HOW DO MOBILE PHONES WORK?

A mobile phone is essentially a two-way radio, like a CB set, transmitting and receiving wireless radio-frequency signals. However, while a CB set is what’s known as a “simplex” device (i e , two people can communicate at the same time but only one person can talk at a time), a mobile phone is described as a “duplex” device (i e , it uses one frequency for transmitting and another for receiving, enabling people on either end of the line to talk and listen simultaneously).

The radio signal from the phone is transmitted through the air to the antenna of the nearest base station, which contains equipment designed to emit radio transmissions and passes the signal to the network and then to its destination. Each base station covers an area of about ten square miles, known as a “cell,” which is why mobile phones are called cell or cellular phones.

Mobile phone signals can reach only limited distances, which is why an intricate network of cells is needed to connect people at greater distances and why mobile phones don’t work in remote areas that have no base stations. Each base station has a finite capacity to receive and transmit signals, and highly populated areas usually have a higher number of base stations to cope with the large number of users.

The reason why a mobile phone can be used while driving for many miles is because the signal moves from one base station to the next so that a number of base stations, and their cells, are utilized.

Mobile phones contain low-power transmitters and lowmass lithium-ion batteries that store a lot of power, two factors that enable them to be very small and light.