I'm not aware of any PCMCIA wifi card that has a connector for an external antennae. I know there are HW hacks for some PC cards to add an antennae.

Nokia C110 802.11b PCMCIA card, and SSID broadcasting Manion Sep 2, 2003 Jump to latest Follow Reply ...

The Wireless Exstreamer from Barix, which with the addition of a PCMCIA WiFi card, will stream MP3s from a PC or Mac to a stereo. One problem: it doesn’t have a remote control, so it’s not ...

In addition, USB EV-DO modems also are beginning to be released that will plug directly into the USB port, eliminating the need for the PCMCIA card (Sierra Wireless has announced some). Check your ...