The basement is underground. Cell phone signals travel through the air, so they are blocked by underground structures. This is why you often have better cell reception on the ground floor of a building than in the basement.
The basement is made of dense materials. Basements are often made of concrete, which is a dense material that blocks cell signals. This is why you might have better cell reception in a room with more drywall or other materials that are less dense.
There are other obstructions in the basement. Other objects in the basement, such as furniture, appliances, and metal objects, can also block cell signals.
If you have a weak cell signal in your basement, there are a few things you can do to improve it.
Move closer to a window or door. This will put you closer to the signal from the cell tower.
Get a cell signal booster. This is the most effective way to boost your cell signal, but it can be expensive. A cell signal booster will amplify the existing cell signal from outside your home, so you'll need to have some signal to start with.
Remove your phone case. Some phone cases can interfere with cell signal. If you're not using a case, try removing it to see if it improves your signal.
Here are some things to keep in mind when choosing a signal booster:
The size of your home. You'll need a different size booster for a small home than you would for a large home.
The number of carriers you use. If you use multiple carriers, you'll need a booster that supports all of them.
The type of signal you need. Some boosters only amplify 4G or LTE signals, while others amplify all types of signals.
Once you've chosen a signal booster, you'll need to install it properly. The installation process will vary depending on the type of booster you choose. However, most boosters require you to mount an outdoor antenna on your roof or in your yard. The outdoor antenna will receive the cell signal from the cell tower and amplify it. The amplified signal will then be transmitted to an indoor antenna, which will distribute the signal throughout your home.