Attaching aerial to nRF52840 Dongle

[maddywoodburn]

Can I extend this aerial on this dongle?

[Kenneth]

Not sure what you mean here, but you can connect external hardware to the gpios if you like. You may find this useful in general:
https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial

I recommend to get an nRF52840-DK for development, since that can also be used to debug the code, it can program third party hardware, and I do believe all the nRF5 SDK examples support this DK out of the box.