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Author Topic: Attic with foil-backed plywood roofing question  (Read 2379 times)

K1VSK

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RE: Attic with foil-backed plywood roofing question
« Reply #15 on: July 04, 2019, 12:49:50 PM »

.

My point is, which underscores your post: empirical observation should most always supercede general, vague suppositions. I don't for a moment think that the foil-back panels (unbonded) help my RF. But it's clear from 7 years of activity that they DO NOT PREVENT me from having a somewhat effective "antenna farm" in the presence of it. My post in response to the OP was one of encouragement, to experiment to see if his site was workable instead of just assuming that the dogma that a foil-backed radiator --- instead of HVAC, wiring and other metal objects --- would degrade or prevent his signals from being effective. I hope others will do this, too.

73,

Frank
K4FMH


It’s hardly “dogma” as we live where foil insulation is the norm rather than an exception and every ham here who has tried attic antennas has lamented the attenuation cause by the foil.

I suspect your subjective opinion lacks any A/B comparison with antennas not under foil wrap.
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W8LV

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RE: Attic with foil-backed plywood roofing question
« Reply #16 on: July 05, 2019, 07:35:09 AM »

Perhaps the foil backed insulation in K1VSK's area is of a different manufacture than the type found at the Doctor's location. Just throwing it out there as a possibility. Or even just the random placement of HVAC for those particular dwellings..

In any case, experimentation with your local situation is key!

For those who are successful, it represents just one more method to overcome the completely arbitrary and oppressive conditions imposed in Homeowner Occupied Territory untill we can put some serious preemption teeth in Part 97 and put the HOA Man in his proper place below and not above the individual homeowner.

The added benefit of having an antenna that is out of the weather and wind is a very attractive one, indeed:
with no climbing, no maintenance, little cost in relative comparison and being able to be modified/upgraded at any time while not under the watchful eye of Gladys Cravitz and the HOA Jackboots looks a least for some hams who can pull it off like a Winning Hand, so Adapt and Overcome!

73 and All the Best!
DE W8LV BILL

« Last Edit: July 05, 2019, 07:40:30 AM by W8LV »
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K4FMH

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RE: Attic with foil-backed plywood roofing question
« Reply #17 on: July 05, 2019, 09:21:44 AM »

Hi Bill,

Well said! And, I agree completely. I've emphasized the lack of electrical bonding (i.e., the expansion gaps) between the panels in my roof. And...it's a nearly impossible task to isolate the singular effects of the HVAC and other wiring influences from the foil-backed radiator roofing. Jeff Blaine AC0C has travel these roads and documented his extensive experiments on attic antenna farms but he did not specifically deal with foil-backed radiator barriers. But denying my seven years of experience just isn't plausible in the discussion. Others may have severe problems. That is something I do not deny at all. To combat the dogma of any large piece of metal universally acting as a Faraday Cage ("a settled or established opinion, belief, or principle," https://www.dictionary.com/browse/dogma), the advice of experimentation in a local situation is what you, Glenn and I have encouraged the OP to do.

Peeling off the foil as a solution reminds me of back when I drove a Porsche convertible. My ham club got on me almost every other meeting to mount a screwdriver antenna on it and put my new FT-857D in the car. Hmm. Yep, that could work but who would actually punch holes in an expensive car just to do HF while driving in it? Lol Instead, I used an MFJ window clip with a flexible HT antenna connected to my HT with a bluetooth earpiece. This worked very well in Atlanta traffic with a one hour commute each way.

I'll let this rest. The OP has plenty of advice from this thread. He can make his own decisions.

73,

Frank
K4FMH

Perhaps the foil backed insulation in K1VSK's area is of a different manufacture than the type found at the Doctor's location. Just throwing it out there as a possibility. Or even just the random placement of HVAC for those particular dwellings..

In any case, experimentation with your local situation is key!

For those who are successful, it represents just one more method to overcome the completely arbitrary and oppressive conditions imposed in Homeowner Occupied Territory untill we can put some serious preemption teeth in Part 97 and put the HOA Man in his proper place below and not above the individual homeowner.

The added benefit of having an antenna that is out of the weather and wind is a very attractive one, indeed:
with no climbing, no maintenance, little cost in relative comparison and being able to be modified/upgraded at any time while not under the watchful eye of Gladys Cravitz and the HOA Jackboots looks a least for some hams who can pull it off like a Winning Hand, so Adapt and Overcome!

73 and All the Best!
DE W8LV BILL


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W8LV

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RE: Attic with foil-backed plywood roofing question
« Reply #18 on: July 05, 2019, 06:25:13 PM »

Agreed! Your car set-up is one I have considered.
I have a relative difficulty with an antenna install in my car, a Prius Prime Advanced.
The entire back hatch is constructed of graphite: This makes for a poor counterpoise.
Add drilling into graphite. Honestly, I just am too busy minding traffic, and find the AM/FM/Satellite radio is plenty of entertainment anyway.

THAT being said, I am certain that someone located in a HOT might use an HT via "Mobile Repeater Mode" as yet another suggestion of how to operate, unless they give you a caneing for leaving your car parked outside, or leaving the garage door up.

73 DE W8LV BILL
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WY7CHY

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RE: Attic with foil-backed plywood roofing question
« Reply #19 on: July 10, 2019, 10:33:52 AM »

Too many people overlook the capabilities of an HF horizontal loop antenna.
1. They are very forgiving of height
2. They can be mixed shapes
3. They can work up to 25% shorter in length
4. Used with an antenna tuner, you can work 80m-10m no problem
5. Attach to the eave / trim of the perimeter of your house and it's hidden and no one can see it.
6. Because of the natural impedance, 75 ohm RG6 tv coax can actually be better many times.
7. Horizontal loops are naturally resonant on numerous frequencies between 3-30mhz, so with a tuner, it works on all bands.
8. If you don't want/need 80m and 40m and up is all you want, then you can make the BEST loop with 140 feet of wire and it will be resonant on 40m/20m/15m without even using a tuner.

240 feet or more of wire (more is better). Attached to the eave and/or trim of your house. Connect the ends of the loop to a 4:1 current balun. Run a coax from the balun to your shack and the antenna tuner/radio and you're good to go.

My loop is about 250 feet long. Average height off the ground is 10-15 feet up. (Single story house). It's 10 sided around the perimeter of my house and attached garage. I've made contacts on 80m/40m/20m/17m/15m in many countries. USA, Canada, Mexico, Central America, South america, Europe, Eastern Europe, Russia, Hawaii, and others. Best all around antenna. Especially if you have limitations on your property such as space, HOA, etc.
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Born Wild - Raised Proud: 73
Cheyenne, Wyoming

W8LV

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RE: Attic with foil-backed plywood roofing question
« Reply #20 on: July 10, 2019, 03:23:32 PM »

Yep... And they are QUIET Antennas...
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WY7CHY

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RE: Attic with foil-backed plywood roofing question
« Reply #21 on: July 10, 2019, 05:56:30 PM »

Yep... And they are QUIET Antennas...
Amen to that. I've used Horizontal loops for years. At my current house, I had originally had a Fan Dipole with 3 dipoles on it. 80/40/20. And the 40m worked on 15m. It worked fine. But because the most height I could get on my house was around 20 feet high, 80m became basically NVIS only; 40m was so-so and 20m was about the only band I could do cross country or overseas. And that's when the bands were good a few years ago. Then I decided to go back to the loop. I get all over the world on most all of the bands. Of course, current band conditions suck being out of the sun spot cycles; but I still make decent contacts around. And the noise difference is amazing. 80m on it's worst day, is around an S-5 noise. 40m and 20m on a BAD DAY is only around S-3. The only thing that could/would be better, would be if I had a a little more than a 1/2 acre, and could put up 4 or 5 50-60 foot poles and mount a 160m 140 feet per side antenna. Then, with NOTHING between it and the ground to reflect; and no neighbors or anything to interfere with the propagation; we're talking about one of the best antennas possible. In my opinion, the horizontal loop IS the best HF antenna; especially for multi-band use.

In today's crappy conditions, I'd use a YAGI for 20m/17m/15m/12m/10m. But for 40m and 80m, NOTHING beats a horizontal loop. And it doesn't have to be very high or pretty and it still kicks butt.
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Born Wild - Raised Proud: 73
Cheyenne, Wyoming

K4FMH

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RE: Attic with foil-backed plywood roofing question
« Reply #22 on: July 12, 2019, 01:55:18 PM »

I have one, as noted in posts above, situated ~ 1 inch underneath the edge of my shingles. It’s reasonant between 160 & 80M but easily matches to 1.8mhz. It’s a great antenna on HF.

Frank
K4FMH

Too many people overlook the capabilities of an HF horizontal loop antenna.
1. They are very forgiving of height
2. They can be mixed shapes
3. They can work up to 25% shorter in length
4. Used with an antenna tuner, you can work 80m-10m no problem
5. Attach to the eave / trim of the perimeter of your house and it's hidden and no one can see it.
6. Because of the natural impedance, 75 ohm RG6 tv coax can actually be better many times.
7. Horizontal loops are naturally resonant on numerous frequencies between 3-30mhz, so with a tuner, it works on all bands.
8. If you don't want/need 80m and 40m and up is all you want, then you can make the BEST loop with 140 feet of wire and it will be resonant on 40m/20m/15m without even using a tuner.

240 feet or more of wire (more is better). Attached to the eave and/or trim of your house. Connect the ends of the loop to a 4:1 current balun. Run a coax from the balun to your shack and the antenna tuner/radio and you're good to go.

My loop is about 250 feet long. Average height off the ground is 10-15 feet up. (Single story house). It's 10 sided around the perimeter of my house and attached garage. I've made contacts on 80m/40m/20m/17m/15m in many countries. USA, Canada, Mexico, Central America, South america, Europe, Eastern Europe, Russia, Hawaii, and others. Best all around antenna. Especially if you have limitations on your property such as space, HOA, etc.

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W6QW

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RE: Attic with foil-backed plywood roofing question
« Reply #23 on: July 13, 2019, 09:22:22 AM »

The foil backed roof sheeting has been a building code requirement for years in a number of states.  The sheets do not form a faraday shield - the aluminum facing  is not bonded to each other and it doesn't completely surround the antenna.  It does effect RF current distributions so you will see some unusual impedance characteristics.

Until recently, I lived in HOA communities for 35 years and still managed to have confirmed 237 countries on 40M and >100 countries on 10M through 20M (never had an interest in 80M or 160M). Lessons learned:

1. Become best friends with you adjacent neighbors.  They would be the ones to most like spot an antenna.
2. Use stealth or temporary antennas.  Most of my antennas would be remotely erected when needed and collapsed when not in use. Easy to do with linear actuator motors. For wire antennas, use Kevlar fishing line and small gauge wires.  Use camouflage paint for everything. Avoid antennas that are visible all the time.
3. High power is your friend.  Proper RF grounding is required but I never had and QRO interference problems.

Don't let the naysayers dissuade you from experimenting.  Unless you're obnoxious about your antennas, you'll probably be left alone.  Many hams work out just fine in HOA situations.

Enjoy..

Don / W6QW

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KF5KWO

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RE: Attic with foil-backed plywood roofing question
« Reply #24 on: September 30, 2019, 04:40:47 AM »

@wy7chy @k4fmh — I had the same thing (horizontal loop) under the eave of my one-story house, gonna be putting it back up soon. The only band that caused me problems was 20, it would trip my home alarm system, so I used my magnetic loop for that. 

I’ve had my magnetic loop in the attic space in my patio cover since January, and have started making a cement-in-bucket-in-huge-planter mount to put it outside, will be painting and decorating it to make it look like a piece of yard art for stealth.  This will add to my stealth 40m vertical.

@all — The point?  I’m lucky to have trees, but also that it CAN be done in some HOAs or restrictive conditions.  I’m even wanting to build a first-for-me moxon to put in that same attic space, foil wrap or no. It will work, albeit at a reduced outcome I’m assuming, but it will work.

@w8lv — I’ve thought about that kind of contest before too! Some ideas I had this summer:

Categories:
1. Indoor single wire
2. Indoor multiple wire/gain antenna
3. Outdoor hidden/stealth single wire
4. Outdoor hidden/stealth multiple wire/gain antenna

Just ideas!  73 to all!

Jeff, KF5KWO
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W8LV

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RE: Attic with foil-backed plywood roofing question
« Reply #25 on: September 30, 2019, 05:11:49 PM »

Sadly, the World is becoming more and more burdened with the infestation of HOA Marschstiefels,
and every HAM should consider it his Patriotic Duty to Protest the Rising Tide of General Conformity to HOA Marschstiefel "Norms",
Support the ARRL, and Worship Hiram Percy Maxim for the God that he is.

In HOT (HOA Occupied Territory) You might consider a Half Square Antenna. Especially if you have a second floor.
You can google it here:  https://dailyantenna.blogspot.com/2019/03/work-low-band-hf-dx-with-half-square.html  
With its low take-off angle and increased gain, this makes for a pretty decent DX Antenna.
                                                        
You can see it better than how I describe it here, but essentially: You have a half-wave,
with a quarter-wave hanging down from each end, and you feed it from the corner.

This might fit right across a roof or attic, with the ends just hanging down (but above where "busy" Humans might come in contact with it.)
Or if your situation is heavy, hidden entirely right inside the walls and attic.

OR the top might fit right above your second-storey windows, and the ends come down and are hidden inside moulding,
or caulked into the edges of nonconductive moulding, and you feed it right from the corner of one of those windows,
OR it goes on the SIDE of an HOA Townhouse. Or: INSIDE the SIDE: Haha!

You might even use coaxial cable to make your half-square with some of the parts, with the whole thing mounted with the same little plastic brackets that the local CATV uses... Just solder the shield to the centre conductor for the elements, and it's just a wire that looks like a coax. And the feedline part IS: Actual, Real Coax! :-)

No matter what: This is a cheap antenna, and you can do this up big or small, depending on your situation.
You can easily put up and take down a temporary one. Or make it a more permanent installation.
There may be a ladder or two involved, but no tower climbing, ever, and no towers to blow over in a Florida Hurricane.
Just "Hanging and Pulling" from your windows means no climbing whatsoever, and this will keep you off that Silent Key Page,
well for at least a little while longer. (But you know what I say about the Silent Key Page... No matter how many times you leave it:
You're always coming back! But let's just SKIP on the Whole Silent Key Candidate Thing for TODAY...
Safety First!)

This will work well in a Florida "Townhouse" kind of Condo situation,
where the Disgusting "Left-Side of the IQ Bell Curve" HOA Marschstiefels are especially brutal to nonconformists.


Oh yea, I almost forgot: It will also work in the near vicinity of an overpriced Clanton Park Toronto Suburb, too...
Where someone will never have to deal with a Frozen Antenna Rotor on the roof of the building again, ever,
that's not supposed to be near anyway, because they just yanked the wires.
And moved on "up" to The Beaches and a proper Half-Square Antenna!

Best of all, the Half-Square starts getting practical dimension-wise for 40 Metres right on down to 10 Metres.
For 20 Metres, here's your low angle Dx Dream. And Gladys Cravitz won't see it, nor will the HOA Marschstiefels find it.
You MIGHT even be able to pull off an 80 Metre (or More!) one, though I've never actually heard of one:
Remember, once it's up, you only worry about the corner where you feed it and operate it!

If a couple of "Non-Resident" Brother Hams show up with a plain white van or panel truck,
and wear the correct attire including hardhats (sans callsigns!) and carry clipboards, the HOA Security Guy
driving around in the Golf Cart (With the stick-on "Security" letters that are half falling off)
might not even ask them what they are up to.

If the van has proper fibreglass ladders lashed to the top of it,
even if you don't need them but you might?
Well, that makes that van an OFFICIAL Van.

This is Best done if the Resident Ham isn't home, but one of his older "kids"
(who is not his kid but is a fellow Ham) is at home to open the door,
and the Condo Office has just closed up shop for the day. And the "Kid" can be busy inside with doing up the feedline stuff,
while the Outside Crew do their thing...

But if he DOES ask them, as is sometimes known to happen and Security Man has a drink in hand and a cooler?

Then (and only then) it's OKAY to take up his offer of a couple of cold drinks for the "Construction" Crew.
Remember, setting the HOA Man Aside, we're all just Happy Happy Little Worker Bees, and we don't ask why:
We just do what's on the clipboard because someone told us to and they pay us, right?
There are LOTS of CATV Subcontractors and such,
and those trucks don't have official logos anyway.

Stickers on your VOM's and antenna analyzers with names and callsigns
are not a good idea. Replace them with temporary "new" labels.
Also, cover the "Antenna Analyzer" name with a sticker that says "company property" or something.
And NO "Home Brew" Stuff! remember you're OFFICIAL!

The "Crew" just needs to get in, try to look "official"...and not like they're not having a good time.
(That comes later when you are On The Air and can Gloat Like a 'Mutah!),
Don't even think of touching any "common" areas, get the job done, and get out.
And remember, next weekend, it's YOUR turn to be Hardhat Builder Guy at YOUR BUDDY'S Place of HOA Imprisonment.

And I HIGHLY recommend that this kind of "Stealth" Antenna Raising party makes for a GREAT Summer Vacation Activity.
Just REMEMBER to do your Homework FIRST and check out the situation and you'll have your MISSION ACCOMPLISHED! ;-)
Caveat Emptor!

73 DE W8LV (and sometimes W8LV/VE3)  BILL



« Last Edit: September 30, 2019, 05:36:25 PM by W8LV »
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