When used in filter design, the 'L' network analysed above is usually referred to as a half section.
As with other artifacts, their minimization is a criterion in filter design.
The amount of ripple can be traded for other parameters in the filter design.
Both of these were important problems in network theory and filter design.
But another group of commercial programs offer filter design as a part of the package.
Although not as extensive in its filter design as some of the above, it is still an impressive product.
Whether or not Zobel's filter design would be good for a hi-fi system is another question.
It is primarily used in active filter design and miniaturization.
Transmission lines and certain types of filter design use the image method to determine their transfer parameters.
Prototype filters are used to make the process of filter design less labour intensive.