Marconi: Between Earth and Air
Tuned
The radio waves created by spark gaps were messy, and could be detected across many frequencies. So early radio transmissions would interfere with each other.
The solution was tuned transmission.
Only radio waves of a particular frequency were transmitted. Receivers could then be tuned to that frequency, to detect only those signals.
This is the tuned transmitter that Marconi
perfected in 1899 during experiments
at the Haven Hotel in Poole.
Tuned Transmitter
Guglielmo Marconi · English · 1899
Inventory â„– 98396
Developing this technology was an important breakthrough for Marconi.
It formed the basis of the memorably numbered 7777 Patent in 1900.
Marconi's handwritten notes and sketches for the specifications for the '7777' Patent, The Bodleian Libraries, University of Oxford
Marconi's handwritten notes and sketches for the specifications for the '7777' Patent, The Bodleian Libraries, University of Oxford
It works by creating a spark in the gap between the brass spheres.
Although the electrical oscillations generated by the spark are messy, only energy at a specific frequency is transferred to the aerial for transmission.
Of the objects I looked at, this was the most evocative.
The yellowed glass with handwritten cataloguing numbers, and the discoloured wires, made inflexible with age, allude to its historical importance.
But it's the roughness of the wood, the twisted metal wires and the rawness of it that evoke an object made by a human hand, in the spirit of experimentation, improvisation and hopefulness.
It was only once tuned transmission was possible that the new radio technology could start to be used for wide-scale communication.