The through-holes in the main tracks are "interesting": ventilation? RF emissions suppression? RF susceptibility suppression??, or "what"????
The through holes go to more circuit traces under the PCB,(copper plated) on the ground side it gives you more overall ground plane to work with, on the signal side it gives you more to play with as far as tuning the circuit for pass and reject filtering, also tweaking the SWR on some of the high end RF signals to/from the mixer stages, some you see are just copper traces that look like they would do nothing, (see photo #7) these act like filter components to knock down spurs and harmonics in the LO and IF signals.
Prototyping a board like this was a headache, at some stage it looked like a bunch of chopped up copper foil, haphazerdly placed here and there, but after a bit of work it gets the job done, trying to get it into production took a bit.