| 摘要 |
PURPOSE:To obtain an attenuation circuit having a frequency of a transmitted phase opposite to that of a conventional pi attenuation circuit by making the impedance resistive at the center frequency, making it capacitive at a lower frequency and making it inductive at higher frequencies. CONSTITUTION:A strip line 5 having a length being integral number of times of 1/2 wavelength whose tip is short-circuited is connected in series with the tip of a resistor 2 having a normalized resistance value RB(RB>1) so as to constitute the circuit. In checking the input impedance of the line 5 viewed from between contacts 3 and 4 next, the impedance ZB of the branch is expressed as ZB=RB(RB>1) and the same characteristic as that of a conventional pi attenuation circuit is obtained. The input impedance of the line 5 is a capacitive impedance and the branch impedance ZB is expressed in equation I . The input impedance at a frequency higher than the center frequency is the inductive reactance and the branch impedance ZB is expressed in equation II. |
