Radiated Susceptibility Testing Using Near-Field Scanning

Determining locations and components in a system responsible for radiated coupling is challenging. Methods, such as near field injection susceptibility scanning or direct power injection, can only find locations and frequencies where a component is sensitive to the near field or to an injected signal but cannot deduce if the component is well coupled to the far-field. In this paper, a method to experimentally determine the levels of radiated coupling within a target system is proposed. A near-field differential loop probe is scanned over the target device while measuring the radiated energy in a stirred-mode tent. By sweeping the near field probe across the device, the total radiated power can be found as a function of its position over the target and used to determine frequencies where the radiated energy is more likely to couple effectively to the system as well as the location of structures that are connected to efficient unintentional antennas. Validation is performed by scanning known radiators, such as patch antennas and dipoles.