[clue-tech] Practical D.I.Y. WiFi antenna info?

[Bruce Ediger]

I need some guidance on the practicalities of WiFi antennas.

Background:
I bought an IBM a22m Thinkpad at a garage sale for $10.  It was in great
shape, and I got it to boot Slackware 13.1.  I ended up downgrading to
Slackware 9.1 for two reasons:

1. It has an ATI "Rage" card, and which XFree86 supports it beautifully,
 	you can only use it as a VESA card under Xorg.

2. I have a PCMCIA WiFi card that I scavenged out of a non-working vintage
 	WAP-11 access point.  Turns out it's an ACX100 based card, well supported
 	by a Kernel 2.4 driver, but not so well by 2.6.

I cracked off the two super-nonstanadard SMA (?) connectors on the PCMCIA
card to get it to fit in the a22m's slot.  That leaves me with 2 empty,
5-hole spots for soldering in connectors.

Strangely even without an antenna, I can get it to associate with my DD-WRT
WiFi router, as long as I'm in the same room with it.

I tried making a co-linear antenna out of coathanger wire, like this one:
http://martybugs.net/wireless/collinear.cgi
but I didn't solder it, I just filed down one end to a taper, and jammed it
into the PCB that sticks out of the PCMCIA slot.  That didn't work so great.
I need some help with antenna practicalities like this:

1. Do you have to use hard-to-get LMR-400 coax, or does other coax work too?
2. Do you have to use ridiculously expensive N-type connectors, or can you
use BNC or other connectors?
3. When I'm trying things out, do I really need to solder an RF jack on the
PCMCIA card, use an expensive pigtail, etc, or can I just jerry-rig it with
alligator clips and stuff?

I can solder a little, but I'm an ex-aerospace structural engineer, and a
software guy, not an electrical engineer.  Where can I go for help on
these practicalities?  Googling doesn't seem to get me anywhere on this
occasion, just a lot of feel-good fluff and ads trying to sell me stuff
that costs more than the a22m laptop did.