[TowerTalk] Looking for typical size attic info

[Lux, Jim]

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 at 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 at 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 at 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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