field strength calculation

I know the input powe(dbm)r to antenna and the antenna gain.
How can I calculate the EM field strength in dbuV at a distance to the antenna.
Please help me.
Thanks

Look at this site for the dBm->dBuV conversion.
But you must translate to the antennas/air
impedance and use the 1/(r)^2 rule to find dBuV/m.

://w\/\/w.radioing.com/hamradio/rfcalc.html

Hope this helps.

in a general case you should know if yhe target is placed in far field, near field or in the "very" near field (induction rather radiated).
For the target in near or far field illuminated by the main lobe (boresight direction) the gain of the transmit antenna is NOT important.
The 1st approssimation is to ommit the sida lobes, so consider that all the power is radiated in the main lobe.
then consider the target received power density (D)(W/m^2), and then by applyin the Ohm law calculate the field streght E=(D*377)^.5, then convert in dBuV.
But pay attention: math. formulas are not exaustive!
The radiated power call for a "direction" of the radiation. Field strenght is an "on air" quantity regarless the direction, in fact the E measurement instruments are shperic!

an accreditate link for E field calculation is the following:
http://www.andrew.com/products/anten...S/default.aspx

Here is the answer:

http://www.maxim-ic.com/appnotes.cfm/appnote_number/808

In a 75 ohms system to convert dBmV to dBm you have to add 48.7506.
In a 50 ohms system to convert dBmV in dBm you have to add 46.9697.
You have to calculate first the field strength in dBm and convert to dBmV

regards

a free software of Andrew can help you .or dBm is Power dBuV is the Voltage since Power= V*V/R dBm =10logPower,dBuV=20logVoltage.so you can calculate yourself simply.

Why not to open the maxim-ic website?