There's nothing on google at the moment (your post will arrive there in a few minutes, and then that's the first and only hit) for "signal 3G dbi". So it's unclear what you want to see.
Why not explain more clearly? Please tell what you want to see, why you want to see it and why you need an Android app to see it. A link to a definition and a few links to other ways to show it would be nice.