Impedance matching network for a varying load
You can use a stripline return loss DC20 directional coupler to tap -20dB of the reflected power into an RSSI chip or a Schottky diode amp and measure the reflected energy due to antenna loading effects on standing waves.

In the old days I did this to tune a small dipole in VHF band and discovered this method is a great motion sensor for over 10 wave
lengths (size of lab)

What you do with the variable phase and amplitude feedback is up to you.  It would be theoretically possible to inject the conjugate feedback signal to modulate the Tx, but I doubt it is worth it.