I have prepared the following PCB layout
I am a hobbyist and when I look at other - professional - boards, mine looks a little strange when considering the empty spaces to the right, and to a lesser extent to the bottom. But Eagle refuses to fill these spaces with GND conductor. I suppose there must be a setting in Eagle that controls fill polygon separation, but is it worth bothering at all?
I have learned (or at least I think I have) that in layouting for analog circuits, especially in the high frequency domain it is very important to have the ground area as close to the signal lines as possible in order to reduce capacitive coupling to environment noise. Preferably a separate dedicated ground plane.
But in my case it is just a pure digital circuit, and it's only up to 20 Mhz clock speed. The circuit works perfectly on my desk, but I have no idea as far as its EMC properties are concerned.
How would I go about the empty spaces? Should I try and separate the other lines until GND can fill the spaces, even if it means enlarging the board? Or should I leave them as they are?