On 2/13/23 6:29 AM, Chuck Dietz wrote:
I understand many (all?) of the newer houses have insulation with aluminum
foil backing inside the roof. My friends who have HOA restrictions, put
antennas on their wood fences. Nowadays with modes like FT8, their stations
can be surprisingly effective.
My attic (which has no real clear space, because of roof trusses, but
which is representative of other attics in SoCal, some of which are
"walkable" - the insulation is on the "floor" of the attic, directly
above the living space. In a former house, which had an unfinished 2nd
floor, all the insulation was below, and when we finished it, we
insulated the walls and the ceiling rafters before putting up the drywall.
That said, antennas outdoors are a lot easier to fix, tend to have less
interactions with wiring and appliances inside (RFI, etc.) and, of some
concern, if the HV at the ends starts a fire, it's not hidden in your
attic. I had a dipole in my (truss and HVAC duct filled) attic, and it
was terrible in terms of tuning (all kinds of weird resonances) and RFI
both directions was a problem - lots of noise on Rx, and when I Tx
(~100W) all kinds of things would malfunction in the house (like the
HVAC thermostat). Putting the antenna on the "outside" of the roof
actually made it a lot better. When the aggressor/victim distance
changes from 1 meter to 2 or 3, it makes a BIG difference.
I didn't have a way to evaluate it, but I'm going to guess the weird
impedance curves meant it interacted with a lot of other conductors, so
the pattern was probably full of lumps and bumps.
The other location other than fences, is eaves (assuming you don't have
a raingutter along that same eave).
Chuck W5PR
On Mon, Feb 13, 2023 at 8:19 AM Mpridesti via TowerTalk <
towertalk@contesting.com> wrote:
Thanks Henry. Good suggestions!
Certainly one challenge would be just building the antenna in close
quarters:)
Regards,
Mark, K1RX
On Feb 13, 2023, at 9:16 AM, Henry Pollock - K4TMC <kilo4tmc@gmail.com>
wrote:
Mark,
You might consider a 2-element Hexbeam. A 20-10 Hexbeam has a turning
radius around 10 to 12 ft which could fit in some attics. To make it fit
higher in tight attics, consider mounting it upside down, making it look
like a normal umbrella.
73,
Henry - K4TMC
On Mon, Feb 13, 2023 at 8:42 AM Mpridesti via TowerTalk <
towertalk@contesting.com> wrote:
Looking at the HOA/condo situation as I get older and wonder what are
the
typical size attics for putting, ideally, a small rotating Yagi for
20-10
m. Key question is what the biggest turning radius one might get?
Regards,
Mark, K1RX
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