I'm looking at a picture of an RF PCB meant to operate at a few GHz, and I'm having trouble understanding exactly what this is:
Obviously there are some transmission lines, and something that looks like a couple of radial stubs.
What are the little silver bits along the transmission lines, and in an arc around the radial stubs? Are they vias, plated slots, or just bits of isolated copper? (At least some of it is not round.) What function do they serve?
Also, what type of transmission line is this: microstrip, coplanar waveguide or SIW?
Note: It may be a bit hard to tell but most of the picture doesn't have copper on the top layer; the very bottom is a solid copper fill with soldermask, but the darker blue is apparently just substrate, and the silver parts are copper plated with something. Sorry, I don't have a better picture, and I've never seen anything like this.
EDIT After @Dan Mills explained that this is chicken dots, I realize I have seen these before - there are usually a lot fewer and bigger of them, for example:
These look really useful for hand tuning. Yay new thing learned :)