JPS6138889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a set-preparation type microwave synthesizer.

Conventionally, in this type of microwave synthesizer, as shown in the block diagram of FIG. 3,3'. In these modulators, microwaves are modulated with baseband signals. The outputs of these microwave modulators 3, 3' are selectively distributed by a signal switching distributor 14 using a diode switch, and amplified to a predetermined level by amplifiers 8, 8', respectively.
The combined output is output at the output terminal 10.
taken out.

Here, 7 is a semi-fixed phase shifter which corrects the phase difference between the microwaves passing through the amplifiers 8 and 8' and provides a phase difference of approximately 90°. Further, 11 is a microwave detector for monitoring the output power, 12 is a microwave detector used when adjusting the phase of the microwave by the semi-fixed phase shifter 7, and the microwave is synthesized at the output end 10. At that time, the output of the microwave detector 12 becomes zero. Further, reference numeral 13 denotes a logic drive board that monitors the operating state of the microwave modulator and drives the diode switches 4 and 4' using a current/standby switching signal in the event of an abnormality.

Next, the conventional signal switching distributor 14 will be explained in detail. As shown in Fig. 2, this distributor 14 is composed of two sets of diode switches 4, 4'T branch 5, and a 3dB hybrid 6, and one of the diode switches 4, 4' is turned on by an external drive current. (i.e. signal passing), the other is OFF
(i.e., signal cutoff) state.

Here, the case where the diode switch 4 is ON and the diode switch 4' is OFF will be described. In the T-branch 5, the distance between the branch point 19 and the first diode 20 of the diode switch is chosen to be 1/4 wavelength (λ). By doing so, the diode 20 becomes short-circuited when the diode switch 4' is OFF, and the impedance looking at the diode 20 from the branch point 19 becomes infinite when the diode 20 is completely short-circuited. However, since the diode 20 generally has some series resistance, the impedance at the branch point 19 is a finite value, but it is much larger than the impedance of the T-branch transmission line, so it is practically This is the same state as when the diode switch 4' is not connected to the T-branch. Therefore, the microwave signal input from the input end 15 passes through the T-branch 5 and appears equally at the output ends 17 and 18 of the hybrid 6.

Next, diode 20 fails and becomes open.
When the condition is reached, the position of the short circuit of the diode switch 4' moves to the position of the diode 21.
Generally, in this type of diode switch, the distance between each diode is 1/4λ electrically, so the distance between the branch point 19 and the diode 21 is 1/2λ.
Therefore, when diode 21 is short-circuited, branch point 19
is also short-circuited, and the microwave signal is transferred to this branch point 1.
9 and no longer appears at output ends 17 and 18. In this way, failure of the diodes 20 and 22 provided on the T branch side of the diode switch results in system failure, which is the biggest drawback of this type of set reserve system.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microwave synthesizer that prevents system interruption when such a diode fails.

The present invention uses a 3 dB hybrid instead of a T-branch in the signal switching divider, and further provides a switch that works in conjunction with a diode switch in the amplifier synthesis circuit to create a microwave synthesizer that does not cause system interruption even in the event of a diode failure. This has been realized.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a configuration diagram of an embodiment of the present invention. The difference between this figure and FIG. 1 is that the T-branch 5 has been deleted and a switch 23 interlocked with a diode switch has been added. Note that the same components as in FIG. 1 are given the same numbers.

Before explaining the operation of this embodiment, the operation of the synthesis circuit shown in FIG. 4 will be explained first. The signal input from the terminal 24 of the 3 dB hybrid 6 is divided into two, and signals with equal amplitude and a phase difference of 90° appear at terminals 26 and 27. In this case, the signal to terminal 27 lags the signal to terminal 26 by 90°. These terminals 26, 2
The signals of 7 are further synthesized by the 3 dB hybrid 9, and have the same phase at the terminal 29 and have the opposite phase at the terminal 28. Therefore, a signal input from terminal 24 is output from terminal 29. On the other hand, the signal applied to terminal 25 is similarly output to terminal 28. Terminals 24, 25 like this
The combined output of the signals applied to the output terminals 29 and 28 appears at output terminals 29 and 28, respectively. That is, the output terminal differs depending on the input terminal of the signal.

Applying this explanation to FIG. 3, the signals passing through the diode switches 4, 4' appear at the output terminals separate from terminals 29, 28. Therefore, a switching device (for example, a latching circulator 23) that operates in conjunction with the diode switch is provided in the output circuit, and when a signal appears at the terminal 29, that is, when the diode switch 4 is operating, the switching device 23 is switched so that the signal passes in the direction of the solid line, and when the diode switch 4' is operating, the switch 23 is switched so that the signal passes in the direction of the dotted line. It can be taken out from 10. Further, the microwave detectors 11 and 12 can be used to adjust the level of each part so that when one is inputting, the other is not inputting, as in the conventional case.

As explained above, if the present invention is used, the diode of the diode switch is changed to 1 as in the conventional device.
Even if one or two of them fail, the system will not be interrupted. Furthermore, when the output of the microwave modulator 3 is used, interference noise due to deterioration of isolation of the diode switch, ie, the output of the microwave modulator 3' becomes a noise source. However, as explained in FIG. 4, since the input from each terminal appears at the other terminal in the output of the combining circuit, the output of the microwave modulator 3' in this case, that is, the interference noise, is suppressed at the output terminal 10. , the quality of the system will not deteriorate due to diode switch failure.

FIG. 5 shows another embodiment of a switching device in which an isolator is added to the output switching circuit 23. A synthesis circuit that operates in this manner may be coaxial, stripline, or waveguide, and the output side switch may be a diode or mechanical type other than a latching circulator. Applicable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional synthesis device, FIG. 2 is a circuit diagram of a conventional signal switching distributor, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a diagram of the synthesis circuit of FIG. The explanatory diagram, FIG. 5, is a circuit diagram of another embodiment of the switching circuit of FIG. 3. In the figure, 1... Signal input terminal, 2, 6, 9... 3dB hybrid, 3, 3'... Microwave modulator, 4,
4'...Diode switch, 5...T branch, 7
... Semi-fixed phase shifter, 8, 8' ... Microwave amplifier, 10 ... Signal output terminal, 11, 12 ... Microwave detector, 13 ... Logic drive board, 14 ... Signal switching distributor, 15, 16...Diode switch input terminal, 17, 18, 24, 25, 26, 27,
28, 29...hybrid input/output terminal, 19...
Branch points of the T branch, 20, 21, 22... diodes, 23... switching devices, 30, 31... isolators.

Claims (1)

[Claims] 1 branching means for branching the input signal to be modulated;
first and second modulating means that respectively modulate each output of the branching means with microwaves; and first and second modulating means that respectively switch each output of these modulating means by a predetermined control signal supplied to a signal switching diode. a first hybrid which inputs the respective outputs of these switching means to the first and second terminals and outputs them to the third and fourth terminals with a phase difference of 90°; A semi-fixed phase shifter connected to the third terminal, an amplifier that amplifies the output from this phase shifter and the output from the fourth terminal, and a 90° phase difference between the outputs of these amplifiers. a second hybrid that outputs each of the signals, a third switching means that switches and outputs each output of the second hybrid according to the control signal, and an output level of each of the modulation means that is equal to or higher than a predetermined value. a logic circuit that generates each of the control signals supplied to the first, second, and third switching means so as to select the first, second, and third switching means.