Richard Clark wrote in message . ..
On 20 Nov 2003 06:09:42 -0800, (emma) wrote:

I will try to make it more clear.
These are some results I arrived at before
I start its construction and carry out the measurements.
Firstly, my aim was to find the exact place of the driven-element
where the SWR is lowest.
I used RICHWIRE for my simulation.This program has an upper limit
for the wire radius.So I had to make two categories of diagams,
one for wire radius 0.00037 [wl], which is rather not realizable,
and one for 0.0037 [wl] ignoring the programs criteria.
I ended up that the Hentenna is unfortunately a narrow band antenna.
So it would be rather difficult to build it.
What I am working on now, is changing the antennas dimensions
so that I would come to an even lower SWR and a broader bandwidth.

Emma


Hi Emma,

How do you arrive at the conclusion your (or any) Hentenna is narrow
band? What data supports this? The numerous links you provided
suggest nothing remarkable except gain. In other words, what
bandwidth do you call narrow? Normal? Wide?

To my eye, this design is a shorted stub that is tapped within to find
a match from a continuum of impedances available as a product of its
resonant geometry and the position of the tap. Loss, being
inferentially linked to bandwidth, is a product of bulk conductor
(wire radius for sure). Wire radius certainly impacts resonance vs.
size (and we are back to geometry of resonance to find the Z of
choice).

73's
Richard Clark, KB7QHC


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 table below could also be usefull



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