On 21 Dec 2006 09:34:22 -0800, "bpnjensen"
wrote:

David wrote:

Energy sets up a field around an antenna.

Yes, an EM field.

It alternates at some rate[s] per second but there are no waves that I know of.

The fact that the field "alternates" or "vibrates" at some frequency,
in either kHz or MHz or etc, and the fact that this vibration can be
detected at distance (in another EM field through an LC circuit), is
the evidence that the signal has properties of a wave. It also, like
any other quantum entity, has properties of particles (photons). All
of the concepts that we normally associate with physical and mechanical
waves - travel (propagation), velocity, resonance, wavelength,
frequency and interference patterns, are exhibited by radio signals.
That is why we use the term "wave" to partially describe the
phenomenon.

Another way to look at it is that the energy of the signal waxes and
wanes, positive to negative, at the rate of the frequency of the
signal. This is also a classic wave signature, and is readly seen in
ocean waves or even ripples in snowdrifts and sand dunes.

Bruce Jensen

Those waves manifest on a boundary between 2 different media as would
be expected by changing density below.

Would waves exist without the passage of time? Would the field still
be there?