Coaxial Connectors

Pigtails

A relative handful of wireless PCMCIA cards for laptops (primarily the Orinoco line) are equipped with a tiny coaxial jack on the outer edge of the antenna bulge. The jack allows the connection of an external antenna with much higher gain, directivity (a narrow beam) or both. A short length of coaxial cable used to connect a wireless card to an antenna is called (colloquially) a pigtail.

The cable is short because at microwave frequencies like 2.4 GHz, radio energy losses in coaxial cable are quite high. Typical pigtail length is from 19" to 42", with an N connector on the antenna end and one of several types of small coaxial connectors on the wireless card end. Such pigtails may be obtained from several Web-based vendors for prices between $20 and $40.

That sounds like a lot of cash for two feet of wire and two connectors. This has led some folks to make their own pigtails, but there are gotchas. A badly-made pigtail will eat a lot of your signal.

Any connector in an RF transmission path will create an impedance bump (a short region of turbulence for radio waves) that increases the loss of signal in the path. The severity of this impedance bump depends heavily on how carefully the connector is soldered or crimped to the cable. Connectors like the RMC and MMCX are tiny, and soldering coaxial cable to it is an art, not a science. Do it badly, and the loss in your pigtail will skyrocket.

I've purchased most of my pigtails from Fleeman, Anderson, & Bird. See the vendor list in Appendix A for contact information