.17. and 172: conventional 7-wire filter, 18: two-circular five-waveguide cavity co-imager, 19: coupling forward, 20: coupled line, 20 main line, 22 and 23: coaxial terminal. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 f (MHz) Figure 6 Figure 7 Figure 8 f (MHz) - Figure 9 Figure 10 Figure 11 f (MHz) Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20

Claims (3)

[Claims] (1) One coupling loop is provided on one of the short-circuit walls, and an element is provided on the cylindrical side wall to separately adjust the resonance frequencies of the H mode and V mode, which have different frequencies,
The device is characterized by being composed of a circular waveguide cavity resonator formed so that the insertion directions into the tube are at right angles to each other and have an angular difference of 45° or 135° with the loop surface of the coupling loop, respectively. Notch filter. (2) The notch filter according to claim 1, wherein an inductive compensation circuit is added to the terminal of the coupling loop via a branch circuit. (3) The notch filter according to claim 1, wherein a capacitive compensation circuit is added to the terminal of the coupling loop via a branch circuit.