jimlux wrote : > And, just as with Omega (10-15 kHz) the height of the ionosphere > changes the effective height of the "waveguide" through which > the surface wave propagates.
Exactly! Folks, this isn't simple "reflections" between the earth and the ionosphere.
At VLF frequencies the wavelength is comparable to the height of the ionosphere (D layer, 70-90 km above earth's surface), so we have "waveguide propagation" in the "earth-ionosphere waveguide". The WWVB phase changes occurring during sunrise and sunset transitions are caused by the change in the dimensions of the waveguide.
Quite a different situation from what we are used to at HF/VHF. ... Martin VE3OAT _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
