Help me with designing a node (feddit.dk)

submitted 1 year ago by EvilCartyen@feddit.dk to c/meshtastic@mander.xyz

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I want to put a node up on my house to act as a repeater or station, but I don't know how to spec it from the PCB available as-is on Aliexpress and other venues.

So - what would you do?

Which board
Which antenna
Which power source (solar + battery?)

It needs to function on an unheated loft in Denmark year-round...

Surely, some of you have done this before, so please halp :)

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[-] captain_aggravated@sh.itjust.works 3 points 1 year ago

I can think of two reasons (well, actually three) why 868MHz is used more than 430MHz.

Many places that allow both frequencies allow more Effective Radiated Power on 868MHz versus 430MHz. Longer wavelengths are more transparent to things like foliage or structures, but a lower power requirement would all but nullify that one advantage.
Antenna size. Antenna size is directly proportional to wavelength, 868 is in the ~33cm range, 430 is ~70cm. Any given antenna design is going to be double the size for 430MHz. A half wave dipole antenna for 868 is going to be about 18cm long, for 430 it'll be about 34cm. Not a problem for stationary nodes like what you picture there, but what about the pocket sized node you pair your phone to? Now you've got an antenna the size of your forearm sticking out of your pocket.
Bonus third reason is the societal tautology: More people use 868 because that's what more people use.

this post was submitted on 13 Aug 2025

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