measured and simlated results not matching

Hello, I have attached the comparison of measured and simulated results of an antenna on which I am working. The simulated S11 parameter is from CST. The measured and simulated results are matching upto 22Ghz but after that from 22- 34 Ghz the results are not mtaching.
Please somebody help me what can I do in this.
Is this any CST problem? or setting I have to change for higher frequencies.?

measured results not exactly matching predicted results from some program? Say its not so!

From your plot actually I see that your measurements just barely match the simulation at only few frequencies. Otherwise, differences are all over the places.
Interesting is that you get better measurement results than the simulator. So you can get rid the expensive simulator from now.

but to send the work in any journal I need to show the good match between the simulated and measured results

The biggest error source in EM simulation is the user, not the software. If you just used the defaults, results can be good or bad. Nobody knows, because every EM model is different. You need to learn how to use your EM tool, and what good settings are for your models.

You need to understand why measured and simulated don't agree (enough) to make progress in your work. You define what is good enough, because only you know what the design requirements are.

To publishing the work in a journal, you don't need simulations. What you need is some new scientific work that was not already published by others. If it's relevant and new, and measurements show good performance, go ahead. Even if you have measurements and simulations that don't agree, and you can explain why there is a difference, that's ok.