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What is your definition of transmission line Q factor?
You can use these equations in ADS DDS window.
y=stoy(dataset_name..S)
Q=-imag(y(1,1))/real(y(1,1))
Remember this is for a 2 port network.
Assuming that Q is relatively high (say >10), you can determine Q based on the complex impedance versus frequency curve.
For a circuit that behaves around its resonant frequency as an RLC circuit (for example quarter wave sections), the -3 dB impedance points are at the positions where |Im(Z)|=Re(Z).
When plotted on a smith chart the curve should cross the horizontal centerline vertically. If not, you should rotate the graph (for example by adding some loss free transmission line section).
You may also match your resonator (lossfree components) to a convenient real impedance so that at the center frequency RC = 0. Where |RC| = 0.33, you have the VSWR=2 frequencies. When they are (for examle) 10 MHz apart, the -3 dB frequencies are 10*sqrt(2) = 14 MHz apart. Now you can calculate Q based on fcenter/(-3dB band width).
Assuming that Q is relatively high (say >10), you can determine Q based on the complex impedance versus frequency curve.
For a circuit that behaves around its resonant frequency as an RLC circuit (for example quarter wave sections), the -3 dB impedance points are at the positions where |Im(Z)|=Re(Z).
When plotted on a smith chart the curve should cross the horizontal centerline vertically. If not, you should rotate the graph (for example by adding some loss free transmission line section).
You may also match your resonator (lossfree components) to a convenient real impedance so that at the center frequency RC = 0. Where |RC| = 0.33, you have the VSWR=2 frequencies. When they are (for examle) 10 MHz apart, the -3 dB frequencies are 10*rt(2) = 14 MHz apart. Now you can calculate Q based on fcenter/(-3dB band width).