Homebrew WiFi Antenna (Proper Cable, LMR-195 GR-58?)

Question

Hey,
I don't know if this is the best forum for my questions, and if not please direct me to one that better suits my needs. I was simply referred to this forum through another one. Anyhow, me and my friend are attempting to build our own wifi antenna and after searching google for a while we have come up dry on a couple things.
1), From the wifi card we wish to attach a cable that will be say 25-50 ft in length which will then attach to the card's reg 3 inch antenna, pretty much extending the antenna from the card. What is the best cable to do this. Originally we were told to use GR-58 50 Ohm Coax cable however after reading further we found that would only be good for 3-4 ft before it pretty much "spills the connection all over the place". We were then recommended to use LMR-195 or better though what type of cable is this as it does not seem to be supplied by Radio Shack. The question is what cable would you guys recomend that could hold a wi-fi signal 25-50 ft from the end of the antenna on one end back into the wifi card on the other, and where can we purchase it?
Thanks in advance and if this is not a good forum for these questions please direct me to another. As time goes on we will build our own antenna but right now we want to get the reg antenna to work over a decent length of cable.

Answer 1

OK. Understood. You have a massive challenge ahead of you. Also be warned that an external antenna that is not properly protected and grounded can be a fire and safety hazard, and that it can accumulate enough of a static charge in dry, windy environmants to blow up your system (not so much like "boom" , but static electricity is deadly to most semiconductors).
Next, you may want to study on how to make a BALUN / UNUN because the WiFI stuff is 50 Ohm impedence, and your average TV antenna is 300 Ohm (assuming it's a classic LPDA - Log Periodic Dipole Array).
An LPDA for TV will have some elements for ~50 MHz, 260 Mhz, 512MHz, and if it's also a UHF antenna, it might be good up into the 900 MHz ranges. LPDA ware pretty wide spectrum, and you'll probably luck out and hit a harmonic somewhere.
You'll need to craft a 6:1 balun, not that big of a deal actually. Shop some of the amateur radio sites (like aesham.com) for materials or to just buy a 6:1 BALUN.
The Gain of a typical ~ 6 ft LPDA could likely provide enough gain to make the system work =-->IF<--= the cabling is very high quality, the cable termination is nearly perfect, your BALUN is efficient enough, and you don't lose too much signal through the protection system (that would be the protection system against lightning and static ... includes a thingy called a "lightning arrestor" that in no way, form, or fashion could do anything to stop lightning).
By the way, you'll want to bring that TV antenna down and clean every connection on every element. Any noisy junction will kill your signal.
All-in-all, the cable shouldn't cost you more than a couple hundred dollars, the materials for the BALUN another ~US$10-20, connectors another US$20-50, protection elements, maybe another US$25-100 depending on who and what you go with.
Here's a link with some good info regarding wireless signal propagation, 802.11, and antenna stuff.
http://www.cisco.com/en/US/products/hw/wireless/ps469/products_data_sheet09186a008008883b.html
Good Luck, make it a great learning experience!
Scott