Hi, I have to wind a coil on a metal rod that is lossy. I measure Q of air coil as 30, and when I insert the rod (6 inch diameter), the Q drops to 2.5 and the inductance changes only slightly from 6uH to 6.7uH. the coil has to be on top of that rod and it is used as a receive coil in wireless power transfer. So I need a good Q.
My question is how to shield the coil from the rod, what materials to use to improve the Q factor ?
I can't change the material for a rod, it has to be what it is, but I can put anything on top of it (it has to be chip and easy to make).