JPH10135712A - Transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission line for which manufacture is easy similarly to the case with a conventional strip line structure, thin profile is attained, the Q is high and a transmission loss is made small. SOLUTION: A transmission line 10 of a strip line structure is made up of a dielectric material 11 such as a ceramic, ground electrodes 12, 13 formed to both major sides of the dielectric material 11, and two signal lines 14, 15 of the same shape made of silver or silver-palladium in the inside of the dielectric material 11. In this case, the two signal lines 14, 15 have the same impedance and the same shape. Furthermore, the two signal lines 14, 15 are short- circuited via a throughhole 16 so that they are of the same potential. Thus, the effective resistance of the signal lines is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a transmission line,
In particular, the present invention relates to a transmission line having a strip line structure including a dielectric, a signal line integrally formed on the inside or the surface thereof, and a ground electrode.

[0002]

2. Description of the Related Art A well-known transmission line used in a high-frequency circuit is a transmission line 50 having a strip line structure as shown in FIG. A transmission line 50 having a stripline structure has a signal line 52 integrally formed in a dielectric 51 and a ground electrode 5 on both main surfaces of the dielectric 51.
3 and 54 are formed. Since the transmission line 50 can be easily manufactured in combination with other circuit elements and can be made thin, it is often used for a circuit inside a device. However, in the transmission line 50, the signal line 52 has a thickness of 10 μm.
Since it is as thin as possible, the effective resistance of the signal line 52 becomes large,
Accordingly, there is a disadvantage that the Q value is low and the transmission loss increases. This is not a problem for short transmissions inside the device, but is not suitable for applications where even a small loss cannot be tolerated, such as an input stage of a receiver or a resonator that requires sharp resonance.

To solve this problem, a transmission line 60 having a strip line structure as shown in FIG. 6 has been proposed. A transmission line 60 having a stripline structure has a signal line 62 and parasitic signal lines 63 and 64 integrally formed in a dielectric 61, and ground electrodes 65 and 6 on both main surfaces of the dielectric 61.
6 is formed. Then, the parasitic signal lines 63 and 6
4 is formed to be slightly narrower than the signal line 62. Also,
The signal line 62 and the parasitic signal lines 63 and 64 are short-circuited by through holes (not shown) so that these lines have the same potential.

[0004]

However, in a conventional transmission line, at least three signal lines are provided in a dielectric.
Since a parasitic signal line is formed, it is necessary to increase the distance between the ground electrodes formed on both main surfaces of the dielectric. Therefore, there is a problem that the transmission line becomes large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and as in the conventional strip line structure, it is easy to manufacture and can be made thin, and has a high Q value and a small transmission loss. It is an object of the present invention to provide a transmission line capable of performing the following.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a strip comprising a dielectric, two signal lines integrally formed on or inside the dielectric and a ground electrode. A line structure is formed, wherein the two signal lines have the same impedance and the same shape, and are short-circuited to each other.

According to the transmission line of the present invention, the two signal lines have the same impedance and the same shape, and are short-circuited to each other. Therefore, the effective resistance of the signal lines is reduced, and the Q value is accordingly reduced. High, and transmission loss can be reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a cross-sectional view of a transmission line according to an embodiment of the present invention and a cross-sectional view taken along the line II-II. A transmission line 10 having a stripline structure includes a dielectric 11 made of ceramic or the like, ground electrodes 12 and 13 formed on both main surfaces of the dielectric 11, and a dielectric 2 made of silver or silver-palladium inside the dielectric 11. And two signal lines 14 and 15. At this time, the two signal lines 14 and 15 have the same impedance and the same shape.

The through-hole 1 is provided between the two signal lines 14 and 15 so that these lines have the same potential.
6 are shorted together. This reduces the effective resistance of the signal line.

Next, Table 1 shows FIG. 1 for each signal line length.
Of the transmission line 10 of the present embodiment and the conventional transmission line 50 of FIG.
And the Q value at the time of no load. However, the distance between the ground electrode 12 and the signal line 14 of the transmission line 10 is 600 μm, the distance between the signal line 14 and the signal line 15 is 50 μm,
The distance between the electrode and the ground electrode 13 is 600 μm, and the width of the signal lines 14 and 15 is 400 μm. The distance between the ground electrode 53 of the transmission line 50 and the signal line 52 is 600
μm, and the distance between the signal line 52 and the ground electrode 54 is 600
μm, and the width of the signal line 52 is 400 μm.

[0011]

[Table 1]

From this table, it is understood that the Q value at no load can be increased by using two signal lines.

Next, the frequency characteristics of the insertion loss and the frequency characteristics of the reflection coefficient when a low-pass filter is formed using the transmission line 10 of the present embodiment and the conventional transmission line 50 will be described. FIG. 3 shows the frequency characteristics of the insertion loss of the low-pass filter, and FIG. 4 shows the frequency characteristics of the reflection coefficient of the low-pass filter. 3 and 4, the solid line indicates the case of the low-pass filter constituted by the transmission line 10 of the present embodiment, and the broken line indicates the case of the low-pass filter constituted by the conventional transmission line 50.

From FIG. 3, it is understood that the low-pass filter constituted by the transmission line 10 of this embodiment has a smaller insertion loss than the low-pass filter constituted by the conventional transmission line 50. FIG. 4 shows that the transmission line 10 of this embodiment is
The low-pass filter composed of the conventional transmission line 5
It is understood that the reflection coefficient is attenuated more sharply than the low-pass filter constituted by 0.

According to the transmission line of the embodiment described above, the two signal lines have the same impedance and are short-circuited to each other, so that the effective resistance of the signal lines can be reduced. Accordingly, the Q value can be increased accordingly, and the transmission loss can be reduced.

Further, since the two signal lines have the same shape, the signal lines can be regarded as signal lines having twice the thickness, and the current flowing through the signal lines is uniformly distributed. Therefore, transmission loss can be further reduced.

Further, since there are two signal lines, the distance between the ground electrodes can be narrowed, and the transmission line can be downsized.

Since the two signal lines have the same shape, they can be formed inside the dielectric by printing the same pattern. Therefore, since only one printing pattern is required, the manufacturing cost can be reduced.

When a filter is constituted by the transmission line of the above embodiment, a filter having low loss and steep attenuation can be manufactured.

[0020]

According to the transmission line of the present invention, since two signal lines have the same impedance and the same shape and are short-circuited with each other, the signal lines can be regarded as a signal line having twice the thickness and flow through the signal line. Since the current is uniformly distributed, the effective resistance of the signal line can be further reduced. Accordingly, the Q value can be increased accordingly, so that the transmission loss can be further reduced.

As a result, when a filter is formed, a filter having low loss and steep attenuation can be manufactured.

Further, since there are two signal lines, the distance between the ground electrodes can be reduced, and the transmission line can be downsized.

Since the two signal lines have the same shape, they can be formed inside the dielectric by printing the same pattern. Therefore, only one printing pattern is required, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment according to a transmission line of the present invention.

FIG. 2 is a sectional view taken along line II-II of the transmission line in FIG.

FIG. 3 is a diagram showing frequency characteristics of insertion loss of a low-pass filter formed by a transmission line of the present invention and a low-pass filter formed by a conventional transmission line.

FIG. 4 is a diagram illustrating frequency characteristics of reflection coefficients of a low-pass filter formed by a transmission line of the present invention and a conventional low-pass filter formed by a transmission line.

FIG. 5 is a sectional view showing a conventional transmission line.

FIG. 6 is a sectional view showing another conventional transmission line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Transmission line 11 Dielectric 12, 13 Ground electrode 14, 15 Signal line

Claims (1)

[Claims] 1. A strip line structure comprising a dielectric, two signal lines integrally formed inside or on the surface of the dielectric, and a ground electrode, wherein the two signal lines have the same impedance. And a transmission line having the same shape and being short-circuited to each other.