Dear all,

      I have a receiver included LNA+downconversion mixer+VCO. It just has RF input and the IF output.
      Actually, how could I measure the port isolation between RF-IF and LO-IF and RF-LO?
      I have two ideas to do this. First method, using the network analyzer, connect port 1 to the RF and port 2 to the IF. S11 measures the input RF impedance and S21 to measure RF-IF isolation.
      Second method, using the signal generator and feed the signal to the RF input port. Using spectrum analyzer to measure the output frequency and see the different power between the input and the output to get the isolation.
       Actually, which method is correct and get more accurate isolation value?
       On the other hand, how could I measure the LO-IF isolation? It is because the LO is generated by the VCO directly.

Best Regards,

wccheng