measuring high power return loss

I will monitor return loss variation on 20W input.
Somebody can help me how to setup it.
My equipments:
1. EMC chamber x1
2. 50W TWTA x1
3. Network analyzer 8510c x1
4. Signal generator R&Sx1, HPx1
5. Spectrum analyzer R&Sx1, HPx1
6. 50ohm transfer to 150ohm adapter x1
7. 50 ohm Dummy loads, 50ohm attenuator...
8. 50W 20dB directional coupler
9. Power meter x1
Thx

Put the directional coupler to the antenna. This will measure reflected and forward power. Drive this with the signal generator driving the TWT. Put your spectrum ananlyzer on the tap of the directional coupler.

Then do the forward test. Put the coupler to measure forward power. Adjust the signal generator for 20W into the antenna. Step the frequencies and record the spectrum analyzer output x 100 (20 dB).

Then reverse the direction of the coupler and do the measurements again.

The ratio of the returned to the foward power is the return loss.

yes,to measure the foward and reverse power as above topic,you can get the vswr at high power conditions.