Smith chart stars/circles not rendered correctly for shorted load

[iwbnwif]

In the following simulations, S[1,1] has a low value resistance as a load while S[2,2] has a short. The electrical length of the transmission line is approximately lambda/2 so there should be a complete circle for both simulations. This only occurs for loads approximately < 0.1R.

smith_problem_0R.zip

[ra3xdh]

I confirm this bug. The solid line curve type is rendered correctly, but the circles is not.

[tomhajjar]

Does it in ngspice as well. You can vary Td over a wide range and plot looks similar. Only star spacing changes.

S-parameter plot.zip