It depends on the polarisation of the radar unit. I doubt those trailer mounted things have anything too special, so odd you would get such a varied difference (maybe when vertical it had less area to detect the signal with?).

It is better to test against the real world equipment than devices that don't give you a fine.

Edit: On my testing, only the multanova is polarised. All other radar units aren't which means it shouldn't matter which way the unit is placed.

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[COLOR="Gray"]550Nm off a 2L... Just wish it was in the dak dak...[/COLOR]