50 Watt Termination DC-8.4 GHz | 50T-713

Fixed Attenuators: Which dB value to select?

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Fixed attenuators are used to decrease the power level of a RF signal.  You can use the linked selection chart to look up your dB value or calculate the dB value.  You only need to know your input power and desired output power level.

Selection Chart:

The selection chart lists output power levels for standard dB values.

Calculation:

The dB value can be calculated using the ratio of input power to desired output power:

dB = 10 x log(output power/input power)

21% reduction in power:  10 x log(79W/100W) = -1.02 dB
37% reduction in power:  10 x log(63W/100W) = -2.01 dB
50% reduction in power:  10 x log(50W/100W) = -3.01 dB
75% reduction in power:  10 x log(25W/100W) = -6.02 dB
90% reduction in power:  10 x log(10W/100W) = -10 dB
99% reduction in power:  10 x log(1W/100W) = -20 dB
99.9% reduction in power:  10 x log(0.1W/100W) = -30 dB
99.99% reduction in power:  10 x log(0.01W/100W) = -40 dB