Hello,
I am measuring inductors that are mounted as shunts and am curious on the smith chart readings I get.
Some readings start as a short and move to the 50Ohm center, but other times the chart shows a negative impedance on the outside of the short that moves into the 50 ohm center. S21 shows a gain where the impedance is negative, but how can this be?
It all depends on whether I am using a co-planar type ground plane or if the coil is actually wrapped to the backside ground plane. Am I really doing something wrong by using a coplanar ground if I see a gain in S21?
I am measuring inductors that are mounted as shunts and am curious on the smith chart readings I get.
Some readings start as a short and move to the 50Ohm center, but other times the chart shows a negative impedance on the outside of the short that moves into the 50 ohm center. S21 shows a gain where the impedance is negative, but how can this be?
It all depends on whether I am using a co-planar type ground plane or if the coil is actually wrapped to the backside ground plane. Am I really doing something wrong by using a coplanar ground if I see a gain in S21?