[Elecraft] E-H Antenna Simulation in NEC

[John, KI6WX]

Trev;
The NEC software is based on a solution of Maxwell's Equations.  For wire
types of structures, it solves Maxwell's Equations using the Electric Field
Integral Equation.  For surface types of structures, it solves them using
the Magnetic Field Integral Equation.  The program is capable of solving
complicated structures.  Its accuracy and limitations are well documented in
the scientific literature, and it can easily solve a fairly simple antenna
structure such as described in the EH Antenna patent.

So the real question is does the EH Antenna embody a new method of
electromagnetic radiation that violates Maxwell's Equations?  I would place
my money on Maxwell's Equations since they have survived for more than a
century and are still considered a exact solution for electromagnetic
radiation.

The EH Antenna is a conventional antenna fed by a matching network.  The
patent states "The phasing and matching network aligns the relative phase
between the current and the voltage of the radio frequency power signal so
that the H-field component of the corresponding electromagnetic signal is
nominally in time phase with the E-field component".  This is exactly what
happens in every antenna and is called the Poynting vector.  If the E and H
fields are not in time alignment, the antenna will not radiate.

I can't tell you what is happening to the power feeding your antenna.
However, it is going to one or more of the following places:
- Radiation from the antenna
- Power dissipation in the antenna
- Power dissipation in the matching network
- Radiation from the coax
- Power dissipation in the coax
- Power dissipation in the transmitter (most people don't realize that
transmitters can dissipate power that is not radiated by the antenna)

You will need to do a carefully controlled set of experiments to determine
where the power is going in your setup.

-John
 KI6WX

> Forgive me for asking this, its a serious question.  Does the EHs
> 'claimed' method of operation not make the use of NEC as a model
> useless? Surely NEC algorithms are based upon conventional antenna
> theory?.
>
> Also, If the EH matching arrangement is that poor, where does the power
> go?  My home-made EH does not even get warm and neither does the 4 foot
> of coax feeding it.
>
> Trev G3ZYY
>
> In message <005e01c2e1f8$e942bfc0$6601a8c0@johnp4>, "John, KI6WX"
> <ki6wx@pacbell.net> writes
> >Stuart;
> >The nice thing about NEC is that it allows you to calculate things that
you
> >can't easily measure.  The antenna cylinders are 98% efficient, but the
> >matching network described in the patent will lose over 99% of the energy
> >passing through it when connected to a 0.03 ohm load.  The overall
> >efficiency of the antenna is less than 1%.
> >-John
> >
> >
> >> John, a clarification please,  certainly the efficiency of the large
> >> cylinders is large, taken as themselves alone, right?  That is the 98
per
> >> cent efficiency you quote?   Because of the losses in the matching
> >network,
> >> (practical network which surely would have a Q of far less than 1000, )
> >you
> >> then see the overall antenna efficiency as only 1 per cent, correct?
IE
> >the
> >> antenna has to be taken as a system and the inefficiency of the
matching
> >> detracts from possible efficiency of the whole.
> >>
> >
> >
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> --
> Trevor Day
>
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