Far field calculation of reflector antenna system

Here is the thing, I want to calculate the far- field of a reflector antenna feeded by a conical horn.

And solid mechanic and ale physic interfaces added to analyse the influence on the result of far-field calculation by adding a force on reflector.

For simplifying the model, body force and fixed constraint feature added in solid mechanic and free deformation in ale.

Solver is set for two step, the first step is stationary with MUMPS and second frequency domain with PARDIOS.

The problem is no matter how big force added on reflector, the norm of electric field of far-field doesn't change. The model and result are in attachment.

Thanks for any help.