EVAL-AD8349 material

I wander the EVAL-AD8349 evaluation board material ,is it FR4 or Rogers material , I can't make sure that if the FR4 material board can go 2.4 GHz

signal well.In the meanwhile,I used FR4 material at a two layer board to operate AD8349,finding it too hot , I wonder why and can I improve it by changing the material or changing 2 layers to 4 layers.  Waiting for answer,thank you.!!!