I can't really help diagnose wireless problems (I find wireless to be too unreliable/spotty as is), but this might explain your problem
. See figure 8 specifically.
Most antennas I've seen used on routers are omni-directional, which means -- depending on how the user chose to position them -- may only be covering an area horizontally
. So if you're directly above the router.......
There's also the issue of many routers having generally low transmit power by default. Router vendors tend to choose low power to keep the FCC happy and so on -- and I will state right here and now that too much
transmit power can actually cause serious problems (excess noise/stomping over everyone elses wireless signals). The whole idea is to "play nice". I tend to set my router to output 100mW, though I could get along fine with 75mW too. My routers' default is 14mW.
My recommendation to you would be to install inSSIDer
and run it. Hide the other SSIDs from other peoples' networks so you get a graph of just your own. You'll get an idea of what your signal level is like to your router. Walk around with your laptop to get an idea of what areas are covered and which aren't.
And alternately, if you have a known laptop whose wireless works good or know someone with such a laptop, have them come over and see what their signal is like in the same position as your laptop. If yours sucks and theirs is good, then you know it's not necessarily the router but is more likely a driver-level quirk or
something physically wrong with your laptop (shoddy antennas, partially connected antenna, too much interference from surrounding components, bad miniPCI card, etc.).
HTH, or at least gives you some things to try + use to investigate/troubleshoot.--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.