Minimum Insertion Loss Filters

A generalized criterion is given for the design of minimum loss Butterworth and Tchebycheff filters of arbitrary bandwidth and component quality. This criterion is chosen to minimize the insertion loss in the center of the band and is particularly useful for microwave filters, where insertion loss must be minimized. Two general curves are given for this design, together with information as to the method followed in obtaining them. It is shown that, if insertion losses are to be minimized, the use of Tchebycheff filters with ripples greater than very small fractions of one decibel must be discouraged.