This Antenna was made for 1090MHz, I used the Calculator provided by m0ukd https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/
Because I basically live in the middle of a forrest with trees on my House I had to make someting that will survive a Bird sitting on it, so I designed a Radome and Mount for it.
The Antenna length is 65.4mm the Groundplanes made from Brass tube soldered to Cable Shoes are 73.2mm from the bend point
3D Design files for the Antenna availbe for Download:
n-buchse.step
radome-polemount50mm.stl
radome_upper1.2mm.stl
radome-lower1.2mm.stl
antenna-cover1.2mm.stl
antenna.stl