I have done some tinkering with the MM8108 HAT PCB files on Morse Micro’s website. I noticed something interesting in the design.
The ground layer seems unusual for this type of RF design. Could someone give some insight in to why the ground plane does not extend to the edges of the board or the RF lines?
As a reference the red is the top layer and the green and white is the ground layer. The green outlines are where the ground plane isn’t included.
Hey @codbu13
The trace negative on the internal ground plane (as marked #2 in your image) was done to allow a wider trace on the top layer while still achieving the impedance required. The wider trace was desired so that we are less susceptible to manufacturing tolerances which originally caused a wider variation in trace impedance. It also allows us to minimise the discontinuities caused by the 0603 component pads.
Your label #4 was done as we were following the recommended footprint provided by the SMA part.
