Will the 4G/5G wireless module of the edge computing box worsen the radiation emission index?

The edge computing box has a built-in 4G/5G wireless module with a transmit power of up to 23dBm. Its carrier waves and harmonics may radiate outwards through gaps in the casing or cables, causing excessive radiated emissions, especially in harmonic frequency bands such as 700MHz, 1.7GHz, and 2.1GHz. Countermeasures include:

1. The module shielding must be properly grounded; a five-sided shielding with openings less than 1mm is recommended.

2. Power feed electrodes with series-connected ferrite beads (PBZ1608E600Z0T) and capacitors to filter high-frequency noise.

3. A strictly 50Ω RF output matching circuit with a series ESDLC3V3D3B common-mode filter; its junction capacitance is only 0.8pF, providing ESD protection without insertion loss.

4. Antenna and overall radiated emission testing should be conducted simultaneously. If harmonics exceed limits, a bandpass filter should be added to the antenna port, and the module should be positioned away from I/O interface cables.

After implementing these measures, the 4G harmonic radiation in the edge computing box decreased from exceeding the limit by 7dB to a margin of 4dB, successfully passing CE RED certification.