I've little problems to make simulation of loop antenna in hfss. The antenna is big 52mm on 32mm (six loops - for 13.56MHz). I get big mesh. In help, I found that I should use low-order solution and lambda ref should be 0.05. When I will get better results if I use low-order and lambda ref or without including them in simulation?
I think you can try with lamda refreshment = 0.3333 as default, and no need to do mesh for simulation as refering to HFSS_v10_full_book.
HFSS will automatically mesh you model and It's the simplest way to overcome big mesh problem.