JPS6322684B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Technical Field of the Invention The present invention relates to a hybrid ring directional coupler, particularly a so-called rat race directional coupler, in which characteristic admittance of at least a portion of an arcuate body having a length of 3/4 wavelength is determined. This invention relates to a hybrid ring directional coupler configured to have different values to achieve a wide band. (B) Technical Background and Problems The so-called rat-lace coupler is generally constructed in the form of a four-aperture circuit and is widely used for signal distribution and signal synthesis. It can operate over a wider frequency band. FIG. 1 shows a conventional example of a rat-lace type coupler as described above. In the figure, 1 is the first arc-shaped body according to the present invention, 2 is the second arc-shaped body, 3 is the third arc-shaped body, 4 is the fourth arc-shaped body, 5 is the first arm, 6 is the second arm,
7 represents the third arm, and 8 represents the fourth arm. Further, in the figure, Y ₀ , Y ₁ , and Y ₂ represent respective predetermined characteristic admittance values, and λ ₀ represents the wavelength of the frequency used. That is, the first to third arcuate bodies 1 to 3 are each constituted by a ring having a length of λ ₀ /4, and the fourth arcuate body 4 is constituted by a ring having a length of 3λ ₀ /4. has been done. For example, a signal input from the first arm 5 is distributed to the second arm 6 and half to the fourth arm 8, and their phases are in the same phase. Further, for example, a signal input from the second arm 6 is distributed to the first arm 5 and half to the third arm 7, and their phases are opposite to each other. Although the above-mentioned coupler has a wider band than the stub-type coupler as mentioned above, since the fourth arc-shaped body 4 is entirely composed of lines having the same characteristic admittance value, the usable frequency band is There were limits to this. (C) Purpose and structure of the invention The present invention focuses on the above points and also aims to expand the limits of the usable frequency band.
The purpose of this invention is to solve the above-mentioned problem by providing locations with different characteristic admittance values within the fourth arc-shaped body 4 having a length of 3λ ₀ /4. Therefore, the hybrid ring directional coupler of the present invention includes a first arc-shaped body having a length of substantially 1/4 wavelength, and a substantial portion of the first arc-shaped body whose one end is connected to one end of the first arc-shaped body. the second with the length of the upper 1/4 wavelength
an arc-shaped body, a third arc-shaped body having a length of substantially 1/4 wavelength with one end connected to the other end of the first arc-shaped body; the other end of the second arc-shaped body and the third arc-shaped body; a fourth arc-shaped body having a length of substantially 3/4 wavelength, with both ends connected between the other end of the arc-shaped body;
A first arm connected at a connecting position between the first arc-shaped body and the second arc-shaped body, a second arm connected at the connecting position between the second arc-shaped body and the fourth arc-shaped body, and the fourth arc-shaped body. It has at least a third arm connected to the third arcuate body at a connection position, and a fourth arm connected to the first arcuate body and the third arcuate body at a connection position, and the second arcuate body In a directional coupler in which the characteristic admittance with the third arc-shaped body is equal and the characteristic admittance is selected to be different from the characteristic admittance of the first arc-shaped body, the fourth arc-shaped body has a wavelength of 1/4 wavelength. In addition to dividing it into three arc-shaped bodies with length,
It is characterized in that the characteristic admittance of the arc-shaped body located at the center is different from the characteristic admittance of the other arc-shaped bodies located on both sides. A detailed explanation will be given below with reference to the drawings. (D) Embodiment of the Invention FIG. 2 shows the configuration of an embodiment of the hybrid ring directional coupler of the present invention, and FIG. 3 is an explanatory diagram showing the theoretical characteristics of the conventional coupler shown in FIG. 1. FIG. 4 is an explanatory diagram showing the theoretical characteristics of the coupler shown in FIG. 2, FIG. 5 is another embodiment of the coupler of the present invention, and FIG. 6 is the theory of the coupler shown in FIG. FIG. 7 is an explanatory diagram showing the above characteristics, and FIG. 7 is an explanatory diagram showing actual measured values of the characteristics of the coupler shown in FIG. In FIG. 2, the symbols 1, 2, 3, 5, 6,
7 and 8 correspond to FIG. 1, and 9, 10, and 11 are segmented arc-shaped bodies, respectively, and represent the fourth arc-shaped body 4 shown in FIG. 1 divided into lengths of λ ₀ /4. There is. In the illustrated case, the normalized characteristic admittance value Y ₄ of the segmented arc-shaped body 10 is made different from that of the other segmented arc-shaped bodies 9 and 11. In the illustrated case, the normalized characteristic admittance value of each arm is (i) Y ₁ with respect to the first arc-shaped body 1,
(ii) Y ₂ for the second arc-shaped body 2 and the third arc-shaped body 3,
(iii) Y ₃ for segmented arcs 9 and 11, (iv) Y ₄ for segmented arc 10, and each arm 5, 6,
Each of 7 and 8 is the normalized characteristic admittance value Y ₀
It is shown as having . To qualitatively describe all the properties of a coupler with many parameters as shown in Fig. 2,
It is extremely difficult. For this purpose, we decided to conduct analysis using a data processing device and change the characteristic admittance values of each of the arcuate bodies to investigate a coupler with constants optimized to perform broadband operation. 3 shows the characteristics of the conventional coupler shown in FIG. 1, and FIG. 4 shows the characteristics of the coupler shown in FIG. 2. Note that the characteristics shown in FIG. 3 correspond to the coupler shown in FIG. 1 having one preferred constant as shown in Table 1, and the characteristics shown in FIG. 4 have one preferred constant as shown in Table 1. Corresponding to the coupler shown in FIG. 2, the theoretical values of the calculated results are shown. The above analysis is performed using the well-known scattering matrix.

[Table] Convenient. That is, if the row vectors whose elements are the square roots of the incident and reflected powers at each aperture of the circuit are respectively [a] and [b], then using the scattering matrix [S] of the circuit, [b] = [S] [ a] −(1). In addition, the element [S] is naturally the normalized characteristic admittance value Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₁ c, Y ₂ c in the case shown in FIG. 5 (described later).
becomes a function of And for the above optimization,
It is assumed that the evaluation function M expressed by the following formula is the minimum value. However, j (j = 1 to N) is the sampling frequency within the band, and the katsuko {...} of equation (2) is calculated at the relevant j, and the values from j = 1 to N are summed. It is. The _{characteristic} shown in FIG _. 3 _{is the first} characteristic _{corresponding} to the normalized characteristic admittance value shown in FIG. It corresponds to the coupler shown in the figure. Moreover, the characteristics shown in FIG. 4 correspond to the coupler shown in FIG _{. 2} , which corresponds to _the characteristic admittance value shown in FIG. There is. In Figures 3 and 4, the horizontal axis represents the normalized frequency, the vertical axis represents the coupling amount (unit d _B ), return loss and isolation (unit d _B ), and Sij is the jth This corresponds to a signal flowing from the arm to the i-th arm. In the coupler, (i) ±0.5 at the point where the coupling amount characteristic is -3 [d _B ] as shown in Figure 4.
There is a tolerance range of about [d _B ] (ii) and -20 in return loss and isolation characteristics.
[ _dB ] Considering that it can be used in the following frequency range, from Figures 3 and 4, the first
The fractional bandwidth shown in the table has been determined. A coupler with the characteristics shown in Figure 4 can be expected to have a wider fractional bandwidth of (33.4-27.6)/27.6≒21 [%] than the coupler shown in Figure 3. In the case shown in FIG. 2 above, the condition of equation (4) above, ie, Y ₁ c=Y ₂ c=Y ₀ −(4) is added. FIG. 5 shows another embodiment of the present invention which corresponds to the case where the condition of equation (4) above is removed. In FIG. 5, the symbols 1, 2, 3, 5, 6,
7, 8, 9, 10, 11 correspond to FIG. 2, respectively,
12, 13, 14, and 15 are the first in the present invention, respectively.
Sections 16, 17, 18, and 19 each represent a second section according to the present invention.

[Table] Table 2 shows constants when optimization is attempted for the coupler having the configuration shown in FIG. FIG. 6 is an explanatory diagram showing the characteristics as shown in FIGS. 3 and 4 for a coupler having the constants shown in Table 2. As can be seen from Figure 6, the coupler with the constants shown in Table 2 has a fractional bandwidth.
50.8%, which is (50.8−27.6)/27.6≒84 [%] wider than that shown in Figure 3. However, the normalized characteristic admittance value Y ₄ =7.735 shown in Table 2 is too large to be realistic. From this, the normalized characteristic admittance value _Y4 is fixed to a realizable value, and optimization is then performed. Table 3 shows four sets of constants obtained so far.

[Table] FIG. 7 shows the results of actual measurements to obtain the same diagram as FIG. 6 for a coupler having the constant (#2) shown in Table 3. Note that distortion of the measurement system is involved in obtaining the measured values shown in FIG. 7, and the dotted line in FIG. 7 represents a line connecting points on the vertical axis that take the same value. The coupler with the characteristics shown in FIG. 7 is a highly practical coupler, and in this case, the fractional bandwidth is 45.3%, which is (45.3−27.6)/ 27.6≒64 [%] Becomes familiar with broadband. In particular, in the case of the configuration shown in FIG. 5, as can be seen from the characteristic diagram, it has bimodal resonance characteristics, and it is possible to obtain a coupler with a wide bandwidth. (E) Effects of the Invention As explained above, according to the present invention, it is possible to provide a coupler having a sufficiently wider bandwidth than the coupler shown in FIG. In particular, this type of coupler affects the band characteristics of the phase shifter or amplifier that uses the coupler, so the present invention makes it possible to widen the band of the phase shifter or amplifier. .

[Brief explanation of the drawing]

FIG. 1 shows an example of a conventional directional coupler, FIG. 2 shows the configuration of an embodiment of the hybrid ring directional coupler of the present invention, and FIG. 3 shows the theoretical structure of the conventional coupler shown in FIG. FIG. 4 is an explanatory diagram showing the theoretical characteristics of the coupler shown in FIG. 2, FIG. 5 is another embodiment of the coupler of the present invention, and FIG. FIG. 7 is an explanatory diagram showing theoretical characteristics of the coupler shown in the figure, and FIG. 7 is an explanatory diagram showing actual measured values of the characteristics of the coupler shown in FIG. In the figure, 1 to 4 are first to fourth arcuate bodies, 5
to 8 are the first to fourth arms, respectively, 9, 10, 1
1 are respectively segmented arcuate bodies, 12 to 15 are each the first
Sections 16 to 19 each represent a second section.

Claims (1)

[Claims] 1. A first arcuate body having a length of substantially 1/4 wavelength;
a second arcuate body having a length of substantially 1/4 wavelength, one end of which is connected to one end of the first arcuate body, and one end of which is connected to the other end of the first arcuate body; A third wave having a length of substantially 1/4 wavelength at some point.
an arcuate body, a fourth arcuate body having a length of substantially 3/4 wavelength, with both ends connected between the other end of the second arcuate body and the other end of the third arcuate body; a first arm that is connected at a position where the first arcuate body and the second arcuate body are connected; a second arm that is connected at a position where the second arcuate body and the fourth arcuate body are connected;
at least a third arm connected at a connection position between the arcuate body and the third arcuate body, and a fourth arm connected at a connection position between the first arcuate body and the third arcuate body, and the second In a directional coupler in which the characteristic admittances of the arc-shaped body and the third arc-shaped body are made equal and the characteristic admittance is selected to be different from the characteristic admittance of the first arc-shaped body, the fourth arc-shaped body is The arc-shaped body is divided into three arc-shaped bodies each having a length of four wavelengths, and the arc-shaped body located at the center is configured to have a characteristic admittance different from the characteristic admittance of the other arc-shaped bodies located on both sides. A hybrid ring directional coupler featuring: 2 Each of the above arms has a characteristic admittance value.
a first section having Y ₀ ; and a second section formed between the first section and the respective connection positions; 2. The hybrid ring directional coupler according to claim 1, wherein the characteristic admittance value of the section portion is different from the characteristic admittance value _Y0 .