A cellular phone amplifier, also known as a signal booster, signal extender, or cell phone repeater, is a device that increases the signal strength of cellular phone signals. It does this by picking up the existing signal from a cell tower, amplifying it, and then rebroadcasting it into a desired area.

There are two main solutions for using mobile signal repeaters to cover tunnels :  Fiber optic repeaters : these repeaters use fiber optic cables to transimit the signal from the cell phone tower to the tunnel .fiber optical cables are less susceptitle to signal attenuation than copper cables,making them ideal for use in tunnels .  DAS(distributed antenna system ):this is a more complex solution that involves installing a series of antennas and amplifiers throughout the tunnel . DAS systems can provide better coverage than fiber optic repeaters .but they are also more expensive to install and maintain

Sometimes, our mobile phone has poor signal reception in our house, the reasons are as below: Distance from the nearest cell tower. The farther away you are from a cell tower, the weaker the signal will be. If you live in a rural area or in a valley, you may be further away from cell towers, which can cause poor reception. Building materials. Some building materials, such as concrete, brick, and metal, can block cell signals. If your home is made of these materials, it can make it difficult to get a good signal.

The type of cell phone signal you need: There are signal boosters for 3G, 4G, and 5G cell phone signals. Make sure to choose a booster that supports the type of signal you need.

here are some factors to consider when selecting a suitable antenna for a cell phone signal booster : The type of cell phone signal booster you have .  The size of the area you need to cover . The location of the cell phone signal booster.  The budget .

Increase in penetration of 5G networks. 5G networks offer much faster speeds than 4G networks, which will require repeaters to be able to amplify these signals.