matching network design for transceiver with differential outputs
First, before you can duplex any antenna, you have to find a way to keep the Tx signal from "blowing up" your Rx circuitry. The 2 most popular methods (that I'm aware of) are notch filtering (complicated &amp; expensive, but allows full duplex) and switching (simpler &amp; cheaper to impliment, but only half-duplex).

Using switching for illustrative purposes, you'll need a (preferrably solid-state) switching device that can disconnect the antenna from the Rx pin(s) when the device is actively transmitting (may possibly have already been done internally to your device).

You then simply attach both differential circuits (Tx &amp; Rx) to the switching device; then attach the switching device to an impedance-matching balun; then attach your unbalance feedline (i.e. coax) or antenna to the other side of the balun.

This assumes you are A: Not using an external amplifier, and B: relying solely on your Tx/Rx chip for filtering (DC blocking simply requires coupling capacitors on the chip's Tx &amp; Tx inputs; the balun can be used to ground any DC [static] charge building on the antenna).

Here is a writeup covering some basic balun design info (keep in mind that at 2.5GHz you WILL NOT need to use a "core"...a 5:1 impedance coil @ that frequemcy is quite small as an air-cored inductor!);

Then you can calculate the "turns ratio" for your impedances as: BalTurns/UnbalTurns = sqrt(BalOhms/UnbalOhms);

Then check out this inductive reactance calculator, and this inductor winding calculator to figure out what exact dimensions you need to use for your balun's coils (remember, you want to have 5x the reactance of your signal impedance on the coil to ensure good efficiency/transfer).