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

• coltonk
In summary, if you want to measure the efficiency of your antenna you need to convert mV/m or nW/m2 into watts.
coltonk
TL;DR Summary
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.

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

Last edited:
Klystron
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.

berkeman said:
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

View attachment 300616
That's what I have..

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.

berkeman and DaveE

## 1. How do you convert mV/m to Watts?

To convert mV/m (millivolts per meter) to Watts, you need to know the impedance of the medium through which the radio power is being transmitted. The formula for this conversion is: Power (Watts) = (Voltage (mV/m))^2 / (Impedance (Ohms)).

## 2. How do you convert nW/m2 to Watts?

To convert nW/m2 (nanowatts per square meter) to Watts, you need to know the area over which the power is being measured. The formula for this conversion is: Power (Watts) = (Power density (nW/m2)) * (Area (m2)).

## 3. What is the difference between mV/m and nW/m2?

mV/m and nW/m2 are two different units of measurement for radio power. mV/m measures the electric field strength, while nW/m2 measures the power density. They are related by the impedance of the medium, as shown in the conversion formulas.

## 4. Why is it important to convert mV/m or nW/m2 to Watts?

Converting mV/m or nW/m2 to Watts allows us to measure the actual power being transmitted by a radio signal. This is important for understanding the strength and potential effects of the signal on living organisms and electronic devices. It also allows for accurate comparison and analysis of different radio signals.

## 5. Are there any online tools or calculators available for converting mV/m or nW/m2 to Watts?

Yes, there are several online tools and calculators available for converting mV/m or nW/m2 to Watts. Some examples include the RF Calculator by Pasternack and the RF Power Conversion Calculator by Everything RF. These tools can make the conversion process faster and easier for scientists and researchers.

• Electrical Engineering
Replies
16
Views
2K
• Electrical Engineering
Replies
6
Views
1K
• Electrical Engineering
Replies
7
Views
2K
• Electrical Engineering
Replies
12
Views
1K
• Electrical Engineering
Replies
27
Views
5K
• Electrical Engineering
Replies
61
Views
7K
• Electrical Engineering
Replies
2
Views
1K
• Electrical Engineering
Replies
9
Views
3K
• Electrical Engineering
Replies
19
Views
2K
• Electrical Engineering
Replies
7
Views
2K