Harmonics

What is a harmonic?

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

if f = 125 MHz, the harmonics would be:

1st harmonic = 1f = 125 MHz

2nd harmonic = 2f = 250 MHz

3rd harmonic = 3f = 375 MHz

4th harmonic = 4f = 500 MHz

..... etc.

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

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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.