802.11g antenna extension

I want to place socket mounted antenna of my PCMCIA and PCI 802.11g adapter's antenna behind the wall to see access point directly. How long and what type of cable (I guess 50ohm impedance) can I use for this?

Regards

Try to use LMR-200. Is relatively cheap with good performance for the price.
Impedance is 50ohms and ~1.8dB/m loss@2.4GHz
http://www.universal-radio.com/catalog/cable/3603.html