This tool converts **Volt-per-Meter** to **dB-Microvolt-per-Mete**r.

Enter the linear field strength value and units using the drop down menu:

- V/m
- mV/m
- μV/m
- nV/m

the tool will calculate the equivalent value in dBµV/m

## Formula

**dBµV/m = 20*Log _{10}(V/m) + 120**

This converter is useful where linear field strength numbers are provided but have to be converted to logarithmic scale for other calculations.

**Background **

**Electric fields are measured in volts per meter (V/m).** A one Volt electrical potential at a distance one meter away will have an electric field of 1 V/m.

In general a deciBel value is used to represent a ratio of two quantities – typically power or amplitude. However when there’s a suffix like in this case dBµV/m, it represents an absolute value.

**dBµV/m** is used in electromagnetic field computations to specify the intensity a certain distance away from a transmitter.

The FCC puts limits on the field intensity. For example, over the range of frequencies in the table below, the FCC has stipulated that at a distance of 3 meters, the **carrier frequency** will not exceed 48 dBµV/m.

Additionally at the frequency ranges starting at 30 MHz and split into bands (e.g. 30 MHz – 88 MHz) there is a limit to the maximum field strength for out-of-band emissions.

RF designers have to keep these limits in mind when designing wireless hardware. Exceeding these limits will result in the product not being approved for commercial use.

**Where is this calculator used?**

Some instruments like the Electromagnetic Field Meter (EMF) shown in the picture below provide measurement results in V/m.

For example the screen reading in the picture is 205 V/m. Use the tool on this page to convert it to the equivalent value in dBµV/m.

**Note that instruments like the one above will not be suitable to determine whether a device passes FCC limits. **This is because they don’t have the front-end filtering for example, to determine the value over specific frequency limits. Instead it provides an integrated value over a range that has limited out-of-band rejection capability. The above measurement for instance states Wi-Fi and Phone. *Accurate, calibrated field strength measurement products cost many tens of thousands of dollars. *

**Example Calculation**

A value of 205 V/m is equivalent to 166.23 dBµV/m.

The table below shows specific values and the conversion using the calculator above

Value | dBμV/m |
---|---|

1 V/m | 120 |

1 mV/m | 60 |

1 μV/m | 0 |

1 nV/m | -60 |

**Related Calculators**

V/m to dBm – use this tool to convert field intensity to power in dBm at the input to a receiver. Both antenna gain and frequency of operation are required.

**References**

[1] Electric Field on Wikipedia