[Nathan]

I'm trying to build antenna's for some 900MHz wifi cards.

Because I'm on a tight budget, I'm building the antenna's myself.

-Nathan

Nathan,
I hope you are doing the appropriate research on biquad antenna dimensioning and scaling to 900 Mhz. The ARRL Antenna Handbook is available at most libraries and has some useful info on antenna design and math. As you have seen in the articles, the authors had some trouble soldering to the outside of the N connector. They thought is was lack of heat, but likely it was the metal used to plate the connector. If you were to use standard hardware to mount the connector to the ground plane, (keep the hardware short please) you could solder a wire directly to the ground plane. To do this, use a longer piece of wire, bend the end (about 1/4-3/8") at 90 degrees and solder to the ground plane. Once soldered trim to the correct length for to set the antenna above the ground plane. At 900 MHz, a helical antenna may be an easier choice to construct and terminate.