The Design of Arithmetically Symmetrical Band-pass Filters

A method is described for the (insertion loss) design of wide-band band-pass filters to exhibit arithmetically symmetrical characteristics. The method consists of a periodic transformation of the frequency variable, truncation of the resulting infinite product in the characteristic function, and finally, correcting the truncation error by a compensating function. The last step involves a certain amount of numerical or graphical approximation, but the required accuracy is usually quite easy to satisfy by elementary methods. As a special case, the design of constant group delay band-pass filters is also described.