On Tue, Sep 3, 2019 at 11:36 AM, RFy wrote:
Any genius/proper methods of measuring over 30dB powered source impedance?
In order to measure source impedance, you're needs to measure amplitude for different loads. Since many RF PA cannot handle open output properly you will need to use two different loads which impedance is compatible with PA output impedance. For example 25 Ohm and 75 Ohm. If your PA has very limited range for load impedance, use something like 40 Ohm and 60 Ohm. The goal is to get more different load to get more precision.
So, you have load R1 and load R2.
Just connect R1 and measure amplitude U1.
Then connect R2 and measure amplidue U2.
Now you can calculate source impedance:
Z = (R1 - R1*(U1/U2)) / (U1/U2 - R1/R2)
The only problem here is to measure RF signal amplitude on the load properly. This is not so easy task. You can use wide bandwidth oscilloscope for that.
