PCB antenna and J1 connector

[Ceow]

Hi all,

I'm trying to measure the transmit power of nRF51 development kit with a spectrum analyzer and I am facing the following issue:

It is specified in the user guide of nRF51 that "When connecting the test probe, the internal switch in the SWF connector will disconnect the PCB antenna". However, in my case, I can still connect to the nRF51 with my phone, while an SWF connector is plugged in the board. I suppose that the trace antenna is still connected. My connection setup is like in this answer.

I was assuming that any SWF connector should work but is the one from Murata specified in the user guide the only one able to achieve this ? If not, do you have any more guidance ?

Thanks in advance

[AmbystomaLabs]

I will assume you are using the correct mating connector. For reference this is the correct one: www.murata.com/.../o33e.ashx

There are a lot of knock-offs of these connectors, so it is entirely possible you have one that isn't from MuRata, but likely works fine.

None of these connectors will fully isolate the nRF from its local environment. All the microstrips, components, the SWF, and even the nRF itself will radiate some RF and allow your phone to connect locally.

What you will see is that the signal strength and thus range will be severely diminished.
However, when nearby even an nRF with no RF connection will still connect just from the signal that radiates from the chip.

[Ceow]

Thank you AmbystomaLabs