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Comment by okl | Hacker News Reader

With a directional/high-gain antenna you're increasing the ERP (effective radiated power) which may well put you above the legal limits in your jurisdiction. So be careful.

Aside from that, a much simpler antenna is this one, which can be built from a metal can + connector + wire stub. Directionality is likely a bit worse but I've used it successfully over a distance a bit lower than a kilometer. https://web.archive.org/web/20060516103023/http://www.saunal...

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Yes! Everyone should own a cantenna or 2, or 3... I built a 2ft diameter version during COVID for radio astronomy.

Can you tell more or link to a description? What where you able to observe?

I observed the "H-Line", https://en.m.wikipedia.org/wiki/Hydrogen_line

Made a GIF of the transit of the milky way using this software on a raspberry pi with some SDR/RF equipment. https://github.com/byggemandboesen/H-line-software

Unfortunately I only have some images on my phone right now, a git page is on my todo.

Yes, be very careful to stay within lawful ERP. Some devices are illegal to use with external antennas. Of those that can connect an external antenna, the specs of acceptable antennas are provided with the equipment.

If you are in the USA, and you have the appropriate Amateur License (Tech class or higher), and you choose channels that are in the Ham Bands, Then it's perfectly fine to use these as ham radio links. https://www.arednmesh.org/

Yeah, be SUPER careful, the Wifi snooper vans are always out… looking for violations. You could be sent to Siberia for this. /s

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