Harmonics

Related wiki pages: Antennas, Propagation, Interference, Gain, SWR, Frequency Wavelength and Period

What is an harmonic?
An harmonic of a particular frequency (the fundamental frequency f) is another frequency that is an integer multiple of the first one. For example:

if f = 125MHz, the harmonics would be: 2f = 250MHz, 3f = 375MHz, 4f = 500MHz ..... etc

In the diagram below it can be seen that harmonics share common nodes.



Mathematically, the basic wave equation is:

$$ \mathit{v}=\mathit{f}\times \lambda $$

v is the velocity of the wave in metres per second - a constant close to the speed of light for radio waves in the atmosphere.

f is the frequency of the wave - how many cycles pass a fixed point per second

$$ \lambda $$ is the wavelength of the wave in metres - the distance between two peaks of the wave.

So, as the frequency increases, the wavelength decreases - a doubling of frequency causes a halving of wavelength etc.