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[Articles Home]  [Add Article]  

Radiant Barrier Myth

from Michael White, W4EZK on January 12, 2019
View comments about this article!

Just to weigh in on the effects of aluminum foil sheath reflectors, I would like to add my experience.

While not an antenna theory expert, I am reduced to experimentation and hopeful outcomes.

I've been a ham for more than 50 years and installed at least 100 antenna's. But for the last 8 years, I have tried to penetrate my radiant barrier, with multiple antenna designs.

To get to the point, the myth is true. It can't be penetrated, not on HF anyway.

I'm now exploring 1) remote station locations , 2) Scorpion mobile antennas andd 3) moving.

Prove my solution is unnecessary and I will be forever in your debt.

W4EZK, Mike

Member Comments:
This article has expired. No more comments may be added.
 
Radiant Barrier Myth  
by YL3GND on January 12, 2019 Mail this to a friend!
https://imgflip.com/i/1t9uia

Like this?
 
Radiant Barrier Myth  
by AA4MB on January 12, 2019 Mail this to a friend!
Mike,

Can you give us a bit more lengthy description of what it is exactly that you’re trying to solve? What is the ‘myth’ you reference? Which ‘solution’(s)’ are you hoping to be unnecessary? I’m wondering if your residence has some sort of foil moisture/weather barrier and you’re maybe trying to use an inside antennna ... is that it?

Matt, AA4MB
 
Radiant Barrier Myth  
by AA4MB on January 12, 2019 Mail this to a friend!
Mike,

I commented before using enough relevant keywords on Google. I also found some discussions on this, finally. Interesting, indeed.

Matt, AA4MB
 
Radiant Barrier Myth  
by KF4HR on January 12, 2019 Mail this to a friend!
What myth?
 
Radiant Barrier Myth  
by G8ADD on January 12, 2019 Mail this to a friend!
Radiant barrier? Never heard of it!
 
Radiant Barrier Myth  
by NN4RH on January 12, 2019 Mail this to a friend!
If I had to guess what he's talking about ...

Maybe it has to do with indoor antennas in houses with foil-backed insulation either in the walls or the attic?

 
RE: Radiant Barrier Myth  
by AA4PB on January 12, 2019 Mail this to a friend!
Installing an antenna inside a radiant barrier is similar to trying to use an antenna inside a screen room. It's not going to work very well, HF or VHF. The best solution is to put the antenna outside of the house and its radiant barrier. Coax will pass the signal through a radiant barrier, no problem. Even without a radiant barrier, antennas are much more effective when placed outside the house.

The positive side of a radiant barrier is that it should minimize any potential RFI issues with devices inside the house (provided the antenna is on the outside).
 
RE: Radiant Barrier Myth  
by AA4MB on January 12, 2019 Mail this to a friend!
There are several types of radiant barriers out there, apparently. Some of the more paranoid tinfoil hat types also apparently use them intentionally only to minimize the 'hazards' of RF coming into their house from the cell tower 2 miles away, hams transmitting in Beijing and/or Radio Moscow. But yes, apparently they inhibit HF quite a bit just like they do VHF. I've never given it much thought and it would seem that many builders now put them on the attic roof and walls now in lieu of conventional rolled insulation.

If only my RFI came from my own house; I'd put this stuff in the walls. No, mine is coming down the coax, generated by the plethora of my neighbors' electronic devices and wall warts in the immediate vicinity - which aren't under my control.
 
Radiant Barrier Myth  
by K2RJK on January 12, 2019 Mail this to a friend!
He may be referring to the foil faced Tyvec type of house wrap that was/is used by some siding installers.
 
RE: Radiant Barrier Myth  
by N4KC on January 12, 2019 Mail this to a friend!


Oh! I thought "Radiant Barrier" was a punk-rock band from the '70s.

Don N4KC
www.n4kc.com
www.donkeith.com


 
RE: Radiant Barrier Myth  
by KF4HR on January 13, 2019 Mail this to a friend!
And alas, the myth continues!
 
RE: Radiant Barrier Myth  
by K0UA on January 13, 2019 Mail this to a friend!
I guess I don't understand the "myth" part. I understand the radiant foil barrier, I had a house with that in the attic. Good stuff, I run my many coaxes thru it on their way to my 100 foot tower.
 
Radiant Barrier Myth  
by VE7VJ on January 13, 2019 Mail this to a friend!
Does anyone proof these 'articles' before allowing them to be posted? My first reaction after reading this was "What???"
 
RE: Radiant Barrier Myth  
by KJ4DGE on January 13, 2019 Mail this to a friend!
Mike, I write articles here as well. Some generate negative comments and I smile some generate positive comments and I smile. But I do not dis the reader. However a bit more than a paragraph might enlighten all of us as to the issue you are having with the "radiant barrier" Have you tried a novel approach and fed your RF to a rain gutter.....?


Life is filled with barriers, its just a matter of overcoming them, large and small, one way is to climb them up or take them down or at best go around them or dig underneath them. There is ALWAYS a way to get on HF.

Best new year to you!
KJ4DGE
 
RE: Radiant Barrier Myth  
by N3HKN on January 13, 2019 Mail this to a friend!
Advanced physics or paranormal? And, it is not yet April.
 
Radiant Barrier Myth  
by WA3SKN on January 13, 2019 Mail this to a friend!
Just tell us the REAL problem you are having.

-Mike.
 
Radiant Barrier Myth  
by AC1DR on January 13, 2019 Mail this to a friend!
If you are referring to a Faraday Shield, it is not a myth. It is Physics 101.
"A Faraday cage or Faraday shield is an enclosure used to block electromagnetic fields. A Faraday shield may be formed by a continuous covering of conductive material or in the case of a Faraday cage, by a mesh of such materials." If the wavelength of the electromagnetic radiation is considerably longer than the mesh opening, no radiation will penetrate.
 
Radiant Barrier Myth  
by K8QV on January 13, 2019 Mail this to a friend!
Not absolutely certain what we're trying to get at here but I do know this.... shielding (barrier?) works whether intentional or not.
 
Radiant Barrier Myth  
by KB5UZB on January 14, 2019 Mail this to a friend!
I've been wondering if the radiant barrier could be used to advantage by grounding it & using it as a ground plane. Could lead to some odd directionality, but might be an interesting experiment.
 
RE: Radiant Barrier Myth  
by KJ4DGE on January 14, 2019 Mail this to a friend!
Lets REALLY break this down since we have so many people to work the "problem"?

Radiant....to radiate or shine upon or cast warmth unto an object. Barrier.....A object put up to block or inhibit something from going beyond it.


Sounds like he is talking about leaky coax?

Yes I know I am being somewhat of a snob but really Mike what is the question if there ever was one? Can you elaborate on your "Radiant Barrier" some more? If only to keep the comment section going in circles :)

 
Radiant Barrier Myth  
by N6JSX on January 14, 2019 Mail this to a friend!
This is what constitutes an 'Article" on eHAM now?!?

eHAM must be getting desperate to generate site/ad clicks as this subject should have ONLY been posted in Antenna 'Forum'!

Maybe eHAM would get more 'ARTICLES' if they rewarded the authors efforts for their x10 hours of work authors GIVE freely to eHAM. Define what constitutes a post-able article too; +2000 words w/pics/diagrams/links/etc? Then weed out all the non-related off-subject (personalized) hijacking comments?!?

The more crappy 'prime' articles like this eHAM posts the more users will drift away greatly reducing the click counter(s).

eHAM use to be an everyday check - now it is a once a month 'maybe' if I'm bored.
 
RE: Radiant Barrier Myth  
by AE5X on January 14, 2019 Mail this to a friend!
eHam moderator: This is the best you can do for an "Article" approval?
 
RE: Radiant Barrier Myth  
by SWMAN on January 14, 2019 Mail this to a friend!
Oh my !!
 
RE: Radiant Barrier Myth  
by K6CRC on January 14, 2019 Mail this to a friend!
eHam is free to readers. Doubt the owners are getting rich here. Authors get nothing.
If you don't like the articles, move on. Or, write something yourself.
 
Radiant Barrier Myth  
by KD8ZM on January 14, 2019 Mail this to a friend!
Just make the radiant barrier into your antenna. If you can't beat 'em, join 'em.
 
Radiant Barrier Myth  
by KD8ZM on January 14, 2019 Mail this to a friend!
Just make the radiant barrier into your antenna. If you can't beat 'em, join 'em.
 
Radiant Barrier Myth  
by KC1GWX on January 14, 2019 Mail this to a friend!
This made me think of a recent post from someone who turned their downspout into an antenna, and has been able to get it to tune up on 160 and other bands. I've also heard of using gutters, by running wires to turn them into a loop. Just something to think about.
 
Radiant Barrier Myth  
by N0GV on January 14, 2019 Mail this to a friend!
Ok, at 1.8 MHz the skin depth of aluminum is 61um or about 2.25 mils. This is about what the total thickness of a radiant barrier insulation's metallization. This means that less than 38% of the incident 1.8 MHz radiation will be able to penetrate the barrier. At higher frequencies even less gets through. If the barrier is thicker than 2.25 mils (usually it is nearly twice that thickness) then you are not going to get much inside the house on the HF-VHF bands. Uhf/microwave can use windows etc. as "holes" as the windows are much larger than the wavelength and some signal will get through.

If you want an antenna for these blocked frequencies it is going to have to be external. On the other hand a nice simple vertical with a few radials on your radiant barrier treated flat roof will work gangbusters as it has a near perfect ground plane under it.....

Good Luck,

Grover Larkins

 
RE: Radiant Barrier Myth  
by N4UM on January 14, 2019 Mail this to a friend!
by K6CRC on January 14, 2019
"eHam is free to readers. Doubt the owners are getting rich here. Authors get nothing. If you don't like the articles, move on. Or, write something yourself"

..what he said...
 
Radiant Barrier Myth  
by NE1U on January 14, 2019 Mail this to a friend!
pseudoscience
 
Radiant Barrier Myth  
by W9YW on January 15, 2019 Mail this to a friend!
Various home bits of insulation and hardware can indeed cause nulls, ineffective radiance, and not such wonderful radiance. Every home is different. It's not a myth, there are indeed barriers to radiance.

Four problems:

1) metal, especially foil.
2) low antenna height
3) ugly, perhaps uneven radiance by weird ground planes so that electrical propagation is strange and uneven
4) occasionally poor common ground/earth problems.

As mentioned plentifully above, getting the signal outside the house helps a lot. There are many apartment and HOA work-arounds, all well-known and documented. It's not a myth. It's a reality of indoor situations in general.
 
RE: Radiant Barrier Myth  
by K6AER on January 15, 2019 Mail this to a friend!
Here’s the bottom line…..

Non HAM related articles will drive the viewership (HAMS with money to spend) away in droves.

No viewers and the manufactures who advertise on E-Ham will go else ware.

Articles need a real peer review.

Posting an article should be done with a simple Microsoft word document.

As it is, getting an article into E-Ham (especially with pictures and diagrams) is like pulling hens teeth.
 
Radiant Barrier Myth  
by K4FMH on January 15, 2019 Mail this to a friend!
I’m sorry that you’re having these issues. I built a house about 6 years ago with radiant barrier roofing plywood. The sheets have a small gap between plywood sheets to allow for expansion during the summer. Thus, the aluminum barrier “tiles” are NOT bonded together. I do not know if yours is installed this way. The roof peek line where the dipole is mounted about 8 inches below is around 40 feet above ground.

But, one of my first contacts was using a MFJ 80/40M dipole and 100 watts on a Kenwood TS-940 in the 40 meter band to Malibu, CA. Mine seems to work!

 
RE: Radiant Barrier Myth  
by KJ4DGE on January 15, 2019 Mail this to a friend!
Understanding the problem and yes rain gutters do work but as stated you have to be very careful with short runs of coax (good coax) and a tuner in the rig is better than and external one due to more signal loss getting in the metal. Also forget doing 160 meters on a gutter unless its a gutter that runs around a very large warehouse and is super thick.

Pork radio operators have for years overcome radiant barriers through use of attics, vent pipes, pruning trees or simply moving the antenna away from whatever bars the signal. I built a vertical recently for 20 meters using wire hanging from a 25 foot bamboo pole and a loading coil at the base, sloping radials of 16 foot sections yes like a ground plane. Not only does it tune 20 with low SWR across the band it tunes 40 as well but that's about it. Im happy to be able to work 20 WHEN its faily decent.

Also as a 40 vertical it is very quiet over my 80/40 dipole in the backyard.
 
RE: Radiant Barrier Myth  
by N6JSX on January 15, 2019 Mail this to a friend!
Wow, do a eHAM ARTICLE search on my call-sign and then get on your knees & apologize.... I'll put up my FREE efforts to eHAM to any of yours! Put-up or shut-up!

So, YES, I have a basis to chastise eHAM!

N4UM on January 14, 2019
K6CRC on January 14, 2019
"eHam is free to readers. Doubt the owners are getting rich here. Authors get nothing. If you don't like the articles, move on. Or, write something yourself"

..what he said...
 
RE: Radiant Barrier Myth  
by K2BEW on January 15, 2019 Mail this to a friend!
N6AER wrote;
"Here’s the bottom line…..
Non HAM related articles will drive the viewership (HAMS with money to spend) away in droves.
No viewers and the manufactures who advertise on E-Ham will go else ware"

Honestly the bottom line is this is an ancient website in terms of the internet. I have been coming to it since 2007 and it has not changed at all. It's a dinosaur, no change to the graphics, menus, layout,content etc... I seldom visit anymore and it seems many forum posts are years old. The shack pictures usually have computer monitors in them that are CRT's, does anyone actually use them anymore?, They're very old pictures. I don't think this website needs to worry about poor articles keeping advertisers or new people away.
 
RE: Radiant Barrier Myth  
by K9MHZ on January 16, 2019 Mail this to a friend!
^^^ Oh well, I guess that’s why there’s a big web with lots of other places to go.
 
Radiant Barrier Myth  
by KK6BXO on January 17, 2019 Mail this to a friend!
Mike,

Thanks for the question. We have a pressed steel roof like this. We chose it for fire resistance:

https://gerardroofs.co.nz/RoofingProducts

As it is on the outside surface of the plywood roof, obviously this doesn’t function thermally as a radiant barrier like the foil-backed insulation products do. Also the individual shingle panels are not electrically bonded to each other. But it mostly bocks RF in and out of our house. VHF, UHF, HF, cell phones, TV broadcast, and everything else I’ve checked are blocked and-or distorted enough that they are unusable. Cell phones work at the “one bar” level if you are next to a window, but not enough to make calls reliably.

I hope you can figure out an external stealth antenna that works well enough that you don’t have to move!

73, Maurice.

(PS. I also hope you can ignore the rude and inappropriate comments. I understood your question just fine, and I appreciate it as well as others’ productive answers.)
 
Radiant Barrier Myth  
by K9CTB on January 20, 2019 Mail this to a friend!
It's all the same. Anytime you surrender control - on the build of your home, or to an "HOA", or to an apartment agreement - the less freedom you have to exercise your privilege. I have no idea what a "radiant barrier" is, but if it's like most of this 'nu-gen' mumbo-jumbo, it's probably misleading. you know, like the "Weather Channel" naming snowstorms. Nobody cares.

But if you think foil-faced insulation affects your amateur radio signal, option 3 is probably your best bet.
 
RE: Radiant Barrier Myth  
by K9MHZ on January 21, 2019 Mail this to a friend!
Maybe we're behind the times here, but new construction is OSB sheathing wrapped on the exterior with Tyvek, and traditional insulation between the studs inside. Haven't seen anything aluminum. Maybe we need to be in a greener state or something.
 
RE: Radiant Barrier Myth  
by AA4PB on January 21, 2019 Mail this to a friend!
https://www.energy.gov/energysaver/weatherize/insulation/radiant-barriers
 
RE: Radiant Barrier Myth  
by N0GV on January 26, 2019 Mail this to a friend!
The radiant barrier is, normally, under the roof.

Many brands of insulation have product lines with foil backing as well as Kraft paper backed products. These foil backed products will also cause problems with an indoor antenna and may be found under floors, in walls and ceilings and so forth....



 
Radiant Barrier Myth  
by N5LS on January 30, 2019 Mail this to a friend!
For all of you hams in Northern states, you've probably never heard of "radiant barrier". This is common in newer construction in Southern (read: Hotter) states. This is plywood roof decking that is lined with aluminum foil on the inner (attic) side. It is meant to reflect radiant heat from the sun, and keep it from getting into the attic. And it works.

But...the question is...does it create a Faraday Cage from the attic? Probably so.

I cannot even consider an attic antenna because of this. Am planning a wire (dipole, fan, OCF dipole or end-fed Halfwave) to go over my roof.

How high ABOVE my roof do I have to keep this wire, so that the radiant barrier roof decking doesn't de-tune the antenna?

Larry
Dallas, TX
 
Radiant Barrier Myth  
by N5LS on January 30, 2019 Mail this to a friend!
For all of you hams in Northern states, you've probably never heard of "radiant barrier". This is common in newer construction in Southern (read: Hotter) states. This is plywood roof decking that is lined with aluminum foil on the inner (attic) side. It is meant to reflect radiant heat from the sun, and keep it from getting into the attic. And it works.

But...the question is...does it create a Faraday Cage from the attic? Probably so.

I cannot even consider an attic antenna because of this. Am planning a wire (dipole, fan, OCF dipole or end-fed Halfwave) to go over my roof.

How high ABOVE my roof do I have to keep this wire, so that the radiant barrier roof decking doesn't de-tune the antenna?

Larry
Dallas, TX
 
Radiant Barrier Myth  
by N5LS on January 30, 2019 Mail this to a friend!
For all of you hams in Northern states, you've probably never heard of "radiant barrier". This is common in newer construction in Southern (read: Hotter) states. This is plywood roof decking that is lined with aluminum foil on the inner (attic) side. It is meant to reflect radiant heat from the sun, and keep it from getting into the attic. And it works.

But...the question is...does it create a Faraday Cage from the attic? Probably so.

I cannot even consider an attic antenna because of this. Am planning a wire (dipole, fan, OCF dipole or end-fed Halfwave) to go over my roof.

How high ABOVE my roof do I have to keep this wire, so that the radiant barrier roof decking doesn't de-tune the antenna?

Larry
Dallas, TX
 
Radiant Barrier Myth  
by WD0BCT on January 30, 2019 Mail this to a friend!
I suspect a troll. He left this ambiguous question and has not been heard from since.
 
Radiant Barrier Myth  
by KJ4RWH on February 12, 2019 Mail this to a friend!
On February 11th the "Radiant Barrier Myth" was elevated to a scientific axiom.
 
Radiant Barrier Myth  
by W4EZK on February 14, 2019 Mail this to a friend!
Hello again. To update my experiences, I telephoned the manufacturer "Tech Shield" to see if they could offer any pearls of wisdom. They were cordial enough but, admitted that their aluminum barrier not only reflects sun rays back so as not to enter my attic and also said it would be just as effective in reflecting RF from my attic antenna in every direction except through their barrier.

Of course, I knew that so I merely asked them how I could remove it. After a brief discussion, we agreed it could be removed if I cut off the roofing nails penetrating the roof sheathing and the aluminum barrier, then grind the nail shanks into the OSB board, then sand or plane 1/64" deep to remove the barrier.

So, I called Scorpion Antenna company and spoke with the owner. Ron said that would work and then explained how I could create a ground plane in the ceiling rafters by covering the attic floor with aluminum. Needlesss to say, finding volunteer help turned out to be an even bigger challenge. I called my PhD son as a last resort and he came right over. Together, we agreed there has to be a better way.


There is. Write your senators and congress members and ask them to support the Amateur Radio Parity Act and then write the FCC and let them know that while you signed your HOA's CCR's, you really didn't know that your HOA was a rule gate keeper and besides, you couldn't find a non HOA home that was suitable (LOL).

 
RE: Radiant Barrier Myth  
by AA4PB on February 21, 2019 Mail this to a friend!
"After a brief discussion, we agreed it could be removed if I cut off the roofing nails penetrating the roof sheathing and the aluminum barrier, then grind the nail shanks into the OSB board, then sand or plane 1/64" deep to remove the barrier."

Then call a roofer to be on standby to replace your shingles after the first high wind comes along and pulls all the short, cut off nails out of the OSB board. :-)
 
RE: Radiant Barrier Myth  
by K9CTB on March 6, 2019 Mail this to a friend!
Trouble with that is that radio amateurs need to begin *acting* like a peer group instead of this nattering and flaming nonsense we keep doing to each other on an otherwise useful forums like this one. If we could master that, perhaps we could *get* more advertisers, more amateurs and more non-hams interested in what we do. Just a casual observation.
 
RE: Radiant Barrier Myth  
by W6EM on March 6, 2019 Mail this to a friend!
Our son, W5AVC, lived in a home for a while with attic dipole possibilities, so I climbed up and took a look. Nope, all of the plywood sheeting under the shingles had foil covering it. I stopped dead in my tracks and thought: a perfect (almost) Faraday cage!!! I didn’t look to see if each section was electrically connected, but didn’t look since I figured it would have been a wasted effort.

I shared my observation with Nick Leggett, N3NL, now a Silent Key. I met Nick through some areas of mutual interest in our hobby. Nick, being far more innovative than me, suggested that I “segmentize” the foil, cutting it and thus creating an imbedded 40M or 20M dipole out of the aluminum foil sheeting. I didn’t have enough time to help our son try that, as he shortly thereafter sold his home and moved. His new home doesn’t have such a large attic space, but as others have said, new homes in the South have the foil to minimize radiation from the roof into the attic space.

Anyway, here’s an extension to Nick’s suggestion: You could try carving what amounts to a large planar bow-tie antenna in the foil. Bow ties are known for their incredibly broadband, almost frequency-independent characteristics. If I had such a situation, that’s what I’d try. Of course, you’d have to make sure that all seams in the foil are electrically bridged so that there aren’t gaps within the bowtie.

Worth a try and a few hours of work with a box cutter knife. How many HF bow-tie antennas are realizable with wire? Not many.


73

Lee
W6EM


 
Radiant Barrier Myth  
by KS3B on March 13, 2019 Mail this to a friend!
Radiant barrier is not a myth, it is a well-known reality. It is also not a Faraday cage, it is just temperature isolation. I lived in such a house and measured the foil attenuation. It was as expected - in the vicinity of 25 - 30 dB. This attenuation is well below the Faraday cage numbers. But it is big enough to spoil your radio communications. You may cut a slot in the foils and make a slot antenna or even cut some more complex geometry and have a surrogate antenna. But anyway you will have a big loss. I recently measured the attenuation of foil free wall on 145 MHz and got about 11 dB for the stucco wall. Wooden wall has about 4 dB. Only a good external antenna should be used.
 
Radiant Barrier Myth  
by KS3B on March 13, 2019 Mail this to a friend!
Radiant barrier is not a myth, it is a well-known reality. It is also not a Faraday cage, it is just temperature isolation. I lived in such a house and measured the foil attenuation. It was as expected - in the vicinity of 25 - 30 dB. This attenuation is well below the Faraday cage numbers. But it is big enough to spoil your radio communications. You may cut a slot in the foils and make a slot antenna or even cut some more complex geometry and have a surrogate antenna. But anyway you will have a big loss. I recently measured the attenuation of foil free wall on 145 MHz and got about 11 dB for the stucco wall. Wooden wall has about 4 dB. Only a good external antenna should be used.
 
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