nRF52840 range Testing

[pratikpanchal44]

Currently, we are testing the nRF52840 range evaluation using the nRF52840 EVK kit.

As of now, we are getting the only 120 to 125-meter range using 125kbps data rate @ 4dBM power in the outdoor activity.

What thing need to change is i need more than 200 meter range ?

[Einar Thorsrud]

Hi,

Are you testing with line of sight? Generally, I would expect you got significantly more than 125 meters outside with line of sight. If you do not have line of sight, then it all depends on the environment, and it is very dificult to predict.

You can also use higher transmitt power, since the nRF52840 support up to +8 dBm, but that should not be needed if we assume line of sight.

You may find this blog post interesting.

[pratikpanchal44]

Yes, We are testing with the line of sight. We have done this testing using the PCB antenna.

Can you provide us the max range achieved using the nRF52840 in line of sight?

We have referred below link for the line of sight calculation

https://www.bluetooth.com/bluetooth-technology/range/#estimator

We have set the below parameter.

Receiver sensitivirty  = -101dBM

Mode = 125 coded mode

Path loss= outdoor

Transmitter power = 4dBM

Transmitter antenna gain = 1dBi

Receiver antenna gain = 1dBi

After setting this parameter i am getting the range calculation appprox 134 to 185 meters.

Still, I am not getting the nearer/average to this number.

[Einar Thorsrud]

Hi,

Ah, I did not consider the PCB antenna. I suspect the problem here is with antenna gain. You have calculated with 1 dBi antenna gain. Where does that number come from? We have not measured the radiation pattern from the PCB antenna, so I do not know in which direction it is best, but it is definitely not an ideal isotropic antenna. By calculating 1 dBi gain you are saying that you are using a "good" direction on the antenna on both sides, but how do you know that?

In the typical use cases for BLE devices, they are used in complex RF environments, where it usually does not matter much, as there will typically be a lot of directions. But in LOS conditions where you want to maximize range, you do want to know which direction to point the antenna. In those cases, where we have tested LOS, we have used external directional antennas, as described here. It is, of course, possible to test the DK in an antenna lab to find it's radiation pattern, but we have not done that.