| 摘要 |
PURPOSE:To control an input signal and to obtain a large quantity of attenuation, by applying the AGC voltage the DC magnetic circuits of the 1st and 2nd high frequency magnetic circuits with voltage changing directions different from each other. CONSTITUTION:The high frequency magnetic circuit L2 of the 1st saturated magnetic circuit 1 is connected between a signal input terminal (p) of an antenna 3 and an earth; and the high frequency magnetic circuit L4 of the 2nd saturated magnetic circuit 2 is connected between the terminal (p) and a circuit of the next stage, e.g., a high frequency amplifying circuit respectively. The amplified output of an amplifying circuit 4 of AGC voltage is applied to a DC coil of a DC magnetic circuit L1. The output of the circuit 4 is inverted by an inverting circuit 5 so that it changes in the relative direction in response to the increment and decrement of the AGC voltage. This inverted output is applied to a DC coil of a DC magnetic circuit L3. |
