i would not use a haipin match but a halfwave transformer
impedance of a folded dipole with parasitic elements is in the 200 ohms area .. so a halfwave transformer is the right choice
the text in the homepage where you found the design has a fault ... a folded dipole does not have 450 ohm ... also not when using the 450 ohms window line (that in real is more 390 ohms or so) ...
hairpin match does not provide balancing and is lossy compared to the halfwave line
