I am about to install a remote access point in the loft, which will hopefully provide much better coverage around the house than the current arrangement of the access point downstairs. I have two high-gain external antennas that connect to the access point via SMA connectors. I am thinking it would be a good idea if one antenna were mounted vertical and the other horizontal, in order to pick up both horizontal and vertically polarized radio waves. This should provide optimum reception for handheld portable devices, laptops etc. Has anybody tried this and does it make a difference using typical equipment?

I do have an understanding of RF, antennas etc, however with regards to WiFi, I am not sure if having the antennas at 90deg to each other will result in problems...

I use a £10 omni directional antenna pointing down from a loft space and it works great for me.

I live in a 3 storey house and have got round the problem by having several access points all with the same SSID and encryption code but on different channels. As I move out of range of one of them the equipment locks on to another automatically.

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Stuart Andrew
Saddleworth, UK
(g3sna)

Edited: 02 February 2009 at 04:47 PM by sandrew

If your access point has 2 Antenna's it is possible that they are being used in diversity mode. If this is correct then the Antenna's should not be installed in seperate locations as they are working together to prevent multipath distortion.

Most WiFi kit is vertically polarised.

Mark

I am also curious about Radiodan's query. Mark's point that more than one antenna are used for diversity prupose, and this is correct. This is known as MIMO technique (multiple input multiple output).

What I want to find out which is related to Radiodan's question: is the WiFi signal transmitted in both vertical and horizontal polarization or just either one (and which one is it)? Once I know this, I can configure the antennas (perhaps one vertical the other horizontal?) for maximum reception.

Awaiting answer/clue :-)

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Dr Yau Hee Kho
Kuching, Malaysia.

Just realised Mark has already replied that most are vertically polarised. Out of curiosity I check the manufacturer's specs but nothing is said about polarisation. How to find this out?

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Dr Yau Hee Kho
Kuching, Malaysia.

I'd bet that most laptops etc. are HORIZONTALLY polarised, since the radio modules are on the main board.

The easiest (?) way to test this would be to seperate two end-points sufficiently, and monitor the signal strength (RSSI) whilst adjusting the polarisation of one end.

This reminds me of folded omni-directional dipoles (in the UK) that are used for FM radio reception. The transmitters are VERTICALLY polarised, but these receive antennas are ALWAYS mounted horizontally...

SimonR

Actually, the antenna in a laptop runs along side the monitor, so they are vertically polarized.
Surely mounting a Tx Ae vertically and a Rx Ae horizontally goes against basic RF principles? is there a specific reason for that then?