10$ portable HF 10-28 MHz magnetic loop antenna "wild strawberry"

FreeCAD source models are included, feel free to modify for your needs.

This is fully 3D printed portable magnetic loop antenna including 3D printed sliding variable capacitor, which can sustain around 40W CW.

The goal is ability to disassemble it, fit into the backpack, walk or cycle and then quickly assemble, also to make it as light and as cheap as possible.

Managed to tune it from 30m band up to 10m band, SWR is around 1.8 on 30m band going down to 1.1 on 10m.

Had successful QSOs in CW on 20m band with this antenna from the bushes.

You will need 7mm diameter fiberglass poles from your unused tent, they are used as holders for the large ring.

Large and small rings are made from the same twin cable, just split up to small ring touching point (see photos) and cut for small ring. Large ring diameter is around 0.9 m. Better to use higher AWG cables, it will increase antenna efficiency.

Also, using 1:1 balun, as had some troubles with currents reaching the mic on my homebrew radio.

Capacitor instructions could be found in another thing description at https://www.thingiverse.com/thing:4024253

Piece of 20 mm cable pipe is used as a holder, also it is used as a storage for tent poles when disassembled, so cut it to the same size as your tent poles or a little bit longer.

The complete price of this antenna is around 10$, cable, filament, tent poles, aluminium sheet for capacitor plates, bnc connector, M3 screws and bolts. Most likely, you already have all these components.