dipole matching

The easiest way to do this would be to use gamma matching. If you do a search on this site, or on the whole internet, you should find plenty of information on this.

I think I have seen papers in IEEE about use of Balun to match and feed printed Dipole.

In a printed circuit dipole is very dificult be near 50 ohm .The best to do is made a stub outside the coaxial with 1/4 l long.(for 2.4 is 31 mm long).
Also the first director must be very closed the dipole between 4 and 6 mm.