One antenna working as receiver and transmitter

I want to know, if an antenna which transmits and receives the reflected signal can be modeled as an impedance.
For example, the antenna is coupled to a Collpits oscillator and sends out an electromagnetic wave which is reflected by, for simplicity, a wall of a conductor. So it receives something which superimposes the sent signal.
Can this configuration be modeled as an impedance?

The idea is to model this configuration as a "kind of lossy transmission line" where a transmission line (tl) has a certain impedance depending on its length.

If so, the impedance varies with the distance of the reflecting wall and tunes the oscillator to a slightly different frequency, which is what I want to find out about.
The goal is to have a function of frequency vs. distance.

I can simulate the S-Parameters of the antenna (not done yet), if this is helpful for you to know.

Edit:
Today I simulated the antenna and the software returns Z-Values and S-Parameters that vary over exciting-frequency and distance of the reflector.
So it shows, that the antenna can be modeled as a complex impedance which varies with distance of the reflector. So we can use this impedance shift to tune the oscillator by putting it into the feedback loop.
But:
As said above the impedance varies also with frequency. So imagine we change the distance of the reflector and get a different impedance, then the oscillator changes its frequency which also changes the impedance. So we have a self-backcoupling massively non-linear equation and I don't know how to get around this problem.
Am I at least on the right track? Is there a way of solving this interrelatedness?