Solder mask on antenna

[Joe Wright]

The example nRF51-DK gerbers have solder mask on the PCB antenna. But for the nRF24L01+ EK gerbers, the PCB antenna has the solder mask removed partially, along the length of the antenna.

I've seen some conflicting things online as to what is best. Some saying having solder mask on will reduce the signal, some saying that leaving it off will mess up your calculations because the HASL finish gets applied. Looking at some cheap modules they seem to have avoided that but I don't think I can do that with the PCB prototyping service I use (you need to have a peelable protection layer over the antenna section?).

The other problem with a solder mask is does that make it too difficult to cut the antenna to tune it?

Thanks for any advice, Joe

[FormerMember]

The solder mask is made of a plastic material. When RF signals pass through plastic, they are typically hardly not damped. I cannot see any reason not to use solder mask, since solder mask is a good way to protect the antenna.

When tuning the antenna, it is not difficult to cut the antenna when there is solder mask on it. The "harder" part is the copper.

[Joe Wright]

Thanks, that's a relief.