help in desgin folded dipole using for FM band

i desgin folded dipole for FM band using cable RG11 which is 75 ohms is no problem SWR is less than 2 but i trying to bulding with 50 ohms cable which i got SWR greater than 2.5
if any one have ideas how to improve it
thxs

The standard solution is to use a transformer. They come just for this application with screw terminals for the antenna side and coax terminal for the receiver side.

u can apply some type of matching circuit like quarter wave transformer for this or increase the size or thickness of antenna for this aim

just a big hint ... .you should be using 75 OHm feed on 88 - 108 FM band anyway ... so why do you even want to use 50 Ohm coax ?

Dave