A Method for Measuring the Transfer Function Inside a Compact Metallic Enclosure Using a Slot Antenna

Radio frequency desensitization issues comprise two components: noise radiation sources and the transfer function from noise sources to the victim antenna. For modern electronic products, noise sources are often located inside a compact metal enclosure, making it difficult to measure the transfer function using conventional methods. Moreover, opening the metallic enclosure would dramatically change the transfer function, and inserting a near-field probe into the enclosure is challenging and may not even be possible because of the limited space inside. In this article, a novel practical method for measuring the transfer function inside a compact metallic enclosure is proposed and experimentally validated. A slot antenna with a known magnetic dipole moment is created on the metallic enclosure, replacing the real noise source. The proposed method is applied to a practical device (a laptop with an embedded Wi-Fi antenna), and the transfer function measurement is successfully validated, with an error of less than 4 dB.