RF Toolkit ยท IEEE Std 100
Converter dB / dBm / mW / EIRP
Enter a value in any unit, the others update automatically. Instant bidirectional conversion.
Absolute Power
Antenna Gain dBi / dBd
Formula: dBi = dBd + 2.15
EIRP / ERP Calculation
EIRP
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dBm
EIRP equivalent
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W
ERP (dipole ref)
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dBm
Formulas
dBm = 10 x log10(mW) ยท mW = 10^(dBm/10)dBW = dBm - 30 ยท W = 10^(dBW/10)dBi = dBd + 2.15 ยท EIRP = Ptx + Gant(dBi) - LcableERP = EIRP - 2.15Frequently Asked Questions
What is the difference between dB and dBm?
dB (decibel) is a ratio unit with no physical unit: 10 dB means a ratio of 10 between two powers. dBm (decibel-milliwatt) is an absolute power unit, referenced to 1 mW. 0 dBm = 1 mW. dBm is used for absolute levels, dB for differences or gains.
How do you convert dBm to mW?
The formula is mW = 10^(dBm/10). Examples: 0 dBm = 1 mW, 10 dBm = 10 mW, 20 dBm = 100 mW, 23 dBm = 200 mW (LTE UE), 30 dBm = 1 W, 40 dBm = 10 W, 46 dBm = 40 W (typical eNB). Conversely, dBm = 10 x log10(mW).
What is EIRP and how do you calculate it?
EIRP (Effective Isotropic Radiated Power) is the power an isotropic antenna would need to radiate to produce the same power flux as the actual antenna in its maximum gain direction. EIRP (dBm) = Tx_power (dBm) + Antenna_gain (dBi) - Cable_loss (dB). Typical: 46 + 17 - 2 = 61 dBm for a macro LTE cell.
What is the difference between dBi and dBd?
dBi measures antenna gain relative to a theoretical isotropic antenna (perfect omnidirectional radiation). dBd measures gain relative to a half-wave dipole. The relationship is: dBi = dBd + 2.15. Examples: a dipole = 2.15 dBi = 0 dBd, a sector antenna 16 dBi = 13.85 dBd.
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