JPS6182501A - Strip line microwave circuit - Google Patents

Abstract

PURPOSE:To widen a range in which a bending structure can be formed by holding a desired electric characteristic, by placing in a line symmetry two distributed constant lines whose characteristic impedance and electric length are equal to each other, respectively, with respect to a straight line for connecting an input terminal and an output terminal. CONSTITUTION:A distributed constant line 6 and 6' are placed in a line symmetry with respect to a symmetrical axis 5 on a dielectric 1, the distributed constant line 6 and 6' are connected by a point 3 and 4 on the symmetrical axis 5, and these two connecting points 3, 4 are input and output terminals of this circuit, respectively. An electric length of the distributed constant line 6 and 6' is an electric length which is equal to that of a circuit of a conventional example. A composite characteristic impedance of the distributed constant line is '40' OMEGA, and a characteristic impedance of the respective distributed constant lines 6, 6' is '80' OMEGA.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to improvements in stripline microwave circuits using distributed constant lines having relatively low characteristic impedance. It is used for such integrated circuit devices.

[Conventional technology]

In the conventional distributed constant line used in stripline microwave circuits, a single line with a width exhibiting the required characteristic impedance Z0 is placed on a dielectric substrate in a straight line or bent. It is generally placed.

[Problem that the invention seeks to solve]

In such conventional stripline microwave circuits, when the characteristic impedance of the distributed constant line is desired to be relatively low, the line width becomes wide, and in this case, the area of the dielectric substrate is occupied widely. Also, for the passing direction,
Because the track width is wide, it is impossible to bend and arrange it. Even if it is bendable, the discontinuous portion of the distributed constant line due to the bent portion will occupy a large proportion of the total area of the line, resulting in characteristics that deviate from those of a straight distributed constant line. This phenomenon occurs when the operating frequency is high (and the length of the distributed constant line in the passing direction is short (
This becomes noticeable when approaching the line width dimension.

FIGS. 3 and 4 are outline diagrams showing the outline of a conventional distributed constant line.

In this conventional strip line microwave circuit, the specific inductivity of the dielectric substrate is r12.7J, the dielectric substrate thickness is r150 Jμm, and the operating frequency is r30JGH.
z, the characteristic impedance of the desired distributed constant line is 40
It is Ω. (a) of the figure shows the case where the electrical length of the line is rO, I J times the wavelength, and (b) of the figure shows the case where the electrical length of the line is rO, 29J, times the wavelength.

In the case of (a) in the figure, it is impossible to bend the track,
The exclusive area of the dielectric substrate cannot be reduced. Also, (b) in the figure
In this case, bending is possible, but the bent portion occupies a large proportion of the entire line, which has the disadvantage that the characteristics deviate from those of a distributed constant line constructed of straight lines.

The present invention aims to eliminate the above-mentioned drawbacks and provides a stripline microwave surface path that is compact and has good characteristics.

[Means for solving problems]

The present invention provides a stripline microwave circuit comprising a dielectric substrate and a distributed constant line having an input end and an output end disposed on the substrate, and as a means for solving the above-mentioned problems. The distributed constant line includes two distributed constant lines each having the same characteristic impedance and the same electrical length, and these two distributed constant lines are arranged line-symmetrically with respect to a straight line connecting the input end and the output end. It is characterized by:

[Effect]

The present invention utilizes the fact that a circuit in which two distributed constant lines having characteristic impedances of r2ZOJ are connected in parallel is electrically equivalent to two distributed constant lines having characteristic impedances of "Zo".

That is, if we set the F matrix of the distributed constant line with the characteristic impedance r2ZOJ (converting equation 13 into a Y matrix, the Y matrix when two distributed constant lines are connected in parallel is...-(4) Equation (4) Converting to an F matrix and applying the A-D-B-C modulus 1, the F matrix of the distributed constant line with the characteristic impedance Z0 is, which is exactly equal to equation (5).

That is, the parallel connection of distributed constant lines with characteristic impedance r2Zo J is equivalent to a distributed constant line with characteristic impedance z0.

〔Example〕

Hereinafter, a circuit according to an embodiment of the present invention will be explained based on the drawings.

FIG. 1 is a schematic diagram showing the outline of a microwave circuit obtained by realizing the conventional circuit shown in FIG. 3 based on the principle of the invention described above, and FIG. 2 corresponds to FIG. 4. FIG. 5 is a characteristic curve showing the relationship between characteristic impedance and line width.
The curves shown by are for the case of two parallel connected lines.

The microwave circuit to which this curve is applied has a dielectric constant of r12.7J and a dielectric substrate thickness of r150. Jμ…
The operating frequency is r30JGH.
This is the circuit of z.

First, the configurations of the first embodiment circuit and the second embodiment circuit will be explained based on FIG. 1 and FIG. 2, respectively. This example circuit includes a dielectric substrate 12 having a dielectric constant of r12.7 J and a dielectric substrate thickness of r150 J μm;
It includes distributed constant lines 6 and 6' and input/output terminals 3 and 4.

Distributed constant lines 6 and 6' are arranged on the dielectric 1 line-symmetrically with respect to the axis of symmetry 5, and the distributed constant lines 6 and 6' are connected at points 3 and 4 on the axis of symmetry 5, and these two connection points 3
and 4 are input and output terminals of this circuit, respectively. The electrical lengths of the distributed constant lines 6 and 6' are equal to those of the conventional circuit.

That is, in the second embodiment circuit, the wavelength is rO, I J times, and in the second embodiment circuit, the wavelength is rO, 29J times.

Also, the composite characteristic impedance of this distributed constant line is “
40''Ω, and the respective distributed constant lines 6 and 6'
The characteristic impedance of is "80" Ω.

Next, the features of this embodiment circuit will be explained based on FIGS. 1, 2, and 5.

In this example circuit, the line width exhibiting the desired characteristic impedance is "30" μm, which is significantly narrower than the line width of r170 J μm in the conventional example circuit. Furthermore, as shown in Fig. 5, the line width of the conventional circuit becomes too large and it is impossible to realize a distributed constant line with a characteristic impedance of 25Ω. By using the principle of the present invention, a line width having a characteristic impedance value of "50" Ω can be used, so a line can be realized.

〔Effect of the invention〕

As explained above, the present invention makes it possible to narrow the line width of a stripline exhibiting the same characteristic impedance compared to a conventional circuit with a single-wire configuration, and enables a folded structure while maintaining desired electrical characteristics. You can expand the scope of your work. This has the effect of increasing the degree of freedom in circuit design, and further has the effect of reducing costs by reducing the amount of expensive dielectric substrate material used due to this folded structure.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the outline of a circuit according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the outline of a circuit according to a second embodiment of the present invention. FIG. 3 shows a conventional circuit having the same characteristics as the circuit according to the first embodiment of the present invention. FIG. 4 shows a conventional circuit having the same characteristics as the circuit according to the second embodiment of the present invention. FIG. 5 is a characteristic diagram showing the relationship between the line width and characteristic impedance of the circuit. 1... Dielectric substrate, 2.6.6'... Distributed constant line, 3.4... Input/output end, 5... Line symmetry axis.

Claims (1)

[Claims] (1) In a stripline microwave circuit comprising a dielectric substrate and a distributed constant line having an input end and an output end disposed on the substrate, the distributed constant line has its characteristic impedance and its electrical length. A stripline microwave circuit comprising two distributed constant lines having the same values, the two distributed constant lines being arranged line-symmetrically with respect to a straight line connecting the input end and the output end.