Mark, I was considering that option also. Frankly, I thought the linear
loading would be easier, but I didn't appreciate that the losses would
be so high, especially with relatively short lengths.
I'll let you know what I do and how it works.
73 and thanks,
Joe
Mark . wrote:
>Joe,
>How about capacitive end loading for shortening your antenna? As far as I
>know, it's the most efficient type of loading.
>You could let the ends droop and attach basic spoke and perimeter wire hats.
>Fashion the hub of each hat such that you can adjust its position on the
>radiating wire for tuning.
>I've made a shorty forty dipole with this method. I don't have anything more
>than a gut feeling for the size you need. Since you have modeling software,
>start with a 4 spoke hat, having a single perimeter wire of, say, 4ft
>diameter.
>I guess you would also want to have tag lines to stabilize the hats in the
>wind, and minimize variable interaction with the suspending towers.
>You could also possibly use forked ends on your wires, and vary the angle of
>the fork with tag ropes to vary the capacitive effect. This might be easier
>to model than the hat assemblies.
>
>Some ASCII ART to illustrate:
>
>end of horizontal radiator
>-------------------------+
> |
> |
> /^\ ends droop with fork
> / \
> / \
>
>
>--...MARK_N1LO...--
>
>Joe writes:
>
><<Jim and Tom, many thanks for your replies. Let me tell you what I'm up
>to.
>
>I would like to put up an 80M EDZ between two towers. However, my
>towers are only 300' apart and I need about 340'. I have considered
>drooping the ends vertically, but I thought either a folded dipole or
>linear loading a few feet on the ends with ladderline would allow me to
>fit it inside the 300' span. I use EZNEC 4+ for modeling.
>
>I wonder if minimal lengths of ladderline for linear loading on each end
>would provide the shortening while making the high resistance losses
>arising from lower Q negligible? I haven't tried modeling it yet. I
>thought I'd first see if anyone had successfully modeled ladderline as
>an antenna element. 73, Joe >>
>
>
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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