Roy Lewallen wrote:

Most authors explain how a wave is generated, then resort to reciprocity
to explain the reception process. But a clear and simple direct
explanation appears in Bailey, _TV and Other Receiving Antennas_ (pp.
141-2), of what happens when an electromagnetic wave strikes a conductor:

"The second, and equally important effect [the first being reflection of
much of the incident energy] is that some energy /does/ enter the outer
skin of the conductor. That part of the energy, which is not reflected,
must enter the conductor. The conditions at the surface of the
conductor, as we have already seen, give rise to a small resultant
electric vector and a large resultant magnetic vector. The presence of
these at the conductor is direct evidence that power is entering the
conductor. The small electric vector acts on the internal electrons of
the conductor and impresses a direction force, tending to drive the
electrons along the skin of the conductor in the direction of the
electric vector. But from experience we know that /no/ electrons can
ever be caused to move without gradually establishing their own magnetic
field, and this usually takes /time/. The motion of electrons (which is
electric current by definition) never takes place without the magnetic
field. How, then, is the electric vector from the electromagnetic wave
going to put these electrons in motion? It can only do so because the
electromagnetic wave /also supplies a magnetic vector/ as well as an
electric vector. And the value of this magnetic vector is exactly
proportioned to supply just the right amount of magnetic field energy
which the electrons require for immediate motion. Thus the electrons do
not have to establish their own magnetic field, since this field is
supplied by the electromagnetic wave. Hence, electromagnetic wave energy
entering the conductor establishes immediate motion of electrons /along/
the conductor, the direction of motion at any instant corresponding to
the direction of the electric vector. If the electric vector changes
direction, the electrons will follow suit."

Hi Roy -

It's certainly true that a moving charge generates a magnetic field, so
perhaps I'm reading it wrong. But it appears to me that Mr. Bailey is
arguing here that an electron cannot be compelled to move simply by the
application of an electric field. Do you think that is what he is
saying? Do you agree?

Other posters have correctly pointed out that an antenna doesn't and
can't receive a signal solely due to the E field;

Given the statement below, I would be interested to know how anyone
could have tested the claim. ;-)

a time-changing E
field can't exist without an accompanying time-changing H field.


Roy Lewallen, W7EL

Jim Kelley, AC6XG

Paul Taylor wrote:

Hi,

I am looking for an explanation of how an antenna receives a signal due
to the E-field of an electromagnetic wave.
I have looked in some books, and can understand transmission, but the
books I have looked in don't explain reception.
I have found an explanation of how the H-field induces a signal in a loop
antenna: a changing magnetic flux will induce a current.
But what about the E-field and a dipole antenna? I guess that the E-field
causes electrons to move in the antenna wire, because in a solid
conductor, electrons will move until the E-field inside the solid is
cancelled out?

I have googled but having difficulty finding a good explanation. Any
pointers?

Thanks & regards,

Paul.