[TowerTalk] Rectangular loops
VR2BrettGraham
vr2bg at harts.org.hk
Fri Oct 15 20:46:56 EDT 2004
W8JI replied:
> > With the vertical portions of the loop about 8m long & the
>bottom of the loop
> > about 4m above the ground, fed at the side is something
>like 40-j160 (with j
> > going down a bit towards 0 across the band, towards where
>the loop is
> > reasonant) on 40 & varying from 1000+j5000 to 4000+j9000
>across 30.
> >
> > Is that something that a typical tuner can handle? I
>think I can put two of
> > these up at close to right angles & route the feeders to
>my balcony on the
> > third floor.
>
>Are you placing the tuner right at the antenna, or at the
>end of a long feedline?
>
>If at the end of a long feedline, you are in trouble for
>loss on 30. If at the antenna, you are in trouble for
>matching.
>
>40 is workable.
Where the two loops could fit should result in fairly short
feeders, say maybe 4 or 5m at the most - perfect for some
bits & pieces of ladder line left over from radial-chopping
Granny at a previous QTH.
When I moved here, the first antenna I put up was a
vertical doublet, reasonant again somewhere between
30 & 40m. For convenience it was fed with coax (coiled
to form a choke at the feed point) & force fed by a tuner
in the shack. It obviously took a hit in line loss on 30, but
usually was better than the current shunt-fed roof tower on
40.
I just don't have a feel for what a tuner might be able to
handle & would prefer to know there's a reasonable chance
of making the loop work before I put one up.
Thanks.
73, VR2BrettGraham
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