If I'm reading the current minimap UI right, that rectangle around the center of the minimap is your sensor range. Assuming this is correct, why not make it more obvious with an effect going off when active sensor burst (ACB) is used? While ACB is active, have the minimap rectangle expand outward, as your range is increasing. It doesn't matter if it goes beyond the minimap's borders. It's just a small effective that can be useful for recognizing what the rectangle is.
And maybe it'll make it not take 3 years for someone like me to recognize what it's for.