JPH02152173A - Micro-wave coplanar line connector - Google Patents

Abstract

PURPOSE:To make it possible to lessen loss due to the change-over in the mode of micro-waves, and thereby enable characteristics in a wide band to come into being by using a coplanar line connector in a shape that a line is divided in half, at the connecting section of a coaxial line with a coplanar line. CONSTITUTION:In a micro-wave coplanar line connector 14 which connects a coaxial line 1 composed of an earth connector 3 arranged in such a way as to have a central conductor 2 enclosed, with a central connector 4 formed on the surface of a substrate 6 and an earth conductor 5, an earth conductor 15 is formed into a shape that the earth conductor 3 of the line section 1 is divided in half, the diameters (a) and (b) of the central conductor 13 of the line connector 14 and the earth conductor are determined in such a way as to lie halfway between the coaxial line and the coplanar line in characteristic impedance, and the substrate 6 is constituted to be closely adhered onto the surface 16 of an earth chassis. By this constitution, loss due to the change-over in the mode form of micro-waves into both of the lines is lessened, and loss in high frequency signal radiation can thereby be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION J Field of the Invention The present invention relates to a microwave coplanar line plug (feedthrough) for connecting a microwave coaxial line and a plane line with a wide band and low loss.

"Prior Art" In microwave equipment such as microwave amplifiers and high-speed external optical modulators, coplanar lines in which semiconductors or dielectrics are mounted on substrates are often used.

When attempting to input and output microwave signals from external equipment to this coplanar line, coaxial lines are usually used, so microwave connections are required to connect the coaxial line and coplanar line to these input/output sections. A stopper is used.

An example of the configuration of a connecting portion between a coaxial line and a coplanar line in a conventional microwave plug is shown in FIGS. 10 and 11.

Figure 10 shows a coplanar line (cpw) as a coplanar line.
), FIG. 11 shows an example of using an asymmetric coplanar strip line (ACPS). 10th
In the figure, ■ is the coaxial line part, 2 and 3 are the center conductor and ground conductor of the coaxial line, 4.5 is the center conductor and ground conductor of the coplanar line, and 6 is, for example, Si, GaAs, L
A substrate made of a semiconductor or dielectric material such as iNb 03, 7 and 8 are the center conductor and ground casing of the coaxial-coplanar line connection section, and 9 electrically connects the coaxial line and the coplanar line. Connecting material such as solder or silver paste. Also, in FIG. 11, 10. ll is the center conductor and ground conductor of the asymmetric coplanar strip line.

In this case, the center conductor diameter a of the coaxial line, the ground conductor inner diameter b
, the width W of the center conductor of the coplanar line, and the gap g between the center conductor and the ground conductor are usually set so that the characteristic impedance 2 is 50Ω.

[Problem to be Solved by the Invention J] FIG. 12 is a sectional view of the first coaxial line 1 and the second coplanar lines 4, 5, 10.11 in the conventional example of FIG. The distribution state (mode shape) of the microwave electric lines of force 12 between the ground conductor and the ground conductor is shown. FIG. 13 shows the case of a coplanar line, and FIG. 14 shows the case of an asymmetric coplanar strip line. As can be seen by comparing FIGS. 12 to 14, the mode shape of the lines of electric force is significantly different between the coaxial line and the coplanar line.

Therefore, when a microwave signal is input/output to/from an input/output section of a microwave device, a power propagation loss occurs due to microwave mode conversion at the coaxial-coplanar line connection section 7 in FIG. 10. In this case, the magnitude of this mode conversion loss varies greatly due to slight variations in the shape of the center conductor 7 of the connection part and the ground casing, and defects in the shape of the connection material 9 between the coaxial line l and the coplanar circuit. Problems have arisen such as ripples occurring in the frequency characteristics of propagation loss, or radiation loss becoming large at this connection portion 7 for high frequency signals, limiting the operating band.

An object of the present invention is to provide a low-loss, broadband microwave coplanar line plug that solves the above-mentioned conventional problems.

"Means for Solving the Problems" The present invention is characterized in that a coplanar line plug, which has a structure in which the ground conductor of the coaxial line is split in half, is provided at the connection portion between the coaxial line and the coplanar line. .

"Operation" According to the above configuration, since the coaxial line is split in half, the mode shape of the microwave becomes intermediate between the mode shapes of the coaxial line and the coplanar line. This reduces the loss associated with mode shape conversion from a coaxial line to a coplanar line, and also suppresses the radiation loss of high-frequency signals, realizing a low-loss, broadband microwave coplanar line plug. can.

Embodiment FIG. 1 is a configuration diagram of an embodiment of the present invention, and is an example in which a coplanar line plug is arranged between a coaxial line and a coplanar line board. Note that the same components as in the conventional example are represented by the same symbols.

In FIG. 1, 13 is the center conductor of the coplanar line plug 14, 15 is the ground conductor, and 16 is the surface of the ground casing connected to the ground conductor of the coplanar line.

In this case, the ground conductor 15 has a shape obtained by dividing the ground conductor 3 of the coaxial line section 1 in half, and
The diameters a and b of the center conductor 13 and the ground conductor of No. 4 are set to have a certain predetermined characteristic impedance. Further, the substrate 6 of the coplanar line is configured to be in close contact with the ground casing surface 16.

FIG. 2 is a cross-sectional view of the coplanar plug portion 14 in one embodiment of the present invention shown in FIG. 1, and is a diagram showing the mode shape of the electric lines of force 12 of the microwave. As shown,
The electric lines of force have a concentrated distribution on the ground conductor 15 side,
The mode shape is intermediate between the mode shape of a coplanar line and a coaxial line (see FIGS. 12 to 14).

Figure 3.4.5 is a sectional view of the coplanar line section when various coplanar lines are connected in the embodiment of Fig. 1, and shows the coplanar line plug and coplanar line arrangement. 3 is a diagram showing a case in which a coplanar line is connected, FIG. 4 is a diagram in which an asymmetric coplanar strip line is connected, and FIG. 5 is a diagram in which a slot line is connected.

In addition, in FIG. 5, 17 is the center conductor of the slot line,
18 represents the ground conductor of the slot line.

FIGS. 6 and 7 are diagrams showing other embodiments of the present invention, in which a coplanar line plug is disposed so as to cover the surface of a substrate of a coplanar line. FIG. 6 is a perspective view showing the overall structure, and FIG. 7 is a sectional view of the coplanar line connector of the present invention.

Here, 19 is the center conductor of the coplanar line connector 20, and 21
are earth conductors and their magnitude a.

b is set to have a certain predetermined characteristic impedance. In this case, in the plug part 20, some of the microwave electric lines of force are distributed also in the coplanar line substrate, so the mode shape conversion becomes low loss, and the frequency characteristics of the microwave transmission loss are excellent. Planar line connectors can be realized.

In the above embodiment, the relationship between the sizes a and b of the center conductor and the ground conductor and the characteristic impedance Zr of the line at that time is determined using the conformal mapping method (Reference: "Applications of Conformal Mapping" by Tatsuji Sasaki) An example calculated using Kogakusha Publishing) is shown in Part 8.
As shown in the figure. Here, ■ is the case of the conventional coaxial line shown in FIG. 12, ■ is the case of the plug part according to an embodiment of the present invention shown in FIG. 2, and ■ is the case of the present invention shown in FIGS. 6 and 7. This is the case of a plug part according to another embodiment. Note that the relative permittivity of the gap between the center conductor of the plug portion and the ground conductor is ε1-1, and the relative permittivity of the substrate 6 in FIGS. 6 and 7 is ε1=18. As can be seen from these figures, the magnitude of the characteristic impedance Zt can be arbitrarily set depending on the magnitude of a/b.

Typically, microwave equipment is configured so that the characteristic impedance of the coaxial line and the coplanar line are the same.

In this case, if the characteristic impedance of the coplanar line connector is also set to the same value, low loss characteristics can be achieved.

If the characteristic impedances of the coaxial line and the coplanar line are different, the characteristic impedance Zt of the coplanar line connector is
You can set it to a size somewhere between them. Also, especially
The length of the plug shown in Fig. 1.6 is set to, for example, 1/4 of the wavelength λ(7) of the microwave signal, and the characteristic impedance Z is set to 11 m (Zc, Z,: coaxial line and It is obvious that when set to the magnitude of the characteristic impedance of a coplanar line, this coplanar line connector not only changes the mode shape but also has an impedance conversion function, and can realize extremely low loss characteristics. be.

FIG. 9 is a diagram showing the characteristics of one embodiment of the present invention.

Here, the case is shown in which an asymmetric Fubrene strip line formed on a lithium niobate substrate is constructed as a coplanar line, and ■ indicates the conventional case, and ■ indicates the case of the embodiment of the present invention shown in FIG. There is. The characteristic impedance of each line is set to 5oΩ. The broken line in the figure represents the transmission loss of the coplanar line. The difference between the broken line and the solid line shown in FIG. 9 is the transmission loss of the coplanar line connector. As is clear from Fig. 9, in the conventional configuration example (■), the frequency is 10 GHz.
A loss ripple occurs above, and the 3clB band is about 10 GHz. In the configuration example (2) according to the present invention, there is no large loss ripple as in the case (2), and the transmission loss is relatively small. The 3 dB band at this time is approximately IF3 CI-1z, realizing a wide band characteristic.

In addition to the embodiments of the present invention described above, the same effects can be obtained by applying the present invention to a planar line such as a microstrip line instead of a coplanar line. In the coplanar line plug/section according to the present invention, a dielectric material may be inserted between the center conductor and the ground conductor.

In addition, although the above embodiments have mainly explained the case where the center conductor is circular and the ground conductor is half-circular in the plug part, the same effect can be achieved even if these shapes are changed to other shapes, such as a square. effect can be obtained.

Furthermore, the sizes a and b of the center conductor and ground conductor of the plug
If you set it to an appropriately small value, you can use it not only in the microwave band but also in
It is obvious that the present invention is effective also for signals in the millimeter wave band or higher.

"Effects of the Invention" As explained above, in the present invention, a coplanar line plug in the shape of a coaxial line cut in half is used at the connection part between the coaxial line and the coplanar line, so that microwave Since it is possible to reduce the loss associated with mode conversion, it is possible to realize broadband characteristics.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the microwave coplanar line connector of the present invention, Fig. 2 is a diagram showing the cross section of the coplanar line part and the distribution of electric lines of force in the embodiment, and Fig. 3. .5 is a cross-sectional view of a coplanar line section showing an example in which various coplanar lines are connected to the coplanar line connector of one embodiment, and Fig. 6 is a coplanar line connector of the present invention. FIG. 7 is a sectional view of a coplanar line connector according to another embodiment of the present invention, and FIG. 8 is a cross-sectional view of a coplanar line connector according to an embodiment of the present invention. A diagram showing the relationship between the size of the center conductor and the ground conductor and the characteristic impedance, Figure 9 is a diagram comparing the characteristics of a conventional example of a coplanar line connection and an embodiment of the present invention, and Figure 10 is a diagram showing the relationship between the size of the center conductor and the ground conductor and the characteristic impedance. A perspective view showing the configuration of a conventional example of a line connector, No. 11
The figure is a perspective view showing the structure of another conventional example of a microwave coplanar line plug, and Figs. FIG. 3 is a cross-sectional view showing the distribution of lines of force. l...Coaxial line, 2...Center conductor of coaxial line, 3...Ground conductor of coaxial line, 4...
... Center conductor of coplanar line, 5... Ground conductor of coplanar line, 6.l... Board, 7... Center conductor of coplanar line connection, 8.・・・
...Earth casing of coplanar line connection section, 9...
Connection material, 10...Center conductor of asymmetrical Fubley strip line, 11...Ground conductor of asymmetrical coplanar strip line, 12...Microwave electric field line, 13・・・・・・
- Center conductor of coplanar line connection part, 4...Coplanar line connection part, 5...Ground conductor of coplanar line connection part, 6...
...Ground [[j, 7... Center conductor 9 of slot line, 8...
... Earth conductor of slot line, 9 ... Center conductor of coplanar line connection part, 0 ... Coplanar line connection part, 1 ... Coplanar line connection part. Ground conductor of the stopper. Figure 1 Applicant: Nippon Telegraph and Telephone Corporation Figure 2 Figure 3 Figure 4 Figure 8 b/a Figure 7 Figure 10 Figure 11

Claims (1)

[Claims] A first center conductor comprising at least a first center conductor and a first ground conductor arranged to surround the first center conductor.
a second microwave coplanar line comprising at least a microwave line, a second center conductor formed on the substrate surface, and a second ground conductor formed on the substrate surface; A third center conductor that connects the first center conductor and the second center conductor, and a third ground conductor that connects the first ground conductor and the second ground conductor. A third microwave coplanar line plug comprising a microwave line, characterized in that a third ground conductor is arranged so as to partially surround the third center conductor. Coplanar track plug.