JPS5815966B2 - Microwave integrated circuit directional coupler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a branch line type hybrid, that is, a microwave integrated circuit directional coupler that can be integrated into an IC in a high frequency band.

As a conventional MIC branch line, the one shown in FIG. 1 or 2 is known.

The solid line is a microstrip line, and the dotted line is a slot line.

Fig. 1 shows a parallel branch line composed of microstrip lines. If the characteristic impedance of the input/output microstrip line is Zo, the characteristic impedances of the microstrip I-IJ tube lines 6 and 7 are Zo and Zo, respectively. /f2, and if a typical circuit is realized in a high frequency band, the line width of the micros l-IJ tube line 7 cannot be ignored with respect to the wavelength, and the circuit characteristics deteriorate.

FIG. 2 shows a series branch line composed of slot lines, and when the characteristic impedance of the input/output casslot line 8 is Zo, the quarter wavelength slot line 9,
The characteristic impedances of 10 are Zo and V'2Zo, respectively.
Therefore, the influence of the line width, which is a drawback in FIG. 1, can be greatly improved, and higher frequencies can be achieved than in the circuit configuration shown in FIG.

However, if higher frequencies are promoted, the spread of the electromagnetic field distribution in the slot line may cause electromagnetic field coupling between the branches, which inevitably deteriorates the circuit characteristics.

Furthermore, as the frequency increases, the characteristic impedance that can be achieved with the same slot width increases, making it difficult to realize a line with low impedance.

Therefore, these circuits cannot necessarily be said to be good as millimeter-wave IC hybrids.

In order to eliminate these drawbacks, the present invention provides a microwave integrated circuit directional coupler in which a branch line is constituted by a circular disc-shaped strip conductor and a slot cavity.

The present invention will be explained in detail below with reference to the drawings.

For convenience of explanation, FIGS. 3a and 3b show cross-sectional views of the antipodal slot line used in the present invention.

Here, d is the thickness of the dielectric substrate, and t is the line width.

This line can easily realize various invinidance characteristics depending on the width t. For example, if t is made negative (the upper and lower conductors overlap) as in b, this is relatively easy to achieve with a normal slot line. It is possible to obtain a low characteristic impedance that is difficult to achieve.

Furthermore, since this line forms a transmission line by interposing the substrate, the degree of concentration of the electromagnetic field increases and coupling between the lines decreases.

FIG. 4 shows an embodiment corresponding to claim 1, in which 1, 2, and 3.4 are input/output ports, 11 is an input/output microstrip line, and 12.13 are FIG. 3 a and b, respectively.
14 is a slot cavity, and 15 is a strip conductor.

The solid line is the front side of the dielectric substrate, and the dotted line is provided on the ground side of the dielectric substrate.

The embodiment shown in FIG. 4 belongs to the parallel branch line shown in FIG.
If the characteristic impedance of 1 is Zo, then Zo
, Zo! 2, but the line 13 can easily achieve low impedance by overlapping the conductor parts 1415, that is, by making t negative as shown in Figure 3, and line 7 in Figure 1 can be easily realized. It does not have the drawbacks of line width, etc., and is capable of higher frequencies.

FIG. 5 shows an embodiment corresponding to claim 2, in which 1, 2, and 3.4 are input/output ports, 16 is an input/output casslot line, and 17.18 is an antenna having the form of FIG. 3a. A podal slot line, 19 is a strip conductor, and 20 is a slot cavity.

In this embodiment as well, the solid line is on the side of the dielectric substrate, and the dotted line is on the back side of the dielectric substrate, which is the ground side.

The embodiment shown in FIG. 5 belongs to the series branch line shown in FIG.
If the characteristic impedance of is Zo, then each of them is Zo.

It needs to be N/″2 Zo.

These characteristic impedances can be easily realized by changing the magnitude of 19.20, that is, by changing the value of t in FIG.

Further, since the concentration of electromagnetic field is high in the 17°18 lines, even if the frequency is increased and the circuit is made smaller, coupling between the lines is less likely to occur, making it possible to increase the frequency.

Therefore, since these circuits use planar circuits such as strip conductors and slot cavities, high frequencies can be achieved due to the circuit structure, and they are promising circuits as millimeter-wave IC hybrids.

As explained in detail above, the microwave integrated circuit directional coupler using the strip conductor and the slot cavity of the present invention has a planar circuit structure, and as an additional effect, an antipodal slot line can be formed. Therefore, it is a promising circuit as a millimeter-wave IC hybrid.

Further, the circuit of FIG. 4 has an advantage that it is effective when the constituent lines are microstrip lines, and the circuit of FIG. 5 is effective when the constituent lines are slot lines.

[Brief explanation of drawings]

1 and 2 are plan views showing examples of conventional branch lines, FIGS. 3a and 3b are sectional views of antipodal slot lines used in the present invention, and FIGS. 4 and 5 are respectively in accordance with the present invention. It is a top view showing an example of. 1.2,3,4...Input/output port, 5,6,7
゜110, ... microstrip line, 8, 9,
10゜16...Slot line, 14,20...
...Slot cavity, 15,19...Strip conductor, 12゜131718...Antipodal slot line.

Claims (1)

[Claims] 1. A circular disc-shaped strip conductor is provided on a dielectric substrate, and four microstrip lines are connected to the strip conductor at approximately equal intervals to form an input/output port, and the above step)
The strip conductor and the circular slot cavity constitute an antipodal slot line by providing a circular slot cavity having a similar size on the ground plane directly below the IJ tube conductor. Microwave integrated circuit directional coupler 2 A circular disc-shaped slot cavity is provided on a dielectric substrate ground conductor, and four slot lines are connected to the slot cavity at approximately equal intervals to form input/output ports, and the slot A circular strip conductor having a similar size is provided directly above the cavity, so that the slot cavity and the circular IJ tube conductor constitute an antipodal slot line. Microwave integrated circuit directional coupler.