[Antennas] Re: E-H antennas

2002年7月04日 13:12:18 -0400

>Has anyone built one of the E-H antennas? I'd like to hear if they 
>actually work, how easy to build, and if any side by side comparisons 
>were made with other antennas, say, a dipole or 1/4 wave vertical...

Terry,
Although I have neither built nor tested an E-H antenna, I have looked
at the designer's web site, and I can state without reservation that you
would be far better off building a dipole or vertical. In spite of what the
designer says, the E-H looks to me like a short biconical antenna, with
the word "short" being the important one here. Almost without exception,
an electrically-short antenna will underperform a larger one.
It's also clear to me from the web site that the designer doesn't have a
strong grasp of electromagnetic theory. He claims that the E-H antenna
allows independent control of the E and H (electric and magnetic) fields
radiated by the antenna. That is simply impossible. Maxwell's equations
tell us that the E and H fields of any electromagnetic wave are "coupled."
That is, the structure of one field dictates the structure of the other, and
vice versa. To say that the E and H fields of an antenna can be
independently controlled is like saying that the voltage across and
current through a resistor can be independently controlled. They can't;
Ohm's law tells us that the voltage must be equal to the current times the
resistor's value.
So, save some money and time and build a simpler (and better-
performing) antenna.
73,
Dave NB4J