signal quality & stength variations

[rodernr]

I am using a D-link 900AP+ in a 2 story home. It's performance is quite unpredictable. At times I can have great signal quailty and strength and at other tiimes I loose the signal al together. This would not seem so strange except that these changes are when I am stationary so the area is is not changing.

Any thoughts?

Also is there any utility that can be used that can determine the best placement for the AP?

Thanks,