WRFP457 Posted May 7, 2020 Report Posted May 7, 2020 I have a shed with a metal roof, but it surrounded by big oaks. I have an area that is more open but no metal roof. Which is better? Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 Ground plane is better then no ground plane. Uhf/vhf height is king. The oaks will attenuate and mask the signals a bit. It really is a wash. If you can set them up temporary in each location you might find which works the best. Me personally, open space with a mast with artificial ground plane. Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 Should also add don't forget the feed line losses of the given line of coax... that could easily sway which way you go. Any gain from antenna design could easily be lost by choose the wrong feed line or being cheap about it. Feed line loss gets pretty bad the higher up you go in frequency. A piece of coax might have a loss of 1.2db at 144mhz but at 470 it might be 6-7 db loss per 100 feet. That is without the connectors. marcspaz 1 Quote
0 marcspaz Posted May 7, 2020 Report Posted May 7, 2020 Unless you have an antenna that doesn't require an external ground plane, you have no choice. Generally speaking, foliage will always absorb some RF energy. However unless you are trying to communicate through dense vegetation, it should still work fine. One of my antennas are in the woods behind my house, below the tree line, and I get great performance out of it. kidphc 1 Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 Unless you have an antenna that doesn't require an external ground plane, you have no choice. Generally speaking, foliage will always absorb some RF energy. However unless you are trying to communicate through dense vegetation, it should still work fine. One of my antennas are in the woods behind my house, below the tree line, and I get great performance out of it.A ham in neighbor hood. Love the trees for his long wires. Hated it for the satellite work. The 2m uplink was fine but the 70cm downlink was constantly wrecked in the the summer due to the leafs. marcspaz 1 Quote
0 marcspaz Posted May 7, 2020 Report Posted May 7, 2020 A ham in neighbor hood. Love the trees for his long wires. Hated it for the satellite work. The 2m uplink was fine but the 70cm downlink was constantly wrecked in the the summer due to the leafs.Oh yea... not surprising. I lose downlink connections if it rains or cloud cover gets really heavy. Got tired of fighting it and decided to stick to local comms (except for the ISS on rare occasions). Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 Oh yea... not surprising. I lose downlink connections if it rains or cloud cover gets really heavy. Got tired of fighting it and decided to stick to local comms (except for the ISS on rare occasions).Don't you live in a circle? I know where you could put your satellite antenna. Lol your neighbors might get the pitchforks out though. Sent from my SM-G975U using Tapatalk marcspaz 1 Quote
0 WRFP457 Posted May 7, 2020 Author Report Posted May 7, 2020 So which type of antenna is best to take advantage of the metal roof? Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 A good 1/2 wave mounted to the roof. If you are going to use it on a mast, you are probably going to be happy with one that has radials.Sent from my SM-G975U using Tapatalk Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 MarcSpaz showed a portable antenna on a mast in the following post. He was kinda enough to put up the SWR number he was seeing both with the Diamond x30 and x50. I could of swore they made a commercial variant of the antenna designed for about the frequency of GMRS. Not sure what the numbers or model were. https://forums.mygmrs.com/topic/1723-new-portable-repeater-antenna-setup-is-done/ It was laird and comet, that made antennas closer tuned closer to the GMRS frequencies. Not sure how well they work. .https://www.theantennafarm.com/catalog/comet-ca-f72gf-1067 You also have the likes of Ed Fong, who customize to your desire, you just have to provide the outer shealth (PVC), which is a jpole design. marcspaz 1 Quote
0 marcspaz Posted May 7, 2020 Report Posted May 7, 2020 Don't you live in a circle? I know where you could put your satellite antenna. Lol your neighbors might get the pitchforks out though. Sent from my SM-G975U using Tapatalk LOL They are mad that my 1984 pickup is in the circle. Plus, within minutes of putting it up, I was asked by one of my neighbors how long the eyesore (portable) was going to be in my driveway for. I can imagine how they would respond to a nice parabolic or steep take-off beam on a single axle trailer out in the middle of the circle. hahaha kidphc 1 Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 LOL They are mad that my 1984 pickup is in the circle. Plus, within minutes of putting it up, I was asked by one of my neighbors how long the eyesore (portable) was going to be in my driveway for. I can imagine how they would respond to a nice parabolic or steep take-off beam on a single axle trailer out in the middle of the circle. hahahaJust tell thjem the white house asked you to put it up for the testing of their early detection of incoming UFOs. Once it starts tracking they may shut up. marcspaz 1 Quote
0 kidphc Posted May 7, 2020 Report Posted May 7, 2020 You really want them to go nuts. After you tell them why, run a script that has it trying to track different sats. So the assembly is going nuts tracking and skipping to another sat and goes nuts again seconds later. Chance are they will grab a sledge hammer and help you tie down some guys through the asphalt. marcspaz 1 Quote
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WRFP457
I have a shed with a metal roof, but it surrounded by big oaks. I have an area that is more open but no metal roof. Which is better?
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