Examples of electric wave filters using ferrite inductors

The paper deals with an application of ferrite inductors where their high Q-factors are of prime importance. The design and performance of two pairs of complementary low- and high-pass filters using ferrite inductors is discussed. The filters provide a discrimination of 40 dB between pass and stop bands. In the first version, the pass band of the low-pass filter ends at 59·4 kc/s and the stop band begins at 60·6 kc/s In the improved version, the transition range has been reduced to 59·7¿60·3 kc/s. The use of these filters as group-separating filters in a 24-circuit carrier-on-cable telephone system is considered.