Calcolatore Perdita di Percorso in Spazio Libero
Calcola l'attenuazione del segnale RF in spazio libero in base a frequenza e distanza.
mW
Ω
Power (dBm)
20.00 dBm
Power (W)0.100000 W
RMS Voltage2,236.1 mV
Power (dBm) vs Power
Formula
## RF Power in dBm ### Formulas **dBm = 10 x log10(P_mW)** **V_rms = sqrt(P x Z)** dBm is decibels relative to 1 milliwatt. Common values: 0 dBm = 1 mW, 10 dBm = 10 mW, 20 dBm = 100 mW, 30 dBm = 1 W.
Esempio Risolto
100 mW transmitter into 50 ohm system.
- 01dBm = 10 x log10(100) = 20 dBm
- 02Power = 100 / 1000 = 0.1 W
- 03V_rms = sqrt(0.1 x 50) x 1000 = 2236 mV
Domande Frequenti
Why use dBm?
dBm simplifies gain/loss calculations to addition/subtraction. A +20 dBm signal through a 3 dB loss becomes +17 dBm.
dBm vs dBW?
dBm is referenced to 1 mW, dBW to 1 W. dBW = dBm - 30. Both are absolute power units.
What does negative dBm mean?
Power less than 1 mW. Wi-Fi receiver sensitivity is typically -70 to -90 dBm (picowatts).
Impara