Field Strength Calculation for an RF Emitter at Varying Distances

AI Thread Summary
The RF emitter produces a field strength of 25 µV/m at 300 meters, which scales to approximately 2.5 mV/m at 3 meters, assuming an inverse square law. The frequency of 900 MHz does not significantly affect this scaling until very close to the antenna. The environment, whether over ground or in free space, also influences the field strength, particularly regarding antenna height. Accurate calculations require consideration of these factors. Understanding these principles is essential for effective RF field strength assessments.
dnyberg2
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If an RF emitter is allowed to produce a field of 25uV/m @ 300 meters distance, how big will the field be at 3 meters? I'm guessing it's a hundred times stronger (2.5mV/m?) but does the 900 MHz frequency of the carrier come into play?
 
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The scaling of the amplitude with distance doesn't depend on the frequency or antenna geometry until you get very close to the antenna.
 
mfb said:
The scaling of the amplitude with distance doesn't depend on the frequency or antenna geometry until you get very close to the antenna.
Also, is it over ground or in free space? If over ground we need to know the antenna heights.
 
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