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[TowerTalk] Folded Monopole

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Subject: [TowerTalk] Folded Monopole
From: babblarr@cwis.isu.edu (Larry Babb)
Date: Sun, 18 Oct 1998 21:10:14 -0600
The article in the compedium is short, but my understanding of antenna
        theory would make me believe that the increase in the feedpoint 
impedance
        would make the matching network less critical for losses.  The antenna
        also is noted to appear inductive, so that matching can be done with
        a parallel capacitor across the load to tune out the reactance, and fed
        through another series capacitor for matching.
        What I find interesting is the shorting cable to also help conjugate 
matching
        of the feedpoint impedance.
        I ordered 500 feet of ground wire last week, so I am intending to put 
the best
        ground under the tower that I can, and alternate ground rods at the end 
of
        every other ground wire.  I don't have space for full length radials on 
160
        meters, so, everything is compromise at best.  Regardless, this is an 
experiment
        for me to get a signal on the topband.
        So, the question, now, the three vertical wires spaced approximately 30 
inches around
        the tower will be 45 feet in length.  The tower is a 50 foot tower.  
This is still a
        short vertical for 160 meters, is the antenna in fact going to appear 
inductive?  Am
        I still going to need a low resistance hi Q coil between the feedpoint 
and the ground
        system to resonate it?  Thanks

Tom Osborne wrote:
> 
> w8ji.tom wrote:
> 
> > I don't have the compendiums, but I do know that Bill Orr and a few >others 
> > (including one manufacturer) incorrectly claim the folded >elements raise 
> > radiati
> 
> Hi Tom.
> Making the vertical into a folded monopole makes it easier to match than
> a single vertical.  I've put up a couple of them for 80 and they are a
> great match to 50 ohm coax.  Are they less effective than a regular
> vertical or about the same.  Thanks and 73
> Tom W7WHY

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