Where To Find This Example
How to use the gamma probe to measure the impedance at an internal location in a circuit.
In this project, there is a very simple schematic called "gamma probe" with a capacitor and an inductor. In between these elements is the gamma probe element. The graph called "gamma" is showing the results from this schematic. The first measurement is plotting the impedance looking to the right of the gamma probe, which is a capacitor and a 50 ohm termination. The second measurement is plotting the impedance looking to the left of the gamma probe, which is an inductor and a 50 ohm termination.
To verify the results, look at the "compare capacitor" and "compare inductor" graphs and see that the responses are identical. Also, look in the output equations block. Equations were used to extract the capacitance and inductance values from the gamma values. For the capacitance, the value of gamma was returned from the measurement. Then impedance was calculated from gamma. The imaginary part of the impedance as calculated. The "f=swpvals()" equation is used to get the project frequencies. Finally the value of capacitance is calculated. Notice that the capacitance and inductance value calculated is identical to the values set in the "gamma probe" schematic.
Notice that if you want to see the results of an equation, you use the ":" operator where type the variable name and then the ":" character to list the variable values. See the output equations to see the results of each equation. Also, you can hit F6 to update equations if a change is made without re-simulation.