Realization of a Band-Stop Filter from a Low-Pass Filter Using a Chain of Bridged T-Networks.

It is a well-known fact that for the realization of a band-stop filter from a low-pass filter the network with a transformer is more economical than one with ladder configuration (approximately 30% fewer components). It is also known that the introduction of a bridged T-network to eliminate the transformer, while maintaining a reduced number of inductances, proves difficult and possible only in certain cases. At the same time, the limit frequencies of the band must necessarily be close to one another. A method is presented for the realization of a band-stop filter by cascading bridged T-networks. This system, while being more economical than the ladder type filter, compared with a single bridged T-filter, offers also a wider range of applicability and notably wider separation for the limit frequencies.