How did you design the antenna ? If you did it on CST you probably gave waveguide excitation from the ports and your ports are probably Z=50 ohms. When you design antenna , you look at S11 measurements of the antenna.Generally you want your S11 to be below -10dB in band. -10 dB S11 means your VSWR=1.92 and Reflection Coefficient=0.316 . This also means you can have maximum impedance of 96.2 +0j Ohm on your antenna. So If your antenna satisfies S11<-10dB you are good with an 50 ohm SMA or N type connector attached after a 50 ohm microstrip line.