feedlines and strange intereactions
 

Paladin wrote:
ON4UN's book on "low band dxing" states that there aren't any
PROGRAMS for linear-loaded ant.'s out there.

That may be true but if we space the parallel conductors
a foot apart, take a look with EZNEC, and it's a dog of
an antenna, we can draw certain conclusions about the
closer spacing of your antenna.
--
73, Cecil http://www.qsl.net/w5dxp

feedlines and strange intereactions
 

Paladin wrote:
The wires are close. The builder used rotor feed line. 3 equal
lengths of wires 70ft. long
THAT make one element. there is one on the oppisite side.

So like this?

70' 70'
-------------------------+ +-------------------------
| |
+------------------------+ +------------------------+
| |
+------------------------+ +------------------------+
| |
| |
| |
feedline
--
73, Cecil http://www.qsl.net/w5dxp

feedlines and strange intereactions
 

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

feedlines and strange intereactions
 

On 16 Nov 2005 08:19:33 -0800, "Paladin" wrote:

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....

Hi OM,

It's "supposed to work" is the key phrase here - according to who?
Perhaps this is your greatest difficulty in finding help for a design
that won't be helped.

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! ! !

Your statement here contains a great degree of success in it. It
would appear that you have higher expectations than could be
reasonably expected.

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.

The linear loading that you have described in further correspondence
is not particularly remarkable. It follows the aphorism to put more
wire higher into the air, but in reality, that more wire also needs
more volume (surface area, what-have-you). The triple-backed rotor
cable has been trotted out here before, and has never been shown to be
anything but a good match - perhaps. You can load a resistor to the
same effect and you may note similar performance issues in that
correlation.

If you want to keep more wire in the air, build a fantail dipole or a
cage dipole and use more than three wires (six to a dozen instead)
with a truly large, effective diameter at the end.

73's
Richard Clark, KB7QHC

feedlines and strange intereactions
 

Cecil Moore wrote:
Paladin wrote:

The wires are close. The builder used rotor feed line. 3 equal
lengths of wires 70ft. long
THAT make one element. there is one on the oppisite side.


So like this?

70' 70'
-------------------------+ +-------------------------
| |
+------------------------+ +------------------------+
| |
+------------------------+ +------------------------+
| |
| |
| |
feedline

Hi Cecil, that's what I understand. To a first approximation, on 160
meters, the radiation from the two segments furthest from the feed point
should cancel. That would leave the effective antenna as a shortened
dipole with a length of 55 degrees per leg [two 80 foot long segments
per side]. This should yield a radiation resistance of somewhere around
10 to 15 ohms with a significant capacitive reactance of between 500 to
1000 ohms.

His 100 foot long feed line is only 69 degrees long. I believe this
short a matching section, i.e. "stub", may be insufficient to achieve a
'50 ohm' match.

I would expect the antenna gain to be -2 to -3 dBd.

Comments??

feedlines and strange intereactions
 

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

HI Reg, Unworthy of what? That's like saying your programs smell, but
not what they smell like-:). I for one an grateful and have used your
programs, and EZNEC. I consider them both an asset to to my knowledge
of antennas.
Gary N4AST

feedlines and strange intereactions
 

feedlines and strange intereactions
 

Thanks a lot, Mike

This antenna IS getting the best of me

feedlines and strange intereactions
 

Well, In it's "finality", I think that for my lot,and my skills,and
my "want" to get on "160meters"
I chose the WRONG antenna. I don't believe that I will ever get
this antenna to work well
enough FOR ME. I would've been better spending the time and
aggrevation on getting my
80m,full-wave loop at 40ft. to cover 160.
Gentlemen, I'm done! Stick a fork in me. I thank all
who tried to understand WHAT
I was trying to do. Maybe next time, I'll stick to "ONLY" the
basic antenna's,and "Keep it
simple , STUPID"!; will be my motto !!
I'll read
more, and do less.........Paladin

feedlines and strange intereactions
 

On 21 Nov 2005 09:58:34 -0800, "Paladin" wrote:

Well, In it's "finality", I think that for my lot,and my skills,and
my "want" to get on "160meters"
I chose the WRONG antenna. I don't believe that I will ever get
this antenna to work well
enough FOR ME.

Hi OM,

Well, you still have options.

Tie all the wires together and use them as a top hat to a vertical.
Verticals have far more reported success on 160M than horizontals.

Of course, you will need to plant more copper in the ground than you
lifted into the air....

73's
Richard Clark, KB7QHC