JP3408499B2 - Multi-frequency duplexer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-frequency demultiplexer, and more particularly to a technique effective in demultiplexing multi-frequency high-frequency signals in, for example, radio communication equipment, mobile communication base station equipment, and the like. .

[0002]

FIG. 17 is a diagram for explaining a schematic configuration of a conventional multi-frequency branching filter. In FIG. 17, 0.
1. 9 GHz band signal, 1.5 GHz band signal, and
A case of demultiplexing a 0 GHz band signal will be described. As shown in the figure, it is input from a common terminal (Tc).
A signal in the 0 GHz band is a bandpass filter (hereinafter simply referred to as BPF) 23 that passes a signal in the 2.0 GHz band.
The signal passes through 0p and is output from the terminal (T ₃₁ ). Also,
A 0.9 GHz band signal and a 1.5 GHz band signal input from the common terminal (Tc) pass through a band elimination filter (hereinafter simply referred to as BEF) 230e that removes a 2.0 GHz band signal. And output from the terminal (T ₃₂ ). The 1.5 GHz band signal output from the terminal (T ₃₂ ) and input to the terminal (T ₂₀ ) passes through the BPF 220p that passes the 1.5 GHz band signal and is output from the terminal (T ₂₁ ). . The 0.9 GHz band signal output from the terminal (T ₃₂ ) and input to the terminal (T ₂₀ ) is 1.5
Passing through BEF 220e that removes signals in the GHz band,
It is output from the terminal (T ₂₂ ). The 0.9 GHz band signal output from the terminal (T ₂₂ ) and input to the terminal (T ₁₀ ) passes through the 0.9 GHz band signal BPF210p.
And is output from the terminal (T ₁₁ ).

[0003]

However, in the conventional multifrequency demultiplexer described above, three BPFs (210p, 210p,
220p, 230p) and two BEFs (210e, 2
20e) formed a multi-frequency branching filter. Therefore, the conventional multi-frequency branching filter has a problem that it is large as a whole and has a large loss because the number of resonant circuit elements increases. On the other hand, in a mobile communication system,
In order to make it possible to use a terminal device in a tunnel or a building, or to prevent undetection, it is considered to install a relay antenna in a tunnel or a building. Even when such a relay antenna is installed, a multi-frequency demultiplexer is required, but such a multi-frequency demultiplexer is required to be small and have little loss. However, the conventional multi-frequency branching filter described above is
Since it is large and has a large loss, there is a problem that it is unsuitable for the use as described above.

Therefore, the inventor of the present application is small in size and
As a multi-frequency demultiplexer with little loss, a multi-frequency demultiplexer shown in FIG. 18 was prototyped. FIG. 18 is a diagram for explaining a multi-frequency branching filter prototyped by the inventor of the present application before filing of the present application. In the figure, 310 is a BPF that passes a 0.9 GHz band signal, 320 is a BPF that passes a 1.5 GHz band signal, and 330 is a BPF that passes a 2.0 GHz band signal. The multifrequency demultiplexer shown in FIG. 18 includes three BPFs (310, 320, 330),
Each is connected to a common terminal (Tc). According to the multi-frequency branching filter shown in FIG. 18, since BEF is not required as compared with that shown in FIG. 17, the overall size can be reduced, and a resonance circuit element corresponding to BEF is also required. Since there is no loss, the loss can be reduced.

However, three BPFs (310, 3
20, 330) is composed of a comb line type BPF or an interdigital type BPF.
The PF or interdigital BPF has a coupled line (or coupled loop element) inside.
The coupled line is set to a wavelength that is a quarter of the wavelength of the high-frequency signal that passes through the BPF. For example,
In the case of the BPF 320 that allows a 1.5 GHz band signal to pass through, the line length of the internal coupled line is a quarter wavelength (50 (= 2) of the wavelength (200 mm) of the 1.5 GHz signal.
00/4) mm). In FIG. 18,
l _2.0 ≈38 mm is the line length of the coupled line inside the BPF 330, l _1.5 ≈50 mm is the line length of the coupled line inside the BPF 320, and l _0.9 ≈83 mm is the BPF 31
The line length of the coupling line inside 0 is shown.

That is, the line length (83 mm) of the coupled line inside the BPF 310 has a wavelength of 2.0 GHz (150 m
m) is close to a half wavelength (75 (= 150/2)), the tip of the internal coupling line is connected to the BPF casing, and the tip of the internal coupling line is the reference potential (ground). (That is, the terminal is short-circuited). For this reason, the multi-frequency branching filter shown in FIG. 18 has a problem in that the 2 GHz signal is short-circuited on the coupling line inside the BPF 310 as viewed from the common terminal, and the characteristics of the 2 GHz signal are deteriorated. The present invention has been made to solve the problems of the prior art, and the object of the present invention is to reduce the size of the conventional technique without deteriorating the electrical characteristics, and
An object of the present invention is to provide a multi-frequency branching filter that can reduce loss. The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007]

To briefly explain the summary of typical inventions among the inventions disclosed in this application,
It is as follows. That is, the present invention may have a coupling line which is connected to the Common terminal therein, wavelength first is lambda _LL
A transmission line having one end connected to a connection point between the first band-pass filter that passes a high-frequency signal, the common terminal, and the coupling line of the first band-pass filter;
The coupling line is connected to the other end portion of the front Symbol transmission line Yes
And, at a high frequency than the first frequency, the wavelength is lambda _HL
A second band-pass filter for passing a second high-frequency signal;
And the other end of the transmission line inside the filter
A coupled line, having a higher frequency than the second frequency,
The length is a third passing the third high-frequency signal is lambda _HH
A multi-frequency demultiplexer and a band-pass filter, before
The internal connection of the first bandpass filter from the common terminal
The line length from the end of the combined line to the short-circuit end is (λ _HL + λ
_HH ) / 8 and the inside of the second bandpass filter
The coupled line has a line length of (λ _HH / 4).
The line length of the coupled line inside the bandpass filter 3 is
(Λ _HL / 4), which is the common terminal of the transmission line
The line length to the other end is (λ _LL / 4) −
It is (λ _HH / 4) .

Further, the present invention has a binding line therein,
First to pass a first high-frequency signal having a wavelength of λ _LL
A band-pass filter, having a coupling line therein, the high-frequency than the first frequency, and a second band pass filter which passes the second high-frequency signal wavelength is lambda _LH, binding to the internal coupling has a line, with the second frequency higher than the frequency has a third band pass filter for passing the third high-frequency signal having a wavelength of lambda _HL, the coupling line therein, before
Note that the frequency is higher than the third frequency and the wavelength is λ _HH .
4th bandpass filter which passes four high frequency signals
And one end is coupled to the first bandpass filter.
Connection between the line and the coupled line of the second bandpass filter
Is connected to a point, and the other end is connected to the third bandpass filter.
A coupling line of a filter and a coupling line of the second bandpass filter
And connected to a connection point with the road, and the one end
A multi-frequency demultiplexer having a transmission line connected to a common terminal between the other end of the first bandpass filter from the common terminal . Short end of internal coupling line
A second bandpass filter from the common end and the common terminal
The line length to the short-circuit end of the end of the coupled line inside is (λ
_HL + lambda _HH) is / 8, the line length of the third band pass inside the coupled line filter, (lambda _HH / 4) and is, the line length of the inside of the coupling line of the fourth bandpass filter Is (λ _HL / 4), and the common of the transmission lines is
The line length from the communication terminal to the other end is (λ _LL /
4)-(λ _HH / 4).

[0009]

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted. [First Embodiment] FIG. 1 is a diagram showing a schematic configuration of an example of a multi-frequency branching filter according to a first embodiment of the present invention. The multifrequency demultiplexer shown in FIG. 1 is a multifrequency demultiplexer in the case of transmission sharing. Like the multifrequency demultiplexer shown in FIG.
GHz band signal, 1.5 GHz band signal, and 2.0
Taking the case of demultiplexing a signal in the GHz band as an example, the multifrequency demultiplexer of this embodiment will be described. In the figure,
110 is a BPF that passes a 0.9 GHz band signal,
120 is a BPF that passes a 1.5 GHz band signal;
Reference numeral 130 denotes a BPF that passes a 2.0 GHz band signal. Reference numeral 2 denotes a housing, and the housing 2 and an internal conductor (11
_{1 to} 11 ₄ ), and B that allows 0.9 GHz band signals to pass through
The PF 110 allows a signal in the 1.5 GHz band to pass through the housing 2 and the internal conductors (12 _{1 to} 12 ₄ ).
However, the housing 2 and the internal conductors (13 _{1 to} 13 ₄ )
Each BPF 130 is configured to pass a signal in the Hz band. 24 is a BPF 110 and a BPF (120, 1
30) is a transmission line composed of a coaxial cable, a microstrip line, and the like.

Reference numeral 21 denotes a coupling line inside the BPF 110 connected to the common terminal (Tc). Reference numeral 25 denotes a terminal (T
_0.9 ) coupled line inside BPF 110 connected to 2)
2 is a BPF 1 connected to the other end of the transmission line 24.
20 is a coupling line inside the BPF 120 connected to the terminal (T _1.5 ), 23 is a coupling line inside the BPF 130 connected to the other end of the transmission line 24, and 27 is a coupling line inside the BPF 130 connected to the terminal (T _1.5 ). , BPF1 connected to the terminal (T ₂ )
30 is a coupling line inside. The _0.9 GHz band signal input from the common terminal (Tc) passes through the BPF 110, is output from the terminal (T _0.9 ), and is supplied to the antenna. Similarly, 1.5 is input from the common terminal (Tc).
The signal in the GHz band passes through the BPF 120 and passes through the terminal (T
_1.5 ) and a 2.0 GHz band signal input from the common terminal (Tc) passes through the BPF 130, is output from the terminal (T ₂ ), and is supplied to the antenna. These BPF (110, 120, 130)
Is a combline type BPF, and each BPF (110,
An example of the attenuation characteristics of 120, 130) is shown in FIG.

FIG. 3 shows each BPF (110, 1) shown in FIG.
20 and 130) are diagrams for explaining the line length of the coupled line and the line length of the transmission line 24. FIG. In FIG. 3, l ₂₃ ≈50 mm indicates the line length of the coupled line 23 inside the BPF 130, l ₂₂ ≈38 mm indicates the line length of the coupled line 22 within the BPF 120, and l ₂₁ ≈44 mm indicates that the BP
The line length of the coupled line 21 inside F110 is set to l ₂₄ ≈45
mm represents the line length of the transmission line 24. Each line length shown in FIG. 3 is obtained by the following equations (1) and (2).

## EQU1 ## l ₂₁ = (λ _1.5 / 4 + λ _2.0 / 4) / 2 = (λ _1.5 + λ _2.0 ) / 8 l ₂₂ = λ _2.0 / 4 l ₂₃ = λ _1.5 / 4 l ₂₄ = λ _0.9 / 4−λ _2.0 / 4 ... (1) where λ _0.9 , λ _1.5 and λ _2.0 are _0.9 GH
z, wavelengths of 1.5 GHz, and 2 GHz, and in the equation (1), λ _0.9 ≈33 mm, λ _1.5 ≈200 mm, λ
By substituting _2.0 ≒ 150 mm, the following (2) is obtained.

[0013]

L ₂₁ = (λ _1.5 + λ _2.0 ) / 8 = (200 + 150) / 8≈44 mm l ₂₂ = λ _2.0 / 4 = 150 / 4≈38 mm l ₂₃ = λ _1.5 / 4 = 200 / 4≈50 mm l ₂₄ = λ _0.9 / 4−λ _2.0 / 4 = (333-150) / 4≈45 mm (2)

In the multi-frequency branching filter shown in FIG. 1, from the branch point (B1) connected to the common terminal (Tc), BPF1
The line length to the short-circuited end of the coupled line 21 inside 10 is 44.
mm, λ _1.5 / 4 (≈50 mm), and λ _2.0 /
4 (≒ 38mm) is close to the length, so at 1.5GHz and 2.0GHz, BP seen from the branch point (B1)
The impedance to the short-circuit end of the terminal end of the coupling line 21 of F110 becomes almost infinite. Thereby, the BPF 110 can prevent the 1.5 GHz band signal and the 2.0 GHz band signal from deteriorating. The line length from the branch point (B1) connected to the common terminal (Tc) to the short-circuited end of the coupling line 121 inside the BPF 120 via the transmission line 24 is 83 (45 + 38) mm, and λ _0.9 / 4 (≒ 83mm)
BPF1 seen from the branch point (B1) at 0.9 GHz
The impedance to the short-circuit end at the end of the 20 coupled lines 121 becomes almost infinite. As a result, BPF (120,
130), it is possible to prevent the 0.9 GHz band signal from deteriorating. Furthermore, since the line length of the coupled line 121 of the BPF 120 is (λ _2.0 / 4) and the line length of the coupled line 131 of the BPF 130 is (λ _1.5 / 4), the signal in the 2 GHz band is deteriorated from the BPF 120, and It is possible to prevent the signal in the 1.5 GHz band from being deteriorated by the BPF 130.

FIG. 4 is a diagram showing a schematic configuration of another example of the multifrequency demultiplexer according to the first embodiment of the present invention. The multi-frequency branching filter shown in FIG. 4 has a multi-frequency branching filter shown in FIG. 1 in that a BPF 100 that passes a signal of 0.8 GHz band is added in parallel to the BPF 110 that passes a signal of 0.9 GHz band. Different from the vessel. The BPF 100 includes a housing 2 and internal conductors (10 ₁ to 10 ₄ ), and 20 is a BPF 100.
The internal coupling line 29 is a coupling line inside the BPF 100 connected to the terminal (T _0.8 ). Transmission line 2
4, one end is a coupled line 20 inside the BPF 100.
Connected to the connection point of the coupling line 21 inside the BPF 110
The other end is the coupled line 22 inside the BPF 120.
Connected to the connection point of the coupling line 23 inside the BPF 130
Is done. Also, one end and the other end of the transmission line 24
The common terminal (T _C) is connected between the. An example of the attenuation characteristic of each BPF (100, 110, 120, 130) shown in FIG. 4 is shown in FIG. 5, and each BPF (10 shown in FIG.
0, 110, 120, 130) of the coupled line length,
The line length of the transmission line 24 is shown in FIG. As shown in FIG. 6, in the multi-frequency demultiplexer shown in FIG. 4, the common terminal
_{(T C)} from the interior of the coupling line 20 of BPF100 end
Line length up to the short-circuit point and _{(l 20),} the common terminal _(T C)
The line length (l ₂₁ ) from the short circuit point to the end of the coupled line 21 of the BPF 110 is 44 mm. FIG.
The same effect as that shown in FIG. 1 can be obtained with the multi-frequency branching filter shown in FIG. As in the case shown in FIG. 4, it is possible to configure a multi-frequency demultiplexer that demultiplexes five, six, seven, and eight waves by adding a BPF. Thus, according to the multi-frequency branching filter of the present embodiment, it is possible to reduce the size and loss compared to the conventional one without reducing the electrical characteristics,
Costs can be reduced.

In the above description, the case where the multi-frequency transmission wave is demultiplexed has been described. However, the case where the multi-frequency reception wave is demultiplexed or the multi-frequency transmission / reception wave is demultiplexed is also described. The present invention is applicable. When demultiplexing a multi-frequency transmission / reception wave, each BPF (100, 110, 120,
130), the interdigital BPF is suitable. FIG. 7 is a cross-sectional view of a main part showing a schematic structure of an interdigital BPF.
FIG. 4A is a cross-sectional view of a main part cut along a plane along the length direction of the resonance bar, and FIG. 4B is a cross-sectional view of a main part cut along a plane perpendicular to the length direction of the resonance bar. In the figure, 1 is a resonance rod, 2 is a housing, 3 is a coupled line (coupled loop), 4 is an input connector, and FIG. 8 shows an equalization circuit of this interdigital BPF. Next, as shown in FIG. 9, the distance between the resonance bars 1 is D, the diameter of the resonance bars 1 is d, and the length l of the resonance bars 1 is set.
Is λo / 4 (λo is the resonance frequency) and the width of the housing 2 is W, the interstage coupling coefficient (M _{k, k + 1} ) of the interdigital BPF is expressed by the following equation (3). The

[0017]

M _{k, k + 1} = M _{Ek, k + 1} + M _{Hk, k + 1} M _{Ek, k + 1} = 10 ^{Mek, k + 1} M _{ek, k + 1} = (− 1.37D _{k , k + 1} / W ₊ 0.91d / W−0.048) M _{Hk, k + 1} = 10 ^{−LH / 20} LH = 54.6D _{k , k + 1} (1−0.3 d / W) F (λo) / 2WF (λo) = (1− (2W / λo) ² ) ^1/2 (3) where M _{Ek, k + 1} is an interstage electric field coupling coefficient, M _{Hk, k + 1} is an interstage magnetic field coupling coefficient, and LH is an interstage magnetic field attenuation.

FIG. 10 is a cross-sectional view of a main part showing a schematic structure of a combline type BPF, and FIG. 10 (a) is a cross-sectional view of the main part taken along a plane along the length direction of the resonance rod. (B) is principal part sectional drawing cut | disconnected by the surface orthogonal to the length direction of a resonance rod. In this figure, 2 is a housing, 3 is a coupled line (coupled loop), 4 is an input connector, 5 is an internal conductor, and FIG. 11 shows an equalization circuit of this combline type BPF. next,
As shown in FIG. 12, the interval between the inner conductors 5 is D, the diameter of the inner conductor 5 is d, the length l of the inner conductor 5 is λo / 4 (λo is a resonance frequency), and the width of the housing 2 is W. At this time, the interstage magnetic field coupling coefficient (M _{Hk, k + 1} ) of the combline type BPF is expressed by the following equation (4).

M _{Hk, k + 1} = 10 ^{−LH / 20} LH = 54.6D _{k , k + 1} (1−0.3 d / W) F (λo) / 2WF (λo) = (1− ( 2W / λo) ² ) ^1/2 ... (4) where LH is the amount of magnetic field attenuation.

Next, a case where a BPF having the pass band shown in FIG. 13 having the Chibi-Sief type characteristic and the attenuation band having the Wagner type characteristic is designed on the basis of the Chibi-Sief type standardized low-pass filter will be described. Assuming that the voltage standing wave ratio (VSWR) in the pass band allowed in the design of the BPF is S, the allowable ripple L _r in the pass band is expressed by the following equation (5).

## EQU5 ## L _r = 10 log ((s + 1) ² / 4S) (5) The allowable ripple L _r is obtained from the five equations and the circuit order n is determined. From the equation (6), element values g ₁ to g _n
Ask for.

G ₁ = 2a ₁ / γ g _k = (4 a _k−1 a _k ) / b _k−1 b _k (k = 1, 2,..., N) γ = sinh (β / 2n) β = ln (coth (L _r /13.37)) a _k = sin ((2k−1) π / 2n) b _k = γ ² + sin ² (kπ / n) (6)

The element values g ₁ to g _n obtained by the above equation (6), the desired center frequency f _{o of} the BPF, and the pass bandwidth B
_{From wr} , the interstage coupling coefficient M _{k, k + 1} can be obtained by the following equation (7).

[Equation 7] _{M k, k + 1 = (} 4 / g k g k + 1) 1/2 B wr / f o ····················· (7) The transmission characteristics of a BPF created using the above equations and having a pass band having a Chibibis characteristics and an attenuation band having a Wagna characteristic can be obtained by the following expression (8).

Equation 8] ATT = 10log (1+ (S- 1) 2 T 2 n (x) / 4S) T n (x) = cosh 2 (ncos -1 x) x = B wr (f / f o -f o _{/ f) / f o ····················· (} 8) where, ATT transmission loss, T _n (x) is a polynomial of Chiebishiefu, f _o Is a center frequency in the passband of the BPF, f is an arbitrary frequency, and _Bwr is an allowable pass frequency bandwidth of the BPF.

[Embodiment 2] FIG. 14 shows the implementation of the present invention.
It is principal part sectional drawing which shows the structure of the multifrequency branching filter of form 2 of
The figure (a) is a plane perpendicular to the length direction of the inner conductor.
Cross-sectional view of the main part showing the cut cross-section, FIG.
Cross section of the main part showing a cross section cut along a surface along the length direction of the body
FIG. In the figure, 7 is provided inside the housing 2.
A partition wall, a housing 2, a partition wall 7, an internal conductor (11₁~
11_Four) To pass signals in the 0.9 GHz band
F110 is the housing 2, the partition wall 7, and the inner conductor (12₁~ 1
2_Four) And BPF that allows 1.5 GHz band signals to pass through
120 is the housing 2, the partition wall 7, and the inner conductor (13₁~ 1
3_Four) And a BPF that passes signals in the 2.0 GHz band
130 are configured. Multi-frequency component of this embodiment
The waver is an inner conductor (11₁~ 11_Four) And inner conductor (12 ₁
~ 12_Four) And the case 2
This is a way to make it more compact. Bond line
The line lengths of the paths (21, 22, 23) are as described above.
It is set to length. Furthermore, the transmission line 24 has a strip shape.
The transmission line 24 also has the line length described above.
The length is set. Also in this embodiment,
It is possible to obtain the same operation and effect as in the first embodiment.
It is. In FIG. 14, reference numerals 31 to 35 denote resonance frequencies.
Number adjustment screw.

[Third Embodiment] FIG. 15 shows the implementation of the present invention.
It is principal part sectional drawing which shows the structure of the multifrequency demultiplexer of form 3 of this.
The figure (a) is a plane perpendicular to the length direction of the inner conductor.
Cross-sectional view of the main part showing the cut cross-section, FIG.
Cross section of the main part showing a cross section cut along a surface along the length direction of the body
FIG. The multi-frequency branching filter according to the present embodiment
In the multifrequency demultiplexer of form 2, the terminal (T_1.5) And terminal
(T₂) And a multi-frequency branching filter. That
Therefore, in this embodiment, as shown in FIG.
_{1.5 / 2}) Connected to the coupling line 2 inside the BPF 120
6 line length (l₂₆) Is 38 (≒ λ_2.0/ 4) mm,
The line length (l of the coupled line 27 inside the BPF 130₂₇)
Is 50 (≒ λ _1.5/ 4) It is set to mm. Real
Also in the embodiment, the same action as in the first embodiment
An effect can be obtained. As described above, the present inventor
The invention that has been made will be specifically described based on the above embodiment.
However, the present invention is limited to the above embodiment.
No change is possible without departing from the scope of the invention
Of course, it is noh.

[0023]

The effects obtained by typical ones of the inventions disclosed in this application will be briefly described as follows. According to the multifrequency demultiplexer of the present invention, it is possible to reduce the size and reduce the loss as compared with the conventional one without degrading the electrical characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of a multi-frequency branching filter according to a first embodiment of the present invention.

FIG. 2 is a graph showing an example of attenuation characteristics of each bandpass filter shown in FIG. 1;

3 is a diagram for explaining a line length of a coupled line and a line length of a transmission line of each bandpass filter shown in FIG. 1. FIG.

FIG. 4 is a diagram showing a schematic configuration of another example of the multi-frequency branching filter according to the first embodiment of the present invention.

5 is a graph showing an example of attenuation characteristics of each bandpass filter shown in FIG. 4. FIG.

6 is a diagram for explaining the line length of a coupled line and the line length of a transmission line of each bandpass filter shown in FIG. 4;

FIG. 7 is a cross-sectional view of a main part showing a schematic structure of an interdigital type band-pass filter.

FIG. 8 is a circuit diagram showing an equalization circuit of an interdigital type band-pass filter.

FIG. 9 is a diagram for explaining an inter-stage coupling coefficient (M _{k, k + 1} ) of an interdigital type band-pass filter.

FIG. 10 is a cross-sectional view of a principal part showing a schematic structure of a comb-line type bandpass filter.

FIG. 11 is a circuit diagram showing an equalization circuit of a comb-line type band-pass filter.

FIG. 12 is a diagram for explaining an interstage coupling coefficient (M _{k, k + 1} ) of a comb line type band-pass filter;

FIG. 13 is a diagram illustrating an example of an attenuation characteristic of a band-pass filter having a pass band having a Chibi Bis-type characteristic and an attenuation band having a Wagner type characteristic;

FIG. 14 is a cross-sectional view of a main part showing a configuration of a multi-frequency duplexer according to a second embodiment of the present invention.

FIG. 15 is a cross-sectional view of a main part showing the configuration of a multi-frequency branching filter according to a third embodiment of the present invention.

16 is a diagram for explaining the line length of the coupled line and the line length of the transmission line of each bandpass filter shown in FIG. 15;

FIG. 17 is a diagram for explaining a schematic configuration of a conventional multi-frequency branching filter.

FIG. 18 is a diagram for explaining a multi-frequency branching filter prototyped by the inventors of the present application before filing of the present application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Resonant rod, 2 ... Housing | casing, 3, 20-23, 25, 26,
27, 29... Coupled line (coupled loop), 4... Input connector, 5, 10 ₁ to 10 ₄ , 11 _{1 to} 11 ₄ , 12 _{1 to} 12 ₄ ,
13 _{1 to} 13 ₄ ... inner conductor, 7 ... partition wall, 24 ... transmission line,
31-35 ... Resonance frequency adjusting screws, 100, 110,
120, 130, 210p, 220p, 230p, 31
0, 320, 330: band pass filter, 220e, 2
30e: Band elimination filter.

Claims (2)

(57) [Claims] 1. A first band-pass filter having a coupling line connected to a common terminal therein and passing a first high-frequency signal having a wavelength of λ _LL , the common terminal and the first band A transmission line connected at one end to a connection point with the coupling line of the pass filter; and a coupling line connected to the other end of the transmission line inside, than the first frequency High frequency, wavelength λ
A _HL and second band pass filter which passes the second high-frequency signal is, the coupling line is connected to the other end of said transmission line therein, a high frequency than the second frequency, Wavelength is λ
A multi-frequency demultiplexer and a third bandpass filter for passing the third high-frequency signal is _HH, short from the common terminal of the end of the interior of the coupling line of the first band-pass filter The line length to the end is (λ _HL + λ
_HH) is _/ 8, the line length of the inside of the coupling line of the second band-pass filter
Is, (λ _{HH / 4)} and is, the line length of the inside of the coupling line of the third bandpass filter
Is (λ _HL / 4), from the common terminal of the transmission line to the other end.
The line length is (λ _LL / 4) − (λ _HH / 4). 2. A has a binding line therein, has a first band pass filter for passing the first radio frequency signal wavelength is lambda _LL, the binding line within said first frequency a high frequency than the second band pass filter which passes the second high-frequency signal wavelength is lambda _LH, has a coupling line inside, at a high frequency than the second frequency, the wavelength is lambda _HL a certain third third bandpass filter for passing a high frequency signal, which incorporates a binding line, a high frequency than said third frequency, a fourth high-frequency signal of wavelength of lambda _HH A fourth bandpass filter to be passed , and one end portion of which is a coupled line of the first bandpass filter
And a connection point between the second bandpass filter and the coupled line
The other end is connected to the third bandpass filter
And a coupling line of the fourth bandpass filter
Connected to the connection point of the one end and the one end
A multi-frequency demultiplexer having a transmission line connected to a common terminal between the other end and the common terminal to the inside of the first bandpass filter
From the short-circuit end at the end of the coupled line and the second terminal from the common terminal
Short-circuited end of the end of the interior of the coupling line of the bandpass filter or
Line length, (λ _HL + λ _HH) is / 8, the line length of the inside of the coupling line of the third bandpass filter in
Is, (lambda _{HH / 4)} and is, the line length of the inside of the coupling line of the fourth bandpass filter
Is (λ _HL / 4), from the common terminal of the transmission line to the other end.
The line length is (λ _LL / 4) − (λ _HH / 4).