I have an NMO Mag mount that I'm using in the attic for now on 2m/440 and an just using a baking sheet. I'm going by Lowe's and wondering if there's something better I can use.
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On the lowest frequency, the ground plane will need to be the largest. So, 144MHz will need about 19.5" in each direction under the antenna. That ideally would be a 39" wide circle with the antenna mounted in the middle. Going out and buying a piece of sheet metal that large would certainly be an option, but it's not necessary.
If you go to where they have their roofing supplies, they should have a pretty good selection of various flashing materials. You should be able to buy a roll of thin sheet metal a couple of inches wide. Just make a big "X" with that, each piece about 40 inches long. Put your NMO mount in the center.
The thinner the material is, the easier it is to cut. If you get something thin enough, you can cut it with a hefty pair of scissors. If not, get your self some cheap sheet metal sheers.
And, the material really doesn't matter too much, other than using ferrous metal will allow the magnet to stick. But, in reality, there shouldn't be any movement or wind in your attic, so all you need is a conductive metal, aluminum, brass, copper, etc. to do the trick.
If you wanted to do a trial, you could even lay down some aluminum foil and put the antenna on that.
You could also go really cheap and just use aluminum foil you probably already have in your kitchen. Just tack/staple/glue it down on a wood support. Could be some 2x4's, plywood, masonite heavy cardboard, etc. anything to give it a nice flat platform.
You could even use scrap wire, chicken wire, wire mesh, aluminum window screen, etc....
Being it's to be in an attic, it should just sit on the aluminum. Unless he has critters in his attic, which would be a subject for another forum. But the OP could just put a small piece of ferrous metal under the middle of the foil X if he was worried about movement. The lid from a metal can (soup, vegetable, whatever) comes to mind. Tack it down where he wants his antenna, apply & tack the foil over it, stick the antenna down, done and done.no problem on support under the metal. Not sure you mag mount would stick to aluminum foil.
Thank you for this. Could I lay the sheet metal you mentioned in an X on wood for support or is it bad to have something under it? Thinking maybe a 2x whatever the rolls of sheet metal are or even plywood. But if that's not a good idea please let me know. I know you mentioned this for the aluminum foil but wasn't sure if it made a difference for the sheet metal. Or what would you recommend to put it on?
Not sure you mag mount would stick to aluminum foil.
Was only around as I have it on top of boxes right now to get it higher. No critters just asked to get support to have it higher. If support would this X or even big square of sheet metal work on top of plywood? Asking cause I don't see the difference in laying it on the plywood which is the floor.
If I buy those rolls of sheet metal and just buy a sheet of plywood big enough for already 19.5" in all directions I could just cover that in the rolls of sheet metal right? But would I just overlap them and every 6 inches screw into both sheets and the plywood? Or what's the best way to connect them?
If there's something around 25"-30" square or round that would do it I'm up for buying that. Just need to support it with plywood if flimsy as I'll have it on top of boxes or may even tack some 2x4s on top existing framing to set this on to get it higher.
Hanging that antenna up in the manner you describe would not IMHO be a good idea. If you can come up with some kind of tripod mount to hold it up there properly oriented, I believe that would result in much better performance for you. If you do experiment with hanging it by the base, at least run the coax away from it at a right angle i.e. along the roofpeak for a few feet. Having it hang down that way parallel and close to the radiator can cause SWR and other issues.My ultimate plan is to get a diamond x50 and hang up upside down by throwing rope over one of the top beam sports that's a few feet from peak of attic. When standing in attic the peak is 20-25 feet high. Then I'll tie the rope to the bottom of x50, hook lmr400 to it and pull out up with the rope and tie it so it stays up.
Until then I have to get by with this NMO Mag mount which is doing pretty good. I'm getting repeaters that are 40 miles "as the crow flies" to my northeast easily, but having issues hitting them 28.51 miles "as the crow flies" to my southwest. However I can hit some that are 35 miles to my west. When going south there's a major road for the town just south of us that some say is a hill but it's not, I think it's due to a lot of potentially RF that's blocking everyone from getting past is good. I can get past it but just can't go as far in that direction. So that's why I plan to get the x50 and get a little higher. It will be about 15-20 feet higher than the NMO Mag mount is right now in the attic.
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Was only around as I have it on top of boxes right now to get it higher. No critters just asked to get support to have it higher. If support would this X or even big square of sheet metal work on top of plywood? Asking cause I don't see the difference in laying it on the plywood which is the floor.
If I buy those rolls of sheet metal and just buy a sheet of plywood big enough for already 19.5" in all directions I could just cover that in the rolls of sheet metal right? But would I just overlap them and every 6 inches screw into both sheets and the plywood? Or what's the best way to connect them?
If there's something around 25"-30" square or round that would do it I'm up for buying that. Just need to support it with plywood if flimsy as I'll have it on top of boxes or may even tack some 2x4s on top existing framing to set this on to get it higher.
My ultimate plan is to get a diamond x50 and hang up upside down by throwing rope over one of the top beam sports that's a few feet from peak of attic. When standing in attic the peak is 20-25 feet high. Then I'll tie the rope to the bottom of x50, hook lmr400 to it and pull out up with the rope and tie it so it stays up.
Until then I have to get by with this NMO Mag mount which is doing pretty good. I'm getting repeaters that are 40 miles "as the crow flies" to my northeast easily, but having issues hitting them 28.51 miles "as the crow flies" to my southwest. However I can hit some that are 35 miles to my west. When going south there's a major road for the town just south of us that some say is a hill but it's not, I think it's due to a lot of potentially RF that's blocking everyone from getting past is good. I can get past it but just can't go as far in that direction. So that's why I plan to get the x50 and get a little higher. It will be about 15-20 feet higher than the NMO Mag mount is right now in the attic.