What Challenges Do Bi-Directional Amplifiers Face in Concrete or Metal Structures?

Have you ever been inside a large building and noticed that your cell phone signal suddenly weakens or disappears? Now, imagine emergency responders facing the same issue while trying to communicate during a crisis. That's where a bi-directional amplifier (BDA) comes in. It helps boost signals to ensure strong emergency responder radio coverage (ERRC) in buildings. However, BDAs face unique challenges when installed in concrete or metal structures. Let's explore why.