Submitted 5 weeks ago by JackbyDev@programming.dev to amateur_radio@lemmy.radio
How poorly would an attic mounted antenna perform? Obviously worse than something outside, I’m guessing, but how much worse?
My office has one of those “side attics.” It has a half sized door. Mounting a long antenna in there is very tempting because of how much easier it would be than doing anything outside. It’s on the second floor as well.
I used to live in a suburb where roof TV antennas were not allowed. Houses either used cable TV or had a TV antenna in the attic.
In my attic, I have an Open-Stub J Pole and a 20m dipole. They work pretty well! You’ll need to make sure that you don’t have a metal roof or any foil layers in the roofing or insulation. If you’re running a dipole, try to avoid electrical wires – if you can’t, have the dipole cross them at a 90º angle.
I might have a foil layer, now that you mention it. I didn’t consider that.
I’ve seen J pole enough not to guess it’s not some weird esoteric thing. Do you know if where I can read a good comparison between J pole, mono pole, vertical di pole, and horizontal di pole? I think I have a mostly good grasp of the others.
Late to the party; I built and ran both a 10m and 20m window/ladder-line j-pole with phenomenal results. It’s really neat in that it does not require a counterpoise as it has a matching section built in. As such, the radiating element and matching sections do not need to be coaxial, so if you’re mounting in the attic space, you are free to run the radiating element horizontally (performance will be reduced as this antenna’s optimal performance is vertical), and the matching section can have a different orientation.
The 20m version is about 44’ long, so when I only had a 30’ mast, I had to string the matching section horizontally:
On 100W and a 10m tall mast, I was able to reach Indonesia on SSB on 20m. It took some working and good prop, but we made a QSO.
I upgraded to a 15m tall mast and got some marginal improvements, but being in the residential area made it hard to compare since there was always so much EMI:
As for comparison to other antenna types, I have a 7-band OCFD that is quite long, and a massive headache to install (I primarily operate portable), and this j-pole blew it out of the water.
Check out KB9VBR’s video about it: youtu.be/RZv94BvNxrQ
Good luck!
What bands are we talking about (HF or 2m/70cm?)
I was thinking about putting my 2m antenna in the attic, I didn’t think about metal though. I have asphalt shingles but I have solar panels basically covering the south face. I’m guessing the brackets, panels, and wiring will all add up to my plan not panning out well.
Solar panels, specifically inverter is likely to generate a lot of noise
wildbus8979@sh.itjust.works 5 weeks ago
What is the roof made of?
JackbyDev@programming.dev 5 weeks ago
Wood and shingles. Typical single family American home.
shortwavesurfer@lemmy.zip 5 weeks ago
On HF it probably wouldn’t be too bad since the signals would generally just go straight through the surface. On VHF and above though it could be problematic.