In most - if not in all - cases, you have one or several Hirose U.FL male connectors on the PCB, then a pigtail (patch cable for RF-signals) and then a RF connector connected to the casing. The antenna is screwed on to that.

• http://www.seattlewireless.net/AntennaHowTo
• http://www.usbwifi.orconhosting.net.nz/ peculiar antennas

Devices with detachable Antennae can be found in the start or with Help of this Tag:

if set.