A Wi-Fi pigtail is a specific type of cable used to make Wi-Fi connections. It is simply a converter cable that adapts one type of connector to another. The pigtail is usually the last connection in the chain between the cable and the computer connector, although the entire cable could be a pigtail if one end differs from the other. You make one by getting the requisite connectors for the Wi-Fi antenna/connection and the Wi-Fi card on a computer, then soldering or crimping them onto the respective ends of a coaxial, USB or other cable.
Cut a length of cable for the pigtail and strip 1/2 inch of the outer insulation off each end using a cable stripper.
Strip 1/2 inch of the outer insulation of the cable without damaging the inner wires' insulation, using the wire stripper. Identify the wires using the colour scheme of each insulator, making sure to match pin-to-pin on the respective plugs.
Strip 1/2 inch of insulation from each inner wire, or position the cable end so that It can be crimped. Heat each wire with the soldering iron and tin it with solder. Then solder or crimp the prepared ends to the connector as applicable. The number of wires to be attached depends on the type of connector on the antenna end.
Repeat Steps 2 and 3 for the remaining connector on the other end of the cable to complete the Wi-Fi pigtail.
If crimp versions of your connectors are available, they are easier to attach than by soldering.