JPH0716121B2 - Duplexer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a duplexer used to extract only one of high frequency signals including two frequency components relatively distant from each other. The present invention relates to a demultiplexer that can be used for separating a local signal (RF) and an IF signal included in a mixer output in a (microwave) receiver.

[Conventional technology]

In the conventional high frequency band, in order to separate high and low two-wave signal components having a frequency difference and to extract only one of them (herein, described as a low frequency component for convenience), as shown in FIG. Circuit configuration is used.

In this figure, 11 is a high pass filter (hereinafter referred to as HPF) and 12 is a low pass filter (hereinafter referred to as LPF).

The important thing in such a circuit configuration is to keep the impedance seen from the input side constant.
It is to complementarily match the characteristics of the crossover part of the above, but this becomes extremely difficult when the signal frequency reaches the microwave band.

Therefore, the configuration shown in FIGS. 7 and 8 is used.

In these figures, 13 is an isolator, 14 is an LPF, 15
Is a bypass filter (hereinafter referred to as BPF).

These are provided with LPF14 or BPF15 which allows only the other (low frequency side) component to pass through on the output side of the isolator 13 in one (high frequency side) frequency component band, and the high frequency component is reflected by these so that the isolator 13 To be absorbed by. In this case, the impedance seen from the input side is determined only by the isolator 13 and kept at a constant value.

[Problems to be solved by the invention]

However, as the isolator 13 used in the demultiplexer having the above-described configuration, it is required to support wideband RF signals, and the isolator 13 is expensive and large, so the demultiplexer is also expensive and large. There was a problem that became.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a duplexer that is inexpensive and has a simple configuration, and that can maintain good matching with a wideband and high frequency band signal. To aim.

[Means for solving problems]

The duplexer according to the present invention has an input end having a constant width and an output end having a different width and connecting them, and a conductor (2) having a taper over a constant section between the input end and the output end, A dielectric (3) configured by being coupled to a conductor at an input end so that the end has a predetermined impedance characteristic over the two frequency components, and a boundary line between the input end and the output end and contacting the dielectric. So that it passes through the slope starting point on the input end side of the taper and traverses the conductor at a slope that includes the taper so that other frequency components of the signal are gradually and largely absorbed toward the output end. And a radio wave absorber (4) having a permittivity different from the permittivity of the dielectric substance.

[Action]

According to the present invention, a constant frequency component of the signal transmitted from the input direction to the output direction of the transmission line is gradually attenuated by the radio wave absorber, and a signal from which the specific frequency component is removed is obtained.

Further, since the attenuation amount is arranged so as to gradually increase, the input end reflection attenuation amount (matching degree) at a specific frequency component also becomes good.

〔Example〕

1 (a) to 1 (c) are an exploded perspective view, a cross-sectional view, and a top view with a lid removed, showing the configuration of an embodiment of the duplexer of the present invention.

In these figures, 1 is a dielectric substrate, 2 is a strip conductor that is a central component of a transmission line, 2a is an input end, and 2b is
Is an output end, 3 is a dielectric, 4 is a radio wave absorber, 5 is a metal stand,
6 is a metal lid.

Next, the configuration will be described.

First, as shown in FIG. 1A, on the metal table 5,
A dielectric substrate 1 having a tapered strip conductor 2 formed on its surface is placed, and a dielectric 3 and a radio wave absorber 4 are placed on the dielectric substrate 1 so as to be in contact with the strip conductor 2. Stack the lid 6 of. The lid 6 is fastened to the metal base 5 with a set screw or the like (not shown in the figure). When the thicknesses of the dielectric 3 and the radio wave absorber 4 are made equal, and the thickness of the dielectric substrate 1 and the depth of the recess of the metal base 5 are made equal, the lid 6 is fastened to the metal base 5. Sometimes these overlap without a gap. A cross-sectional view of this taken near the center is as shown in FIG. 1 (b). As is well known, if both ends of the strip conductor 2 are input and output ends 2a and 2b are used, a high-frequency transmission line called a strip line. Is formed.

As is clear from FIG. 1 (c) showing the state in which the lid 6 is removed, the contact areas of the strip conductor 2, the dielectric 3, and the radio wave absorber 4 change complementarily.

That is, the contact area between the dielectric 3 and the strip conductor 2 is large on the input end 2a side and gradually decreases toward the output end 2b, while the contact area between the radio wave absorber 4 and the strip conductor 2 is opposite. It is configured such that it is small on the input end 2a side and gradually increases toward the output end 2b side. When a desired frequency and an unnecessary frequency are input to the input end 2a, the strip conductor 2 and the dielectric 3 are coupled to each other at the input end 2a so that both frequencies are matched. By crossing the strip conductor 2 toward the end 2b, the change of the line impedance due to the loading of the radio wave absorber 4 does not suddenly occur, and the input in the frequency band where the absorption effect of the radio wave absorber 4 is large. This is to improve the end reflection attenuation amount characteristic.

It should be noted that with such a configuration, if the radio wave absorber 4 is arranged at a right angle to the signal direction in order to form a transmission line, the radio wave absorber 4 is also a dielectric, so that a specific impedance can be formed. Although there is a possibility, the radio wave absorber 4 can be used as the entire desired band based on the frequency characteristics shown in FIG.
Causes the impedance to be disturbed. Therefore, reflection from the radio wave absorber 4 is prevented by gradually attenuating unnecessary frequency components according to the length (signal direction) when the radio wave absorber 4 crosses the strip conductor 2.

Further, the width of the strip conductor 2 is changed according to the contact area with the dielectric 3 or the radio wave absorber 4, in the frequency band where the absorption effect of the radio wave absorber 4 is small. Absorber 4 constants (dielectric constant, magnetic permeability)
This is for compensating for the change in the characteristic impedance of the transmission line due to the difference between, and keeping it constant. In this embodiment, it is assumed that the dielectric constant of the radio wave absorber 4 is higher than that of the dielectric body 3 (if these dielectric constants are opposite in magnitude, the contact area between these and the width of the strip conductor 2 are assumed. It suffices to reverse the relationship with, for example, FIG.
This corresponds to the case where the strip conductor 2 is formed in the opposite direction in (c).

If the radio wave absorber 4 that absorbs a large amount of specific frequency components is selected to have a characteristic that attenuates only high frequency components, only low frequency components are transmitted to the output end 2b. At this time, since the high frequency component is absorbed by the matching load, the reflection to the input end 2a does not occur.

As shown in FIG. 1C, the strip conductor 2 and the electromagnetic wave absorber 4 intersect each other at a point where the strip conductor 2 starts to incline on the input end side, and the electromagnetic wave absorber 4 includes a taper of the conductor. Is configured as follows. The location of these intersections is
It is far from the input end. As can be seen from FIG. 1 (c), high-frequency components that are not impedance-compensated (that is, easily reflected) due to the taper of the strip conductor 2 at a position apart from the input end that is matched by a dielectric material are The electromagnetic wave absorber 4 gradually absorbs and attenuates the vicinity of the taper.

FIG. 2 is a diagram showing an example of the attenuation amount (absorption amount) -frequency characteristic of the electromagnetic wave absorber 4 that is actually used, and FIG. 3 uses the electromagnetic wave absorber 4 having the characteristic shown in FIG. It is a figure which shows an example of the transmission characteristic of the comprised demultiplexer.

That is, it can be seen from FIG. 3 that the signal components of 3 to 7 GHz and the signal components of 500 MHz or less can be separated with a difference of attenuation of 20 dB or more, and the matching is good over the entire band.

In the case of this embodiment, the ground plane (width of the recess of the metal base 5) is set to about
The length is 20 mm and the length of the transmission line (in this case, the same as the length of the strip conductor 2) is about 50 mm, and it is extremely small and lightweight and sufficient performance can be obtained.

On the other hand, when greater isolation or good matching is required, it can be easily realized by increasing the total length of the transmission line and gradually changing the contact area between the strip conductor 2 and the electromagnetic wave absorber 4. .

Further, in the present invention, the form of the transmission line is not limited to the strip line, and it is conceivable that any transmission line may be used. For example, as shown in FIGS. Besides being applicable to a line, it may be applied to a coaxial line as shown in FIGS. 5 (a) and 5 (b), and the same effect can be obtained. In these figures, the same reference numerals as those in FIGS. 1A to 1C indicate the same members, and in FIGS. 5A and 5B, 7 is an inner conductor, 8 is an outer conductor, and 9 is a radio wave. It is an absorber.

In the above embodiment, the case where the high frequency component is blocked and the low frequency component is taken out has been mainly described. However, by using the radio wave absorber having the characteristic of absorbing only the low frequency component, on the contrary, only the high frequency component is extracted. It is obvious that the circuit for taking out can also be easily realized.

〔The invention's effect〕

As described above, according to the present invention, the radio wave absorber is arranged on the conductor such that one frequency component (unnecessary frequency component) is gradually and gradually absorbed toward the output end, and the radio wave absorber serves as the absorber. In the other frequency component that does not work (pass frequency component), since the dielectric constant differs between the dielectric and the electromagnetic wave absorber, good matching cannot be obtained, so that the desired impedance is obtained at the input end and the output end, respectively. By connecting the conductor width with a taper between them,
With the configuration that obtains good matching characteristics over the desired entire band, it is possible to obtain a demultiplexer with a simple configuration that can output a desired frequency component with less reflection to the input of multiple frequency components. There is.

[Brief description of drawings]

1 (a) to 1 (c) are an exploded perspective view showing a structure of an embodiment of a duplexer of the present invention, a cross-sectional view and a top view with a lid removed, and FIG. 2 is attenuation of a radio wave absorber. The figure which shows an example of a quantity-frequency characteristic, FIG. 3 is a figure which shows an example of the transmission characteristic of one Example of the duplexer of this invention, FIG. 4 (a)-(c), FIG. 5 (a) , (B) are diagrams for explaining the configuration of another embodiment of the present invention, and FIGS. 6, 7, and 8 are diagrams showing the configuration of a conventional duplexer. In the figure, 1 is a dielectric substrate, 2 is a strip conductor, 3 is a dielectric, 4 and 9 are radio wave absorbers, 5 is a metal stand, 6 is a lid, 7 is an inner conductor, and 8 is an outer conductor.

Claims (1)

[Claims] 1. A demultiplexer which is formed of a transmission line, receives a signal containing at least two high and low frequency components, demultiplexes one frequency component and extracts the other frequency component, and removes the other frequency component. A conductor (2) having an input end having a constant width and an output end having a different width and connecting the two, and having a taper over a certain section between the input end and the output end; and the input end having the two frequencies. A dielectric (3) configured to be coupled to a conductor at an input end so as to have a predetermined impedance characteristic over a component, and a boundary line in contact with the dielectric between the input end and the output end is the taper. It passes through the slope starting point on the input end side and crosses the conductor at a slope including the taper, and is coupled so that other frequency components of the signal are gradually and gradually absorbed toward the output end. Configured Duplexer is characterized in that a wave absorber (4) having a dielectric release index different dielectric constant of the dielectric.