1. Why are they so important?
Radio Waves
Why are they so important?

2. What is a Radio Wave?
Radio is the transmission of signals through the air in the form of electromagnetic waves (EM).
The visible light we see is only a small fraction of the total EM spectrum
Radio waves can be as short as 1 mm or many kilometers long!

3. Wavelength
A wavelength is the linear measurement of a wave (in meters) from crest to crest or trough to trough
A wave cycle is the period that a wave vibrates between its crest and trough.
Amplitude is the height of a wave
Frequency is the number of complete wavelengths that pass a given point in a second and is measured in Hertz (Hz).

4. Frequency Frequency is measured in Hertz (Hz). Common Frequency Units
Hz = hertz = 1 cycle/second
KHz = kilohertz = thousand (1,000) cycles/second
MHz = megahertz = million (1,000,000) cycles/second
GHz = gigahertz = a thousand million (1,000,000,000) cycles/second

5. Wavelength
When the waves are transmitted they bounce off the ionosphere and find their way to a receiver.
Low frequency radio waves do not travel very far through the atmosphere and are absorbed rather quickly. The high frequency waves pass through the ionosphere and escape into space while the low frequency waves reflect off the ionosphere and essentially "skip" around the earth.

6. Polarization of Radio WavesB E
Transmitting
antenna
A "vertically polarized" electromagnetic wave of wavelength has its electric field vector E (orange) oscillating in the vertical direction. The magnetic field B (white) is always at right angles to it, and both are perpendicular to the direction of propagation (the way the wave travels).

7. Reception of Radio WavesB E
Receiving antenna works best when ‘tuned’ to the wavelength of the signal, and has proper polarization
Electrons in antenna are “jiggled”
by passage of electromagnetic wave
electric field vector E (orange) and magnetic field B (white)

8. The Radio Band
The Radio spectrum has many sub-bands, grouped by frequency.
Frequency is the number of complete wavelengths that pass a given point in a second and is measured in Hertz (Hz).
BAND
FREQUENCIES
EXAMPLE
LF (Low)
kHz
Short-wave radio
HF (High)
MHz
AM radio
VHF (Very High)
MHz
FM radio
UHF (Ultra High)
300 MHz GHz
Government use

9. Analog vs. Digital Waves
Analog waves are smooth and continuous (sometimes called a sine wave)
Digital waves are square, and segmented having two distinct values – on and off
Analog wave
Digital wave

10. How do we use radio waves?
Cell phones
Wireless LANs
Keyless entry
AM & FM radio
Garage-door openers
GPS
Dog collars
Microwave ovens
Police radar
Radar detectors
Doppler radar
Infrared remote controllers
Satellite radio, tracking & communications

11. Infrared
Infrared waves can send small packs of data via invisible waves. Infrared signals require a line of sight between the receiver and broadcaster in order to function properly.
This form of radio wave communication is cheap to produce, but unreliable. As a result it’s use is mainly in television-remote communication and other transmissions of small data packets.

12. WiFi
Wireless networks use a system similar to Radio and Mobile networks. It requires a base station with an antenna that transmits data that is translated into a radio signal.
The computer then receives this radio transmission and converts the radio wave back into data. It then requests more data back to the base station which uses a physical connection (Ethernet) to find the information on a remote server.

13. Mobile Networks
Mobile networks use a microwave form of electromagnetic radiation. Your voice is transmitted as a sine wave to a transmitter.
The signal is then sent to a mobile tower which then forwards the signal to another mobile. The same process is used to receive the voice back from the other end.

14. Radars Radars are used to identify objects, for use in boats etc.
They are also used to identify the speed of an object.
They can also be used to map out an area.
They accomplish this by sending out a radio wave, and waiting for the signal to be bounced back from the object. This is especially useful if it’s impossible to visually identify the speed/distance of the object.

15. Satellite Navigation
Satellite Navigation uses a GPS (Global Positioning System) to find the co-ordinates of your longitude and latitude using the the reference of three separate satellites.
The navigation system then cross references these co-ordinates with a onboard saved map to demonstrate your location visually.
It then uses a algorithm to find the best route to a destination you set.

16. Conclusion
There are many different forms of radio communication in use today. Many of these have proved vital in the progression and safety of the human race. • Some of these forms of communication are not traditionally associated with radio waves, but that is where they hold the basis of their function.