Self-phased quadrifilar helix antenna for ADSB reception

Here is another quadrifilar helix antenna design, this time for ADSB (aircraft mode-S transponder) reception at 1090 MHz. Unlike other antenna types this antenna has a spherical coverage with 120° 3dB beamwidth and estimated peak gain of 4.6dBi at 1090MHz.

ADSB Self Phased QFH Antenna

The basic design was done using Antenna Magus 5.2 and I just used the calculated dimensions. See report for details.

ADSB QFH Return Loss ADSB QFH VSWR

Return loss and VSWR.

ADSB QFH Feed point detail

Feedpoint detail.

To make things easier you may use the drill template. Glue around a plastic pipe with 20mm outer diameter and drill 1.5mm holes in the circle centers. Then build after the description.

Notes:

  • Lengths of volute 0&1 are the wire lengths from lower to upper stubs.
  • This antenna is RH circular polarized while usual ADSB and transponder antennas in airplanes are vertical polarized. Advantage of circular polarization is the multi-path rejection and immunity against polarization mismatch due to antenna installation/position.

 

ADSB QFH Design description
ADSB QFH Design description
ADSB-QFH.pdf
Version: 1
1.8 MB
481 Downloads
Details
ADSB QFH Drill template
ADSB QFH Drill template
ADSB-QFH-Drill-Template.pdf
Version: 1
6.5 KB
363 Downloads
Details

2 thoughts on “Self-phased quadrifilar helix antenna for ADSB reception

  1. I will love to do such kind of antenna, but working at 869MHz.
    I know that using more loops or changing the longitude or diameter you can shape the radiation pattern, but unfortunately I can´t access to Antenna Magus software.

    Do you know any software where I can easely test what radiation pattern can I achieve?

    • FEKO or CST are some other tools but not easy accessible either. Magus has some design limitations as well, so one cannot freely change design parameters.

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