Development of a Non-Contact Ground Noise Injector on Flexible PCB for RF Immunity Test of a Mobile Phone

In this article, a novel test methodology is developed to evaluate the radio frequency (RF) immunity of a mobile phone by using a dual-coil system for RF noise injection and measurement. This method involves an injection coil to introduce noise to the device under test (DUT, mobile phone camera module), and a sensing coil to measure the noise transmitted to the DUT. Electromagnetic simulations were used to optimize the coil’s geometry and design variables to maximize power delivery to the DUT and minimize intercoil coupling. Coil printed circuit boards (PCBs) were fabricated, and their performance was assessed by measuring the S-parameters, the power reflected from the injection coil, and detected by the sensing coil. Furthermore, the injected RF noise effectively induced a malfunction in the DUT, and the results can be used to estimate the relative immunity of the DUT.