**Introduction**

The calculator converts from radiated power (EIRP) at the output of the transmitter in **dBm **to the electric field strength* **dBµV/m** (deciBels micro-volt per meter).

**Electric Field Strength and Electric Field Intensity refer to the same thing*

Typically this measurement is made at 3 meters for the purposes of FCC testing. However you can specify any distance in the calculator.

**Calculator**

**Example Application**

Use this calculator to determine if you will pass the FCC limit test by making a measurement of the transmit power (EIRP) at the RF IN/OUT port of your device.

Let’s say for example you want to certify your receiver product. Here are the steps you would use to find the field strength:

- Connect the RF input port to a spectrum analyzer and make a measurement at a desired frequency.
- Measure the signal power at this frequency (in dBm).
- Next use this calculator to find the EIRP (in dBm) taking the antenna gain into consideration.
- Use the EIRP in the calculator on this page and it will give the Field strength in dBuV/m at any specified distance

**Example Calculations**

For an EIRP of -10 dBm, the field strength at 3 meters is calculated to be 85.2 dBuV/m.

The dBuV/m to dBm tool provides the reverse calculation. For example if the FCC limit is specified to be **55 dBuV/m at a 3m distance**, then the maximum EIRP is not to exceed **-40.2 dBm**.

Note that there is a frequency dependence to this limit (i.e. the field intensity limit will vary with frequency) so the EIRP should be taken account based on this.