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Author Topic: Radiant Barrier  (Read 701 times)

N4CEO

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Re: Radiant Barrier
« Reply #15 on: April 26, 2020, 11:17:28 AM »

I would avoid the attic antenna.  Beyond the foil backed roof sheeting problem, you will find lots of home-grown RFI, both on the RX and TX side on the HF frequencies.  The 20 ft "flagpole" vertical will work just fine.  Just remember that the need for an abundant ground radial field is necessary for any sort of transmission efficiency.  You can even elongate the vertical radiator by adding aluminum MIG wire (0.030" or 0.035") painted with a flat black or camouflage color.  Use the MIG wire as either  an extended top-hat or inverted-L.  The wire is strong enough (I've had stealth antennas using the MIG wire and it only breaks on occasion - most likely from a bird flying into the wire.  Easy enough to replace though.  The painted MIG wire is virtually invisible - hard to see from ten feet away. Another option is to insert a multi-band vertical (Hustler, Hygain, etc) into a thin-walled PVC pipe. Finances permitting, the small Steppir vertical will suffice for the higher HF frequencies - add a loading coil for the lower frequencies.

BTW, the FCC OTARD regulations allow an outdoor "TV" antenna mounted on the roof inclusive of a mast extending 12 ft above the roof-line.  A little creativity will open up lot's of stealth antenna possibilities.

A VHF/UHF stealth antenna is also easy.  If you can extend a roof vent so that it's 19", you an tape a vertical to the outside.  Lot's of other possibilities.

Scour  to Internet to see what others have done.
I have radiant barrier and a strict HOA. I tried dipoles in the attic and I can attest that they don't work. I have worked dipoles in previous homes with no radiant barrier with no problems (digital modes - low power). I have since given up on HF and only work vhf/uhf now. I don't chase wall paper anyway. BTW, I have a dual band vhf/uhf ventanna on one of my vents and it's been there for 7 years and still works great. The feedline goes down inside the pipe and I drilled a hole in the pipe in the attic to feed the coax down to my transmitter. I don't see the Ventenna advertised anymore so here's a link to their site: https://www.ventenna.com/
73's
« Last Edit: April 26, 2020, 11:20:44 AM by N4CEO »
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K0UA

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Re: Radiant Barrier
« Reply #16 on: April 26, 2020, 02:27:06 PM »

DMR (or D star or Fusion)  walkie with hotspot and good internet connection. Talk all over the world. Just an idea.
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73  James K0UA

W1TRY

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Re: Radiant Barrier
« Reply #17 on: April 26, 2020, 02:29:51 PM »

Radiant barrier = shield room or Faraday cage which means no RF penetration.  Either a flagpole antenna or an excellent mobile antenna system and when parked, run the coax to the shack from the vehicle.
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K4KYV

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Re: Radiant Barrier
« Reply #18 on: May 19, 2020, 12:24:27 PM »

The flagpole vertical sounds like the best idea.  But you will need a lot of ground radials to make it work.

Rather than bury them, cut the grass as short as you can.  Lay down as many copper wire radials as you have room for, each one as long as possible, preferably all the way to the property line.  Clip them in place with metal stakes, made from steel wire, bent like a hairpin.  The grass will grow over them and you can mow, with the mower set to cut the grass as high as possible.  The clips will keep the mower from sucking up the wire into the mower.  After a few months and a few mowings, the thatch from the cut grass will begin to turn to sod, and within a season or two, the radial wires will be self-buried in the sod, and probably difficult to pull up even if you  tried.  Insulated wire will be better protected from corrosion, but in most soils bare wire will last for many years. Avoid steel or aluminium radial wires, although plastic-covered wire might be OK.

I have a friend in a suburb of Chicago who lives on a postage-stamp size city lot.  He has an inverted-L wire antenna for 160m, and about 100 ground radials, varying in length from a few feet to over 100' as space permits.  He puts out a very competitive signal on 160m.

But the vertical often makes a very poor receiving antenna because it picks up a lot of local electrical noise; at most locations a separate receiving antenna is a must.  My friend uses a couple of small rotatable receiving loops which null out his noise problem very effectively.  I live out in the country where I have a full size 127' tall quarter-wave vertical for 160m with 120 quarter-wave  radials for 160.  My home-built indoor loop often picks up signals I can't even hear with the vertical.
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AA4PB

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Re: Radiant Barrier
« Reply #19 on: May 25, 2020, 07:10:44 PM »

Is it possible to lay insulated dipole wires actually on the roof? My house has a hip roof with some "hidden" dips. It could be possible to mount a balun without being seen and then run insulated wire of the same color as the composite shingles; tucking the wire some shingles along the way. I'm wondering whether the aluminum radiant barrier on the other side of the roof with reflect the signal back. Just a thought.
The radiant barrier that close to the wire dipole will act as a capacitor shunting across the two sides of the dipole. It'll probably seriously detune the dipole and add a lot of loss.
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Bob  AA4PB
Garrisonville, VA

KK4OBI

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Re: Radiant Barrier
« Reply #20 on: May 28, 2020, 07:58:46 PM »

I found that laying antenna wire directly on shingles has a seriously bad effect on SWR. A few inches up off the shingles does wonders.  For this I found the Amerimax Hidden Hook 1 pc, #MO622B (white) #M1622B (brown).  It has a foot that slips under a shingle and grabs it firmly.  The vertical part stands 4 inches high which is perfect for antennas.  I got mine at Lowes.

Having both a long wire and a vertical gives you the freedom to switch to find what works best at any moment.
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KK4OBI - the Old Band Instructor
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K4FMH

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Re: Radiant Barrier
« Reply #21 on: July 01, 2020, 01:53:57 PM »

i lived in an HOA community near Lakeland, FL. I have a single family home on a corner lot. I am not allowed to have any outside antenna, although I am allowed up to a 20' flag pole. I'm considering a flag pole vertical for HF but this will be a first for me. I have no idea where to start. The other option is the attic. The attic is only accessible via a pull down ladder. There is nothing up there except blown insulation and a radiant barrier on the inside of the roof. The barrier is highly reflective aluminum foil used to lower temperatures during the summer. I don't know for sure, but I surmise that the radiant barrier is an RF killer.

I want to ability to work CW and phone on HF and also access local repeaters on 2 meters. I'm open to suggestions and resources that may be able to help.

Thank you.

Do use the flagpole option. But I have a radiant barrier in my large attic. I have several antennas on HF there and use them with some effectiveness. Yes, there's RFI but be vigilent for suppression strategies. People argue all the time that the foil-backed radiant barrier is a "killler" but my first contact using an MFJ 80/40 dipole in my attic was to Malibu CA on 40M SSB. I was the only signal on the frequency according to the other ham.

Just be persistent...

73,

Frank
K4FMH
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K4NYM

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Re: Radiant Barrier
« Reply #22 on: July 26, 2020, 12:21:14 AM »

Since I first started this thread I have figured away to deal with the HOA restrictions. When it comes to antennas, here is what my HOA documents state:

Section 18, Utility Wiring and T.V, Antennae
All public or private transmission and service wiring for electrical, gas, telephone and cable television communication
services and service lines pertaining thereto must be installed and buried underground where permitted in accordance
with applicable codes that may be imposed or imposable by any public or private electrical, gas, telephone or cable
television communication service servicing the subject property. No satellite TV reception dish shall be permitted
exceeding 18” in diameter, and no such reception dish shall be placed within the front yard of any residence or lot.

Well, I am not seeking to install a satellite dish. By law a television antenna cannot be refused, but I am not seeking to put up that type of an antenna. I want to put up and HF antenna in my yard. The HOA board understands there is a huge loop hole in their documents, so we have entered into a discussion about a "reasonable accommodation". That reasonable accommodation seems to be a 10-40 HF vertical with a 6 meter attachment. I'm going to use a J-pole for 144/440. I'm also doing a lot of portable work with POTA (Parks on the Air), so I'm getting my HF fix.
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W1VT

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Re: Radiant Barrier
« Reply #23 on: July 26, 2020, 02:32:25 AM »

The Freedom to Display the American Flag Act of 2005 requires reasonable accommodations by HOAs.
If you live in Florida there is a similar law that has more detail on what is allowed, as well as what HOAs can't do.
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K1VSK

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Re: Radiant Barrier
« Reply #24 on: July 26, 2020, 05:54:04 AM »



The HOA board understands there is a huge loop hole in their documents, so we have entered into a discussion about a "reasonable accommodation...

Quite common that HOAs don’t specifically regulate ham radio antennas among other types which they do, I.e., sat dishes . I actually helped my HOA,  after they realized the same loophole, write a ham radio antenna provision which is a performance based standard rather than a prescriptive one - essentially if it can’t be seen from the front, it’s okay regardless of what type, design or height.

They agreed the  most “reasonable” approach was - if people can’t see it, it doesn’t matter what it is.
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