Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N1ETL, Dec 3, 2018.
I doublet/dipole with ladder line us not intended to be resonant. No need for coax with a tuner
Why make such a statement? It's not very helpful to anyone.
If "dozen wavelengths away from everything else" was a requirement for effective HF antennas, or a prerequisite for getting meaningful results from antenna experiments, that would exclude most hams in their current QTH.
These discussions always seem to go South and end up being the proverbial PP contest.
As a previous poster mentioned, keep the flat top length shorter. (we use 125')
You'll be perfectly fine with a great antenna! No further troubles required.
Due to the installation, especially with the element tips only 15' above earth, that's not really an 80m dipole anymore.
To demo the impact of the proximity of earth under the element tips, if you have a 6' aluminum stepladder, place that under one end where the doublet end hangs down and take another plot. That will still be 9' below the wire, but 9' on 80m or even 40m is very close. So is fifteen feet.
Doesn't really matter if that's the best you can do -- it is what it is.
What are you babbling about.
This is another post where somebody wants to know why their utterly random antenna system installation gives utterly random results.
How can anybody give advice?
Here it is, almost 50 years of experience:
Put up a random antenna, get random results.
$pend money randomly trying to fix it.
I'd suggest modeling your antenna with the demo version of EZNEC to better understand your antenna. Not only will it model the effect of height above ground, transmission line impedance transformation, and wire insulation, but you can arbitrarily remove these factors to better understand how your antenna works.
If you ever watched The Deer Hunter, "This is This"
I never even measured SWR or impedance on my doublets.
But All antennas i build in the past 17 yrs. are modelled in MMANA-GAl and with difficult antennas even in 4NEC2X and MMANA-GAL, to decrease moddeling software problems I encountered in the past in MMANA-GAl.
There is not a single antenna no-more that I build without carefull moddeling and comparing the last 15 yrs.
I started moddeling Yagis in 1996 with Yagimax311 and Yagi anaaliser, and was so positivly surprised with the very good results I got in building my own yagis, i started to use computer moddeling on otther antenna types also as soon i could find decent free userfriendly software.
MMANA-GAL basic surely is.
I even am going to feed my trapped homebrew (W3DZZ) dipole for 80 and 40 with homebrew real ladderline so I can use it on 60 and 30-10 mtrs.
And I know how long the ladderline is going to be right now, it is going to be that long that I can reach my homebrew tuner.
But I must say W5DXP does have nice and good tips and ideas to play around with feedline length to get better tunable impedances on your doublet, I am of the other kind of hams, that say "my tuner will not tune my antenna", so I will build myself an other tuner.
But that is just because I love to build tuners and antennas, I find that building all 200+ antennas in the past and 6 tuners, gave me such rich knowledge, and I just like building things.
And I am using my 10th or even 12th 80 meter wire antenna now at home, I still manage to improve the performance even though just slightly, because my knowledge is still increasing.
And the room that I have for this antenna is still the same after 20 yrs.
You might be thinking of the W5GI Mystery Antenna...