wrote:
(snip)
I suggest you read:

http://www.w8ji.com/radiation_and_fields.htm
(snip)

I am trying to soak up the information on this page.

In the graph of field impedance versus distance (about half way down
the page, is this showing the ratio of E field to H field intensities
I would measure with very small electric and magnetic pickups placed
at these distances?

It looks like this is showing that a mag loop creates a larger E field
at some distances than a dipole that is creating the same far field
energy propagation. This is quite counter intuitive, so I want to
make sure I have not got it wrong.

John Popelish wrote:
Is "height" in "effective height" really referring to effective
radiating length, rather than something to do with elevation above
ground (assuming that one is talking about a monopole above a ground
plane)?

In other words, is the "effective height" of a horizontal dipole
actually related to its end to end length, not its distance above ground?

I am just trying to get started on the right foot in my reading.

Never mind. I found something you wrote in an earlier thread:

"There's a common term for the relationship between
the field strength and the length of a conductor,
called the "effective height" or "effective length".
The voltage at the center of a dipole in a field of
E volts/m is simply E * the effective length.
The concept is valid for any length conductor,
not just short ones. The effective length of a
uniform-current dipole is equal to the wire length.
The effective length of a short conventional dipole is
0.5 times the wire length. The effective length
for receiving is the same as the effective length for
transmitting -- in transmitting, it relates the strength
of the field produced to the *voltage* -- not power --
applied across the feedpoint.

If you apply 0.5 volts to a standard dipole
and 1.0 volts to a uniform-current dipole,
the power applied to each will be the same
because of the 1:4 ratio of radiation resistance,
and the generated fields will be the same.
This is consistent with the antenna gains being the same."

This cleared up a lot of the terminology and concepts for me.

"Effective length" refers to dipole type antennas in free space.
"Effective height" is the equivalent property of a grounded monopole.
They're often used somewhat interchangeably.

Roy Lewallen, W7EL

John Popelish wrote:
Is "height" in "effective height" really referring to effective
radiating length, rather than something to do with elevation above
ground (assuming that one is talking about a monopole above a ground
plane)?

In other words, is the "effective height" of a horizontal dipole
actually related to its end to end length, not its distance above ground?

I am just trying to get started on the right foot in my reading.