Radiated Emission Tests for High-Frequency Router Systems in Class A: Discussion and Improvement

The standards for radiated emissions (RE) test in FCC Part 15 and CISPR 32, and the related literature concerning the limit line extrapolation, testing methods and challenges in the RE test are reviewed herein. In particular, factors to be considered during the RE test for the equipment in Class A operating above 10 GHz are discussed including: 1) possibilities to miss the maximal electric field (Emax); 2) specifications of the 2 dB rule; 3) falloff factors in the conversion between the measured electric (E) field at closer distances (1 m or 3 m) to 10 m. Methods that might be considered for improvement are proposed to increase the confidence of the multi-modular systems in passing/failing the RE standard and compliance with other devices in terms of: 1) according to 2 dB rule, 63.1% of the optical modules are proposed to represent the radiation of the fully loaded router system; 2) statistical falloff factors are needed in converting the E field at 1 m/3 m to 10 m at high frequencies (> 10 GHz); and, 3) specific limit lines are preferred at high frequencies for router/multi-modular systems.