I live in a restricted community and am thinking about putting a 20 meter dipole in the attic. I know most of the issues with doing this but I don't know the effect the roofing material will have on my signal. The roof is 1/2 in thick cement tiles. Has anyone had experience with this setup?
Thanks, Larry, KB5DXY K1 #2269 --------------------------- Yep! Not all tiles are equal, so you may be better off. I moved several times about 15 years ago, always living in an apartment. I managed to get a top (second) floor apartment in each case and installed a doublet in the attic in each case. It was hung just under the rafters. In one apartment I noticed that I didn't get out very well, compared to my previous QTH, but my antenna arrangement was very similar! On air testing is just about useless to determine how well an antenna is working so I didn't panic over it. But, over several months a suspicion grew. One day I noticed walk near my building a piece of roofing tile that had apparently dropped there while some repairs were being done. Curious, I took it indoors. It was a hot summer day and the tile piece was quite dry. I put it in my microwave oven (with a glass of water to avoid running it 'empty') let it cook for a minute or two. The roof tile was very hot! That's a sure sign it's pretty opaque to RF. Of course, it's probably more opaque at microwave frequencies than at HF, but it's still going to be lossy. If you can get a piece of tile, do the test for yourself. You may be a lot better off than I was. I did a little research and found that those tile mixes often have a lot of stuff not normally found in concrete and that the formulas vary substantially from one supplier to another. That's about all I could dig up on the subject. Let me say that I made a LOT of contacts from under those tiles, using QRP on 40 and 20 meters, including substantial DX. That's the problem with on-air testing. A punk poor antenna can sound *great* when the band conditions are right. So if that's what you have to do to get on the air, go for it. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
