Specification for zigbee antenna

Hi,
I have seen a 30 mm wired antenna on zigbee modules. I tried those in bluetooth modules and works fine. I would like to use it for bluetooth since in my product the antenna should be projected out of the metal enclosure.
Now my question is, is that 30cm thick wired antenna a standard one? Is there any specification for that and can I purchase it from anywhere or should I make it using the same gauge wire with same length?