analyzing balun results

i have made a microstrip line to strip line transition with double slots also do it for w band.i have one question about results my return loss for microstrip line side is better with wave port of 50 ohm and on the slot side i attach 100 ohm port which is my antenna's impedance.now my results are in attach file now question is that
1. insertion loss curve that i normally saw in paper looks like a straight line curve rather than what i obtained. i am just taking it like S21 from s parameters of software am i right in taking that S21 as insrion loss?
2.secondly my S22 is not exactly below 10 db ans varies -8 -12 db at my frequencny region when i plot magnitude impedance v/s frequencny curve then it value was changing from 100-130 ohm mine antenna is of 100 ohm so when i go for fabrication will it make huge change in results or not?
3.also i am still confused about port impednace as according to my thinking i should attach differnet port impedance on different sides as i done 50 ohm wave port to microstripline and 100 ohm port to slot lines but normally papers do balun results.zipnot have such port .am i right in doing this?
plz guide me about it