On 18 Jun, 21:36, art wrote:
On 18 Jun, 19:30, Tom Ring wrote:





Dave wrote:
"art" wrote in message
roups.com...
On 6 Jun, 18:00, Mike Coslo wrote:
(Richard Harrison) wrote in
news:28667-46639927-
:

Jimmy D wrote:
"Wouldn`t it be nice if Art did the comparison?"
Yes. I thought a Gaussian was a 17-sided polygon.
heptakaidecagon?

73 de Mike KB3EIA -
Newsgroup members,
Thought I would give you another example to laugh at.
Looking at the 17th eddition of the ARRL Antenna handbook
page 11-18 I came across an optimised 20 metre antenna,
The shortest boom length was 16 feet for 3 element
and the spec was 20db F/B, SWR 2:1 and going for
maximum gain which amateurs seem to think is every
thing
The ARRL antenna achieved 7.5 dbi max
My antenna which is of GAUSSIAN form was also a 3 element
and achieved an average of 30 F/B and 20 db worst case.
SWR was 2:1 ofcourse ranging from 1.34 :1 worst case.
Gain figures were 11.45,11.3 and 10.9 dbi
The main lobe was 62 deg BW and TOA 14 degrees.
I didn't use the 16 foot boom length as the starting
point but held the beam to the required 3 elements.
So instead of using the ARRL 16 foot boom I used a
8 foot boom. Again I forced the antenna into a planar
mode so a reasonable comparison could be made.
So have at it. Point out the areas of specs that
the antenna fails and have a laugh at the same time.
I'll leave you to find the deliberate error if
there is one so you can have your moment in the sun.
Art

define 'gaussian form'.

All I'd like to see is a couple real hard numbers. Like element length
and position on boom.

And I'd bet lunch at Ruth's Chris, even though I don't like steak at
all, that if the thing really shows the numbers Art claims, that the
real drive point impedance is in the range of 5 ohms or less.

Come on Art, you won't give away a million dollar idea if you publish
the construction details of an 8 foot long 3 element 20 meter beam. You
will be able to squash anyone like a bug with your 30 foot version.

tom
K0TAR- Hide quoted text -

- Show quoted text -

No,No.No. The criteria used by the arrl woulod not allow me to do
that.
I never go below 20 ohms so I can use a 2:1 balun.
Actualy I just added another element to make it 4 el on a 8 foot boom
I havent finished it yet but at the moment it is around 40 ohms, less
than 2:1 swr
F/B is 30 db worst case and the gain is about 1/2 db more than the
three element.
The elements are std length as per a yagi but bent a bit so they
are all in equilibrium. Anyway, I added one element but I have only
optimised
two elements so far so it probably will get better when I include
the other two elements in situ for optimisation. Tom what you don't
realise
is that the boom length on a Yagi is to focus the main lobe, it does
not
supply an increase in actual radiation so getting 11dbi with a 8 foot
boom
is no big deal as the gain is limited regardles of boom length or
elements used.
The beam width will always be around 60 degrees because of the lack of
focussing.
As far as giving out details of the design I have done all that.
Limit the boom length and then use an optimiser on all dimensions.
Elements are best made of at least three sections each
With respect to the low impedance you were expecting. I mentioned
right at the onset
that F/B,SWR and gain across the band has symetry so compromises are
not required
as per a yagi. But why would you want details of a Gaussian antenna
since it has been thoroughly discounted by all as well as confusing
people
as well as what it looks like. Amateurs on this group can smell a
fake
and don't need to know how it is made. I gave a model of a extended
zepp
with a loop antenna at the center. One guy said he could smell a fake
so didn't need to model it. I am amazed that a antenna compamy hasn't
offered employment to a lot of the posters after seeing their
interlects
have no bounds. I have no need for more money so I am not disapointed
that the headhunters have not come after me, after all I am a fraud.
Regards
Art- Hide quoted text -

- Show quoted text -

Correction;
I said worst case F/B was 30 db
Should have read Front /Rear worst case 30 db
No big deal as it still meets the ARRL criteria of
20 db F/B
Art