I have been attempting to calculate the noise figure of a feedforward amplifier using the CNF parameter. The results have not always made sense.
In reviewing my calculation I took apart the system to make the calculation simpler and found an anomoly with the model for the single directional coupler (Coupler). It seems that if I simply cascade a coupler on the front of an amplifier, the calculated noise using the CNF parameter does not always make sense. Replacing the Coupler with an attenuator of equivalent loss, yields a noise figure that seems correct.
Any ideas what I am missing or have done wrong?
In reviewing my calculation I took apart the system to make the calculation simpler and found an anomoly with the model for the single directional coupler (Coupler). It seems that if I simply cascade a coupler on the front of an amplifier, the calculated noise using the CNF parameter does not always make sense. Replacing the Coupler with an attenuator of equivalent loss, yields a noise figure that seems correct.
Any ideas what I am missing or have done wrong?
Please send a copy of the workspace to support@eagleware.com and
mention what you're seeing. We can confirm the diagnosis or, if something else is at play, we can help to identify that for you.
In the meantime, you may experiment by changing the isolation in
the coupler to some very high value such as 100dB, see if that causes
the results to cooperate more as would be expected.
Again, please send a copy of the workspace to the email mentioned
above. We'll gladly review & confirm / comment. Also please be
sure to include what operating system is on the PC and what is the
serial number of the hardware key and version of Genesys software
you're using (both available within Genesys from main menu HELP,
ABOUT...)