Measured Internal Coupled Electromagnetic Fields Related to Cavity and Aperture Resonance

Preliminary internal coupling tests using an infrared (IR) measurement technique were conducted with a hollow metal cylinder having a thin slot aperture. Internal field mapping shows dramatically that the energy coupled through an aperture into a given structure is strongly dependent on frequency. In particular, frequencies corresponding to the resonance of the cavity and resonance of the aperture show significant coupling into the cylinder, while those frequencies slightly off a resonance frequency show a greatly reduced internal field confined to the immediate region of the aperture.