Helical Antenna Generator

1. Print the bending jig. Print it upright with no supports, 3–4 perimeters and 20 % infill. If it comes in several segments, stack them on a rod or tube through the bore and line up the groove ends.
2. Bend the wire. Push the wire end into the straight feed groove, then wind the wire tightly along the helical groove. Unscrew the coil off the jig. Copper springs back a little, which is what the springback setting compensates for. Wind a test coil and measure it, then adjust the percentage.
3. Print the holder. Kit ribs print flat with no supports. Glue the tabs into the base and top ring. The rib with one index hole is the first rib counter-clockwise from the feed hole when you look from above. A one-piece holder prints upright.
4. Mount it. Bolt the base to the ground plane with the feed hole over the connector. Pass the feed lead through to the connector pin and snap each turn into its rib slots.
5. Match and tune. The helix's impedance (shown in the results) is far from 50 Ω. Solder a copper strip to the first ¼ turn as a quarter-wave transformer, or press that section closer to the ground plane while you watch the SWR. Check the result with a NanoVNA.

PLA and PETG detune the antenna slightly because of their permittivity. Thin ribs keep the shift small. All formulas are textbook approximations (Kraus; King & Wong). Treat them as a starting point, not a guarantee.