This is a remix of the Quadrifilar Helix Antenna by @jhsandell for 1090MHz (ADS-B)
The following updates have been made:
- The 'bug' that jhsandell noted where the code was using diameters rather than radii has been fixed
- This version makes a left-handed helix for right-handed polarization, rather than a right-handed helix for left-handed polarization*
- Settings have been adjusted for ADS-B frequencies (1090 MHz)
There are a variety of pros/cons for a QFH antenna for ADS-B:
- Using circular polarization, antenna is not sensitive to changes in aircraft orientation
- Radiation pattern is more or less omni-directional around a single hemisphere (note that this would be in the direction of the feedpoint!)
- Multi-path rejection
- It's purty
- ADS-B is by standard vertically-polarized, so using a circularly-polarized antenna means a 3dB loss
- Takes up significantly more space than a simple vertical or J-pole
- Construction is more complicated than other antenna types, and care must be taken to attach the feedpoint properly
The wire used in the photographs is 10awg copper wire - this is equal to the 2.5mm wire diameter suggested by the calculator as an optimum for this frequency. However, for a smaller gauge might be recommended for easier construction.
*The photographs show a left-handed polarized (so right-handed helix), rather than the LHP version in the OpenSCAD file. For ADS-B, polarization-handedness is unimportant.
A strong and non-brittle filament is recommended here - this version was printed using PETG. Materials such as ABS are not likely to survive the construction process, as it takes some work to get the copper wire correctly placed.