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.
Comment on Antenna mounted in attic?
Domiku@beehaw.org 6 days ago
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.
JackbyDev@programming.dev 6 days ago
skillissuer@discuss.tchncs.de 5 days ago
What bands are we talking about (HF or 2m/70cm?)
JackbyDev@programming.dev 4 days ago
Is setting up a permanent 2m/70cm antenna even really worth it?
I was thinking like 10m or something maybe. I’m more asking in general, but I know it changes based on wavelength lol.
skillissuer@discuss.tchncs.de 4 days ago
If you don’t live in complete wilderness and especially if you are in repeater range then yes, there’s a lot of use of 2m/70cm. There are even commercial duobanders for this, but you can also make your own
Lots of things change between HF and VHF. Matching methods, baluns, and materials are completely different. You can get away with 70cm band antenna made of 8mm aluminum tube, and it’ll get you some reasonable bandwidth just because of how wide it is, but if you want to scale it up to 20m it’s suddenly over 20cm wide. This is not practical anymore, but you also don’t need bandwidth like this. HF antennas (other than masts) are mostly made of wires and rely on things other than thickness to make them wideband enough. If you want to use monopole, on VHF/UHF you can use metallic roof as a groundplane. On HF you’ll need to use actual ground with network of wires, which is lossy. For dipoles, distance to ground will be many wl long on UHF, and it’ll work mostly like in free space, but on HF this changes impedance, losses and radiation pattern. On HF, polarization is scrambled after reflection from ionosphere, on UHF it just goes through
UID_Zero@infosec.pub 5 days ago
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.
skillissuer@discuss.tchncs.de 5 days ago
Solar panels, specifically inverter is likely to generate a lot of noise
JackbyDev@programming.dev 6 days ago
I might have a foil layer, now that you mention it. I didn’t consider that.