If your antenna is 50 Ω and your source is 30 Ω + j10 Ω then, add a series capacitor of -j10 Ω to cancel out the +j10 Ω effect of the inductor.
This now means you are trying to match 30 Ω resistive to an antenna of 50 Ω resistive.
Then use an L-pad calculator like this: -
You can double check the formula derivation on that site.
- Series inductance needs to be about 1.6 nH
- Parallel capacitance needs to be about 1.1 pF
Then, if you went back to the start of the problem and analysed what value of inductance is needed to produce the j10 Ω in your driver output impedance, you'd calculate it to be 0.663 nH at 2.4 GHz.
This means that you can actually dispense with the added series capacitor of -j10 Ω (as originally proposed) because you need 1.624 nH from the above calculator. The upshot of this is that 1.624 nH might as well be 1.663 nH so, the external series inductor you need to add is 1 nH.