How can an RC plane receive when the polarization of the antennas is nog alligned?
Any antenna has an effective aperture (measured in square metres) and all the watts per square metre flowing through that aperture get converted to the received signal. The effective aperture is calculated mathematically with this formula: -



If you are using 27 MHz, wavelength is 11 metres. Ignoring antenna gain (G) i.e. treating the antenna like an isotropic device, the aperture is about 10 square metres.

As the aeroplane flies over the centre of the dead spot of a vertical monopole transmitter there may indeed be zero watts per square metre flowing directly through the middle of the aperture but that isn't true of the outer parts of the aperture and the antenna will receive a signal even if the simplified geometry suggests it won't.

Clearly, at 2.5 GHz the aperture is much smaller and this can become a problem as frequency rises but, remember that a decent radio receiver can "work with" a vast dynamic range of signal levels so only a tiny fraction of the power transmitted needs to be received for it to work.

A typical device might be sensitive to 1 uV RMS from the antenna - for a 50 ohm system that's a power received of only 20 fempto watts.