Microwaves and Mobile Phones
Phone calls from mobiles travel as microwaves from the mobile to the nearest transmitter/mast.
The transmitters receive and send signals from one another, and then these get sent back to your phone.
Microwaves have short wavelengths. Therefore, little diffraction occurs.
Microwaves affected by Earth's curvature, and blocked by hills and large obstacles.
If near obstacle, you'll receive a bad signal or no signal.
Microwave frequencies partially absorbed by water. In storms or near lakes, signal loss can occur.
Interference also affects signal strength.