denote the th pole of the lossless prototype. Neglecting phase in the loss filter , the substitution
only affects the pole radius, not angle.
Assuming , pole moves from to
Desired Pole Radius
Pole radius and are related by
The ideal loss filter therefore satisfies
The desired delay-line filters are therefore
Now use invfreqz or stmcb, etc., in Matlab to design low-order filters for each delay line.