On Wed, 28 Dec 2005 21:38:46 GMT, Owen Duffy wrote:

On 28 Dec 2005 10:53:34 -0800, "Ron J" wrote:

Hey all,

I'm still skeptical about this formula:

Field Strength (uV/m) = 10 ^ ( (107 - |dBm| ) / 20 )

Is this valid? I saw this formula somewhere and jotted it down.

Your expression does not apply in general, it is the unstated
assumptions that are the issue (freq, receiver R, antenna factor.
bandwidth).

With an Antenna Factor of 0dB/m (eg 0dBi gain at 30.83... MHz), a rx
power of 0dBm/Hz in a matched receiver, would be the result of a field
strength of ~107dBuV/m/Hz. So, the lhs of your formulat is in units of
dBuV/m, and assumes AF=0dB/m and 1Hz bandwidth. AF depends on antenna
gain and frequency, and antenna / receiver R.

Owen


The calculator at http://www.vk1od.net/sc/FS2RPCalc.htm my be of
interest.

Owen


Thanks!
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