Bandstop filter with two or more quartz crystals - is designed to permit filter to cover several stop bands

摘要

The bandstop filter allows two or more quartz crystals(Q1, Q2) to be incorporated thereby permitting the filter to be used for several stop bands. The two crystals are connected into a crossed circuit whose diagonals contain reactances that are roughly the reciprocal of the resistance in the pass-bands. The two or more stop bands are attained by choosing the diagonal reactances such that they have a phase condition that is roughly an odd integral multiple of 90 deg. at the given stop frequencies. Specified resonant circuits are connected in parallel with the longitudinal and/or diagonal reactances.