Issue with emonPi Antenna

Hi Guys,

I recently face the following issue with an RSSI readings on a new set of emonPi.

The graph shows the RSSI reading from emonPIs configured to the 2 same emonTHs.

The older emonPi is on the left while the newer emonPi is on the right
Initially the older emonPi displayed RSSI reading between -50 to -55 dBm and the newer emonPi had -72 to -85 dBM

I then swapped the antennas between the emonPis and the RSSI readings on the older emonPi with the newer antenna became worst (-67 to -85 dBm) and the newer emonPi with the older antenna showed better RSI readings(-57 to -50 dBm)

Please note the batteries in the emonTH are new. The 2 emonPi are in the same location and equidistant from the 2 emonTH which are siting side by side. The antennas are also similar in dimentions.

Can you please advise what we can do ? Can we get a replacement or something?

If the two antennas were put in exactly the same place when they were swapped, then it certainly looks as if one is not performing as it should.

What is the distance between the emonTH and the emonPi, and is it a clear line of sight?

I think you probably need to email The Shop ( [email protected] ) and mention this topic.

Hi Robert,
The distance is exactly 8meters and as you can see from this picture.

Tested by placing the sensors on the floor and also on a chair


Also I have one more question, I also found an old antenna that my predecessor had purchased for a much older emonPI/emonTX set but which is currently not working.

I noticed it had a much larger antenna. They seem to give much better/lower RSSI readings
Are those antenna still available for purchase?

Any help or advice would be very much appreciated.


Hi Santheep,

Thanks for your post, this is very interesting. We’ve not made any changes to the antennas we use on the emonPi for a long time. I can see from your photos that the two antennas as the same, it’s very strange that one is performing better than the other. This is the antenna we use:

The only thing I can suggest is that the new antenna could be faulty in some way? Seems unlikely, but we would be happy to send you another antenna to test with?

Could this be relevant?

I’ve no idea whether that one is the same antenna as this, but it’s worth considering.

Thanks, these two issues sound related.