Plotting conductance circles to find shunt resistor to stabilize bjt using ADS.

Good day,
I am designing the front end for a 2m HAM radio. I have selected and bjt and simulated the load stability and found it to be unstable. I have chosen the method of a shunt resistor on the collector. The method requires me to plot conductance circles on the smith chart as close as possible to the plotted load stability circle. Then read of the value on the diameter of the smith chart(the real normalized value) and normalize the value and place this in shunt with the collector of the bjt. I have used information from agilent forums to plot a circle but instead of giving me one circle it gives me many different circles creating a bigger circle.
The equation I used was conductance_circle=circle(center, radius, numPts).
I have tried to increase the radius but this causes my circle to disappear off the smith chart.
I look forward to the insight on this matter.
Thank you.