pls help, i am a newbie in dipole antenna design

I am using a freescale ZigBee transceiver
which has a differential tx and rx port

in matching the dipole antenna to the port,
what impedance of the dipole should be ?

because i am confused by differeential impedance.


is it also a 50Ohm matching?
but in the case, a differentiial impedance with 50Ohm?

The impedance of a dipole in free-space is approximately 72 ohms.
The impedance of a microstrip dipole is affected by the substrate.
To match the dipole you need a balun.
http://emacademy.org/piers2k5ZJ/subm...1211225409.pdf

The default for matching network is 50 ohm .

But it could change the impedance in variable frequency with reality.

so you can see return loss (s11) for your reference .

Normally , for VSWR < 2

The return loss is lower than -10 dB .

It's also used to define the bandwidth .