We report on field-induced variations of the microwave surface resistance at 9.6 GHz of Ba<Subscript>0.6</Subscript>K<Subscript>0.4</Subscript>BiO<Subscript>3</Su bscript> crystals. Energy losses have been investigated as a function of the static magnetic field in the range of temperatures 4.2 K <InlineEquation ID="Equ4"> <EquationSource Format="TEX">$\div T_c$</EquationSource> </InlineEquation>. By analyzing the experimental results in the framework...</equationsource></inlineequation><//su></subscript></subscript></subscript>