Based on my experience, FR-4 is not working well above 5 GHz.
Yes that's true, there are circuits designed for 5.8 GHz on FR-4, but they are working on a very narrow band.
If you want to design for a very wide band, it is required to use a RF substrate such as Taconic, Rogers etc as mentioned by tony_lth.
Sometime ago I've done a 1-4 power divider using 3 wilkinson power dividers working in 1 - 11 GHz range. I used 3 stage wilkinsons on Taconic TLX-0 and measured results were very promising with the simulated results in ADS.
Another advice, if you are going to do a project in uni, it's not bad to look at the requirements and available resources. Hope you'll do it next time...
cheers