NVIS QSO is not so easy with a mobile whip antenna especially when the distance is short because the takeoff angle is almost directly upward 90 degrees.
The efficiency of a short whip is typically abt 1% which means a 20dB gain loss. But to get the best results it is clear that a NVIS whip
antenna should be installed to the front, rear or side of car roof but not in the middle to avoid deep null upward. See location simulation here.
This is a 1.5 meter long NVIS whip antenna orientation comparison on 80 meter in a simple caravan model.
Vertically orientated whip antenna model |
45 degrees tilted whip antenna model |
Horizontally tilted whip antenna model |
Vertically orientated whip antenna elevation plot in dBi scale |
45 degrees tilted whip antenna elevation plot in dBi scale |
Horizontally tilted whip antenna elevation plot in dBi scale |
Verdict of an roof edge mount whip antenna orientation
NVIS car whip antenna should not be installed in the middle of car roof to avoid deep null upward.
Tilting 45 degrees an edge mount whip seems to best compromise for NVIS and medium range QSOs.
Horizontally tilted whip seems to worsen the overall performmance.
Update 2023-02-03 OH7SV
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