This study investigates the effect of magnetic Fe3O4 and Ag conductive material mixing with ITK epoxy on the noise suppression of bandpass filters. The bandpass filters is based on half wavelength resonators . The simulator HFSS was employed to simulate the characteristics of filters and the simulated results were compared with experimental results . It is found that the center frequency of filters is not affected after the coating of noise suppression materials ; however , the harmonic of the filters is suppressed with the cated films.