[Antennas] All steel 26ga roof

[Philip Atchley]

Hi,

I live in a 14x65 foot Mobile home here.  All sheet metal roof with a 
large metal awning on either side.  I'm not sure how well bonded 
together the whole thing is, but it 'seems' to make a very good 
groundplane.  There is a Hustler 6BTV vertical mounted in about the 
center of the roof lengthwise, but offset to one side some (mast comes 
up between awning and roof).  It's ground is tied to the metal roof 
several times.  This seems to work VERY well, I get quite distinct 
"resonant points" or low SWR nulls, particularly on the lower bands, 
indicating there is little ground loss under the antenna (vs very wide 
nulls indicating poor grounding).  My primary complaint is that the 
antenna is way TOO narrow on 76 and 40M ;-)

By the way, this antenna will be replaced by an HF-2V for 80,40& 30M 
next month!

So, a metal roof CAN make a good ground plane,  but it sure makes a 
LOUSY antenna.  When I first moved in 6 years ago I tried clipping an 
antenna lead to it a couple times for receiving only , and I got more 
noise than signals!
 
73 de Phil  KO6BB


J Setcer wrote:

>I agree that the roof would make a NOISEY antenna because of the
>nails/screws and the joints.
>But my experience has shown that the roof may not even make a decent
>reflector.  You certainly will NOT be able to put antennas in the attic!
>
>I used a BTV-4 (or btv-5) on a steel roof  a few years ago.  Even with all
>that steel I still got much better results by elevating the antenna-- the
>height of a tripod (maybe 5 ft)-- and adding sloping radials -- two per
>band -- from the bottom of the antenna to the corners/edges of the roof.
>
>also, a few years ago I put the same antenna on the crows nest @12 ft above
>a 25 ft. X 25 ft steel mesh floor of a 112 ft tall tower.  The antenna was
>LOUSY until I put two radials per band from the bottom of the antenna
>slopping to the railing around the tower.
>
>also interesting (at least to me).... We put a Force 12 C-3 just above the
>crows nest.  We put the BTV-4 above the beam.  The vertical worked pretty
>well on..... you guessed it.... 10, 15, & 20 meters.  Didn't work well on 40
>meters(the 4th band).
>-----------------------
>None of these pictures show the vertical antenna.  But they do show the
>tower, the deck, the c-3, etc.
>
>73, J. Setcer, N5QJ
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