Antenna Polarization
Polarization is the orientation in space of the electric field component of the radiated wave, and it is set by the physical direction of the antenna. A vertically standing whip antenna radiates vertically polarized, a horizontal one horizontally polarized. Having the transmitting and receiving antennas in the same plane is a link advantage gained without any hardware change.
The receiving antenna only collects the component that falls along its own direction. As the angle between the two antennas grows the collected share decreases; at 90 degrees it theoretically falls to zero.
- Rule: using vertical polarization on both sides is the standard approach in industrial installations.
- On handheld remotes the antenna direction changes with how the operator holds it; for that reason the receiver side must be kept vertical and one has to rely on the help of reflections.
- Reflections partly rotate polarization, which is why in practice the link does not break completely at 90 degrees but suffers heavy loss.
The simplest rule to apply during installation is this: do not lay the receiver antenna on its side on the enclosure, position it upright. Tilting an antenna brought out through a cable gland because of lack of space produces a measurable loss of range, and it is the kind of loss that can be recovered at no extra cost.
Context in which this term is used: 433 MHz or 2.4 GHz?