JPS6156882B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a waveguide choke used in microwaves.

In microwave coaxial lines or waveguides, when two coaxial lines or two waveguides are mechanically non-contact and electrically connected, a quarter-wavelength choke is provided in the non-contact part. There is a need.

FIG. 1 is a perspective view showing an example of a two-frequency band common waveguide yoke. In the figure, 1 is an inner conductor, 2 is an outer conductor, and 3 is a coaxial line, 4 is a circular waveguide, 5 is a circular waveguide 4
The yoke H and 6 operate on the TE ₁₁ mode wave in the high frequency band _H propagating in the coaxial line 3, and the yoke L operates on the TEM mode wave in the low frequency band _L propagating in the coaxial line 3.

FIG. 2 is an enlarged cross-sectional view of a part of the yoke H5 and the yoke L6.
The side portion is C, the non-contact portion located between A and C is B, the bottom portion in the depth direction of the yoke L6 is D, and the coaxial line 3 side portion of the yoke L6 is E. Part B is also at a position intermediate between parts C and D. Let the distance between A and B portions and B and C portions be l _H , and the distance between B and D portions and B and E portions be l _L .

First, the principle of operation of the yoke H5 will be explained.

When the TE ₁₁ mode wave propagates in the circular waveguide 4,
A TE ₁₁ mode wave of the coaxial line is excited in the chain H5. This is shown in FIGS. 3 and 4. In the figure, the arrow shown in the circular waveguide 4 indicates the electric line of force of the TE ₁₁ mode wave of the circular waveguide, and the arrow shown in the yoke H5 indicates the TE ₁₁ of the coaxial line when the yoke H5 is used as a coaxial line. Shows the electric field lines of mode waves.

FIG. 4 is a sectional view of the portions indicated by A and B in FIG. 3.

Now, let the tube wavelength of the coaxial line TE ₁₁ mode wave in the chain yoke H5 for _{the H} wave be λg ^TE11 _H , and l _H = λg ^TE11 _H /4 ...(1), then the A part of the yoke H5 is electrically Since they are short-circuited, portions B and C are electrically open and short-circuited, respectively. Therefore, although the circular waveguide 4 is mechanically non-contact at the portion C, it is electrically short-circuited, and thus operates as an electrically continuous circular waveguide 4.

Next, the principle of operation of the yoke L6 will be explained.

The operating principle of the yoke L6 is similar to the operating principle of the yoke H5 described above. That is, since the TEM mode wave propagates through the coaxial line 3, the TEM mode wave is excited in the chain yoke L6. For this reason, the wavelength of the TEM mode wave in the chiyoke L6 is set to λ
^TEM _L and the depth l _L of the yoke L6 as l _L =λ ^TEM _L /4 (2), the E portion is electrically short-circuited.

The electric characteristics of each of the yoke H5 and the yoke L6 are relatively good over a wide band. However, within the used band, the performance deteriorates slightly at frequencies other than the design frequency.

When using a short-circuited cheese yoke H5 where the C portion is electrically incomplete, the coaxial line in the yoke H5
The TE ₁₁ mode wave leaks into the cheese yoke L6 through the non-contact portion of the B portion, and the TE ₁₁ mode wave of the coaxial line is excited in the cheese yoke L6. If the tube wavelength of the TE ₁₁ mode wave of the coaxial line excited in the cheese yoke 6 is λ ^TE11 _L , then the integer multiple of 1/2 of λ ^TE11 _L is l _L
At a frequency equal to , the B portion of the chain yoke L6 becomes electrically short-circuited.

Therefore, the portion C of the yoke H5 becomes electrically close to an open state, and the circular waveguide 4 using the yoke H5 exhibits electrically discontinuous characteristics.

Therefore, in the conventional two-frequency band common cheese yoke, even if the yoke H5 and the yoke L6, which are optimally designed for _H and _L waves, are used, _{the H} ,
Depending on the frequency ratio of _L , deterioration of VSWR and increase in transmission loss may occur in high frequency bands used. For this reason, conventionally, in order to avoid such a phenomenon, the shape of the joint yoke L6 of the two-frequency band common yoke was limited, which had the disadvantage that an optimal design for _{the L} wave could not be performed.

In order to eliminate these drawbacks, the present invention provides a slit in which a resistor is inserted in the tube axis direction of the tube wall on the coaxial line side of the choke for low frequency bands, and will be described in detail below with reference to the drawings.

FIG. 5 shows an embodiment of the present invention, in which numerals 1 to 4 are the same as those shown in FIG. 7 is a resistor-containing slit in which a resistor is inserted into a long slit in the tube axis direction provided in the tube wall on the side of the coaxial line 3 of the yoke L6 in FIG. This is a slit-equipped cheese yoke L that operates against the slit. Although not shown in the figure, the yoke H5 shown in FIG. 1 is provided between the slitted yoke L8 and the circular waveguide 4 in the same manner as in FIG. FIG. 6 shows an enlarged view of the resistor-containing slit 7. Four resistor-containing slits 7 are provided symmetrically in the circumferential direction.

The slit 7 with a resistor is a chiyoke L with a slit.
8, the wall current of the TEM mode wave flowing through the outer wall with the slit has only a component in the direction of the tube axis, so it has almost no effect. However, the resistor-containing slit 7 has the effect of greatly attenuating the circumferential component of the wall current of the TE ₁₁ mode wave flowing in the outer wall with respect to the TE ₁₁ mode wave excited in the slit-equipped cheese yoke L8.

Therefore, the slitted cheese yoke L8 exhibits good electrical characteristics similar to the conventional cheese yoke L6 for TEM mode waves in the low frequency band _L of the coaxial line 3, and exhibits good electrical characteristics in the high frequency band L of the circular waveguide 4. _{HTE 11}
Regarding mode waves, the coaxial line _TE11 mode waves excited in the slitted cheese yoke L8 cause almost no deterioration in transmission characteristics.

Therefore, in this two-frequency band shared waveguide choke, regardless of the frequency ratio of the _L and _H waves,
It is possible to design the chiyoke shape to be optimal for each of the _L and _H waves, and it is possible to obtain good electrical characteristics for both the _L and _H waves.

In addition, although the case in which the number of slits is four has been described above, it is not limited to four, and the axial length of the slits may be shorter than the axial length of the choke for low frequency bands.

As described above, in the dual-frequency band joint choke according to the present invention, the high frequency band excited in the low frequency band choke by the resistor-containing slit provided in the tube axis direction on the outer wall of the low frequency band choke.
Since the TE ₁₁ mode wave is attenuated, it is possible to optimally design a cheese yoke for low frequency bands, and it is possible to obtain a cheese yoke that exhibits good electrical characteristics over a wide range of both low and high frequency bands. There are advantages.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional two-frequency band common waveguide chain, Figure 2 is a cross-sectional view of the chain section in Figure 1, and Figure 3 is a coaxial line TE ₁₁ excited in the high frequency band station section. 4 is a sectional view of parts A and B in FIG. 3, FIG. 5 is a perspective view of an embodiment of the present invention, and FIG. 6 is a diagram for explaining mode waves.
FIG. 6 is an enlarged view of the slit portion containing the absorbent body in FIG. 5; In the figure, 1 is an inner conductor, 2 is an outer conductor, 3 is a coaxial line, 4 is a circular waveguide, 5 is a chain H, 6 is a chain L, 7 is a slit with a resistor, and 8 is a chain L with a slit. . It should be noted that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1. The TE 11 mode is provided in the inner conductor of a transmission line having a structure in which a circular waveguide in which the TE ₁₁ mode wave propagates is provided in the inner conductor of the coaxial line in which the TEM mode wave propagates, and the TE ₁₁ mode is combined concentrically. In the two-frequency band shared waveguide cheese consisting of a cheese for waves and a cheese for TEM mode waves, the TEM mode wave
A waveguide chain for dual frequency bands, characterized in that a plurality of slits elongated in the tube axis direction are provided symmetrically in the circumferential direction on the side wall surface of the coaxial line of the mode wave chain, and a resistor is inserted into the slits.