You can't just connect your VNA to the circuit as you have drawn. Doing so will change the behavior of the network you are trying to measure.

You can still do what you want though. Just disconnect the transmission line from the transmitter and connect your VNA there. Do a one port reflection measurement of the transmitter, and from this design your matching network. You can then do another measurement to confirm the match. This is then repeated for the receiver. Disconnedt transmission line, connect VNA, measure reflection, design matching network, verfiy network.

Now each side is matched. You can connect your transmission line back in and everything should work.

Depending on the frequency of operation and the type of transmission lines you are working with connecting and disconnecting these things may not be trivial. If you arent careful you can introduce error in your measurement.

You can't just connect your VNA to the circuit as you have drawn. Doing so will change the behavior of the network you are trying to measure.

You can still do what you want though. Just disconnect the transmission line from the transmitter and connect your VNA to the transmitter at this point. Do a one port reflection measurement of the transmitter, and from this design your matching network. You can then do another measurement to confirm the match. This is then repeated for the receiver. Disconnect transmission line, connect VNA, measure reflection, design matching network, verify network.

Now each side is matched. You can connect your transmission line back in and everything should work.

Depending on the frequency of operation and the type of transmission lines you are working with connecting and disconnecting these things may not be trivial. If you aren't careful you can introduce error in your measurement.