Finite grounds can be defined by including a Strip layer instead of the infinite ground/slot layer(s). The size is important in terms of electrical length/width - if you have a finite ground that is 1 wavelength in both directions, you would have at least 20*20=400 cells to simulate plus edge mesh. Edge mesh can usually be ignored in finite grounds, though. So use finite grounds only if you are absolutely sure you need them. When you do use them, you typically need to define the signal ports as Internal ports and associate Ground Reference ports with them that are placed on the finite ground layer.

Any idea on how to define the size of ground plane? It seems like ADS use infinite ground plane..how about the layers and so forth? TQ!!!

Thanks again...my doubt is almost cleared. TQ!