A question about matching network between FEM and ANT,thanks

I want to match an ANT to FEM , but I don;t know how to choice the matching network , the S11 measured is changing with FREQ ,and I can't find a network to keep all four FREQ of GSM and DCS inside the circle of SWR<3

can you tell me how to design the network ? thanks

To have a good match between Front End Module and antenna at all four GSM frequencies, the antenna itself shall have a good S11 at these frequencies.
S11 without any matching network shall be better than –10dB for frequencies between 824MHz to 960MHz and 1710MHz to 1990MHz. Probably the best antenna for this multiband application is PIF Antenna (Planar Inverted F). This antenna usually requires a simple L or T matching network.

regards