On 26 Nov 2003 08:36:52 -0800, (emma) wrote:

Hi Richard,

I found your comments really interesting.
Firstly, I would like to explain why
I think that the Hentenna is a narrowband antenna.
My design results for SWR vs frequency,
while the antennas dimensions vary,
are shown at

http://antennas.ee.duth.gr/recradioa...q/Hentenna.htm

The traces should be separable in their display. In other words, dot
markers for one Z, box markers for the next Z, delta markers for the
last Z and so on.

Further, since you admit dimensions vary, for GHz designs this could
bring a substantial bias in results.

The table below could also be usefull

In the future, please observe newsgroup protocol and use "fixed font"
when aligning text columns of data.

BANDWIDTH

50 Ohm 75 Ohm 300 Ohm
H = wl/2 W = wl/4 : - - 14.4 %

H = wl/4 W = wl : - 3.6 % -

H = wl W = wl/4 : - 3.6 % -

H = wl/2 W = wl/6 : 2.7 % 3.6 % -

Moreover, IMHO I don't think that the Hentenna
is a shorted stub .The distance W is
longer than the distance between two transmission
lines.
I would be most grateful if you could make
any more comments.

Emma

Hi Emma,

A shorted stub it is. A simple look at the geometry is intuitive to
this statement. Resonance provides the logical basis for this
statement. Obviously distances and wire diameter are chosen on the
basis of Z desired. I've done dozens of models of this style, and
variations of it, years ago. I observed then that the characteristic
of "miracle antenna" applied to it now is overstated.

73's
Richard Clark, KB7QHC