this post was submitted on 05 Dec 2024
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Amateur Radio

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My first magnetic loop for 2m :)

Really simple construction: bent ca. 2mm brass pipe soldered directly to the outside of an SMA plug, inside of the plug soldered to the red wire as "input coil". Tunable by squeezing the ends more or less close together.

SWR of <1.2 at resonance, not bad. Impedance is at roughly 44+j2 Ohm, also not bad for totally eyeballing it without any prior calculations.

I can reach the nearest 2m relais just fine at 2W, although to be fair I can do the same with a short whip antenna. More testing to follow. Holy shit, this actually works!

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[–] LH0ezVT 0 points 4 weeks ago* (last edited 4 weeks ago) (2 children)

Especially since the "plates" are just some overlapping pieces of the brass coil covered in heatshrink... It makes me wonder how to make a 70cm loop, at that point, the capacity would be so small, I might get away with a horseshoe design of some kind.

[–] [email protected] 2 points 4 weeks ago

Oh yeah, I would definitely be careful about how much power I put into that then LOL.

[–] [email protected] 2 points 4 weeks ago

For higher power, you could use some PTFE tubing as an insulator instead of heatshrink.