volts/meter

[alfacentauri]

Hi, i need, and i don't know if it's possible, to convert a dbm indication sourcing from a tv field meter into volts/meter for elettrosmog control, can someone help me? thanks

[MarcoMar · Accepted solution]

Hi!!

dbm is and adimensional unit used in power measurements --> 1dbm = 10 log [Power (mW)/1 (mW)]

while

volt/m is a dimensional unit used in electric field measurements.

In order to relate them, you need to know the Characteristic Impedance of the propagation medium and the extension of the surface.

Pretending to be working in the vacuum at a typical distance r = 1m from the source, you get:

Zc = 377 ohm

S = 4/3 pi r^2 = 1,04m^3

so, you can calculate the absolute power:

P(watt) = 1/1000*10^[dBm/10]

and the corrispondent power density:

P/m^2 = P(watt)/S = P(watt)/1,04

that is equal to:

P/m^2 = V/m A/m

You know that:

A/m = V/m 1/Zc

so:

P/m^2 = (V/m) ^2 *1/Zc

and you have:

Volt/meter =    [(P/m^2)*Zc)] ^ (1/2)

Have a great day!

[alfacentauri]

Good. Thanks for the exhaustive answer. i enclose a writed kudos (i dont'now how to send it). hi.