Electromagnetic (radio) waves

What was discovered

With a spark oscillator and a resonator, Hertz generates and detects electromagnetic waves, measures their speed and demonstrates that they reflect, refract and polarise like light. It confirms Maxwell's theory and opens the invisible spectrum.

Hertz declared that his waves had 'no use whatsoever'.

What it led to

• Radiotelegraphy (Marconi, 1895) and telecommunications
• Radar, television and mobile telephony
• Radio astronomy
• Photoelectric effect (observed by Hertz in 1887)

Built on

• Maxwell's equations1861-1865
• Induction coil
• Lodge's and FitzGerald's experiments

Made possible

• Millimetre waves and galena detector (J. C. Bose)1895-1901
• Wireless telegraphy (radio)1895–1901
• Yagi-Uda antenna1926
• Radar1935
• Dipole antenna

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