I have use CST frequency solver to simulation a double layer 13.56Mhz PCB spiral coil. I try to set the boundary to open, the simulated inductance is not correct (only around 40nH, it expect to be around 2.2uH). I try to set the boundary to open add space with default quarter wavelength space. However, because the frequency is low around 10MHz, the space is thus very large, and it thus spend a lot of time in generating the mesh. I try to set the space to a much smaller value and the simulated inductance is 1.7uH (It is much closer to the expected value). What is the effect of setting the space much smaller tan quarter wavelength. Will it affect the simulation accuracy. The CST project is attached. How can I do to solve the problem. Please tell me what space size should I set in this project to get sufficiency simulation accuracy
