Q:

Why can't I place a portal shield on a portal?

I have a portal shield in my inventory, and on a portal I have placed 8 resonators.
How do I place the shield on the portal?
I have checked the upgrade menu and I can't see anything about the shield.

A:

In the upgrade menu, click one of the squares above the resonator wheel. You can now select a mod to apply to the portal.

