Author Topic: How to install an antenna on a metal building?  (Read 4606 times)

Offline outoforder2day

  • Survivalist Mentor
  • *****
  • Posts: 399
  • Karma: 37
  • Semper Ubi Sub Ubi
    • The End Of The Tunnel
How to install an antenna on a metal building?
« on: September 15, 2016, 11:12:44 AM »
I'm very fortunate to have a nice, large, metal, 3 story barn near the top of my new homestead. This appears to be an excellent place to set up a few antennas, and it's even got a separate area inside for a nice shack/office setup. However, I've never done anything other than portable (HT) and mobile (mag-mount) operation before. This will be my first permanent base station install. So, I'm writing here for thoughts and ideas on how to proceed.

Details:
  • I have an IC-7000 that I used for mobile, but would like to use it for my base station now.
  • I'm primarily using 2m/70cm because I never had a mobile HF antenna. I'd like to start with 2m/70cm in my fixed setup and expand to HF shortly thereafter.
  • The barn is an old post-and-bean barn (circa 1890s) that was clad in metal siding and roofing.
  • The barn has its own power that comes in right below the office space.

Questions:
  • What antennas should I look at for purchase? I'd like a good VHF/UHF omni antenna. Been out of the game for a while and not sure what to look at.
  • How should I actually mount it on the roof? I'm assuming a standard tripod mount, at the apex of the roof, will work. Do I just use sheetmetal screws, daubed in silicon caulk, to attach it? Or should I look at reinforcing the roof underneath with wood and screwing to that?
  • How do I safely bring the cables in to the barn itself? There aren't any double-hung windows to create a simple passthrough, so what would be the next best way to go about it?
  • I was planning on the dual-band antenna going on the left part of the roof and later running an HF antenna off of the right side (in the pic below).

Any thoughts, comments, opinions, or links to books/articles would be appreciated.

The Barn

The lean-two section is where the office space is.

Thanks,
-D

Offline Smurf Hunter

  • Survival Veteran
  • ********
  • Posts: 7172
  • Karma: 334
Re: How to install an antenna on a metal building?
« Reply #1 on: September 15, 2016, 01:07:44 PM »
This should be a good thread.

Offhand the biggest limitation might be antennas inside/under the roof won't work well.
In my wood frame and roof house, I have 3 different antennas in my attic that work reasonably well. 

Do you necessarily need an HF antenna "on the building" or could you have some form of HF wire antenna off in trees with a feedline coming into the barn/shack?

You might be limited to vertical antennas, as anything horizontal would have the RF "bump" into the metal roof, and behave like ground.

Make sure you review these threads:

http://thesurvivalpodcast.com/forum/index.php?topic=58718.0
http://thesurvivalpodcast.com/forum/index.php?topic=58658.0
http://thesurvivalpodcast.com/forum/index.php?topic=58731.0

Offline outoforder2day

  • Survivalist Mentor
  • *****
  • Posts: 399
  • Karma: 37
  • Semper Ubi Sub Ubi
    • The End Of The Tunnel
Re: How to install an antenna on a metal building?
« Reply #2 on: September 15, 2016, 02:53:18 PM »
I'm not planning on *any* internal antennas. Only externals.
The Dual-band antenna will be an omni vertical. I'm looking at a GP-15. I want that on top of the barn so I get the height advantage. I should be able to get it 45 feet in the air pretty easily that way.
External HF would be fine. I view HF as a phase 2 thing for now.

I also have concerns with grounding, because I have lightning rods on the top of the barn. I'm assuming that that same ground system should be tied into the building ground... though that just seems like a bad idea to me. No backsurging from the lightning grounds into the building ground system if it's interconnected?

I'm reviewing this video now, and will likely look into his sources.
https://www.youtube.com/watch?v=_sKDuwQA_p0

Thanks for the links. I'll review them shortly.

Offline Carl

  • Mr HamTastic!
  • Forum Veteran
  • *********
  • Posts: 13105
  • Karma: 714
  • COW?...No ,I haven't seen your cow.
Re: How to install an antenna on a metal building?
« Reply #3 on: September 15, 2016, 06:07:42 PM »
I was outside ,experimenting with an antenna..
I suggest a tripod mount or EVE BRACKET and a dual band ground plane antenna with good coax like RG8X or better. See links

http://www.randl.com/shop/catalog/product_info.php?cPath=1500&products_id=39008

http://www.randl.com/shop/catalog/product_info.php?cPath=1500&products_id=65608&osCsid=5rdtbscgergq7gicik23lc3e17

http://www.randl.com/shop/catalog/product_info.php?cPath=11030&products_id=61435

http://www.randl.com/shop/catalog/product_info.php?cPath=11030&products_id=61420

https://www.amazon.com/Winegard-SW-0010-Tripod-Mount-Antenna/dp/B001DFZ5J2/ref=sr_1_1?s=electronics&ie=UTF8&qid=1473984211&sr=1-1&keywords=antenna+tripod+roof+mount

https://www.amazon.com/Winegard-SW-0012-Gable-Mount-Antenna/dp/B001DFTGUQ/ref=sr_1_1?s=electronics&ie=UTF8&qid=1473983900&sr=1-1&keywords=antenna+eve+bracket

this is a good selection for VHF/UHF and I suggest a dipole cut for ONE BAND if no auto tuner is desired  or a single wire W3EDP antenna with an LDG tuner (about $200 for tuner) or a manual tuner for $139 to $$$. I would set up the VHF/UHF station first and make decisions on the HF gear as time and funds allow additional equipment and installation .
The wire antennas would attach at the high eve of the barn and slope to a post or tree for support and the tree end would need a good spring or pulley and counter weight as trees move and barns don't.

Plenty more details available as you choose a direction and what level of performance you wish to obtain.

Offline outoforder2day

  • Survivalist Mentor
  • *****
  • Posts: 399
  • Karma: 37
  • Semper Ubi Sub Ubi
    • The End Of The Tunnel
Re: How to install an antenna on a metal building?
« Reply #4 on: October 03, 2016, 12:47:07 PM »
Thank you all, again, for the thoughts. Since I'm not in a rush to get on the air, and I want to do this as "right" as possible, I'm going to start this with the basics and work my way up. Basics in this case, means good grounding.

I confirmed that NEC dictates common ground *including* lightning protection systems, so that's where I'm starting. It turns out that the lines running to the lightning rods weren't even attached to anything. They were, quite literally, laying on the ground... So I went out and purchased two copper ground rods. I will attach the lightning rod lines to those and use some #4 solid wire to attach it to the existing ground rod, which I don't really trust at this point. I'm also going to replace the copper line running from the panel to the ground rods since I don't trust that either! This building is the definition of "creative wiring" :facepalm:

After the grounds are properly installed, I'm going to set up a single-point ground inside the shack. I'm planning on using a copper pipe as the bus to keep it cheap and effective. I understand that this may not be required with modern gear, but nothing's saying I'm going to use all modern gear, or that I may not homebrew something a bit odd. Better to get into good safety habits out of the gate.

I found the following reading very helpful:
http://www.arrl.org/lightning-protection (specifically "Lightning Protection for the Amateur Station 1-3")
http://www.bwcelectronics.com/articles/WP30A190.pdf
Polyphaser Manual

On antenna's, I also remembered that I have a dualband J-Pole somewhere in storage. I'm going to track that down before purchasing anything new.