JPH06350308A - Signal transmission circuit - Google Patents

Abstract

PURPOSE:To obtain a signal transmission circuit with a simple circuit configuration, a small transmission loss in an in-band frequency, a large loss in a harmonic frequency band in which sufficient distribution performance is obtained. CONSTITUTION:The transmission line is formed by providing a 2-line coupling line formed by a main line 1 and a sub line 2 provided in a case 4. A dielectric material 3 is inserted between the main line 1 and the case 4 and between the sub line 2 and the case 4 respectively and a radio wave propagation constant in the even mode in the said coupling line is made an integral number of multiple of the radio wave propagation constant in the odd number mode in the coupling line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission circuit in microwave and millimeter wave frequency bands, and more particularly to a distributor and a multiplexer having frequency selectivity.

[0002]

2. Description of the Related Art A conventional band divider for frequency selection is
As shown in FIG. 8, a circulator (CIR) 13, a low pass filter (LPF) 14, a band pass filter (BP)
F) 15 and a terminator (LOAD) 10. In the signal output from the amplifier (AMP) 12, the signal in the in-band frequency range of the band pass filter 15 is output to the output terminal 16, and the signal in the range above the cut-off frequency of the low pass filter 14 is the terminal 17 of the circulator 13. , Is absorbed by the terminator 10, and is not reflected by the amplifier 12.

A signal having a harmonic frequency equal to or higher than the second harmonic is reflected by the low pass filter 14, rotated by the circulator 13, and absorbed by the terminator 10 via the terminal 17 of the circulator 13.

[0004]

In the conventional band divider, the circulator 13 covers the entire frequency range.
It needed to operate in a very wide band. It is difficult to manufacture such a wide band circulator, and it is difficult to sufficiently exhibit the distribution performance.

Further, the conventional band divider has a complicated circuit structure, and the circulator used requires a very wide frequency band, so that the pass loss is small at the in-band frequency f ₀ ,
It was difficult to obtain sufficient distribution performance with large loss in the harmonic frequency band. Since a signal in the harmonic frequency band equal to or higher than the second harmonic passes through the band pass filter 15, it is necessary to put the low pass filter 14 in the signal path.
There was a problem that the circuit was complicated and the passage loss was large.

The present invention solves the above problems and provides a signal transmission circuit having a simple circuit configuration, a small pass loss at an in-band frequency and a large loss at a harmonic frequency band, and sufficient distribution performance. Is.

The harmonic frequency is represented by n × f ₀ , and n is an integer of 2 or more. The power of the harmonic frequency component output from an amplifier or the like (hereinafter referred to as the harmonic power) increases as n increases. It is generally said that the case of n = 2 should be considered because it decreases. Therefore, the main purpose is to reduce the harmonic power of the second harmonic.

[0008]

According to the present invention, in a signal transmission circuit having a two-line coupling line formed of a main line and a sub line provided in a case, the main line is provided. A first dielectric and a second dielectric are respectively inserted between the case and the case, and between the sub line and the case, and either the first dielectric or the second dielectric is inserted. By changing the relative permittivity of one of the relative permittivities and the relative permittivity of the capacitance between the main line and the sub line, the even-mode radio wave propagation constant in the coupled line is changed to the coupled line. A signal transmission circuit characterized in that it is an even multiple of the odd-mode radio wave propagation constant in (1) is obtained.

Further, according to the present invention, in a signal transmission circuit having a two-line coupling line formed by a main line and a sub line provided in a case, the main line and the sub line By inserting a dielectric into the coupling portion with and changing the relative permittivity of the dielectric, the even mode radio wave propagation constant in the coupling line is set to be an even fraction of the odd mode radio wave propagation constant in the coupling line. A signal transmission circuit characterized by the above is obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a signal transmission circuit (hereinafter referred to as magic H) according to the present invention will be described with reference to FIGS. As shown in FIG. 1A, the magic H has a case 4
Two dielectrics 3 extending in a predetermined direction at equal intervals are arranged therein, and the two dielectrics 3 are configured to include a main line 1 and a sub-line 2, respectively. A cross-sectional view of FIG. 1A is shown in FIG. 2 (a) and 2 (b) are shown in FIG.
It is an equivalent circuit of the magic H shown in (a). The main line 1 and the sub line 2 are coupled to each other, and conventionally, measures have been taken so that the even-mode propagation constant γ _e and the odd-mode propagation constant γ _{0 in} that case are equal. That is, because it was not possible to analyze characteristics when the difference between the propagation constants γ _e and γ ₀ was large, it was thought that increasing the difference would lead to performance deterioration.

Here, the ratio between the propagation constant γ _e of the even mode and the propagation constant γ ₀ of the odd mode is set to K, and the ratio K is changed to perform the characteristic analysis of the magic H. As a result, the isolation characteristics and return loss characteristics deteriorated as expected. When γ _e = k × γ ₀ was set and k was gradually increased from 1, the peak of the coupling characteristic decreased at 180 °, and the isolation characteristic tended to deteriorate in the high frequency region. FIG. 5 shows a characteristic analysis diagram when the value of k is further increased and k = 2. As you can see from Figure 5,
The isolation IS deteriorates at a high frequency, and when θ = 360 °, all input signals are output to the isolation terminal 8.

Next, a calculation method for analyzing the characteristic of the magic H according to the present invention and the characteristic will be described.

2 (a) and 2 (b) are equivalent circuits of the magic H shown in FIG. 1 (a). Here, the voltage and current at the main line input terminal 5 are V _1L and I _1L respectively, and the voltage and current at the main line output terminal 6 are V _1L and V _1L , respectively.
₁₀ and I ₁₀ , the voltage and current at the sub line input terminal 7 are V _2L and I _2L, and the voltage and current at the sub line output terminal 8 (isolation terminal) are V ₂₀ and I respectively.
_{If it is 20} , the relational expression of the voltage and the current is given by the equation 1.

[0014]

[Equation 1]

When input to the input terminal 5, the output power output to the terminal 6 is P ₁₀ , and the input power input to the terminal 6 is P
_At this time, the passing attenuation amount TR at the terminal 6 is P
It is represented by the ratio of ₁₀ to P ₀ . When the output power output to the terminal 7 is P _2l , the coupling attenuation amount CP at the terminal 7 at this time is
It is represented by the ratio of P _2l and P ₀ . The output power P ₂₀ output to the terminal 8 is set, and the isolation attenuation amount IS at the terminal 7 at this time is represented by the ratio of P ₂₀ and P ₀ . The power reflected at the terminal 5 is P _r, and the return loss RL at the terminal 5 is represented by the ratio of P _r and P ₀ . Even (ev
FIG. 4 shows the transmission characteristics to each terminal when the propagation constants of the en) mode and the odd mode are equal, that is, when k = 1. In the calculation example in this case, when the coupling degree is 3 dB and the power source impedance is Z _i , the even mode impedance Z _e and the odd mode impedance Z ₀ are set to Z ₀ × Z _e = 1.1Z _i ^2. There is.

The value of k set as γ _e = k × γ ₀ is 2
Then, the transmission characteristic to each terminal is as shown in FIG. Incidentally, FIG.
In the case of, the calculation example is a case where the coupling degree is set to 10 dB, and the coupling degree can be changed by two line coupling coefficients. At this time, the value of K is ε ₁₁ , which is the relative permittivity of the line capacitances of the main line 1 and the sub line 2, respectively.
If ε ₂₂ and the relative permittivity that constitutes the inter-line capacitance are ε ₁₂ , as shown in Equation 2, ε ₁₁ or ε ₂₂ and ε
_Expressed as a ratio of ₁₂ .

[0017]

[Equation 2]

That is, as can be seen from the equation (2), when K = 2, the dielectric constant ratio of ε ₁₁ and ε ₁₂ should be approximately 4. If K = 1/2, then ε ₁₁
It can be seen that the permittivity ratio between ε ₁₂ and ε ₁₂ should be approximately 1/4. At this time, changing both the values of ε ₁₁ and ε ₁₂ ,
The value of K that should be obtained may be set, or ε ₁₁ and ε ₁₂
The value of K to be obtained may be set by changing one of the values. Further, the number 2 is similar be replaced by epsilon ₁₁ to epsilon _22, epsilon ₁₁ by changing the value of epsilon ₂₂ instead of, or by setting the value of the to be determined K.

Assuming that the case of (1 / j) γ _e L = 360 ° is f ₀ , the passing attenuation amount TR at the terminal 6 becomes large and almost no output is made at the terminal 6, as shown in FIG. Without it, the isolation attenuation amount IS at the terminal 7 becomes 0, so that it is understood that all the power input to the input terminal 5 is output to the output terminal 8. The frequency of 2 × f ₀ , which is a harmonic frequency, has a characteristic of (1 / j) γ _e L = 720 °, and as shown in FIG. 5, the isolation attenuation amount IS at the terminal 8 becomes large, and conversely, at the terminal 6 It can be seen that the input attenuation power of the terminal 5 is all output to the terminal 6 at the harmonic frequency of 2 × f ₀ , since the passing attenuation amount TR at 0 is 0. In the frequency band of 2 × f ₀ or more, the frequency is an odd multiple of f ₀ , and the output is to the terminal 8, and the even frequency is a output to the terminal 6.

FIG. 3 shows a block diagram in which the magic H according to the present invention is connected to the output part of the amplifier (AMP) 12.
The input terminal 5 of the magic H is connected to the output section of the amplifier (AMP) 12. A terminator 10 and a terminator 11 are connected to the terminals 6 and 7, respectively. With the above configuration, the circulator and the low-pass filter are not used as compared with the conventional case, so that the configuration is simple.
Further, as described above, the signal having the frequency component of 2 × f ₀ is not output from the terminal 8 but is output from the terminal 6 because the isolation attenuation amount IS at the terminal 8 is large.
That is, since only the fundamental wave and the signal having the frequency component of an odd multiple of f ₀ are output from the terminal 8, the signal of the second harmonic frequency component is separated from the signal of the fundamental wave and the frequency component having an odd multiple of f _0. , Can be removed. In addition, the magic H of the present invention
Shows that γ _e = kγ _0, and the second harmonic frequency is separated when k = 2. However, similar performance can be obtained from the radio wave repeatability even when k is an even multiple.

Another embodiment of the magic H according to the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a view showing the internal structure of the magic H, and FIG. 7 is a sectional view taken along the line AA ′ of FIG. A dielectric 3 is inserted and fixed in the coupling portion between the main line 1 (not visible in FIG. 6) and the sub line 2 where the odd mode is the main component. Inter-line coupling capacitance C ₁₂ (Fig. 2 (b)
The relative permittivity ε ₁₂ of the dielectric body 3 constituting the above is changed so that the value of K is divided into even numbers such as 1/2 and 1/4, and the odd mode propagation constant γ ₀ is propagated to the even mode. It should be larger than the constant γ _e . For example, γ _e = kγ _0, and k =
It has been found that when the frequency is halved, the second harmonic frequency component of the fundamental wave is separated. Even when the value of K is 1 / N (N is an even number of 2 or more), the second harmonic frequency component of the fundamental wave is separated in the same manner as above.

FIG. 7 shows an example of the result of calculation of the transmission characteristics when k = 1/2. As shown in FIG.
When (1 / j) γ _e L = 180 °, all the electric power input to the input terminal 5 is output to the terminal 8, and (1 / j) γ _e L =
When it is 360 °, it is output to the terminal 6. As in the case of k = 2, if the fundamental frequency f ₀ is adjusted to the position of 180 ° and the length L is adjusted, the frequency component of the second harmonic wave is separated and output to a terminal different from the fundamental wave. Is shown. Also in this case, if k is set to be an even number of 2 or more, the angle is shifted by an even number of one, so that the separation characteristic for the second harmonic wave remains.

As described above, when the ratio k of the propagation constants of the even mode and the odd mode is set to be an even multiple or an even fraction, the output of the magic H is a fundamental frequency and an odd multiple harmonic frequency and an even number. It can be separated to double the harmonic frequency and output to another terminal.

As described above, although k = 2 and 1/2, the same characteristic can be obtained even if k is close to the value because the basic characteristic is a wide band.

Although the separation performance has been described in this embodiment, the present invention also has a synthesis performance because the input and output are reversible. That is, when the fundamental frequency is input to the terminal 8 and the second harmonic frequency is input to the terminal 6 in FIG. 2A, both waves are combined and output to the terminal 5.

[0026]

According to the present invention, the odd-mode and even-frequency components are separated by setting the even-mode propagation constant and the odd-mode propagation constant to be even multiples or even fractions.
It is possible to take out to separate terminals, and it is possible to obtain sufficient distribution performance in which the passage loss is small at the in-band frequency f ₀ and the loss is large in the harmonic frequency band.

Further, since it is possible to separate the signals in the harmonic frequency band of the second harmonic or higher without inserting the band pass filter, the low pass filter and the circulator in the signal path, the circuit configuration is simplified. Therefore, the pass loss in the band pass filter and the low pass filter can be eliminated.

[Brief description of drawings]

1 (a) is a diagram showing an internal structure of a signal transmission circuit of the present invention, and FIG. 1 (b) is an A- line in FIG. 1 (a).
It is an A'line sectional view.

2 (a) is a diagram showing an equivalent circuit of the signal transmission circuit of the present invention, and FIG. 2 (b) is a main line, a sub-line in the signal transmission circuit of FIG. 2 (a), It is the figure which showed the equivalent circuit which considered the capacitance between and and a line.

FIG. 3 is a block diagram showing a signal transmission circuit of the present invention.

FIG. 4 is a diagram showing characteristics of a conventional signal transmission circuit.

FIG. 5 is a diagram showing characteristics of the signal transmission circuit of the present invention.

6 (a) is a diagram showing the internal structure of another embodiment of the signal transmission circuit of the present invention, and FIG. 6 (b).
FIG. 7 is a sectional view taken along the line AA ′ of FIG.

FIG. 7 is a diagram showing characteristics of another embodiment of the signal transmission circuit of the present invention.

FIG. 8 is a block diagram showing another embodiment of a conventional signal transmission circuit.

[Explanation of symbols]

 1 Main Line 2 Sub Line 3 Dielectric 4 Case 5 Main Line Input Terminal 6 Main Line Output Terminal 7 Sub Line Input Terminal 8 Sub Line Output Terminal 9 Cover 10, 11 Terminator 12 Amplifier 13 Circulator 14 Low Pass Filter 15 Band Pass Filter 16 Band pass filter output terminal 17 Circulator terminal

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[Procedure amendment]

[Submission date] July 14, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

2 (a) and 2 (b) are equivalent circuits of the magic H shown in FIG. 1 (a). Here, the voltage and current at the main line input terminal 5 are respectively set to V _{1L ′} I
_{1 L} , the voltage and current at the main line output terminal 6 are V _{10 '} I ₁₀ respectively, and the voltage and current at the sub line input terminal 7 are V _2L' I _2L respectively, and the sub line output end
Assuming that the voltage and current at the child 8 (isolation terminal) are V _{20 ′} I ₂₀ respectively, the relational expression of the voltage and current is expressed by Formula 1.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

When input power is input to the input terminal 5 , the output power output to the terminal 6 is P ₁₀ and the input power input to the terminal 5 is P _0. At this time, the passing attenuation amount TR at the terminal 6 is
It is represented by the ratio of P ₁₀ and P ₀ . The output power output to the terminal 7 is P _21, and at this time the coupling attenuation amount C at the terminal 7
P is represented by the ratio of P ₂₁ and P ₀ . The output power P ₂₀ output to the terminal 8 is set, and the isolation attenuation amount IS at the terminal 7 at this time is represented by the ratio of P ₂₀ and P ₀ . The electric power reflected at the terminal 5 is defined as _Pr, and at this time, the terminal 5
The return loss RL at is represented by the ratio of P _r and P ₀ . FIG. 4 shows the transmission characteristics to each terminal when the propagation constants of the even mode and the odd mode are equal, that is, when k = 1. In the calculation example in this case, when the coupling degree is 3 dB and the power source impedance is Z _i , the even mode impedance Z _e and the odd mode impedance Z ₀ are set to Z ₀ × Z _e = 1.1Z _i ^2. There is.

Claims (2)

[Claims] 1. A signal transmission circuit having a two-wire coupling line formed of a main line and a sub line provided in a case, wherein the main line and the case and the sub line are connected to each other. A first dielectric and a second dielectric are inserted between the line and the case, respectively, and the relative dielectric constant of either the first dielectric or the second dielectric and the main dielectric By changing the relative permittivity ratio between the relative permittivity and the relative permittivity that constitutes the capacitance between the line and the sub line, the even mode radio wave propagation constant in the coupling line is an even multiple of the odd mode radio wave propagation constant in the coupling line. A signal transmission circuit characterized in that. 2. A signal transmission circuit having a two-line coupling line formed of a main line and a sub line provided in a case, wherein a dielectric is provided at a coupling portion between the main line and the sub line. A body is inserted, and the relative permittivity of the dielectric is changed so that the even-mode radio wave propagation constant in the coupling line is set to an even fraction of the odd-mode radio wave propagation constant in the coupling line. Signal transmission circuit.