antenna-theory.com

[fastfish]

Hi, I am building a large 2.4ghz wifi mesh network in a down town area with lots of brick buildings and trees.

radio: om2p 26 dBm 3dbi stock antenna http://www.open-mesh.com/index.php/products/access-points/om2p.html

I have been replacing the 3dbi antenna with a 9dbi rubber duck antenna http://www.l-com.com/wireless-antenna-24-ghz-9-dbi-rubber-duck-antenna-rp-sma-plug-connector

On the roof of my building I have a 9dbi omni http://www.roc-noc.com/product.php?productid=236

Q1. I replaced the 9dbi roof antenna with a 15dbi antenna http://www.l-com.com/wireless-antenna-24-ghz-15-dbi-omnidirectional-antenna-n-female-connector and got slightly worse reception. Any ideas why?

Q2. On the access points changing out the 3dbi w/ the 9dbi rubber duck sometimes doesn't get me any gain. I would expect a 3x gain but don't always see it. Should I just trust the the manufactures have the best antenna for the job and stop buying the 9dbi?

Open to any suggestions.

-wirelessly challenged

[Schubert]

9 dBi gain antenna means the antenna is more focused in a particular direction. If you are receiving wifi, and it is coming from many directions or not line of site, you will probably do worse with a higher gain antenna.

Most wifi routers have low gain antennas so that they can receive energy from any direction.

So the lesson is more gain isn't better, unless you know exactly where the signal is coming from.