An electromagnetic coil with improved insulation properties at high temperatures. A bobbin is insulated by a thin ceramic composite layer that is produced by winding a glass or ceramic fiber over the support structure and impregnating it with a pre-ceramic polymer. The pre-ceramic polymer is then modified to form a ceramic SiO2 matrix around the fibrous layer. The ceramic matrix secures the glass or ceramic fibers in place and produces a dense layer. A ceramic coated magnet wire is then wound around the insulated support structure. The magnet wire is a conductor that is spiral-wrapped with a glass fiber impregnated with a pre-ceramic polymer.