I'm trying to figure out (with not a lot of success) as to what I need to consider when I want to minimize reflection coefficient below a certain point. I'm trying to design a low-pass shunt stub filter with reflection coefficient below -12 dB (and a given \$f_C\$, but that part is easy).
I tried different orders of Chebyshev filters and I tried swapping the filter design to Buttersworth/Bessel, but they all had their own characteristic reflection coefficients that way exceeded the desired value (example, Bessel's reflection coefficient would be very big towards f=0 Hz and would decline somewhat fast, though it was still too high of a value from what I desired).
So I have a few things I'm pondering about it.
If my pass-band is whatever it is, do I usually have to care about the reflection coefficient at extremely border cases (just at the cut-off frequency or after it or at near-zero frequencies when the cut-off frequency is at GHz scale)
What things should I consider when I want to minimize reflection coefficient up to a point?
And if someone thinks that I've fundamentally approached the problem in a bad manner, that'd be great to know as well.