| 摘要 |
PURPOSE:To control an input signal and to obtain a large quantity of attenuation, by applying the amplified output of an AGC voltage to DC magnetic circuits corresponding to the 1st and the 2nd high frequency magnetic circuits so as to obtain different varying directions of voltage for the amplified outputs. CONSTITUTION:The high frequency coils of high frequency magnetic circuits L2 and L4 provided to the 1st and the 2nd saturated magnetic circuits 1 and 2 are connected in series between a signal input terminal 3' of an antenna 3 and an earth. The amplified output of an amplifying circuit 4 of AGC voltage is impressed to a DC coil of a DC magnetic circuit L3. An inverting circuit 5 inverts the output of the circuit 4 so that it changes in the relative direction and in response to the increment/decrement of the AGC voltage and then impresses it to the DC coil of a DC magnetic coil L1. The saturated magnetic circuit gives the magnetic saturation to the high frequency magnetic circuit with the DC voltage which is impressed to the DC magnetic circuit and therefore varies the high frequency resistance. As a result, an input signal is controlled and then transmitted by impressing the amplified output of AGC voltage to each DC magnetic circuit with different varying directions of voltage. |
