EIRP (mW)-to-dBm

The Effective Isotropically Radiated Power calculator converts an EIRP, Effective Isotropically Radiated Power, measured in mw (milliwatt) to the unitless ratio of dBm (ratio of decibel to 1 milli-unit).

INSTRUCTIONS: Choose units and enter the following:

• (P_mW) Power in milliwatts.

The Math / Science

The ratio of the measured power to the reference value is defined as:

`N_dB = 10* log10( P_"(measured)"/ P_"(ref)")`

When the ratio of the measured value to the reference value were a thousand, we might us the notation that:

`N_"dBm" = k_"dBm" = 10*log_10(P_"mW"/(1"mW"))`

Effective Isotropically Radiated Power (EIRP) is a key concept in telecommunications and radio frequency (RF) engineering. It represents the total power that a theoretical isotropic antenna would emit in all directions if it radiated equally. It helps engineers compare the power output of a real antenna with a perfect isotropic antenna, which doesn't exist in practice but serves as a reference.

Key components of EIRP:

• Transmitter Power: The actual power the transmitter generates.
• Antenna Gain: The increase in power that the antenna achieves by focusing energy in a specific direction.
• Losses: This includes any losses due to cables, connectors, or other components in the system.

EIRP Formula:

EIRP=P_T×G

Where:

• P_T is the transmitter power (in watts or dBm),
• G is the antenna gain (relative to an isotropic antenna, often measured in dBi).

EIRP is typically expressed in decibels relative to one milliwatt (dBm) or watts (W).

Why is EIRP important?

• Regulatory compliance: Many countries regulate the maximum EIRP that wireless devices can transmit to limit interference with other systems.
• Coverage planning: EIRP helps determine the reach and strength of the signal in a given area, which is critical for designing communication systems like cell towers, Wi-Fi networks, and satellite links.

In summary, EIRP combines the actual transmitted power with the effect of antenna gain to give a meaningful measure of how strong the signal would be if radiated in all directions.

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