Where should I place the antenna?
Bring the antenna outside the metal panel, fix it in a vertical position and keep it a few centimetres away from large metal surfaces. Move it as far as possible from interference sources such as motor cables, inverters and welding machines. Most range losses stem not from distance but from faulty antenna placement.
The antenna is the most critical and most neglected part determining the range of the system. For correct placement, observe the following:
- Keep it outside: a metal enclosure behaves like a Faraday cage and largely absorbs the signal. The antenna must be brought outside the panel cover.
- Keep it vertical: since the transmitter antenna is also typically held in a vertical position, the polarisation match is achieved this way.
- Keep it away from metal: an antenna stuck to a large sheet metal surface suffers both reflection and absorption; separating it by a few centimetres makes a noticeable difference.
- Keep it away from interference: leave a distance from the inverter, motor cables and welding machine cables. The cheapest and most effective noise measure is distance.
- Keep it high: an antenna close to the floor and between racks gives a noticeable gain when raised a few metres.
Never shorten the antenna cable or extend it with a splice; the impedance and length match is spoiled and the range drops. After installation, repeat the test from the furthest and most shadowed point of the working area with the inverter running.
The full topic: 433 MHz or 2.4 GHz?