EW Academy · Contents · Chapter 3 · Nederlandse versie
Chapter 3: The electromagnetic spectrum
What electromagnetic waves are, their properties (wavelength, frequency, amplitude, phase), interference, the structure of the EMS and the basics of AM and FM.
3.1Electromagnetic waves
An electromagnetic wave (EM wave) is an oscillating electric field and an oscillating magnetic field that sustain each other and travel through space together. The electric field (E) and the magnetic field (B) are perpendicular to each…
Read §3.1 →3.2Properties of the electromagnetic wave
To recognise, describe and influence signals, you have to be able to characterise an EM wave. Four characteristics define a wave completely: frequency (or wavelength), amplitude , phase and polarisation . This section covers the first…
Read §3.2 →3.3The electromagnetic spectrum
The electromagnetic spectrum is the complete range of EM radiation, ordered from low to high frequency (and therefore from long to short wavelength). The boundaries between the regions are conventions, not hard physical transitions:
Read §3.3 →3.4Amplitude modulation and frequency modulation
To carry speech or data you vary something about the radio wave. With AM the strength of the wave varies, with FM its frequency. That makes FM much less sensitive to noise and interference.
Read §3.4 →3.5Conclusion
The key points of this chapter:
Read §3.5 →