[TVARC] Advice wanted: Wire antennas in attics

[Ed Deichler]

Bob,
One of the things to check when you get to the attic is whether there is
any aluminum insulation backing in the rafters or elsewhere.  I live in the
north end of TV near route 42 in a regular home (not a villa).  I had built
a Moxon for 12 and 17 meters in my garage attic section a few years ago.
It worked ok but being only 12 feet off the ground was not that great for
DX.  Later, I installed an MFJ Cobweb antenna in the attic that gave me 20
through 10.  The antenna worked well once it was adjusted for each band
but, again, height was a factor when trying for DX.

I thought about a 40M bent dipole running through the rest of the attic but
the ductwork and insulation running through it discouraged that idea.

I've been happy with my 6BTV vertical and a dual inverted V for 12 and 17.

73 de Ed

On Sat, May 27, 2023 at 2:58 PM Jim Worthington via TVARC <
tvarc at mailman.qth.net> wrote:

> I have some experience with attic antennas. The closest to what you
> suggest are 40-20-10 meter fan dipoles I’ve installed for in a couple homes
> near Melbourne, FL. The 40 meter section works on 15 meters giving 4 bands,
> but requires the internal tuner on 15.
>
> In addition, I have a makeshift 40-10 meter doublet in an attic in Fenney
> and a couple of switchable, perpendicular 10-6 meter fan dipoles in my
> attic in Atlanta to cover all directions.
>
> The first issue is what space is accessible, as you have already
> mentioned. I rented a 2 bedroom villa in Chitty Chatty last summer. The
> attic had very limited accessible space for antenna. Consequently, I didn’t
> attempt to install anything in that attic. I used an AlexLoop instead. Your
> home may be different. Don’t hesitate to have some bends in your fan dipole
> legs if you can get the length you need that way. I have also thrown the
> end of a leg, with a weight on the end, to an area of an attic I couldn’t
> reach. It worked fine.
>
> Of course, attic antennas are a compromise due to a few factors:
> 1. There are usually metal and other RF-unfriendly substances in the
> attic/roof to absorb or otherwise disturb your signal. They will also
> affect the resonant frequency.
> 2. The height above ground in The Villages will typically be 20’ or less
> giving higher than ideal takeoff angles, particularly on the lower bands.
> 3. There are often noise sources near an attic antenna, so you may have a
> high noise level.
>
> On the positive side, it won’t cost you much to give it a try. Speaker
> wire from and TV coax from Loew’s will work for the fan dipole. You can use
> fishing line or string for insulation and connection to supports,
> especially with QRP.
>
> If you find there is not accessible space in your attic for the fan dipole
> you envision, consider a couple of other options. The increasing sunspot
> count can provide a lot of contacts with modest antennas at low heights on
> 10-12-15 meters. You may be able to fit a fan dipole for those bands. You
> could also pick one band and install a 2 or 3 element wire yagi for it.
> Years ago, I put a 3 element 15 meter wire beam in my attic up 25 feet
> favoring Japan. It was 3 S-units better in that direction than my 40 meter
> dipole up 60 feet up broadside to Europe.
>
> Let us know how it goes. I’m sure others can benefit from your experience.
>
> 73,
> Jim AD4J
>
> > On May 27, 2023, at 9:33 AM, Bob Easton <bob at bob-easton.com> wrote:
> >
> > My primary interests, QRP HF CW, work fairly well from temporary
> verticals in my backyard. Those temporary antennas are great for short term
> use and portable operation. However, I'm looking for something more
> permanent and am considering a well tuned 4 band fan dipole inside the
> attic. (40m, 30m, 20m, 17m) Well tuned because I don't want to give up any
> of those 5 watts to a tuner, even though my favorite rig, a Penntec TR45-L,
> has a built-in Z-match tuner that can even out the rough edges.
> >
> > I have lots of unknowns about such an antenna might fit and welcome the
> advice of others who have tried something similar. Among my unknowns are
> that I've never seen the inside of my attic, (don't yet have a ladder long
> enough - 10ft tall exterior walls and equally high ceilings). Nor do I know
> if the builder laid any sort of flooring up there. The house is about 3
> years old, in Chitty-Chatty, south of US 44. Size wise, the overall
> dimensions of the building measure 72 feet on diagonals. So there should be
> enough space ... if I can get to it.  Assumption: wire antennas are
> inexpensive, while attic stairs and flooring not so much.
> >
> > Will this be a good opportunity, or a multi-thousand dollar boondoggle?
> THANKS for all advice.
> >
> > Bob, N4REE
> > also: https://www.qrz.com/db/N4REE
> >
> > --
> > “Have nothing in your home that you do not know to be useful or believe
> to be beautiful.” - William Morris
> >
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