Thank you Mike!
I found an article about measuring the difference of the mounting height of SMLs using existing signals from 77 kHz to 28 MHz here:
Would you pls. point me to the LZ1AQ setup with test transmitter in the far field?
Could I perhaps also use my NanoVNA for this purpose (then S21) by connecting the SML to one (receiving) port and a small coil to the other VNA port (transmitting)?
Dirk