"Jim Lux" napisal w wiadomosci
...

Where dispersion becomes interesting (and is actually measured) is
when comparing signals at two separated frequencies, e.g. 8.4 GHz and
32 GHz. Or, for a closer to earth example, L1 & L2 for GPS (separated
by a couple hundred MHz at 1500 MHz) allow for compensation for
ionospheric delays.

It is what I was looking for.
Speed of all waves are frequency, amplitude and temperature dependent.
I realize that for radio waves the effects are small. It seems that for
radio amateurs too small.
GPS is extremely precise and there the effects must be measured.
Thanks you very much.

Best Regards,
S*