Radio Power Conversion: Convert mV/m or nW/m2 to Watts

[coltonk]

TL;DR

Converting units of transmitted power

I have searched the internet and spoken to the manufacturer of my equipment and can not find an answer. I am using RFExplorer (test equipment) to measure the power generated by my ham radio antenna. The only options for displayed power is mV/m or nW/m2. I am trying to find out how to convert these into transmitted watts so I can see how efficient my antenna is radiating and my radio output is watts.

 

[berkeman]

Can you just borrow an SWR meter instead? BTW, mV/m is the E-field strength.

https://www.wimo.com/en/cn-901hp-swr-meter

Is this your meter/spectrum analyzer?

 

[DaveE]

nW/m² is the best your meter can do with power measurements. It is the power measurement at the measurement location, a surface measured in m². The problem is your meter doesn't know about how the antenna radiates in the other directions. With everything else being equal a more directive antenna will give you a higher reading on the beam axis, and lower readings off of the beam axis.

So, if you could measure in every direction, you could add up the total power. Really, you're integrating the measurements over a closed surface around the antenna. Alternatively, if you know the radiation pattern of your antenna, maybe you could use the meter to calibrate a theoretical summation over all directions.

 

[coltonk]

Can you just borrow an SWR meter instead? BTW, mV/m is the E-field strength.

View attachment 300618
https://www.wimo.com/en/cn-901hp-swr-meter

Is this your meter/spectrum analyzer?

View attachment 300616

That's what I have..

 

[Baluncore]

Is computation of absolute efficiency important?
Why not set up a test range with a far field meter, say beyond 60λ. Then you can make comparative measurements to improve the design relative to a simple dipole. If you have a rotator for your antenna under test you can also map the radiation pattern.