Investigation of resonance phenomenon in metallic cavity with aperture based on theory of diffraction

For optimizing the layout structure of components in shell of electronic equipment, the field distribution in metallic cavity with aperture must be studied deeply, especially when the resonance phenomenon occurred. The frequency which result in resonance phenomenon was obtained by means of experiment in this paper, meanwhile the field distribution in cavity was measured at this incident frequency. The field was calculated theoretically by the Modified Fresnel-Fraunhofer´s formula which based on the Fresnel-Fraunhofer´s diffraction theory. The results showed that theoretical results were very similar to the experiments and could basically represent the characteristics of field distribution in cavity with aperture.