CC11xx 868/915MHz RF matching S-parameters.zip contains two S-parameter files. 
EM_filterbalun_868.s3p contains the simulated S-parameters for the CC11xx filterbalun.
EM_filterbalun_868_without_SEfilter.s3p contains the simulated S-parameters for the CC11xx filterbalun withouth the single ended filter.

Port1 RF_p
Port 2 Ant
Port3 RF_n

The reference plane is at the pins of the CC11xx