JPS62183601A - Microwave transmission line - Google Patents

Abstract

PURPOSE:To adopt the simple structure subjecting no strain and to reduce the transmission loss by using a 3db directional coupler so as to divide an input electromagnetic wave into two with a phase difference of 90 deg. to each other and coupling them with a rectangular waveguide equally at a distance of a 1/4 of guide wavelength corresponding nearly to the center frequency in the frequency range of the operating electromagnetic wave. CONSTITUTION:An input terminal 1 is connected to the 1st terminal 9a of the 3db directional coupler 9 having four coaxial terminals 9a, 9b, 9c, 9d (1st, 2nd, 3rd and 4th coaxial terminals), an electromagnetic wave from the terminal 9a is divided equally into two electromagnetic waves having a phase difference of 90 deg. to each other, they are outputted to the 2nd and 3rd terminals 9b, 9c and the electromagnetic waves inputted to the 2nd and 3rd terminals 9b, 9c are combined and outputted to the 4th terminal 9d. Through the constitution above, one end of inner conductors 11a, 12a of coaxial lines 11, 12 is inserted into a rectangular waveguide 3 through a respective slit 3a with an equal insertion length and the distance of them is selected to be 1/4 of the guide wavelength in the axial direction of the rectangular waveguide 3. The 3db directional coupler 9 and the coaxial lines 11, 12 are constituted that they are supported incorporatedly to a support base 7 and moved axially along the slit 3a while the insertion length and the distance of the coaxial line inner conductors 11a, 12a are kept constant.

Description

[Detailed Description of the Invention] [Industrial Application Fields] This invention is a microwave system that transmits electromagnetic waves from a coaxial line to a rectangular waveguide and outputs them, and allows the distance between the input end and the output end to be freely changed. Regarding transmission lines.

[Prior Art] FIG. 3 is a perspective view showing a conventional transmission line of this type, as disclosed in, for example, Japanese Patent Application Laid-Open No. 56-47101, in which (1) is a signal input end, and (2) is a signal input end. Output end, (3) is 8
A slit (3a) provided along the axial direction in the center of the surface
(4) is a coaxial line, (4a) is the inner conductor of this coaxial line (4), and one end of it is a rectangular four-wave tube (
3) is inserted into it through the slit (3a). (5) is a non-reflection terminator connected to one end of the waveguide (3), (6) is an isolator provided between the input end (1) and the coaxial line (4), and electromagnetic waves are transmitted from the input end ( 1) to the coaxial line (4) only. (7) is a support stand movable in the axial direction of the rectangular waveguide (3) so as to grip it, and the outer conductor (4) of the coaxial line (4) is attached to this support stand.
4b) is mechanically fixed, which is connected to the coaxial line (
The structure is such that the inner conductor (4a) of 4) can move in the axial direction while keeping the length of insertion into the rectangular waveguide (3) through the sulin l'' (3a) constant.

In the above configuration, the electromagnetic wave applied to the input end (1) is transmitted to the coaxial line (4) via the isolator (6), and the coaxial line protrudes into the rectangular waveguide (3) through the slit (3a). The inner conductor (4a) of the coaxial line (4) protrudes into the rectangular waveguide (3) by the inner conductor (4a) of the line (4).
transmits a part of its energy into the rectangular waveguide (3). The electromagnetic waves transmitted into the waveguide (3) propagate in both directions in the axial direction of the waveguide (3) from the connection point with the coaxial line (4), with one reaching the output end (2) and the other reaching the output end (2). The energy reaches the non-reflection terminator (5) and is absorbed by the non-reflection terminator (5). Electromagnetic waves reflected from the coaxial line (4) without being coupled to the rectangular waveguide (3), the coaxial line (
4) enters the isolator (6), where the energy is absorbed and is not transmitted to the input end (1). The non-reflection terminator (5) absorbs the electromagnetic waves transmitted to it, but without the non-reflection terminator (5), the electromagnetic waves propagated in this direction would be reflected here and directed toward the output end (2). This will cause interference with the output electromagnetic wave directly transmitted to the output end (2). As mentioned above, the transmission line that transmits electromagnetic waves is supported by
7), the slit (3a) of the rectangular waveguide (3)
The input end (1) can be moved by a distance approximately equal to the length of the input end (1), and the distance between the input end (1) and the output end (2) can be freely changed.

FIG. 4 is a vertical cross-sectional view of another conventional example shown in, for example, Japanese Patent Application Laid-Open No. 56-47102, and in the figure, (1) to (4)
) and (7) indicate the same or equivalent parts as the same reference numerals in Fig. 3, the isolator (6) in Fig. 3 is deleted, the non-reflection terminator (5) is replaced with the coaxial line conductor (4a) The structure includes a shorting plate (8) that is movable in the axial direction together with the support body (7) at a predetermined constant interval.

In this configuration, the coaxial line inner conductor (4a) and the shorting plate (
The distance between the inner conductor (4a) and the rectangular waveguide (3) is normally set to about one-fourth of the internal wavelength of the electromagnetic wave transmitted by the rectangular waveguide (3). The phase of the electromagnetic wave that directly advances from the coupling point to the output end (2) can be matched with the phase of the electromagnetic wave that is reflected by the shorting plate (8) and advances to the output end (2), and the non-reflection terminator (5) 1/2 compared to when absorbed
transmission loss.

[Problems to be Solved by the Invention] Since the conventional transmission line is configured as described above, the example shown in FIG. In the example shown in Figure 4, the transmission loss is improved compared to the above, but the support base (7) and the shorting plate (8) are connected through a thin slit (3a), and the mechanical In addition, the shorting plate (8) must move while sliding on the inner wall of the rectangular waveguide (7), which imposes a large mechanical load and tends to strain the strength.

The problem was that it was easily damaged.

This invention was made to solve the above-mentioned problems, and it is a microcomputer with a simple structure that does not require excessive strength, and the distance between the input end and the output end can be freely changed to reduce transmission loss. The purpose is to obtain a wave transmission line.

[Means for solving the problem] The microwave transmission line according to the present invention includes a first, second,
It has four coaxial terminals, a third and a fourth, and converts the input electromagnetic wave from the first terminal into two electromagnetic waves with a phase difference of 90°.
A 3db directional directional generator is provided, which equally divides the waves and outputs them to second and third terminals, and combines the input electromagnetic waves from the second and third terminals and outputs them to a fourth terminal. The input end is connected to the first terminal of the , and the non-reflective termination is connected to the fourth terminal of the edge.

The inner conductor is inserted with equal insertion length into a slit provided along the axial direction in the opposite direction of the H-plane of a rectangular waveguide with one end as the output end, and the inner conductor is inserted along the slit approximately in the frequency range of usable electromagnetic waves. 174 of the waveguide internal wavelength corresponding to the center frequency
They are connected so that they can be moved in the axial direction of the waveguide while being maintained at an interval of .

[Function] In the transmission line of the present invention, the input electromagnetic wave from the input end is divided into two electromagnetic waves having a phase difference of 90' by the 3db direction generator, and the power is divided into two electromagnetic waves with a phase difference of 90', and the power is divided into two electromagnetic waves with a phase difference of 90' from each other. Coupling from the slit to the rectangular waveguide. Both types of magnetic waves with a phase difference of 90° coupled into the rectangular waveguide have equal power because the insertion lengths of the inner conductors of the two coaxial lines into the rectangular waveguide are equal, and they each travel inside the rectangular waveguide. It splits and propagates in both directions. In addition, the conductors in the coupling 2 coaxial line are installed in the tube axis direction of the rectangular waveguide at a distance of 174 times the tube wavelength, which corresponds to the center frequency of the usable frequency range. Electromagnetic waves of equal power in both directions are transmitted to one side with the same phase and strengthen each other, and to the other side with opposite phases and cancel each other out and weaken.

By providing the output ends in this mutually reinforcing direction, electromagnetic waves can be transmitted from the input end to the output end with less loss. - The reflected wave from the connection point between the ten-way coaxial waveguide and the rectangular waveguide returns to the 3db directionality device, is absorbed by the non-reflection end connected to its fourth terminal, and returns to the input end. There isn't.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 is a perspective view showing one embodiment of the present invention, and Fig. 2 is an explanatory diagram of its operation.
) (3a) (7) is the same as the conventional one shown in Figure 3, (1) is the input end, (2) is the output end, (3) is the rectangular waveguide, and (3a) is the A slit (7) is provided along the axial direction in the center of the H-plane of the rectangular waveguide (3), and is a support base mounted movably in the axial direction to grip the rectangular waveguide (3). (9) is a 3db direction genitalia having four coaxial terminals (9a), (9b), (9c), and (9d), the first, second, third, and fourth, and the first terminal (9a) Connect the input terminal (1), and the electromagnetic wave from this terminal (9a) is 9
It is divided into two equal parts of electromagnetic waves with a phase difference of 0" and the second and third waves are divided into two.
The electromagnetic waves output to the terminals (9b) (9c) and input to the second and third terminals (9b) (9c) are combined to form the fourth
The configuration is such that the signal is output to the terminal (9d). (1
0) is the fourth terminal (9d) of the 3db direction genitalia (9)
The non-reflective terminals (11) and (12) are connected to the second and third terminals (9b) of the 3db directional genitalia (9).
) A pair of coaxial lines of equal length connected to (9c), (l
la) (llb) are these coaxial lines (11) (12)
The other ends of the inner conductors of the coaxial line are inserted into the rectangular waveguide (3) through the slit (3a) thereof with equal insertion length, and the distance of the inner conductor (lla) (12a) of the coaxial line is the same as that of the rectangular waveguide (3). They are arranged in the axial direction of the waveguide (3) so as to have an internal wavelength of 174, and these 3 db direction generator (9) and coaxial lines (11) and (12) are integrally supported on a support base (7). , the coaxial line inner conductor (lla) (12a) is configured to be able to move in the axial direction along the slit (3a) while keeping the insertion length and distance thereof constant.

The electromagnetic wave applied to the input end (1) is divided into two electromagnetic waves with a phase difference of 90' by the 3db direction generator (9), which enter the coaxial lines (11) and (12) and are connected to a rectangular conductor. The inner conductor (ll) of each of the coaxial lines (11) and (12) inserted into the slit (3a) of the wave tube (3)
a) Transmit part of the energy by (llb) into the rectangular waveguide (3), respectively. Some of the electromagnetic waves transmitted to the rectangular waveguide (3) travel toward the output end (2), while others travel in the opposite direction. In addition, a rectangular waveguide (3
) and then to coaxial lines (11) and (12). The progress of these electromagnetic waves is as indicated by the arrows in FIG.

In coupling the coaxial line (11) and the rectangular waveguide (3), the coaxial line (11) is connected to the output end (2) of the rectangular waveguide (3).
), the coupling coefficient (electric field coupling coefficient) is C
Then, the coupling coefficient of the coupling going in the opposite direction to the output end (2) is also C, and the coupling coefficient goes in the opposite direction to the output end (2) inside the rectangular waveguide (3). The coupling coefficient by which the in-wave is coupled to the coaxial line (11) is also C.

The coaxial line (12) is the same as the coaxial line (11), and the length of the inner conductor (12a) inserted through the slit (3a) of the rectangular waveguide (3) is also the same as the inner conductor (11) of the coaxial line (11).
lla), the coupling between the coaxial line (12) and the rectangular waveguide (3) is the same as that for the coaxial line (11), and its coupling coefficient is C. Connect the terminal (9b) to the coaxial line (11) here, and connect the coaxial line (11) to the coaxial line (11).
) and the rectangular waveguide (3), and the distance between the connection point of the coaxial line (12) and the rectangular waveguide (3) is L, then the output power of the output end (2) and the input end ( 1) Ratio P to the input power
2 and output terminal (2) and the power and input terminal (
The ratio P3 to the input power in 1) is as follows, where 2a is the width of the H-plane of the rectangular waveguide.

- In the case of the conventional power cylinder shown in Figure 3, the ratio of the output power at the output end (2) to the input power at the input end (1) is P2', and the power going in the opposite direction to the output end (2) and the input end ( If the input power ratio of 1) is p31, then p,'=c''p,'=c2 where L=--.

WRJ-10 is used for the rectangular waveguide (3), and the usable frequency range of this rectangular waveguide (3), that is, 8GIIz to 1
Assume that a 2 GHz electromagnetic wave is passed through the transmission line of this embodiment.

Same wave number! ], 8G) The free space wavelength and pipe wavelength for Iz, 8 GHz, and 12 GHz are λg and λ, respectively,
If λg and λH1λgH, then λ.

One = 0.6245 λgL λg.

1=1.38 P2'2 C'F(c)=1--+0.827f;F=-vr:+
o, 527) 2+1-(0,527)")...(1
0) F(c)=1.827, so 1.3347≦F(c)<1.827, L334
7≦−<1.827.

P2' Letting the right side of equation (9) be f (c).

C2 f(c)=1---0.827fr;F=-(fi-C
t-0,827)"+1-(0,827)2)...
(12)=0.165, and takes the minimum value when C=0, and f(c)=0.158, so f(c)≦0.
It becomes 165.

From the above results, for the rectangular waveguide WRJ-10.

By setting the spacing between the coupling parts between the two coaxial lines and the rectangular waveguide to 1/4 of the pipe wavelength corresponding to the frequency of 9.8 GHz, the distance between the input end and the output end can be improved over the entire operating band (8 to 12 Gllz). The transmission loss can be reduced by 1.2 db to 2.6 db compared to the conventional one shown in FIG. Further, the power directed in the opposite direction from the output end can be reduced by about 8 db compared to the conventional one shown in FIG.

When the coupling coefficient is smaller than 1/fX at the two coupling points between the coaxial line (11) (12) and the rectangular waveguide (3), the connection is made between the coaxial line (11) (12) and the rectangular waveguide (3). There is power that remains uncombined. This power is reflected at the coupling part and returns to the 3db directional coupler (9) again, but this reflected power is combined in the 3db directional coupler (9) and output to the fourth terminal (9b). Non-reflective termination (10)
absorbed into.

Although the basic configuration of the present invention was shown in the above embodiment, there is a connection between the input end (1) and the 3db directional connector (9) in the direction from the input end (1) to the 3db directional connector (9). An isolator may be inserted in consideration of directionality so as to pass electromagnetic waves through the rectangular waveguide (3), and a non-reflection terminator may be provided on the side opposite to the output end (2) of the rectangular waveguide (3). By providing the above-mentioned isolator and non-reflection terminator, interference with reflected power can be eliminated, and the characteristics can be further improved.

[Effects of the Invention] As described above, the present invention uses a 3 db direction generator to divide input electromagnetic waves into two equal parts with a phase difference of 90'', and transmits the input electromagnetic waves into a rectangular waveguide with approximately the center frequency of the frequency range of usable electromagnetic waves. Since they are coupled equally at a distance of 1/4 of the corresponding wavelength in the waveguide, transmission loss can be reduced.
In addition, since only one pair of coaxial lines can be moved while connected to the rectangular waveguide, there is no need to provide a shorting plate that slides inside the rectangular waveguide, making the structure simple and mechanically easy. This has the effect of making it possible to easily change the distance between the input end and the output end at a low cost.

[Brief explanation of drawings]

Fig. 1 is a partially cut-out perspective view showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of its operation, and Fig. 3 is a partially cut-out view showing an example of a conventional microwave transmission line. The perspective view and FIG. 4 are longitudinal sectional views showing another example of the conventional one. In the figure, (1) is the input end, (2) is the output end, (3) is the rectangular waveguide, (3a) is the slit, (7) is the support base, (
9) is a 3db directional connector, (9a) (9b) (9c
) (9d) are the first, second, third, and fourth terminals, (lO
) is a reflection-free termination, (11) and (12) are coaxial lines, (ll
a) (12a) are their inner conductors. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] (1) Transmitting an input electromagnetic wave to a rectangular waveguide having a slit provided along the axial direction in the center of the H plane via a coaxial line coupled to the slit at a movable position in the axial direction, The microwave transmission line output from one end of the rectangular waveguide has four coaxial terminals, first, second, third, and fourth, and input electromagnetic waves from the first terminal thereof. is divided into two equal electromagnetic waves with a phase difference of 90°, and the second
, a 3db directional coupler which outputs to a third terminal, combines input electromagnetic waves from the second and third terminals, and outputs the resultant to a fourth terminal, Connect the input end to the terminal, connect the non-reflection termination to the fourth terminal, connect one end of a pair of coaxial lines of equal length to the second and third terminals, and connect the other end of these coaxial lines. , an inner conductor is inserted into the rectangular waveguide through the slit with an equal insertion length, and is maintained at intervals of 1/4 of the wavelength in the waveguide corresponding to approximately the center frequency of the frequency range of usable electromagnetic waves along the slit. A microwave transmission line characterized in that the microwave transmission line is coupled so that the waveguides can be moved in the axial direction when the waveguides are connected. (2) A patent claim in which the 3db directional power feeder and the pair of coaxial waveguides are placed on a support stand provided to grip the rectangular waveguide so as to be movable to the rectangular waveguide. The microwave transmission line according to item 1.