If you have a rod antenna it has horizontally 360 degrees but vertically a very small angle and never more than a few dregrees.
30 degrees are physically not possible.
So this kind of antenna should be installed at nearly the same high as the access point ashore.
However if you have a directional antenna you will have this characteristic as shown in the scheme.
But you have to turn it always to the direction of the access point.
I change the antenna depending of the situation temporary.
Amel Sharki #60
Currently Kalamata, Greece