Dezibelmilliwatt

Dezibelmilliwatt, abbreviated dBm, is a unit of power level used primarily in telecommunications and RF engineering. It expresses power relative to 1 milliwatt on a logarithmic scale: P(dBm) = 10 log10(P in milliwatts). By definition, 0 dBm corresponds to 1 milliwatt, while positive values indicate powers greater than 1 mW and negative values indicate powers below 1 mW.

The dBm scale is widely used to describe transmitter output, received signal strength, and link budgets because it can cover a large dynamic range with simple additive arithmetic when combining gains and losses. It is common in wireless networks, radio equipment, and audio–video systems. In practice, dBm values are tied to a reference impedance, typically 50 ohms in RF engineering, because power depends on voltage and impedance through P = V^2/R.

Relation to other units and conversions: dBW is a related unit that measures power relative to 1 watt, with P(dBW) = P(dBm) − 30. Thus 30 dBm equals 1 watt. To convert voltages to dBm, the impedance must be known: P = V^2/R, and then P is converted to dBm using the standard formula. Examples: 0 dBm = 1 mW, +10 dBm ≈ 10 mW, +30 dBm = 1 W, −10 dBm ≈ 0.1 mW (100 µW).

Overview: Dezibelmilliwatt is a practical, logarithmic unit that enables compact expression of widely varying RF power levels and is preferred for specifying and comparing signal strengths, transmitter powers, and noise floors in communication systems.