HF multiband antenna mounted over large metal roof.
doehme
multiband HF verticals and
basically I'm after some recomedations on what to get based on my
restrictions.
I dont have a big plot of land and can't fit in a multiband dipole
unfortunately. Due to
various other pressures I can't put a vertical with radials up high.
(an "eyesore")
I've got a 50' X 50' (14.5m X 14.5m) fairly flat (gently sloping -
about 7 degrees) corrugated
steel roof and I'm hoping I can put something low over the middle of
this 2500 square feet of
steel.
Would it be appropriate to mount something like a Butternut HF9V,
Diamond CP6, HyGain DX88 or maybe a Hussler BTV5 as close as possible
above the middle of the roof with a total height above the ground of
about 15 feet and electrically connect the roof to where the radials
normally would go and use the roof as a ground plane?
I've alos read that I should place the antenna feedpoint as close to
the roof level as possible. Ie not elevate it at all. Would others
agree?
Which of the antennas listed (or any other multibands you can think
of) be best for my
installation?
My only other alternative is to put a ground independant antenna
(Comet CHA250BX or similar)
about 8m (25') up on a pole off to the side of the house. It's not
out of the question but
the ground independants like the Comet seem to get some pretty bad
reviews and I'd rather use
a "normal" antenna, or as normal as possible.
Any other thoughts or recomendations gratefully accepted.
Thanks,
Dene
atec 7 7
The major consideration is ground plane bonding , dependant on roof
construction if insufficient metal bond is available then to avoid rf
problems and tvi you may need to bond the sheets in some manner , often
it's fine but you wont really know until tried , resonant radials are
often better but again dependant on the vertical it might not matter and
in this case I expect adding them later will be reasonably easy ?
I run a simple vertical with a remote base tuner on 40 and 15 with a
balloon supported vertical wire if I need the lower bands against
everything metal in the house and fences with no problems ( but that
took a lot of additional copper strap)
Good luck
Dili
"atec 7 7" <"atec 77"@hotmail.com> wrote in message
news:h3c5fd$eaj$1...@news.eternal-september.org...
well I have used and owned all those antennas mention plus more commerically
made units, and HB
you never mentioned a GAP TITAN, end fed half wave, works very well, I had 2
GAP titans and worked mucho 7Mhz DX with them,
forget the COMET DUMMY LOAD, DX-88 is ok, but there is better,
currently I use a HF10V Butternut, it is a HF9V with a TBR160 Mtr kit,
the HF9V works better sitting 18-24" above ground with at least 2 radials
per band, too risky as mentioned before in regards ROOF MOUNTING, re
readiated rf and tvi and the neighbours speakers rectifying the rf, and all
that goes with it,
unless you can mount elevated, and use ABOVE GROUND radials, as you can use
less,
if you want 160/80/40 and maybe a 20 mtr kit,
a HF2V (32'10") is a very very good option,
I have never used a wire antenna, always verticals,
good luck
ps
a very good antenna i used for some years is a SCREWDRIVER MOB ANTENNA
mounted 3ft above ground, and a squidpole with 30ft wire taped to it, an use
the 20x2" S/DRIVER coil to resonate the vertical, excellent 30/40/80
antenna, you can then unclip the 30ft wire and attache a shorter wire etc ,
no end to what you can do
got to think out of the box
cheeers
toowoomba4350
> "atec 7 7" <"atec 77"@hotmail.com> wrote in messagenews:h3c5fd$eaj$1...@news.eternal-september.org...
>
> - Show quoted text -
Recently read an article about an allband HF antenna which costs next
to nothing: the "loop skywire" which is not too much of an eyesore.
considering this myself on my future place which is in a new area and
has lots of "don'ts"
follow this link for more info: http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
Cheers
Bert VK4FAPV
toowoomba4350
>
> - Show quoted text -
Just found another (better?) link: http://www.k5rcd.org/hor%20loop%20instruct.htm
which has clear details
Bert
VK4FAPV
I_dont_think_so
news:7a355440-0db4-4d38...@x25g2000prf.googlegroups.com...
Hi Dene, haven't tried the antennas mentioned by yourself or other users,
but have used the Andy COMAN 10/15/20/40/80m vertical. Mine is currently
ground mounted with 4 radials per band except 80m (as per the manual) - and
performs extremely well - I cannot say anything wrong about it. It is an
awesome performer and I always speak well about it - the only minor blemish
that I found with it (as many owners have commented), the construction
manual is well ummm, average to put it nicely.
Mounted on the top of your roof, it should work very well - despite what
some have said, I would still run a set of 4 radials per band even if you
are running it on the top of a large steel roofed shed.
Get one of the Coman antennas (a VK manufacuter by the way) and you will not
regret it.
Dili
"I_dont_think_so" <no_way@not_giving_my_addy.com> wrote in message
news:zvCdnerwu8mvaMTX...@netspace.net.au...
Get one of the Coman antennas (a VK manufacuter by the way) and you will not
> regret it.
yep, well the W/WULF Vertical in question is a copy of the BENCHER
BUTTERNUT HF6V, with H/Brew type capacitors, not ceramic doorknobs, they
work very well with a couple of radials, % less loss then other multi band
designs,
you can still attache a TBR-160 160MTR kit to this antenna also, as the
basic electrical design is similar
doehme
> Get one of the Coman antennas (a VK manufacuter by the way) and you will not
> regret it
Sounds like worth a look. Where can I find some details? I did a bit
of a Google and couldn't find a web site. Who sells/distributes for
him and where can I get some info?
Thanks, Dene
Brad VK2QQ
> I'm trying to sort through the plethora of information available on
> multiband HF verticals and
I am running an old HyGain 18AVT mounted to a satellite antenna tripod
in the middle of a 6x7m steel shed roof. It works very well. The steel
shed frame is also steel and I believe I have reasonable bonding
between all of the sheets, not to forget the overlapping capacitance
between sheets.
The radiating angle of this type of antenna/groundplane combination is
quite high, perhaps 45 degrees upwards. If you want a lower angle of
radiation toward the horizon, then radial wires will be required
instead of the flat iron. I can mount a second antenna on the peak of
my house roof, also corrugated iron, and that condition would be
pretty much satisfied.
A word about the instructions, once the antenna is mounted on such a
large conducting surface, the dimensions specified will be all
different when compared to wire radials or earth.
Brad.
I_dont_think_so
Andy Coman doesn't have a website - as far as I can tell he only advertises
in AR.
atec 7 7
oldgre...@gmail.com
rickindalla...@gmail.com
link
http://www.radiomanual.info/schemi/ACC_antenna/Hy-gain_18-AVT_WB-S_user.pdf
Actually shows a metal roof with radials and the band ..like 20 meters is so long; they paired the radials ..one pair going opposite directions for each band... I'm getting a Cushcraft CHA-250B Monday; may try the radials on my metal roof; concerned with the lightning.. NN7ET 73's
Rick