nRF52840 external antenna

[Joel V]

Hi,

I wanted to replies to Mister Martin Sivertsen from this post https://devzone.nordicsemi.com/f/nordic-q-a/81235/nrf52840-dongle-external-antenna

I accidently locked the discussion so I am making this post to continue :

To answer your questions:

" Have you added a PA and an LNA to the nRF24L01 and would like to do the same on the nRF52840?

How did you attach the PA and LNA to the nRF24L01?

What antenna are you using?

How are you attaching it, do you have pictures? "

I am using nRF24L01 et PA and LNA already designed and this is 2 picture of the PCB with and without the antenna:

I want to reproduce the ranges of this PCB but with my nRF52840. I was wondering if you could give me the Pi-network for an antenna of this size (105 mm) with frequency of about 2.4 GHz - 2.5 GHz so I could try to have more range that would help me very much. Further more I was wondering if you had some gerber file of PA and LNA for such antenna to add it to my board with the nRF52840. Meanwhile, I checked your white paper which was very helpful in the understanding of tuning antenna. Unfortunatly, I don't have a VNA to make the analysis of my antenna and tuning it perfectly. 

I thank you for your time, much appreciated.

Joel V.

[Martin Sivertsen]

Hello Joël,

I was wondering if you could give me the Pi-network for an antenna of this size (105 mm) with frequency of about 2.4 GHz - 2.5 GHz so I could try to have more range that would help me very much.

The values of the components in a PI- shaped tuning network need to be determined by doing measurements on the finished board itself, as the size and shape of the ground plane, vicinity to other components or materials can affect the antenna performance.

As I said in my last post: You won't get a lot more range with a different antenna (especially if the original antenna is tuned correctly).

Further more I was wondering if you had some gerber file of PA and LNA for such antenna to add it to my board with the nRF52840.

We have the nRF21540 range extender, but the design is quite new so we don't have any PCB layout publicly available just yet. 
There are also other good range extenders out there, but the bottom line is that you'll have to design a custom board with an nRF52840 and range extender, you can't connect a range extender or different antenna to the nRF52840 dongle as it is. 

Best regards,

Martin S.

[Joel V]

Martin Sivertsen said:

There are also other good range extenders out there, but the bottom line is that you'll have to design a custom board with an nRF52840 and range extender, you can't connect a range extender or different antenna to the nRF52840 dongle as it is. 

I am doing a custom board. The problem is that the nRF52840s are backorder right now at our distributor and so I am trying to make our custom board by soldering the dongle on it. That way, the signal became very poor (probably due to the custom board causing interference on the signal). That's why I wanted to add an extender to the dongle. That'S also why I wanted to bypass the antenna of the dongle with another set of antenna that would be already tuned. I will try something with the nRF21540.

[Martin Sivertsen]

Hi,

Trying to connect the RF signal on the nRF52840 dongle to a different board or antenna sounds like a real challenge, and I have a hard time believing you can accomplish it without significant loss to the signal.

Also, if soldering the dongle down on another board, make sure that the part on the dongle with the antenna hangs outside of the board below it, because it is designed to not have any metal under it.

Regarding nRF52840 being on backorder, we also have nRF52833 and nRF52820 which have the same radio as the nRF52840 , but a reduced feature set, you can see if you can fins any of those two if they fit your project.

Best regards,

Martin S.