Hi Group,
Recently,I put up a linear-loaded dipole for
160-10m. It's ladderline,4/1 balun,
to coax,to good brand auto-tuner. It's supposed to work with 100ft.
of ladderline,BUT....
It wouldn't cover the lower portions of 160. To get this antenna to
work on 160, I had to cut
off 20ft. of ladderline, AND also use a 50ft. piece of coax! I tried
using only 20ft. of coax
because that's all I need to get to my tuner,but it didn't work! ! !
What happened here, to me,goes against almost everything
that I learned about
feedlines! Change the lenth of coax ? The 100ft. of ladderline
was at least 1/4 wavelenth
of 160,right? The feedpoint is at 55ft. on a tower ( about 2ft.
away the tower) the ends are
in an inverted-"V" at about 15ft. above the ground. I do have a 80m/
272ft. loop also in the
1/8 of an acre back yard. Some small 2 & 6m beams hung of the
tower,not near enough to
cause intereaction. WHY AM I HAVING such a hard time getting this
antenna to cover
this bandspread ??? Also, IF I have a multi-band antenna,feed with
ladderline ONLY, to
a very good tuner; Why are the signals that I rercieve on the higher
bands,(160-10m)
usually SO LOW in strength ? Ex: On 160 or 80,the antennas s-meter
usually reads
over s-9 at night,o.k. Now, the same antenna on 10m or 20m during
the day are reading
very low; mostly around 3's and 4's. I guess that I really don't
think that calling THESE
antennas "a 160-10m antenna" or my Loop a 80-10m antenna! ! I've
had both antennas
up now for at least a month. Signals for 20m-10m need a different
antenna, In my
opinion. BUT, I'm still trying to understand exactly just WHAT
antennas can or cannot
do for me.
73's,and keep
radio-active,


Paladin

Paladin wrote:
BUT, I'm still trying to understand exactly just WHAT
antennas can or cannot do for me.

That's what antenna modeling programs are for. A free demo
version of EZNEC is available at www.eznec.com and will
probably do what you want done including the primary
transmission line length.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil,
I do not know how to use such programs. I'm a "late"
bloomer,in computor terms.
I guess that I'm stuck with trial and error until I find a way to
shorten my feedline in the
same way that the antenna builder did in shortening the elements of
the linear-loaded
dipole. Long sentence,huh?
Paladin
The elements are 70ft. long each,BUT the electrical lenth IS really
210ft. per side.
I know that 100ft. of 450 ladderline didn't work.

"Cecil Moore" wrote
That's what antenna modeling programs are for.

----------------------------------------------------------------------
Cec, You should realise it's a waste of time pointing people towards
computer programs which require a 6-weeks full-time training course to
understand what its all about. And which they don't possess anyway.

Especially when a few sentences of plain English can provide an
adequate explanation to the enquirer.
----
Regards, Reg.

Reg Edwards wrote:
"Cecil Moore" wrote
That's what antenna modeling programs are for.

----------------------------------------------------------------------
Cec, You should realise it's a waste of time pointing people towards
computer programs which require a 6-weeks full-time training course to
understand what its all about. And which they don't possess anyway.

Especially when a few sentences of plain English can provide an
adequate explanation to the enquirer.
----
Regards, Reg.
Hi Reg., The question was certaintly not a few sentences of plain
English. If the enquirer had shortened his description to a few well
defined sentences he might have some answers by now.
The demo version of EZNEC is free, as are your programs. Niether
require 6 weeks to learn.
My advice is to model the antenna, or give more precise question(s).
Gary N4AST

Reg Edwards wrote:
Cec, You should realise it's a waste of time pointing people towards
computer programs which require a 6-weeks full-time training course to
understand what its all about.

Reg, if I can learn ELNEC in two years, anyone can do it. :-)
--
73, Cecil http://www.qsl.net/w5dxp

I guess that an old man who hasn't been into electronics very long.
But, I do possess a fair amount of common sense. I can see that
you guys can't or won't help me figure out my problem. Too many
issues here. Everyone has SOME area of excellence.
I just haven't found the right person who WILL help. Life is
filled
with people who can only see their way. Words are not as
powerful as IDEAS. Thanks for the "words", fellas.

Paladin wrote:
I guess that an old man who hasn't been into electronics very long.
But, I do possess a fair amount of common sense. I can see that
you guys can't or won't help me figure out my problem. Too many
issues here. Everyone has SOME area of excellence.
I just haven't found the right person who WILL help. Life is filled
with people who can only see their way. Words are not as
powerful as IDEAS. Thanks for the "words", fellas.

I think there are people willing to help but from your original
posting, there was not enough information for me to model your
antenna. I don't recall you even telling us the length of your
inv-V dipole. And what did you mean by "linear loaded"?
--
73, Cecil http://www.qsl.net/w5dxp

Paladin wrote:
"I just haven`t found the right person who will help."

Help, it seems, is the answer Paladin wants to hear. When you want to
put 8 pounds of crap in a 4-pound bag, life is often that way. You
quickly run out of good advice.

When a respondent says there`s no computer program to tell you how to
linearly-load an antenna wire, you are invited to prove him wrong. The
ARRL Antenna Book says:
"Since the dimensions and spacing of linear-loading devices vary greatly
from one antenna to another, the best way to employ this technique is to
try a length of conductor 10% to 20% longer than the difference between
the shortened antenna and the full-size dimension for the linear-loading
device. Then use te "cut-anhd-try" method, varying both the spacing and
length of the loading device to optimize the match."

You might write a program for that.

Best regards, Richard Harrison, KB5WZI

"Cecil Moore" wrote
Reg Edwards wrote:
Cec, You should realise it's a waste of time pointing people
towards
computer programs which require a 6-weeks full-time training
course to
understand what its all about.

Reg, if I can learn ELNEC in two years, anyone can do it. :-)
====================================

Cec, What is ELNEC? OK, I can guess!

Quite truthfully, if you had pointed ME towards EZNEC then I am unable
even to download and un-zip it.

Acually, I do have a copy. Some years back Roy took pity on me and,
without any request from me, very kindly broke the rules and airmailed
me a free parcel of 3.25" floppy disks. It took me a week to print out
the instruction handbook and another 2 weeks just to read it by which
time I had forgotten what the problem was.

'Experts' should realise, from the manner in which questions are
written, the predicament some questioners are in and make allowances
instead of leaving them to flounder about in a sea of frustration and
despondency.

N4AST's comments are unworthy.
----
Regards, Reg.