Simulating X-band antenna in ADS Momentum, is it accurate to assume sheet metal?

Due to skin effect of 0.6 um, most of the current flows on the edge, so will it be a good idea to assume sheet metal to reduce simulation time drastically? I've simulated several single-patch antennas and I didn't see a big change but if I try to simulate full-sized antenna with thick metal, ADS creates over 100,000 elements and my computer literally doesn't have enough memory to handle.

Antenna simulation with sheet metal is accurate in Momentum. You are right with thick conductor simulation will be slow especially if you are taking thick conductor as 3D-distributed.