There are "special" smokescreens out there which can defeat thermal imaging & such things.
As for the antennas, I agree that HE rounds, cluster weapons and stuff like that have the best chance of eliminating them. It would be hard to do with a machinegun. But the optics too are hard to hit and the prisms are somewhat more durable than average glass.

But the wheels of tanks are designed to withstand amall arms fire so I wish equally good luck trying to shoot 'em off with an assault rifle.

However, one thing any tank rules should take into account is the limited visibility from a tank when it is buttoned. Even with the modern gadgets a buttoned tank has a hard time in dense terrain.