[TowerTalk] Modeling Ladderline as an Antenna Element

[Joe Giacobello]

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 >>
>
>
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