Would those of you with a theoretical background be able to comment on
the following. Looks interesting, but I have never seen the principle
applied.

http://www.eh-antenna.com/library/EH...DEFINITION.pdf

Here is a quote from the article:

"Next we see the EH antenna is created by shifting the phase of the
applied current relative to the applied voltage. This causes H to be
delayed an additional 90 degrees, and is now 180 degrees relative to
the applied voltage. H has also been delayed 90 degrees and is now
in phase with the applied voltage."

Can the effect described be achieved in practical terms, and if so,
what would be the simplest way to demonstrate it?

IOW how is the phase shift described actually implemented in terms of
basic hardware?

Thank you for your reply.

Klaus Jensen

"Klaus Jensen" wrote in message
...
http://www.eh-antenna.com/library/EH...DEFINITION.pdf

It's pretty bogus. His analysis is over-simplistic: Sure, if you look at the
fields close to a Hertzian antenna, they're *nearly* (but not exactly) 90
degrees out of phase, and thus most of the energy present is just circulating
around rather than radiating, but whatever energy *does* end up radiating is
already present in that near field! It's just that the equations for the
vector magnitudes of the E and H fields have different dependencies on R, so
what you "see" changes as you move away from (or up and down) the dipole. An
antenna with a given applied terminal voltage and radiation resistance
radiates the identical power as any other antenna with the same voltage and
radiation resistance -- the only thing you can change is the *pattern* of that
radiation. Similarly, loss in an antenna comes about from the finite
resistance of the materials constructing it. It's true that this can vary
from one antenna to another, since you can modify the current distribution on
the material and loss is I^2*R, but the paper cited only discusses terminal
voltage and currents (and not current along the antenna itself), so the claim
that it's inherently less lossy is quite dubious.

I'm not suggesting that the "EH antenna" isn't useful, just that the theory
presented is wrong. The deal here is that, in a certain sense, signals *like*
to propagate, and it's surprising what you can string up and still get to work
OK, even though what's *really* going on isn't what you think. See, e.g.:
http://www.w8ji.com/e-h_antenna.htm -- or just Google around some.

Klaus Jensen wrote:
Would those of you with a theoretical background be able to comment on
the following. Looks interesting, but I have never seen the principle
applied.

http://www.eh-antenna.com/library/EH...DEFINITION.pdf

Here is a quote from the article:

"Next we see the EH antenna is created by shifting the phase of the
applied current relative to the applied voltage. This causes H to be
delayed an additional 90 degrees, and is now 180 degrees relative to
the applied voltage. H has also been delayed 90 degrees and is now
in phase with the applied voltage."

Can the effect described be achieved in practical terms, and if so,
what would be the simplest way to demonstrate it?

IOW how is the phase shift described actually implemented in terms of
basic hardware?

Thank you for your reply.

Klaus Jensen
Klaus,

I make antenas all the time. my site is www.fwt.niat.net these are not
EH antennas but an innovative form of dielctricl embedded antennas with
dielctric shaped wave front forming.

This antenna use a phase shifted (90 degree) signal to drive the H field
singal when compared to the E fieled driving point.
This creates an antenna that can be consider a two element phased array.
if you have an antenna elemnt, and you add a second element and control
its electrical phase as well as it physical spatial phase, when you
observe the effectvie radiated signal you can get higher gain, or lower
sidelobs by adjusting the phase.

Clearly this unit will be of narrow bandwidth as a constant 90 phase
over a wide frequency band is typically band limited. a constan length
of feedline has a phase that increase proportionate with frequency...

Best Regards,

marc