It is amazing because of:
- Very good height
- Very small length of coax, only about 2 meters
- Clear view of about 180 degrees
- Extra coverage beyond 180 degrees due to reflections of 1090 signal from high-rise building nearby.
- V-Stub antenna, though it’s contribution is not the main cause of outstanding performance
Most likely you need a LNA
CoCo antenna’s performance depends on accuracy; (1) determining accurate length of pieces based on using accurate Velocity Factor, and (2) accuracy in workmanship.
Only few lucky DIY Coco makers get good performing Coco. Most makers of Coco end up in poor or moderate performing Coco. Since they do not compare it with other antennas, they believe it is good even when it is just moderate.
The V-Stub requires an instrument for tuning it’s VSWR. I have used “RF Vector Impedance Analyser N1201SA” for this purpose. If you do not have such instrument, then better try Spider antenna, which is naturally tuned, and does not require a tuning instrument. An easy to make version is Quick Spider
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