INSpiREzine Making Waves | Page 46

RADIO WAVES

Radio waves have the longest wavelengths in the EM spectrum, ranging from about 1 millimeter to more than 100 kilometers. They also have the lowest frequencies, from about 3,000 cycles per second, or 3,000 hertz (3 kHz) up to about 300 billion hertz (300 GHz).

Many objects, both natural and man-made, emit radio waves. Naturally occurring radio waves are made by lightning, stars, planets and other astronomical bodies. Artificially generated radio waves are used in a

large number of applications including, communication satellites, computer networks, ultrasonography, radios, television, cellphones, etc.

Depending where you are on the wave spectrum you can transmit different types of data. As a rule of thumb, a low frequency, high wavelength property - low bandwidth - is great for sending small amounts of data very far (maritime navigation, AM radio). A high frequency, low wavelength property -high bandwidth - can send lots of data much shorter distances (wi-fi, interspace satellite communication).

MICROWAVES

Microwaves are very often grouped together with radio waves, albeit overlapping at the far right of the radio wave spectrum. Microwaves have

wavelengths in the EM spectrum, ranging from 1 millimeter to 1 meter and equivalent frequencies ranging from 300 GHz to 300 MHz.

Common everyday applications of microwaves include garage door openers, keyless entry systems and of course, microwave ovens! A microwave oven works by passing microwave radiation through the food, usually at a frequencyof 2.45 GHz (a wavelength of 12.24 cm).

More advanced applications include medical cauterization, radar, and satellite communications. Microwaves are particularly good at penetrating haze, light rain and snow, clouds, and smoke, and are thus utilized in satellite weather forecasting.