What is a dbm in relation to radio frequency?

Answer 1

'dBm' is a unit used to describe power. It's very very common in measurements

of signal levels in radio transmitting and receiving equipment, mainly because it's

a unit that can describe such an enormous range of low- to high- powers without

awkward numbers. But there's no reason that any power level encountered in any

physical system can't be expressed in units of dBm .

Definition:

'dBm' doesn't describe an amount of power that you can hold in your hand.

It describes how any amount of power compares to 1 milliwatt (0.001 watt).

Any power level, in dBm = 10 x log ( the power level/0.001 watt )

1 milliwatt = Zero dBm

2 milliwatts = +3 dBm

1/2 milliwatt = -3 dBm

10 milliwatts = +10 dBm

100 milliwatts = +20 dBm

Examples:

-- 1 millionth of a millionth of a watt = 1 'picowatt' = 0.000 000 000 001 watt = -90 dBm

-- 1 whole watt = 1.0 watt = +30 dBm

-- 1 'kilowatt' = 1,000 watts = +60 dBm

-- Maximum capacity of Braidwood Nuclear Generating Station,

serving Chicago and northeastern Illinois . . . . .

2,360 MegaWatts = 2,360,000,000 watts = +123.7 dBm