where can I find the antenna

[LeonardoRoy]

Hi , I am leo . from China .

Where can I buy an antenna???  

  

[Øyvind]

Hello, 

Connector J1 is for conducting measurements of the RF signal using a spectrum analyzer. See RF measurements chapter in nRF52840 DK User Guide. The nRF52840 DK has a built-in PCB antenna

Kind regards,
Øyvind

[LeonardoRoy]

HI,yvind, nice to see you .  as I shown in lower picture red circle , Isn't it a signal interface? Isn't it used to amplify the Bluetooth signal?

[Øyvind]

Yes, the connector, marked in the image with a red circle, is J1. It is used for conducting measurements of the RF signal using a spectrum analyzer. No amplification is done on BLE signal with the J1 connector, this is handled by the radio in the device.