No, thatn is a wrong assumption.
In Bioresonance therapies quite different frequencies are used.
But those are *clean* straight frequencies.
However in elektrosmog, the frequencies are not clean.
Here we see a generated clean signal of 100Hz.

And here a recorded DECT 100Hz pulsrate.

Many high frequency signals do contain a lot of dirty frequencies, mostly in the lower ranges.
With a 30kHz detector I could find an UMTS as well as an airport radar signal, because oftheir lower frequency *dirt*.