No, don't do that. There is a report on a study by Cisco that Jeff can link for you, but basically, it confuses the system if the antennas are different, directional or too far apart and can make things whacky. These antennas are meant to be in the same place both transmitting/recieving to the same clients - only seperated a bit.
Apart from that, it's not too clear what your setup is. Is it your pc acting as router or do you have another router in the basement?
Instead of running an antenna cable upstairs, run an ethernet cable from your existing router to upstairs and use an additional access point or router (operating as access point) where ever coverage is too weak.
In fact, if you don't need wifi in the basement, just operate the AP/ Router upstairs and it may cover the upper two floors.
There may be some advantage to using a pc as router, and a wireless pci card for an AP, but in most cases, I think it's limiting, more trouble and complicates things without saving any money. Generally best to get an inexpensive wireless router.
Also, consider if you really need the speed of N because you are planning to stream video around your house ? If not, then G is less expensive and very good choice.
Holdit. You're mixing up MIMO and diversity reception. The article I was referring to:
is only about diversity reception, not MIMO.
If you remove all but one of the typically 3 antennas from a MIMO router, you get essentially 802.11g speeds. If the error rate is insufficient to maintaint MIMO speeds, the router will revert to
802.11g. I presume (not sure) that the multiple antennas revert back to a diversity receive mechanism when not running MIMO speeds. Therefore, diversity reception issues might still apply and become a problem. I'm admittedly a bit muddled about exactly how the MIMO chips operate under non-ideal conditions and will need to do some testing and reading before offering any more bad guesses.
Also note that MIMO comes in two flavors. Spatial Diversity and Beam Forming. The routers with visible antennas are spatial diversity. The ones with internal PCB antennas are beam forming. The characterists of these technologies are very different and should never have been conglomerated into one acronym and one (preliminary) standard.
OK. My bad. Thinking I understood! So, it's not the same at all as diversity, though it might be ultimately have similar problems when the antennas are seperated from each other?
How's this ?
" You can't seperate the multiple antennas in a multiple antenna radio (be it diversity or MIMO) and expect it to work like two or more radios in different places, sending and receiving appropriately to each client connecting seperately to each antenna. Instead, it will likely confuse the radio causing it to drop back to G (if N) and possible attempts to transmit on one antenna in response to reception on another - generally screwing the link up when multiple users connect to different antennas with different coverage."
Please correct me Jeff (no doubt you will!) I'm just trying to extract some direct advice out of the confusion.
Related question? If I understand correctly, the only way to run multiple antennas with different coverage (on the same radio) is to use an RF splitter (expensive, with some losses) on a single antenna jack, so as to transmit and receive on all antennas simultaneously?