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[Towertalk] Re. HF2V

To: <>
Subject: [Towertalk] Re. HF2V
From: (
Date: Sun, 7 Jul 2002 15:52:10 -0600
On Sun, 7 Jul 2002 13:13:30 -0400 "Tom Rauch" <>

> When I lived in Rockdale county, despite having a uphill slope 
> towards Europe and rocky ground, a 35 foot vertical almost always 
> tied my 120 foot or so high dipole for long DX on 80.  (W8JI)
N4KG:  EVERYTHING seems to work better to Europe from GA
        than from ALA :-(   My HIGH Dipoles seem to play better
        to Central EU than my GP but the GP is often 6-10 dB
        better to LA / SM / OH.  

> > N4KG: SO, you AGREE that a TOP LOADED Vertical is superior
> >  to a BASE LOADED vertical over a limited radial field
> >  typical for most city lot limited users?
> Depends. Like many things, it is a juggling act.
> As the loading coil height is increased in a basically uniform cross 
> section radiator, coil loss for a given design generally increases 
> while ground loss decreases. The change in efficiency depends on how 
> poor the ground system is, how poor the coil is, and if the antenna 
> has a top-hat of significant dimensions.
> There will be some point that optimizes the results.
> The larger the top hat, the less critical the coil becomes, so I 
> would agree that top hat loading is a better choice, but 
> unfortunately that also means the coil location is NOT important!
> In other words, I'd be really careful to look at things before just 
> moving the coil up high. I would not hesitate to add a large 
> capacitance hat at top, because that makes everything less critical.

N4KG:   GOOD   EXPLANATION.  Thank you.
>  >  In other words, a short tower / tribander, shunt fed
> >  (or even set up as an Elevated GP) would be a 
> >  MUCH better antenna than a Base Loaded (HF2V)
> >  vertical on a small city lot.   (N4KG)
> I don't know how you would feed a grounded tower as a groundplane, 
> since by definition it is grounded and the ground path can have a 
> large effect on efficiency. My choice would be to do something 
> predictable, like install a good ground system and use traditional 
> shunt feeding. 

N4KG:  Understand.  My 'Reverse Fed Elevated GP' *plays*
        very well to EU / JA / UA0 on 80M with another tower 70 ft
        to the South which I assume acts as an inefficient
        reflector based on modeling of 2L arrays and comparisons
        with another vertical in the SE corner of my 4 acre lot
        which plays better to SA / LP.  (See JUNE 1994 QST
        or ARRL Antenna Book...Note 54 ft of feedline coiled
        up at the feedpoint...may provide some feedline isolation).  

N4KG:   I *believe / feel* that this 80M Elevated GP plays better than 
        a base loaded 32 ft vertical over a short (1/8 WL) radial field.  

N4KG:   I *believe* this is a good and reasonable option for those 
        with space limitations, especially since it eliminates the tower
        interaction problem by using the tower as the radiator.

N4KG:   Shunt feeding a 40 to 50 ft tower / beam against ground 
        radials is probably even better, assuming a reasonable 
        radial field can be installed.
W8JI:  I am not recommending anything, other than people do the best 
>they  can and experiment. Some people, as unbelievable as it might seem,

> will do pretty well with a short vertical whether base loaded or 
> not..even if they can not get in a perfect or near perfect ground.

N4KG:  W4NS / K4CEF did amazingly well on 160M with a shunt
        fed 100 ft R25 Tower Top Loaded by a TH7 and NO radials.
        I can't explain it but he was 'competitive' in the pileups.

> My only point is to add technical accuracy to some points of this 
> discussion, not to tell people what will work when there are dozens 
> of unknowns.
> People generally can make better decisions with facts or 
> understanding of HOW something interacts, rather than anecdotal 
> evidence.
> > N4KG:What do you recommend to the guy who lives on a 60 by 
> 120 ft lot?
> I only recommend they look at what is around them, try to the 
> understand any resources they have, and decide what they want 
> to try in order to get the results they might want.
> They only clear thing in any of this is to avoid magic antennas, and 
> use systems with good engineering.
N4KG:  AGREE.  Thanks for the enlightenment on the topload / coil
> 73, Tom W8JI

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