Cellular Phones

Millions of people in the United States and around the world use cellular phones. They are such great gadgets -- with a cell phone, you can talk to anyone on the planet from just about anywhere!
These days, cell phones provide an incredible array of functions, and new ones are being added at a breakneck pace. Depending on the cell-phone model, you can:
Store contact information;
Make task or to-do lists;
Keep track of appointments and set reminders;
Use the built-in calculator for simple math;
Send or receive e-mail;
Get information from the Internet;
Play simple games;
Integrate other devices such as PDAs, MP3 players and GPS receivers.
But have you ever wondered how a cell phone works?
One of the most interesting things about a cell phone is that it is actually a radio -- an extremely sophisticated radio, but a radio nonetheless.…