Lisa,
Rather than giving you one formula I will give you an algorithm (easier
for me to remember).Assuming that the Walkie Talkie is really radiating
5 watts and we have an isotropic antenna:
1) Chose a distance. Let's say the distance is 1 meter. This is
far-field at 430 MHz.
2) The area of the 1 meter radius sphere is 4(PI)(r^2) = 12.6 square
meters.
3) 5 watts covers the 12.6 sq meters. The power density per square meter
is 5/12.6 = 0.4 watts/sq m.
4) Using P = (V^2)/R, solve for V which is V = (PR)^0.5. R is 377 ohms
and P is 0.4 watts.
5) V = 12 volts/meter at 1 meter distance from the Walkie Talkie
Assuming a dipole pattern the antenna gain is 2.1 dB and the E-field
will be 15V/m at 1 meter.
Dave Cuthbert
Micron Technology
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Thursday, January 13, 2005 7:31 AM
To: [email protected]
Subject: Question on RF conversion
Good morning all,
Quick question, maybe..
If I have a Walkie Talkie that emits 5W at 430MHz, how does this
translate
to V/m so that I can correlate
the field strength with radiated immunity testing?
Thank for any input
Regards,
Lisa
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