A Brief Analysis of the Application of Antenna Feed Lightning Protection Devices in Practical Life

1. Core role

• Lightning protection and overvoltage protection
  Antenna feeders are usually exposed outdoors (such as antennas) and are susceptible to direct or induced lightning strikes. High voltage pulses generated by lightning may enter equipment along the feeder, damaging core components such as transceivers and amplifiers. Lightning protection devices limit overvoltage within a safe range by quickly releasing lightning current.

• Suppress surges and electromagnetic interference
  In addition to lightning, power grid fluctuations, electrostatic discharge, and other factors may also cause surges on feeders. Lightning arresters can absorb these transient overvoltages and reduce interference with sensitive electronic components.

• Ensure signal transmission stability
  High quality lightning arresters need to have low insertion loss and high frequency response characteristics, while not affecting the normal signal transmission of the antenna system (such as high-frequency signals for 5G and microwave communication) during lightning protection.

2. Working principle

• Gas discharge tube/varistorUsed for amplifying current, with fast response speed (nanosecond level), to guide lightning current into the ground.

• high-pass filterPartial lightning arresters integrate filtering circuits to block low-frequency interference while releasing surges, while retaining high-frequency signals.

• impedance matchingEnsure that the lightning arrester is connected without affecting the impedance characteristics of the antenna feeder (such as 50 Ω or 75 Ω systems), and avoid signal reflection.

3. Typical application scenarios

• Mobile communication base stationThe feeder between the tower antenna and the base station equipment needs to be equipped with lightning protection devices to prevent lightning strikes from damaging the RRU (RF unit) or BBU (baseband unit).

• Broadcasting and Television SystemSatellite antenna and transmission tower feeder protection.

• Military and AviationThe lightning protection requirements for radar and navigation systems are demanding and must meet high reliability standards.

• Photovoltaic/Wi Fi and other civilian fieldsThe antenna of the photovoltaic inverter and outdoor wireless AP may also be equipped with lightning protection devices.

4. Selection and installation points

• Flow capacityAccording to the lightning risk selection (such as 20kA, 40kA, etc.), it must comply with IEC 61643 or GB/T 18802 standards.

• frequency rangeTo cover the working frequency band of the overhead line (such as the 800MHz~6GHz 5G system).

• insertion lossGenerally, it is required to be less than 0.5dB to avoid signal attenuation.

• Grounding requirementsThe lightning arrester must be reliably grounded (grounding resistance<4 Ω), otherwise the protection effect will be greatly reduced.

• Installation locationUsually located near the input end of the device and coordinated with the lightning protection system of the main device to form multi-level protection.

5. Precautions in practical applications

• regular testingLightning arresters may age due to multiple lightning strikes and require regular performance checks (such as indicator light status or professional testing).

• Distinguish from isolatorsLightning arresters focus on overvoltage protection, while isolators are used to block DC or low-frequency interference. The two functions are different but complementary.

• environmental adaptabilityOutdoor lightning arresters must have waterproof and corrosion-resistant design (IP65 or above).

summary

The lightning protection device for the antenna feeder is a key link in the "last mile" of communication system lightning protection engineering. Through rapid leakage and voltage clamping, it effectively protects expensive high-frequency equipment while ensuring signal transmission quality. In practical applications, it is necessary to comprehensively select based on system parameters, lightning protection level, and environmental factors, and pay attention to installation standards and maintenance.