JPS6337701A - Composite band stop filter - Google Patents

Abstract

PURPOSE:To generate an electromagnetic wave which is an elliptic polarized wave and to cancel interference components between an H-mode circuit and a V-mode circuit at each resonance frequency by a vectorial method by inserting an adjusting screw for mode correction in directions of + or -45 deg. based on the electric field vector of a V mode. CONSTITUTION:A main cylindrical waveguide resonator body 1 is provided with a coupling loop 2 having a 45 deg. angle difference from the electric field vectors EH and EV of the H and V modes which differ in frequency from each other, the length from the terminal of this coupling loop to a coupling point for an external circuit is set to an odd-numbered multiple of a quarter of wave- length in terms of electric length, and the adjusting screw 6M for mode correc tion is provided having + or -45 deg. angle differences on the basis of the electric field vector of the VB mode. Consequently, there is no interference between the H mode and V mode which coexit and resonate in a cylindrical waveguide resona tor and the constitution is simple and sized small; and the load Q is high be cause the cylindrical waveguide resonator is used, and consequently the whole constitution is simple and sized small and the insertion loss is reducible when a constant impedance diplexer is formed by using this resonator.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to, for example, television broadcasting, where video transmission power Pv (frequency fυ), video color signal power Ps
(frequency fS) and audio signal power ρ^ (frequency fn), and intermodulation noise (
It is used as a constant impedance diplexer to remove 2fv -fs) and send it to one antenna, or as a signal synthesis circuit in wireless communication with multiple carrier waves as in automatic IIj' and II. (
The present invention relates to a composite band 1[- filter that is effective as a component of a constant impedance diplexer or the like suitable for performing multiplex communication using an antenna.

BACKGROUND ART FIG. 1O is a block diagram showing a constant impedance diplexer conventionally used in ultra-high frequency band (U) IF) television broadcasting, and FIG. 11 is its equivalent circuit diagram. Reference numeral 82 denotes an input/4 coupler (input is the transmission wavelength), which is composed of a 3 dB coupler or a hybrid circuit. 91 and 92 are band-stop filters made of a 74-turn axial resonator or a rectangular waveguide resonator that resonate with intermodulation noise (:lRv fs), and 10+ and 102 are the frequency f^ of the audio signal' gravity PA. A band-stop filter consisting of a rectangular waveguide resonator that resonates with the resonator 9.
1 and 10. Each connection point to the line is connected to each other by g/2
(where n is an arbitrary positive integer and λg is the tube wavelength), and each coupling point of the resonators 92 and 102 to the line is also formed so as to be spaced from each other by n g/2. It is.

9s is the admittance of the circuit viewed from the connection point to the line to the resonator 91 or 92 side, and t^ is the 7 domitance of the circuit viewed from the connection point to the line to the resonator 10+ or 102 side.

FIG. 12 is an equivalent circuit diagram of only the band-stop filter part in FIG. is n=02.4. ---That is, it is +1 for even orders and -1 for odd orders.

Since all 7 domitances of the resonant circuits connected at intervals of λg/2 exhibit the same characteristics, the circuit in Fig. 12 is
This is equivalent to the circuit shown in the figure.

Problems to be solved by the invention: The constant impedance diplexer shown in Figure 51O has the following problems:
Since four band-elimination filters are required, the overall configuration becomes complex and large.

In order to eliminate this drawback, a circular waveguide resonator is used, and the coupling loop with the external circuit is provided with an angular difference of 45 degrees for each electric field vector of H mode and V mode. Since it is possible to configure a band-stop filter for two waves with different frequencies, it is possible to configure the constant impedance diplexer shown in Fig. 1O with two band-stop filters, but circular waveguide resonance If the coupling loop in the device is provided with an angular difference of 45 degrees with respect to the ath field vectors of H mode and V mode, interference will occur between H mode and V mode, resulting in undesirable circuit operation.

Means for Solving the Problems The present invention provides a method for converting the coupling loop in a circular waveguide resonator to l(
45° for each of the field vectors of mode and V mode.
By inserting adjustment screws for mode correction +E into the tube from ±45 degrees with the electric field vector of the mode as a reference, the drawbacks of the conventional circular waveguide resonator can be removed, for example, It is an object of the present invention to realize a composite band-elimination filter that can simplify the overall configuration and reduce insertion loss when an impedance diplexer is configured.

Action ■By inserting the mode correction adjustment screw into the tube from a direction of ±45° with respect to the electric field vector of the mode,
Embodiment 1 is a front view showing an embodiment of the present invention, which generates an elliptically polarized electromagnetic wave and cancels the interference component between the H mode circuit and the V mode circuit in a vectorial manner at each resonant frequency. Figure 2 shows
In both figures, l is the main body of a circular waveguide resonator, and the axial length is set to be equal to λg/2 or shortened as appropriate. Reference numeral 2 denotes a coupling loop, which is provided so that its loop surface forms an angular difference of 45° with respect to each of the electric field vectors of the H mode and the ■mode. 3 is a coaxial terminal, 4H is a resonant frequency fine adjustment screw for H mode, 5V is a resonant frequency fine adjustment screw for ■ mode, and 6H is an adjustment screw for mode correction, which is the gist of the present invention, based on the electric field vector of ■ mode. ±
It is inserted into the tube with an angular difference of 45° (45° or 225°).

In FIG. 1, EH is an electric field vector in H mode, and EV is an electric field vector in ■mode.

In the embodiments shown in FIGS. 1 and 2, the coupling loop 2 with the external circuit is provided on the end wall of the circular waveguide resonator body 1, but the third factor is the front view. As shown in FIG. 4, which is a cross-sectional view taken along the line A-A in FIG.

Other symbols and structures in FIGS. 3 and 4 are the same as in FIGS. 1 and 2.

-1- Resonant frequency fine adjustment screw 411 in each embodiment described above
．． 5V and mode correction adjustment screw 6F+ are most effectively inserted into the tube from the side wall corresponding to the extension of the axial length of the circular waveguide resonator main body l, but it is best to insert it at a location shifted to the left or right. Also, although the figure shows an example in which two fine adjustment screws are provided at symmetrical locations with respect to the waveguide axis, it is also possible to omit one of the fine adjustment screws and provide one each. The present invention can also be implemented in this manner.

In any of the above embodiments, the H-mode load Q (Q
LH), the insertion length (including zero) of the mode correction adjustment screw 6N into the tube is adjusted according to the six values of the V-mode load Q (QLV) and the ellipticity of the circular waveguide resonator, and the coupling By determining the area of the loop surface of loop 2 according to the required load Q, the desired characteristics can be obtained.Furthermore, by forming the loop surface of coupling loop 2 to be rotatable, it is possible to obtain resistance to H mode and V mode. Each degree of coupling can be changed.

The length from the connection point to the external circuit of the composite band-stop filter of the present invention to the terminal of the coupling loop 2 is approximately g/4.
(where n is an arbitrary integer among positive integers), at frequencies other than the resonant frequency, the impedance seen from the connection point to the external circuit to the resonator side becomes almost infinite, and H
At the resonant frequency of the mode and the resonant frequency of the V mode, a short circuit occurs at the connection point to the external circuit, and the equivalent circuit thereof can be shown in FIG.

The circuit configuration of FIG. 5 is similar to the circuit configuration of FIG. 13, and the circuit properties are also similar.

Each circuit constant in FIG. 5 can be expressed by the following equations.

However, YH: 7 domitance of the circuit resonating in H mode, Yy: 7 domitance of the circuit resonating in v mode, Zs: impedance z of the circuit resonating in H mode, J: 7 domitance of the circuit resonating in V mode, Impedance to of the circuit: Resistance element v of the circuit resonating in H mode
: Resistance component of the circuit resonating in V mode LM : H
Actance of the circuit resonating in mode IV: Actance of circuit resonating in V mode toH: Resonance frequency fOν of H mode: Resonance frequency f of ■mode: Transmission frequency Quc: Circular waveguide resonator No load Q238e/D
(cm) F City Quc = □ D Diameter of the circular waveguide resonator main body fc: Cutoff frequency of the circular waveguide resonator fc = 300/input c (GTo) 80: Circular waveguide resonator cutoff Wavelength input c = 1.7080 Diameter of circular waveguide resonator main body l, each resonance 14 wave number foH and rov of H mode and ■ mode, each load Q in H mode and V mode, QLH and QLV ゛p By doing so, each circuit constant can be obtained from equations (2) and (3).

Finding the basic matrix of the circuit shown in Figure 5, ... (9) Transmission 1. The ν property is determined by the following formula.

In addition, the input/output impedance Zuv and the input/output admittance Y)IV can be calculated using the following equations.

I11, generally R=Zo;1...(ll)Z,
: Characteristic impedance of the external circuit I of the resonant circuit shown in Figure 5 [Specular reflection coefficient F, 1 soba,
From equations (2) to (8) and (12), Yo can be found as the characteristic admittance of the external circuit, and from equation (2), the phase characteristic 0 can be found as, and the delay time characteristic is (x ) is τ(ri=τu(
x) + τV(riBwn: 3 dB attenuation frequency bandwidth θ(
1: Delay time characteristic in H mode Bwv: 3 dB attenuation frequency bandwidth 0υ in V mode: Delay time characteristic in ■mode can be obtained.

FIG. 6 is a schematic plan view showing a constant impedance diplexer constructed by combining the composite band-stop filter of the present invention with a hybrid circuit, and FIG. 7 is a schematic side view thereof. In both figures, 71 and 72 are The composite band-stop filter of the present invention is an 81 and 82 hybrid circuit.

FIG. 8 shows the operation theory II of the hybrid circuits 81 and 82.
In this diagram, the relationship between the output voltages K1 to E3 of the terminals T1 to T3 and the phase when a voltage io is applied to the terminal To is expressed by the following equation.

jcslnO,: El=-===IEo...(16) 11-σcosOc +jsinO+゛E3=0
・ ・ ・ ・ (18) In the above equation, C: Coupling coefficient of the hybrid circuit Oc: Coupling line length of the hybrid circuit, and C and OC are generally c = I/ fT θc = 900, and this general Substituting the conditions, equations (16) to (I8
) is expressed by the following equation.

EI=jCEc...(19) Ez=fY:...(20) and 3
20... (21) (19)
) to (21), the [≦] matrix is as follows.

・ ・ ・ ・ (22) Figure 9 is a combination of Figures 5 and 8, and Figure 6 and Figure 7.
This is a diagram for explaining the operation of the constant impedance diplexer shown in the figure. When a voltage EO is applied to the terminal FT+o, the output 1f pressure of the terminals Tll and TI2, that is, the branch point B
The voltages E and B12 applied to E1 and B2 are E11==jcEo...(24) i:12=, l'i'' and 1°...
(25), and the reflected voltages EI Ir and B12F generated at the branch points B1 and B2 are expressed by the following equations.

E++r=jCr++vEo...
(2G) Eur=Mei rHvEo...(2
7) Terminal T when the reflected voltage E12 is applied to the terminal T11 and the reflected voltage E12 is applied to the terminal TI2.
When each output voltage of IO to T13 is calculated, it is as follows.

(28) As is clear from the set I, all reflected voltages generated at the branch points 81 and B2 are output to the terminal T13.

The voltage Eo applied to the terminal TIO is the voltage Eo applied to the hybrid circuit 8.
1, and the composite band-stop filter circuit 7 of the present invention
1 and 72 to the end of the hybrid circuit 82 T2o
and +23.

Voltages E20 and I applied to terminals 720 and +23
J3 is expressed by the following formula.

E2o=jC(1-Irnv12)Eo −・(2
9) E, +3 =7T7(1-lr1+v12)'Eo
・−・−(30) Using equations (29) and (30), determine the terminal T in FIG. 9? ? The output voltage of is calculated as follows.

Since c = 1t5÷, ・ ・ ・ ・ (31) From equation (31), the power transfer characteristic LIO-/2 between terminal TIO and 722 is ・L+o-;+2= (1-l ruv12)...
・(32) As a result, the transmission of the composite type band-stop wave device according to the present invention 4. Consistent with +F nature.

In addition, voltage Ei2 is applied to the terminal T21 of the hybrid circuit 82.
1, the reflected voltages E20r and E23r are distributed and outputted by the hybrid circuit 82, reflected by the voltage reflection coefficient j''uv in the composite band-stop filters 71 and 72 of the present invention, and outputted to the terminals T20 and T23. teeth,
It is expressed by the following formula.

E20"=jCrHVE121...(33)E23
r= F￥3 r++vEt2+ ・・・・
(34) From the above equation, the input voltage of terminal Tel and terminal T2
The relationship between the output voltages of 2 is as follows: ・ ・ ・ ・ (35)

Terminal T2! When voltage 121 is applied to
The voltage EO22f output to is Eo22r=j t
nvEt2+ − (36).

Therefore, when the voltage l:0 is applied to the terminal TIG and the voltage Etz+ is applied to the terminal T21, the terminal T22 (7) output voltage EO? 2 is Eo22=j
(1-l ruv12)”Eo +j r++vE
+2+・ ・ ・ ・ (37)

To explain the case where the constant impedance diplexer explained with reference to FIGS. 6 to 9 is used for synthesizing video (first wave and audio signal wave) in television broadcasting, the video signal wave fv and the color signal are connected to the terminal TIO of the hybrid circuit 81. Signal wave fS and color bee) 2fv fs are added, and the terminal T? of the hybrid circuit 82 is applied. The audio signal wave f^ is added to l, and the composite band-elimination filters 71 and 7
When 2 is caused to resonate with 2rv-r^, signal waves fv, ``S, and fA are combined and output from the terminal 772.

Also, since the spurious 2fV-fs applied to the terminal TIQ is output to the terminal T13, by connecting a non-reflection terminator to the terminal TI3, the spurious 2fV-fs applied to the terminal T2.・2f for the output of
V-fs is never included.

Effects of the Invention The composite band-stop filter of the present invention does not cause interference between the H mode and the ■ mode that coexist in resonance in the circular waveguide resonator, has a simple and compact configuration, and has a simple and compact configuration. Therefore, when a constant impedance diplexer is formed using the composite band-stop filter of the present invention, the overall structure is simple and compact, and the insertion loss can be reduced. .

[Brief explanation of the drawing]

1 to 4 are diagrams showing examples of unreleased 1311,
FIG. 5 is an equivalent circuit diagram thereof, FIGS. 6, 7, and 9 are diagrams showing a diplexer using the filter of the present invention, and FIG.
The figure is a diagram for explaining the operation of the hybrid 2 circuit.
Figure 0 shows a diplexer using a conventional resonator.
11 to 13 are equivalent circuit diagrams thereof, where l: circular waveguide resonator body, 2: coupling loop, 3: coaxial terminal, 4
11: H mode resonant frequency fine adjustment screw, 5ν:V
Mode resonance frequency a fine adjustment screw, 6M: mode correction adjustment screw, 71 and 72: composite band-stop filter of the present invention,
81 and 82: Hybrid circuit, 91.92.101
and 102: a resonator.

Claims (5)

[Claims] (1) A coupling loop is provided in the circular waveguide resonator body with an angular difference of 45° for each electric field vector of H mode and V mode, which have different frequencies, and the terminal of this coupling loop is connected to an external circuit. A composite band characterized in that the length up to the coupling point is an electrical length that is an odd number multiple of the electric wavelength, and mode correction adjustment screws are provided with an angular difference of ±45° with respect to the V-mode electric field vector as a reference. Blocking filter. (2) A composite band-stop filter according to claim 1, wherein the coupling loop is provided on the end wall of the circular waveguide resonator body. (3) A composite band-stop filter according to claim 1, wherein the coupling loop is provided on the side wall of the circular waveguide resonator body. (4) A composite band-elimination filter according to any one of claims 1 to 3, wherein the coupling loop is formed so that the loop surface can be rotated. (5) A composite band-elimination filter according to claim 1, which is provided with respective resonant frequency fine adjustment screws for H mode and V mode.