1. Frequency

Definitions

• Frequency: The number of complete cycles that occur in each second
• Cycles are complete vibrations
• Wavelength is the length of each cycle

Units of measurement

• Hertz or Hz: cycles per second

Working with big numbers

Symbol	Name	Multiplication by	Amount	Power of 10
p	pico	0.000000000001	trillionth	-12
n	nano	0.000000001	billionth	-9
µ	micro	0.000001	millionth	-6
m	milli	0.001	thousandth	-3
K	kilo	1,000	thousand	3
M	mega	1,000,000	million	6
G	giga	1,000,000,000	billion	9
T	tera	1,000,000,000,000	trillion	12

Formula

• v = fλ where v is speed of light, f is frequency, λ is wavelength

Examples of frequencies

• public electricity supply: 50 Hz
• BBC transmission on FM (SG): 88.9 MHz
• Middle A on a piano: 440 Hz
• heart beats: 1 Hz
• spin dryer rotation: 16.6 Hz
• Human ear can hear up to 20 kHz

Notes

Frequency Spectrum

• Sound → Radio → Heat → Infra-red → Light → Ultra-violet → X-Ray (↑ frequency)
• Useful radio frequencies range from about 10 KHz to beyond 30 GHz
• Each part of the radio frequency spectrum has its own characteristics
• Only a small range of frequencies are suitable for certain popular activities
• Frequencies that are capable of traveling around the world are subjected to world wide controls
• approximate lower band edge frequency of each amateur band up to 3400 MHz
• Most radio amateurs refer to their bands in terms of wavelength, e.g. 20 meters

Other services using the radio spectrum: Shipping, Aircraft, Military, Citizens Band, Navigation, Public Services, Telecommunications, Weather Services, Remote Control, Security Systems and Satellites

	Wavelength range	Frequency range	Name	Amateur bands	Uses
1	10 km – 1 km	30 kHz – 300 kHz	LF (Low frequency)	None	Low
2	1 km – 100 m	300 kHz – 3 MHz	MF (Medium frequency)	1.8 MHz (160m)	Amateur Radio AM Broadcasting (not as common now)
3	` 100 m – 10 m`	3 MHz - 30 MHz	HF (High frequency)	3.5 MHz (80m) 7 MHz (40m) 10 MHz (30m) 14 MHz (20m) 18 MHz 21 MHz 24 MHz 28 MHz	Broadcast short wave bands Amateur Radio
4	10 m - 1 m	30 MHz - 300 MHz	VHF (Very high frequency)	144 MHz	Broadcast (FM, TV) Amateur Radio
5	1 m - 100 mm	300 MHz - 3 GHz	UHF (Ultra high frequency)	430 MHz(70cm)	Amateur Radio Microwave ovens television, WiFi
6	<100mm	above 3000 MHz	SHF (Super high frequency)		Radio astronomy microwave devices WiFi radar

Challenges in hearing a station due to:

• frequency
• time of day
• season
• sunspot
• noise/inteference

Public broadcasting services transmits the same program several times on a selection of frequencies in order to obtain world wide coverage