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Author Topic: Using aluminum house trim for antenna?  (Read 334 times)

GEORGEMINK

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Using aluminum house trim for antenna?
« on: November 25, 2022, 09:55:39 AM »

I have a small all brick house that is basically 57'x39' rectangle in shape. The only metal on the house is aluminum siding that goes around the Eaves at a 10' height. It is one continuous run with a 10' break over the front door forming an open loop. I'm wondering if anyone has used the metal siding as an antenna before? and their results?

I was thinking of using a 9:1 unun and feeding one end like a random length wire. I even thought about running a length of wire along the bottom edge as well, but at a minimum I'll make sure the overlapping panels are electrically connected with screws.

My main concern is the shape and height off the ground. I have a HOA so no external antennas permitted. I have several antennas in the attic now but they are all compromised designs.

Thank you for your input!

George
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K9AO

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Re: Using aluminum house trim for antenna?
« Reply #1 on: November 25, 2022, 10:27:08 AM »

You might want to remember that there will be high voltage points along that loop antenna you are thinking about. Where they are depends on the wavelength you're using at the time and it will change with band changes.

You'd be better off feeding it as a balanced loop across the gap if you decide to do this.

If there is a high voltage point you would need to be concerned that the wood insulation would be dry and not subject to any arcing from the RF, otherwise you'll have a fire. I expect this would violate your homeowner's insurance.

A magnetic loop in the patio might be a better and safer solution.
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K5LXP

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Re: Using aluminum house trim for antenna?
« Reply #2 on: November 25, 2022, 10:39:09 AM »

I think the arcing scenario is quite unlikely approaching improbable.  As far as shape/height it is what it is - it's not like you have a different option.  Whether it's a continuous conductor would be the question to answer first, then start trying things - fed as a loop, single ended or as part of another conductor like a wire along the roof peak.   The notion of better or best isn't a consideration here, you have a set of constraints to work with and you won't know how any arrangement of of options will work until you try them.

Mark K5LXP
Albuquerque, NM
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K9AO

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Re: Using aluminum house trim for antenna?
« Reply #3 on: November 25, 2022, 11:21:11 AM »

Difficult to say improbable. Any potential is a possible. As an engineer I would never ever have RF in contact with wood, either the wood directly or through mounting nails or screws into the framing. Nor would I take the chance of a nail or screw coupling sections of soffit together from loosening and arcing. But that's me and I think the caution is worth considering. Loss of a home is a serious worst-case miscalculation, and the loss of homeowner's insurance to remediate the damage is just as bad.

It wasn't too long ago, last year I think, that another ham had his separate shack burn down due to RF arcing to wood when it was damp via a feedline. Luckily it was far enough from the house that there was no damage to the dwelling.

At 100 watts the end of a dipole or the voltage point along it can be at 6200 volts. That's high enough to easily arc to something lossy enough to conduct and there is enough energy there to ignite combustible materials.

I would try a magnetic loop if this were my situation. That's not near any RF absorbing materials and would likely work well. You could setup the soffit loop as a receiving antenna and have that to switch to if you needed it.
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GEORGEMINK

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Re: Using aluminum house trim for antenna?
« Reply #4 on: November 25, 2022, 11:31:38 AM »

Loss of a home is a serious worst-case miscalculation, and the loss of homeowner's insurance to remediate the damage is just as bad.

I'd have to agree, being that I'm an insurance agent! lol

I have a end fed random antenna that I just purchase, the Ultimax 100 with 36' wire that should come in next week that I'm going to install in the attic replacing a horrible 12' long trap dipole that I'm using now. I should be able to run the end fed as an inverted V with a 25' apex. I just thought I would try using the trim around the house to see how it performs.

Running a wire along the bottom of the eave might be a better approach than actually using the metal trim? 
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AI5BC

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Re: Using aluminum house trim for antenna?
« Reply #5 on: November 25, 2022, 11:56:55 AM »

Disregard all comments about safety and electrical codes. Hams have never cared one bit about such things as rules and physics do not apply to hams. That is why no one cares when a ham falls off a tower.
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K7JQ

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Re: Using aluminum house trim for antenna?
« Reply #6 on: November 25, 2022, 01:20:38 PM »

There are better and safer options than what you are considering. Check out Tarheelantennas.com, and go to their “pictures” segment. I’ve had a lot of success with a stealth installation in my HOA community.
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KC0PUN

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Re: Using aluminum house trim for antenna?
« Reply #7 on: November 25, 2022, 02:47:42 PM »

Depending on the attachment method (spikes and ferrules or hangers) either way, you can ziptie a insulator on them and run a wire thru
them and create a dipole, feed point at your option. Been there, done it, got the tshirt.  Another option somewhat trickier is to obtain a expansion
joint, on long runs the steel or aluminum gutter and will shrink or expand so said joint is a must. The gutter is cut, joint is installed and now it
becomes a dipole.  However word of warning your downspouts are hot when key down also they must not touch the ground, once again have the
shirt  The first way was effective as I drilled a hole and fish taped the coax thru the eve sealed it well and went down thru a wall and to a tuner,
worked very well. second method was on a long ranch house and it too worked well. Just be sure water doesn't pool up any where near the joint.
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GEORGEMINK

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Re: Using aluminum house trim for antenna?
« Reply #8 on: November 25, 2022, 04:32:48 PM »

No gutters and downspouts so only the trim around the house. I got feedback on my other post that the wire run around the house behind the trim would not be a good choice.
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WA3SKN

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Re: Using aluminum house trim for antenna?
« Reply #9 on: November 27, 2022, 03:03:05 PM »

This can be done, but with caveats... certainly not your best option.
Now what band(s) do you want to operate and at what times?
Who are you trying to talk to?

-Mike.
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GEORGEMINK

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Re: Using aluminum house trim for antenna?
« Reply #10 on: November 27, 2022, 03:59:01 PM »

This can be done, but with caveats... certainly not your best option.
Now what band(s) do you want to operate and at what times?
Who are you trying to talk to?

-Mike.

Well I'm scared now to try it with the talk of burning down the house! haha

I was just going to give it a try since it's the only way I'm going to get more that 36' of wire up anywhere in my yard.
I measured and got around 241' in length around the house with a 10' gap over the front door where the siding is not run.
I'd like to get on 160 and 80, I think the long wire that I'm going to put in my attic should be fine for 40, 20, 15, and 10.

Not really looking to do any DX with it, just want the flexibility of getting on the lower bands even if it's going to be relatively close contacts.
I spend most of my time listening in the late evening.
 
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WA3SKN

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Re: Using aluminum house trim for antenna?
« Reply #11 on: November 28, 2022, 08:44:28 AM »

With HOA restrictions, just run a wire insulated under the eves of the house, but end feed it with a tuner against ground.  It will be NVIS, but should work OK for 80/160m in the evenings.  Keep power at 100 watts or less.

-Mike.
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