[Moved]: differantial antenna input impedance

Hi every one!

The input impedance of a single ended antenna is usually assumed to be 50 ohm, I wanna know what is the typical input impedance of a differential antenna? I mean if I want to match the impedance to what my PA needs, what impedance must be matched?the differential input impedance is 50 ohm (25 ohm each side) or 100 ohm (50 ohm each)?

can anyone help me? I don't know anything about antenna!:D
thank you so much!