Waves and the spectrum

The physics every radio is built on.

Electromagnetic wavesElectric and magnetic fields travelling together at the speed of light.Frequency and wavelengthTwo ways to describe the same wave, tied together by the speed of light.The radio spectrumLF to microwaves: where the bands sit and what each is good for.PolarizationThe orientation of a wave's electric field, and why antennas must match it.DecibelsThe logarithmic scale for gain, loss and signal strength.Noise and signal-to-noise ratioWhere noise comes from and why SNR decides what you can copy.