8 antenna placement mistakes to avoid aka don’t put that Wi-Fi point there!
Access point and antenna placement can have a significant effect on on Wi-Fi performance. Here are 8 antenna placement mistakes we see regularly.
1) Placing APs among pipes and ducts
APs placed in the ceiling among metal air ducts, grids, and large lamp reflectors cause the signal to face a lot of reflection and obstruction, and those conductive objects in close proximity will detune the antenna.
Multiple reflections and refractions lead to several copies of the signal arriving at receivers, which drops data rates. Signal strength suffers at both ends when radio waves reflect in random directions. It’s much better to bring APs down below the ceiling grid.
2. Sticking antennas through ceiling holes
Another way an antenna will get detuned is if you have the AP in the ceiling and stick the dipole antennas through small holes in a metal ceiling panel, an AP cover, or a metal grid. Part of the energy will be directed upward, creating a messy signal.
3. Placing an antenna against a surface
It’s not effective for antennas to be pushed up against a surface, like a wall, where the AP is mounted. The antenna detunes to another frequency, and the radiation pattern and impedance matching alter at the target operating frequency. You’ll also experience wasted signal with this mistake.
4. Placing high-gain antennas high above the clients
If you’re putting the signal up in a very tall ceiling, it’s more wasted coverage — you’re not covering where the clients actually are. The APs also hear each other very well since they’re together up high, increasing self-interference. They have antennas with narrow beams pointing sideways, so overshooting and additional co-channel interference will occur.
Those APs will also respond to all the probes of every device that travels by. This is a challenge in big public spaces since APs could be getting hundreds of probes a minute from devices.
Instead, you can hang APs some distance below very high-ceiling buildings or mount APs on the wall using directional antennas.
5. Placing APs near thick or outside walls
When APs with omni-directional antennas are positioned next to a thick wall, half of an antenna’s coverage pattern is lost. This is because it tries to pick up signals from the wall, which is in an unused direction. Thus, a lot of wasted signal just fires into the wall.
6. Mounting APs with horizontal gain on a wall
Instead of mounting APs with sideways gain patterns on the ceiling — where they were designed to be installed — mounting them on the wall will cause the gain to go up and down, amplifying interference and decreasing signal levels. This mistake also leads to wasted coverage and a signal that’s not where the clients are.
7. Placing the client (or AP) in a metal enclosure
When clients like laptops are placed in a metal enclosure or a cart, it leads to antenna detuning and obstruction. The proximity of the conductive metal means the energy won’t be able to radiate outside the box – a Faraday Cage. There is an exception to this though – if you are in a freezer the metal walls allow you to reuse the limited amount of non-overlapping 2.4G channels for hand-held scanners inside and outside. 2.4GHz is a bit more forgiving around pallet racking and many scanners don’t support 5GHz.
8. A hand covering a Wi-Fi VoIP phone
This is more of a planning and surveying issue rather than an AP or antenna placement issue. Some network planners forget that VoIP terminals, such as smartphones, are often placed against the human head with a hand covering the other side. This can obstruct the signal. Site surveys with a laptop card and appropriate standard limits can provide completely different results.
If you are using omni-directional antennas then you need to remember three things:
- They perform best in open spaces — clear of walls and obstructions.
- They perform best near the centre of their intended coverage area – not in a corner.
- Put the signal where the clients are. It’s no good covering an area no clients. Think about where people will congregate.
For assistance with your Wi-Fi or wired networking, just contact us. ICS Technologies is in Brisbane, Australia.
