nRF52840-CKAA-R(WLCSP-94) Frequency generate internally or externally

Well, if you don't need to use the radio, you don't need the antenna. Else, you will indeed need the antenna. 

I suggest you look for a module, that will make it easier for you to get started: https://www.nordicsemi.com/Nordic-Partners/3rd-party-modules

Could you please share the on board antenna trace width size, its length and corner dimensions?

Thank you. 

If you make it ~23 mm long, 2-3 mm wide and a distance to the ground plane of more than 10 mm, you should be fine. You need to trim the length for max range in your product as it will vary a bit with the size of the ground plane. Meaning that can't just copy the DK antenna 1:1, but it's a good start.

If you make it ~23 mm long, 2-3 mm wide and a distance to the ground plane of more than 10 mm, you should be fine. You need to trim the length for max range in your product as it will vary a bit with the size of the ground plane. Meaning that can't just copy the DK antenna 1:1, but it's a good start.