4 The Need for Lightning Protection

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4

The Need for Lightning Protection

The LNB is remotely powered from the satellite receiver. The same coaxial cable that carries

the IF signal from the LNB to the receiver carries power from the receiver to the LNB. The 13V

to 18V DC is generated by a dedicated IC, a LNB Voltage Regulator.

This device can be damaged by any lightning strike on the coaxial cable or the antenna that can

generate high current - high voltage surge at the voltage regulator.

This surge can be simulated according to the IEC61000-4-5 standard:

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R = 12

Ω

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Figure 5.

IEC61000-4-5 current waveform

In case of lightning events, the current surge at the LNB voltage regulator (IC) inputs ranges

from 250 A (when 3 kV is applied) to 500 A (when 6 kV is applied). This IC can not withstand

such high value energy.

To comply with this IEC regulation and to protect the LNB Voltage Regulator IC against any

damage from lightning events, a dedicated and optimized protection device is required in front

of the voltage regulator.

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8 µs

20 µs

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8 µs

20 µs

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