Hey, you didn't show anything about the antenna!
No antenna shape.. nothing except the results..
Anyhow, I said this because the radiation pattern is quite like a monopole one!
So i wanted to see your design and how did it lead to such a pattern..?
Also, It depends on your application you're trying to fabricate the antenna for.
Anyhow, it's a 7-14GHz antenna which doesn't fully fulfill the standard American range from 3.1-10.6GHz.
Finally, even though the band isn't too wide as it should be, the return loss is quite suspiciously looking.. it's too smooth with no fall downs (bellies).. It's near to a too perfect thing for this range exactly. If it becomes like this to satisfy the full range, it'll be a somehow magical work, especially if the spectrum analyzer's result was the same or nearly the same..
Actually you don't have any other choice than having a wild spectrum analyzer to show you the actual result. Try to see some other universities in your area, they may have been provided with such instruments.
Good Luck with your project.. I think you're finishing it by now, because my post is about 1 month late!