| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable attenuator for microwaves which makes a reflection quantity zero, even when varying an attenuation quantity. SOLUTION: This attenuator is provided with aλ/4 line 4 having an electrical length ofλ/4 at a using frequency, plural serial resistors 3a and 3c connected serially to the input side of theλ/4 line 4, plural serial resistors 3b and 3d connected serially to the output side of theλ/4 line 4, plural parallel resistors 5a and 5b connected serially between an input terminal 1 and the serial resistor 3c on the input side, a metallic line 6 and connecting terminals 7 and 8 for short-circuiting and inserting these resistors 3a to 3d, 5a and 5b. Then the reflecting quantity of the attenuator is made zero by cancelling the reflecting quantities of the serial resistors 3b and 3d by loading these parallel resistors 5a and 5b, and the reflecting quantity is made zero even varying the attenuating quantity by connecting a serial resistor and a parallel resistor by switching.
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