Radio wavesFrequency to wavelength conversionPolarizationRadio spectrumHow radio signals travelLayers above the earthGround waveSkywavesDistances and the angle of radiationMultiple reflectionsChordal hopCritical frequencyMUFLUFSkip zoneState of the ionospherePropagation predictionVHF and aboveTropo-scatterSporadic EMeteor scatterFrequencies above 3 GHz