JPS6117601Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to improving the characteristics of a microwave integrated circuit type directional coupler using striplines.

Conventional microwave integrated circuit (hereinafter referred to as MIC)
The basic structure of the type directional coupler is
The length of the coupled line is set to 1/4 wavelength as shown in the top view and the side sectional view taken along the l-l' plane in the top view in Figure a and Figure 1b, respectively. A device having ~4 terminals is known. In FIG. 1b, 5 and 5 are coupled lines, 6 is a dielectric substrate, and 7 is a ground conductor. The operation of such a conventional MIC type directional coupler is such that the microwave signal inputted from the input terminal 1 shown in FIG. This can be taken out from the terminal 3 as a proportional output signal. At this time, it is ideal that the remaining signal coupled from the input terminal 1 to the terminal 3 is distributed to the terminal 2, and that no leaked output signal is propagated to the terminal 4.

However, in the conventional basic structure shown in Figure 1 a and b, the electrical lengths of the even mode and the odd mode in the distributed coupling section are different, resulting in a difference in propagation velocity between the two modes, and the directionality is There was a drawback that the coupler did not have sufficient directionality, and the signal leaked to the terminal 4 shown in FIG. 1a. As a method to compensate for the above-mentioned drawbacks, an overlay method using a dielectric material for mode matching and coupling and a coupling strip is known.

The conventional overlay method is shown in FIG.
This is an example of a MIC type directional coupler. Figure 2b
In the figure, 8 is a coupling strip and 9 is a dielectric. That is, coupled lines 5', 5', dielectric substrate 6',
The basic structure consisting of the ground conductor 7' etc. is the same as the conventional one described above, but by adopting a structure in which the dielectric material 9 and the coupling strip 8 are placed over the entire surface of the coupling lines 5', 5', , the difference in propagation velocity between the odd and even modes is eliminated, and the directional characteristics are significantly improved. However, on the other hand, the addition of this overlay structure changes the impedance of the coupling line, and the so-called input terminal There are also problems such as a decrease in return loss when viewed from the side, which has the disadvantage of requiring the impedance design of the coupled line to be redesigned.

The present invention aims to eliminate the above-mentioned drawbacks and provide a MIC type directional coupler with long directional characteristics, little impedance change, and high return loss on the input terminal side. The gist is that both ends are folded and the central part is placed almost parallel,
In a microwave stripline type directional coupler in which the microwave strips are formed in the same shape and symmetrically and are installed so that at least a part of the adjacent portions arranged substantially parallel to each other are covered with a dielectric material, A signal input terminal is provided on the outside of the folded line, and a portion of the dielectric material protrudes toward the input terminal side, so that the signal input terminal is provided on one side away from the center and on a part of the upper surface of the coupled line. The present invention relates to a microwave integrated circuit type directional coupler, characterized in that the dielectric plate having a substantially uniform width is covered on the input terminal side in substantially parallel to the adjacent portion.

The structure of the present invention will be described below with reference to the drawings. FIGS. 3A and 3B are a top view and a side sectional view taken along the plane nn' of the top view, respectively, of an embodiment of the present invention. In FIGS. 3a and 3b, 10 indicates a dielectric plate. As shown in FIGS. 3a and 3b, in contrast to the conventional basic structure consisting of coupled lines 5'', 5'', dielectric substrate 6'', ground conductor 7'', etc., coupled line 5'',
A structure is adopted in which the dielectric plate 10 is placed only on a part of the upper surface of the 5''.

Here, the dielectric plate 10 has a dielectric constant of 2 to 12.
Connect the connecting lines 5″, 5″ terminals 1,
Approximately 3 of the total length of the coupled lines 5'', 5'' from the end on the 3 side
Place it so as to cover up to about 1/2 inch of the area, move it parallel to the track direction, adjust the position, and fix it to obtain the best characteristics. The length of the dielectric plate 10 left over in the long side direction is made to protrude outside the lines in the line direction of the coupled lines 5'', 5''. By making a portion of the dielectric protrude and protrude, the distribution of electric lines of force on the input terminal side is made different. Also, the length of the dielectric plate 10 in the short side direction is at least the distance d between the inner edges of both coupled lines 5'', 5''.
It shall be larger than the distance D between the outer edges at the maximum, and placed on the conductors of both coupled lines 5'', 5'' with an equal width.

Here, we will discuss three types of structures: the conventional basic structure, the structure based on the overlay method, and the structure based on the present invention.
In the case of a MIC type directional coupler, the coupled output from input terminal 1 to terminal 3 (solid line), the leakage output from input terminal 1 to terminal 4 (dotted line), and the return loss of input terminal 1 for each example. Characteristic diagrams for (dotted chain line) are shown in FIGS. 4 to 6.

In the case of the configuration of the present invention shown in FIG. 6, the leakage output from input terminal 1 to terminal 4 was about -28 dB in the conventional basic structure shown in FIG. By changing the distribution of the electric lines of force, it was significantly improved to -46dB.
Furthermore, the characteristics are much better than -41 dB in the case of the conventional overlay structure shown in FIG.

In addition, the return loss of the input terminal 1, which corresponds to the voltage standing wave ratio, is -20 dB or more over the entire frequency band in use if the width of the stripline 4 is kept as it is in the drawing and the configuration of the present invention is used. Secure the fifth
The present invention improves the characteristic defect that makes it difficult to secure -20 dB or more over the entire band in the case of the structure using the conventional overlay method shown in the figure. It maintains its excellent properties.

Furthermore, in the case of the structure of the present invention, compared with the conventional overlay method using a dielectric and a coupling strip,
Since only a portion of the coupled line is covered with a dielectric plate, there is no large impedance change, so there is no need to redesign the impedance of the coupled line.

As described above, the present invention has both ends bent and the central parts arranged approximately parallel to each other to form a symmetrical shape with the same shape, and at least a part of the adjacent parts arranged approximately parallel to each other to be dielectric. In a microwave stripline type directional coupler installed so as to be covered by a body, an input terminal for a signal on the outside of the folded microwave stripline is provided, and the dielectric body is aligned with the input terminal side. The dielectric plate is made to protrude and protrude, and on one side away from the center and on a part of the upper surface of the coupling line, the dielectric plate having an approximately equal width is covered on the input terminal side substantially parallel to the adjacent portion. While the configuration is simplified by the characteristic microwave integrated circuit type directional coupler, various characteristics as a MIC type directional coupler are improved, and a dielectric material is added to the basic structure of the conventional MIC type directional coupler. It has a very simple structure in which a plate is placed, the adjustment method is easy, and it can be realized at low cost, making it an extremely practical idea.

[Brief explanation of the drawing]

Figure 1a is a top view of the basic structure of a conventional MIC type directional coupler, Figure 1b is a side cross-sectional view taken along the l-l' plane of the same top view, and Figure 2a is a MIC type directional coupler using the overlay method as well. A top view of a directional coupler, FIG. Figure 3b is a side sectional view taken on the n-n' plane of the same top view, Figures 4 and 5 are the conventional basic structure and the structure based on the overlay method, respectively, and Figure 6 is the MIC type structure according to the present invention. FIG. 3 is a frequency characteristic diagram of a directional coupler. 1...Input terminal, 2-4...Terminal, 5,5,
5', 5', 5'', 5''...coupled line, 6, 6',
6''...Dielectric substrate, 7, 7', 7''...Grounding conductor, 8...Coupling strip, 9...Dielectric, 1
0...Dielectric plate.

Claims (1)

[Scope of utility model registration request] The micros are arranged such that both ends are bent, the central parts are arranged substantially parallel, the micros are formed in the same and symmetrical shape, and at least a part of the near parallel parts are covered with a dielectric material. In a wave stripline type directional coupler, a signal input terminal is provided on the outside of the folded part of the microwave stripline, and a portion of the dielectric material protrudes and protrudes toward the input terminal side. a microwave integrated circuit type, characterized in that the dielectric plate of substantially equal width covers the input terminal side on one side separated from the input terminal and in a part of the upper surface of the coupling line substantially parallel to the adjacent section; Directional coupler.