how to design coaxial feed Microstrip antenna using CST

hi, can any one help me how to design the coaxial feed for Rectangular patch antenna using CST..i tried but still i cant get the result...i used to get the port by choosing 2cylinders radius 4 and 1.12 respetivly...so plz can any help me out through this

Hello,
You should design the feed alone and put two ports, one each at either side. Simulate for wide frequency band and look for S - parameters. They should be within the specified limits. As for physical dimensions for coaxial feed, you may look on internet for common SMA connector layouts. Most common SMA use PTFE as dielectric to get 50 ohm impedance.
Regards
Praful