different coverage changing place: is important the speed of wi-fi?

[arruba]

I Ben,
Thank you for the answer.
I forgot to mention that I placed the antenna on the roof over a large plate of steel, acting as ground plane.
Later I'll post some pictures.

[F-EGLF1]

Roberto,
It could be that the aluminium frame was acting as a ground plane for the antennae, try getting a large steel baking tray or similar and putting the antennae on the centre of that, you may find that you get a good increase that way (a 1/4 wave antennae needs a good ground plane if it is to work well, a dipole or co-linear will work fine without one)
Ben.

[arruba]

I know, the title is a little obscure.
I placed my Raspberry with a DVB-T stick and the antenna (1/4 wave, stylo) near my router, with the antenna posed on the frame of the aluminium window, at last floor of the building.
This way I get a coverage only in a restricted beam around 240° and receive aircraft until 210 miles.
The Raspberry was connected with a cable, and now via wi-fi.
When all was working, I placed the same hardware on the flat roof (a terrace), which is not obstructed and the antenna has a 360° sky visibility.
Now, I get a near 360° coverage BUT ONLY UNTIL 40 Miles and no more!
All is the same, antenna cable, hardware, position, only the place is 3 meters high. The only thing different is the distance from the router: it will be possible that a weak signal interfere with the coverage? I believe it is impossible, but why placing the antenna in a better position DECREASE my coverage?
Perhaps will be a saturation problem? I don't have any RF source in the neighbor...
Any suggestion?

Than you!
Roberto
T-LIMJ5 and T-LIMW3