As 5G deployment advances in France—with nearly 31,000 sites authorized by the National Frequency Agency (ANFR) as of December 1, about 21,000 now technically operational—many areas still face weak or spotty coverage. For those impacted, a professional 4G/5G signal booster offers a reliable fix.
A 4G/5G booster, also called a repeater, amplifies existing mobile signals for stronger reception. It captures the weak outdoor signal and rebroadcasts it indoors. Note: it requires some baseline signal and won't work in total dead zones (white zones). Key components include an external receiving antenna (placed where signal is strongest, aimed at the nearest cell tower), an amplifier, and an indoor antenna to distribute the boosted signal.
Before buying, check your operator's frequencies. In France, 5G uses legacy 2G/3G/4G bands (700 MHz, 800 MHz, 900 MHz, 1.8 GHz, 2.1 GHz, 2.6 GHz) plus new ones at 3.5 GHz and 26 GHz. Lower bands travel farther and penetrate obstacles better; higher ones support more data traffic.
4G/5G boosters are widely available online, but their use isn't entirely unregulated. You must get permission from your mobile operator(s). Operating without it is illegal, punishable by up to six months in prison and a €30,000 fine. A poorly configured unit can interfere with nearby frequencies, similar to a jammer—but operators detect this via relay antennas and alert ANFR.
ANFR handles around 150 interference cases yearly from unauthorized repeaters. As radio equipment, boosters must comply with EU Directive 2014/53/EU (RED) and carry CE marking. Use ANFR's Cartoradio.fr to map nearby antennas over 5 watts, including operators, locations, and orientations.
For tinkerers, DIY 4G amplifiers exist online (e.g., coffee can designs inspired by Popular Science videos for GSM/2G phones). Adapt for modern smartphones, but limit to brief, educational experiments only—legal risks remain.
Check your phone's signal strength: On Android, go to About Phone > Status > Network (dBm value; closer to 0 is better—e.g., -40 dBm excellent, -120 dBm poor). iPhone steps differ slightly.
Choose based on network type and frequencies (dual/tri/quad-band models available). Expect €150–200+ for quality units. For antennas: omnidirectional for urban areas (signals from multiple directions); directional for rural (aim at tower). Use short, straight coaxial cables to minimize signal loss.
Though regulated and costly, 4G/5G boosters excel in poor-coverage zones. Bonus: they let phones use less power (amplifiers max 10 mW vs. phones' 250 mW at 900 MHz), reducing exposure.
