I have looked online a bit and it seems to me that the general belief is that the larger the ground plane (up to a certain extent), the better.
I am trying to design a patch antenna, so I ran several full-wave simulations and increased the ground plane size each iteration, extracting the gain. I observed that as I increase the ground plane size, the gain increases at first and then decreases. Additionally, I've read a paper which claimed that the gain of the antenna changes periodically with the ground plane size.
Does anyone with experience relating ground plane size to antenna gain know of any useful resources?
Best Answer
I am no RF expert, but I do know as you change the ground plane size you change the field distributions at the edge of the antenna.
Thus, if you keep your feed point in the same spot the impedance will have changed due to the field distribution change. Because the impedance changes, the antenna will no longer be in the sweet spot (the 50 \$\Omega\$ spot), meaning that it will suffer impedance mismatch loss.
Therefore, as you increase the size of your ground plane, you need to redetermine where to feed the signal so as to minimize impedance mismatch loss.